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Filed Pursuant to Rule 424(b)(5)
Registration No. 333-199179

The information contained in this preliminary prospectus supplement is not complete and may be changed. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell these securities, and we are not soliciting an offer to buy these securities, in any jurisdiction where the offer or sale is not permitted.

PROSPECTUS SUPPLEMENT (Subject to Completion)                                                                                                              Issued October 6, 2014
(To Prospectus dated October 6, 2014)

22,500,000 Shares

LOGO

DYNEGY INC.

COMMON STOCK



We are offering 22,500,000 shares of our common stock.

Our common stock is listed on the New York Stock Exchange under the symbol "DYN." On October 3, 2014, the reported last sale price of our common stock on the New York Stock Exchange was $31.27 per share.



This offering is part of the financing for the Acquisitions (as defined herein). Concurrently with this offering, we are offering, by means of a separate prospectus supplement, 4,000,000 shares of our Series A Mandatory Convertible Preferred Stock (the "Mandatory Convertible Preferred Stock Offering"). In addition, subsequent to this offering and the Mandatory Convertible Preferred Stock Offering, we expect to obtain debt financing (the "Debt Financing"). We expect that this offering, the Mandatory Convertible Preferred Stock Offering, the Debt Financing and cash on hand will provide the funds necessary to complete the Acquisitions. The completion of this offering is not contingent on the completion of the Mandatory Convertible Preferred Stock Offering or the Debt Financing, and neither the Mandatory Convertible Preferred Stock Offering nor the Debt Financing is contingent on the completion of this offering. In addition, none of this offering, the Mandatory Convertible Preferred Stock Offering or the Debt Financing is or will be contingent on the consummation of the Acquisitions. This prospectus supplement is not an offer to sell or a solicitation of an offer to buy any securities being offered in the Mandatory Convertible Preferred Stock Offering or the Debt Financing.



Investing in our common stock involves risks. See "Risk Factors" beginning on page S-23 of this prospectus supplement.



PRICE $              PER SHARE



 
 
Price to
Public
 
Underwriting
Discounts and
Commissions
 
Proceeds to
Dynegy Inc.,
Before Expenses

Per Share

  $                 $                 $              

Total

  $                 $                 $              



Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities, or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The underwriters may also purchase up to an additional 3,375,000 shares of our common stock at the public offering price, less the underwriting discounts and commissions, within 30 days of the date of this prospectus supplement. If the underwriters exercise this option in full, the total price to the public would be $              , the total underwriting discounts and commissions would be $              and the total proceeds to us would be $              .

The underwriters expect to deliver the common stock to purchasers on or about                           , 2014.



Joint Book-Running Managers

MORGAN STANLEY   BARCLAYS

 

CREDIT SUISSE   RBC CAPITAL MARKETS   UBS INVESTMENT BANK



Co-Managers

BNP PARIBAS   BOFA MERRILL LYNCH   CREDIT AGRICOLE CIB

DEUTSCHE BANK SECURITIES

 

J.P. MORGAN

 

MUFG

SUNTRUST ROBINSON HUMPHREY

                           , 2014


Table of Contents


TABLE OF CONTENTS

Prospectus Supplement

 
  Page  

Glossary of Terms and Abbreviations

    S-i  

About This Prospectus Supplement

    S-iii  

Industry and Market Data

    S-iii  

Summary

    S-1  

Risk Factors

    S-23  

Special Note on Forward-Looking Statements

    S-38  

Use of Proceeds

    S-40  

Capitalization

    S-42  

Price Range of our Common Stock

    S-44  

Dividend Policy

    S-44  

The Transactions

    S-45  

Ratio of Earnings to Fixed Charges

    S-49  

Overview of Financial Condition, Liquidity and Capital Resources

    S-50  

Description of the Operations of the Duke Midwest Assets and the ECP Assets

    S-51  

Industry Overview

    S-54  

Description of Common Stock

    S-60  

Description of Certain Indebtedness and Other Obligations

    S-63  

Material U.S Federal Tax Considerations

    S-66  

Underwriting

    S-70  

Where You Can Find More Information

    S-76  

Incorporation by Reference

    S-76  

Legal Matters

    S-77  

Experts

    S-77  

Prospectus

 
  Page  

About This Prospectus

    1  

Risk Factors

    2  

Special Note on Forward-Looking Statements

    2  

Where You Can Find More Information

    2  

Incorporation by Reference

    3  

Dynegy Inc. 

    4  

Use of Proceeds

    5  

Ratio of Earnings to Fixed Charges

    6  

Description of Securities

    7  

Plan of Distribution

    8  

Validity of Securities

    8  

Experts

    8  

Table of Contents


GLOSSARY OF TERMS AND ABBREVIATIONS

        Unless the context indicates otherwise, throughout this prospectus supplement, the terms "Dynegy," "the Company," "we," "us," "our," and "ours" refer to Dynegy Inc. and its direct and indirect subsidiaries. As used in this prospectus supplement, the terms contained herein have the meanings set forth below.

        Acquisitions refers to the Duke Midwest Acquisition and the ERC and Brayton Acquisitions.

        Acquisition Termination Event means either (1) one or both of the Duke Midwest Purchase Agreement or ERC Purchase Agreements are terminated or (2) we determine in our reasonable judgment that one of the Acquisitions will not occur.

        AER Acquisition refers to the transaction completed on December 2, 2013, pursuant to the agreement between Ameren and Illinois Power Holdings, LLC, an indirect wholly-owned subsidiary of Dynegy ("IPH"), pursuant to which we acquired AER and its subsidiaries, Ameren Energy Generating Company ("Genco"), Ameren Energy Fuels and Services Company, New AERG, LLC (successor to Ameren Energy Resources Generating Company) ("AERG") and Ameren Energy Marketing Company ("AEM") from Ameren (such entities, collectively, the "AER Entities").

        Brayton refers to Brayton Point Holdings, LLC.

        Brayton Point Energy refers to Brayton Point Energy, LLC, a subsidiary of Brayton.

        Combined Company refers to Dynegy and its subsidiaries after completion of the Transactions, including the Acquisitions.

        Debt Financing refers to the proposed incurrence of debt to finance a portion of the purchase price for the Acquisitions.

        Duke refers to Duke Energy Corporation.

        Duke Energy Commercial refers to Duke Energy Commercial Asset Management, LLC.

        Duke Energy Retail Sales refers to Duke Energy Retail Sales, LLC, Duke's retail energy business.

        Duke Midwest Acquisition refers to the proposed acquisition of membership interests in certain Midwest assets from certain subsidiaries of Duke announced by us through our Current Report on Form 8-K filed on August 26, 2014. See "Summary—The Duke Midwest Acquisition."

        Duke Midwest Assets refers to Duke Energy Commercial's interests in 11 generation facilities and Duke Energy Retail Sales, which we will acquire in the Duke Midwest Acquisition.

        Duke Midwest Purchase Agreement refers to the Purchase and Sale Agreement, dated as of August 21, 2014, pursuant to which we will acquire the Duke Midwest Assets.

        Duke Ohio refers to Duke Energy Ohio, Inc.

        ECP refers to Energy Capital Partners, a private equity firm.

        ECP Assets refers to 10 generation facilities which we will acquire in the ERC and Brayton Acquisitions.

        ERC refers to EquiPower Resources Corp.

        ERC and Brayton Acquisitions refers to the proposed acquisition of equity interests in ERC and Brayton announced by us through our Current Report on Form 8-K filed on August 26, 2014. See "Summary—The ERC and Brayton Acquisitions."

        ERC Purchase Agreements refers to two agreements, each dated as of August 21, 2014, pursuant to which we will acquire the ECP Assets. See "Summary—The Transactions."

S-i


Table of Contents

        Financing Transactions refers to this offering, the Mandatory Convertible Preferred Stock Offering and the Debt Financing, in each case only to the extent they are completed.

        Homefield Energy refers to IPM's retail business which was acquired in the AER Acquisition.

        Mandatory Convertible Preferred Stock Offering refers to the concurrent preferred stock offering to finance the Acquisitions.

        Target Companies refers to Duke Energy Commercial, Duke Energy Retail Sales, ERC, and Brayton.

        Transactions refers to the Acquisitions and the Financing Transactions.

        Further, as used in this prospectus supplement, the abbreviations contained herein have the meanings set forth below.

AER   New Ameren Energy Resources, LLC
ATSI   American Transmission Systems, Inc.
CAISO   The California Independent System Operator
CFTC   U.S. Commodity Futures Trading Commission
ComEd   Commonwealth Edison
CPUC   California Public Utility Commission
DH   Dynegy Holdings, LLC (formerly known as Dynegy Holdings Inc.)
DMG   Dynegy Midwest Generation, LLC
DMT   Dynegy Marketing and Trade, LLC
DYPM   Dynegy Power Marketing Inc.
EEI   Electric Energy, Inc.
EPA   Environmental Protection Agency
FCA   Forward Capacity Auction
FERC   Federal Energy Regulatory Commission
GHG   Greenhouse Gas
HSR   Hart-Scott Rodino Act of 1976
IPM   Illinois Power Marketing Company (formerly known as Ameren Energy Marketing Company)
ISO   Independent System Operator
ISO-NE   Independent System Operator New England
KW   Kilowatt
KWh   Kilowatt Hour
LGE   Louisville Gas and Electric Company
LMP   Locational Marginal Pricing
MISO   Midcontinent Independent System Operator, Inc.
MMBTu   One Million British Thermal Units
MRTU   Market Redesign and Technology Update
MW   Megawatts
MWh   Megawatt Hour
NERC   North American Electric Reliability Corporation
NYISO   New York Independent System Operator
NYSE   New York Stock Exchange
OTC   Over-the-counter
PJM   PJM Interconnection, LLC
PRB   Powder River Basin
PRIDE   Producing Results through Innovation by Dynegy Employees
RMR   Reliability Must Run
RPM   Reliability Pricing Model
RTO   Regional Transmission Organization
SEC   U.S. Securities and Exchange Commission
SO2   Sulfur Dioxide
TVA   Tennessee Valley Authority
TWh   Terawatt Hour

S-ii


Table of Contents

ABOUT THIS PROSPECTUS SUPPLEMENT

        This prospectus supplement and the accompanying prospectus are part of a registration statement that we filed with the SEC using a shelf registration process.

        This document is in two parts. The first part is this prospectus supplement, which describes the specific terms of this offering and certain other matters relating to Dynegy, the Target Companies and the Combined Company, and also adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference into this prospectus supplement and the accompanying prospectus. The second part, the accompanying prospectus, gives more general information, some of which does not apply to this offering.

        Both this prospectus supplement and the accompanying prospectus include or incorporate by reference important information about us, our common stock and other information you should know before investing. You should read both this prospectus supplement and the accompanying prospectus, as well as additional information incorporated herein and therein, as set forth under "Incorporation by Reference," before investing in our common stock.

        Neither we nor the underwriters have authorized anyone to provide you with any information other than that contained or incorporated by reference in this prospectus supplement and the accompanying prospectus. We and the underwriters take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. Neither we nor the underwriters are making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information contained in this prospectus supplement and the accompanying prospectus and the documents incorporated by reference is accurate only as of their respective dates. Our and the Target Companies' business, financial condition, results of operations and prospects may have changed since those dates.

        Unless we specifically state otherwise, the information in this prospectus supplement and the accompanying prospectus, including the documents incorporated by reference herein and therein, assumes the underwriters for this offering of common stock do not exercise their option to purchase additional shares of common stock. In addition, unless we specifically state otherwise, the information in this prospectus supplement and the accompanying prospectus, including the documents incorporated by reference herein and therein, does not give effect to the Acquisitions, the Mandatory Convertible Preferred Stock Offering or the Debt Financing.



INDUSTRY AND MARKET DATA

        We have obtained some industry and market share data from third-party sources that we believe are reliable. In many cases, however, we have made statements in this prospectus supplement and in the documents incorporated by reference into this prospectus supplement regarding our industry and our position in the industry based on estimates made from our experience in the industry and our own investigation of market conditions. We believe these estimates to be accurate as of the date of this prospectus supplement or the date of the document incorporated by reference, as applicable. However, this information may prove to be inaccurate because of the method by which we obtained some of the data for our estimates or because this information cannot always be verified with complete certainty due to the limits on the availability and reliability of raw data, the voluntary nature of the data gathering process and other limitations and uncertainties. As a result, you should be aware that the industry and market data included in this prospectus supplement and in the documents incorporated by reference into this prospectus supplement, and estimates and beliefs based on that data, may not be reliable. We cannot, and the underwriters cannot, guarantee the accuracy or completeness of any such information.

S-iii


Table of Contents



SUMMARY

        This summary does not contain all the information that you should consider before investing in our common stock. You should read this entire prospectus supplement and the accompanying prospectus, including the documents incorporated by reference herein and therein, before making an investment decision.

Our Company

        Our primary business is the production and sale of electric energy, capacity and ancillary services. We operate a portfolio of generation assets that is diversified in terms of dispatch profile, fuel type and geography. Our Coal and IPH segments are fleets of baseload coal facilities located in Illinois that dispatch around the clock throughout the year. Our Gas segment operates both intermediate and peaking natural gas facilities, located in the Midwest, the Northeast and California. In addition to generating power, our generating facilities also receive capacity revenues through structured markets or bilateral tolling agreements, as local utilities and ISOs seek to ensure sufficient generation capacity is available to meet future market demands.

        We sell electric energy, capacity and ancillary services on a wholesale basis from our power generation facilities. In connection with the acquisition of AER and its subsidiaries on December 2, 2013, we began serving residential, municipal, commercial and industrial consumers through our Homefield Energy retail business in Illinois. Wholesale electricity customers will, for reliability reasons and to meet regulatory requirements, contract for rights to capacity from generating units. Ancillary services are the products of a power generation facility that support the transmission grid operation, follow real-time changes in load and provide emergency reserves for major changes to the balance of generation and load. Retail electricity customers purchase energy and these related services in the deregulated retail energy market. We sell these products individually or in combination to our customers for various lengths of time ranging from hourly to multi-year transactions.

        We do business with a wide range of customers, including: regional transmission organizations and ISOs, integrated utilities, municipalities, electric cooperatives, transmission and distribution utilities, power marketers, financial participants such as banks and hedge funds, and residential, commercial and industrial end-users. Some of our customers, such as municipalities or integrated utilities, purchase our products for resale in order to serve their retail, commercial and industrial customers. Other customers, such as some power marketers, may buy from us to serve their own wholesale or retail customers or as a hedge against power sales they have made.

Recent Developments

The Acquisitions

        In August 2014, we entered into an agreement with Duke to purchase certain of its facilities located in the Midwest and its retail energy business and we entered into an agreement with ECP to purchase ERC and Brayton. The Acquisitions will increase our generation capacity by approximately 12,500 MW to nearly 26,000 MW. We anticipate that the Duke Midwest Acquisition and ERC and Brayton Acquisitions will each close by the end of the first quarter of 2015. However, we cannot assure you that the Acquisitions will be consummated or, if consummated, that they will be consummated at the price, within the time period or on the terms and with the anticipated benefits contemplated by this prospectus supplement. The closing of one Acquisition is not contingent upon the closing of the other Acquisition and this offering is not contingent on either or both of the Acquisitions occurring on a timely basis or at all. See "Risk Factors—Risks Relating to Our Proposed Acquisitions" and "The Transactions," each included in this prospectus supplement.

 

S-1


Table of Contents

The Duke Midwest Acquisition

        We will acquire the Duke Midwest Assets for a purchase price of $2.8 billion in cash, subject to certain adjustments. The Duke Midwest Acquisition is subject to receipt of FERC approval, HSR approval and other customary closing conditions. The Duke Midwest Assets are comprised of (1) 100% ownership interests in five natural gas-fired power facilities located in Ohio, Pennsylvania and Illinois, (2) 100% ownership interest in an oil-fired power facility located in Ohio, (3) partial interests in five coal-fired power facilities located in Ohio and (4) Duke's retail energy business. The facilities operate in the PJM wholesale market, have a diversified fuel mix with baseload coal-fired units, as well as combined cycle and peaking natural gas-fired units, and have an aggregate net generating capacity of approximately 6,200 MW. We will operate two of the five coal-fired plants for which we will obtain partial ownership interests, the Miami Fort and Zimmer facilities.

        Duke Energy Retail Sales serves retail electric and gas customers in Ohio with energy and energy services at competitive rates. Duke Energy Retail Sales serves approximately 25% of switched load within Duke Ohio's service territory, which is the largest share of opt-in mass market customers in that territory, and provides approximately 7 TWh of customer load primarily in Ohio.

        The following table sets forth certain information with respect to the generating facilities:

Facility
  Net
Generating
Capacity
(MW)(1)
  Primary
Fuel
Type
  Dispatch
Type
  Location   Region   Interest
to be
Acquired
 

Dicks Creek

    153   Gas   Peaking   Middleton, OH   PJM     100.0 %

Fayette

    649   Gas   Intermediate   Masontown, PA   PJM     100.0 %

Hanging Rock

    1,296   Gas   Intermediate   Ironton, OH   PJM     100.0 %

Lee

    712   Gas   Intermediate   Dixon, IL   PJM     100.0 %

Washington

    648   Gas   Intermediate   Beverly, OH   PJM     100.0 %

Killen

    204   Coal   Baseload   Wrightsville, OH   PJM     33.0 %

Stuart

    904   Coal   Baseload   Aberdeen, OH   PJM     39.0 %

Conesville

    312   Coal   Baseload   Conesville, OH   PJM     40.0 %

Zimmer

    628   Coal   Baseload   Moscow, OH   PJM     46.5 %

Miami Fort (Units 7 and 8)

    653   Coal   Baseload   North Bend, OH   PJM     64.0 %

Miami Fort (CT)

    80   Oil   Peaking   North Bend, OH   PJM     100.0 %
                             

Total

    6,239                        
                             
                             

(1)
Unit capabilities are based on winter capacity.

The ERC and Brayton Acquisitions

        We will acquire ERC and Brayton for approximately $3.25 billion in cash and $200 million of our common stock, subject to certain conditions and adjustments. The ERC and Brayton Acquisitions are subject to receipt of FERC approval, HSR approval and other customary closing conditions. ERC owns (1) 100% interests in five combined cycle gas turbine facilities in Connecticut, Massachusetts and Pennsylvania, (2) 100% interests in two gas and oil fired peaking facilities in Ohio, (3) 100% interests in one coal-fired facility in Illinois and (4) a 49.5% interest in one natural gas-fired peaking facility in Illinois. Brayton owns a 100% interest in the Brayton Point coal facility in Somerset, MA, which is scheduled to be retired in June 2017. The ECP Assets consist primarily of highly efficient and clean-burning natural gas-fired facilities and have an aggregate net generating capacity of approximately 6,300 MW.

 

S-2


Table of Contents

        The following table sets forth certain information with respect to the generating facilities:

Facility
  Net
Generating
Capacity
(MW)(1)
  Primary
Fuel Type
  Dispatch
Type
  Location   Region   Interest
to be
Acquired
 

Brayton Point(2)

    1,493   Coal   Baseload   Somerset, MA   ISO-NE     100.0 %

Kincaid(3)

    1,108   Coal   Baseload   Kincaid, IL   PJM     100.0 %

Milford

    579   Gas   Intermediate   Milford, CT   ISO-NE     100.0 %

Lake Road

    856   Gas   Intermediate   Killingly, CT   ISO-NE     100.0 %

Dighton

    187   Gas   Intermediate   Dighton, MA   ISO-NE     100.0 %

MASSPOWER

    280   Gas   Intermediate   Indian Orchard, MA   ISO-NE     100.0 %

Liberty

    600   Gas   Intermediate   Eddystone, PA   PJM     100.0 %

Richland

    447   Gas   Peaking   Defiance, OH   PJM     100.0 %

Stryker

    19   Oil   Peaking   Stryker, OH   PJM     100.0 %

Elwood(4)

    780   Gas   Peaking   Elwood, IL   PJM     49.5 %
                             

Total

    6,349                        
                             
                             

(1)
Unit capabilities are based on winter capacity.

(2)
Brayton Point is scheduled to be retired from service in June 2017.

(3)
Kincaid is physically located within the MISO market, but is interconnected to the PJM market and sells both energy and capacity in the PJM market only.

(4)
In addition, ERC expects to acquire an additional 0.5% interest in Elwood from Dominion Energy, Inc. in the fourth quarter of 2014, which additional interest we would receive in connection with the ERC and Brayton Acquisitions.

Combined Company Power Generation Portfolio

        The following table illustrates the Combined Company operating generation facilities:

Facility
  Total Net Generating
Capacity (MW)(1)
  Primary
Fuel Type
  Dispatch Type   Location   Region

Dynegy

                     

Baldwin

    1,800   Coal   Baseload   Baldwin, IL   MISO

Havana(2)

    441   Coal   Baseload   Havana, IL   MISO

Hennepin

    293   Coal   Baseload   Hennepin, IL   MISO

Wood River(3)

    446   Coal   Baseload   Alton, IL   MISO
                     

Total Coal Segment

    2,980                
                     

Coffeen

    915   Coal   Baseload   Montgomery County, IL   MISO

Joppa/EEI(4)

    802   Coal   Baseload   Joppa, IL   MISO

Newton

    1,225   Coal   Baseload   Jasper County, IL   MISO

Duck Creek

    425   Coal   Baseload   Canton, IL   MISO

E.D. Edwards

    695   Coal   Baseload   Bartonville, IL   MISO
                     

Total IPH Segment

    4,062                
                     

 

S-3


Table of Contents

Facility
  Total Net Generating
Capacity (MW)(1)
  Primary
Fuel Type
  Dispatch Type   Location   Region

Moss Landing Units 1-2

    1,020   Gas   Intermediate   Monterey County, CA   CAISO

Units 6-7

    1,509   Gas   Peaking   Monterey County, CA   CAISO

Kendall

    1,200   Gas   Intermediate   Minooka, IL   PJM

Ontelaunee

    580   Gas   Intermediate   Ontelaunee Township, PA   PJM

Oakland

    165   Oil   Peaking   Oakland, CA   CAISO

Casco Bay

    540   Gas   Intermediate   Veazie, ME   ISO-NE

Independence

    1,064   Gas   Intermediate   Scriba, NY   NYISO
                     

Total Gas Segment

    6,078                
                     

Total Fleet

    13,120                
                     

Duke Midwest Assets

                     

Stuart

    904   Coal   Baseload   Aberdeen, OH   PJM

Miami Fort

    653   Coal   Baseload   North Bend, OH   PJM

Zimmer

    628   Coal   Baseload   Moscow, OH   PJM

Conesville

    312   Coal   Baseload   Conesville, OH   PJM

Killen

    204   Coal   Baseload   Wrightsville, OH   PJM
                     

Total Coal

    2,701                
                     

Hanging Rock

    1,296   Gas   Intermediate   Ironton, OH   PJM

Washington

    648   Gas   Intermediate   Beverly, OH   PJM

Fayette

    649   Gas   Intermediate   Masontown, PA   PJM

Lee

    712   Gas   Intermediate   Dixon, IL   PJM

Dicks Creek

    153   Gas   Peaking   Middleton, OH   PJM

Miami Fort (CT)

    80   Oil   Peaking   North Bend, OH   PJM
                     

Total Gas

    3,538                
                     

Total Fleet

    6,239                
                     

ERC and Brayton

                     

Brayton Point(5)

    1,493   Coal   Baseload   Somerset, MA   ISO-NE

Kincaid(6)

    1,108   Coal   Baseload   Kincaid, IL   PJM
                     

Total Coal

    2,601                
                     

Milford

    579   Gas   Intermediate   Milford, CT   ISO-NE

Lake Road

    856   Gas   Intermediate   Killingly, CT   ISO-NE

Dighton

    187   Gas   Intermediate   Dighton, MA   ISO-NE

MASSPOWER

    280   Gas   Intermediate   Indian Orchard, MA   ISO-NE

Liberty

    600   Gas   Intermediate   Eddystone, PA   PJM

Elwood(7)

    780   Gas   Peaking   Elwood, IL   PJM

Richland

    447   Gas   Peaking   Defiance, OH   PJM

Stryker

    19   Oil   Peaking   Stryker, OH   PJM
                     

Total Gas

    3,748                
                     

Total Fleet

    6,349                
                     

Total

    25,708                
                     
                     

(1)
Unit capabilities are based on winter capacity.

 

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Table of Contents

(2)
Represents Unit 6 generating capacity. Units 1-5, with a combined net generating capacity of 228 MW, are retired and out of operation.

(3)
Represents Units 4 and 5 generating capacity. Units 1-3, with a combined net generating capacity of 119 MW, are retired and out of operation.

(4)
We indirectly own an 80% interest in this facility. Total output capacity of this facility is 1,002 MW. Additionally, Joppa has 235 MW of natural gas-fired capacity which is currently not operating and therefore excluded from the table above.

(5)
Brayton Point is scheduled to be retired in June 2017.

(6)
Kincaid is physically located within the MISO market, but is interconnected to the PJM market and sells both energy and capacity in the PJM market only.

(7)
In addition, ERC expects to acquire an additional 0.5% interest in Elwood from Dominion Energy, Inc. in the fourth quarter of 2014, which additional interest we would receive in connection with the ERC and Brayton Acquisitions.

Strategic Evaluation of California Assets

        Recently, we began a strategic evaluation of our California assets including Moss Landing, Oakland and Morro Bay. We will continue operating and investing in these assets under normal course during this evaluation.

Power Prices and Spark Spreads

        Our financial results are significantly impacted by fuel and commodity prices. Other factors impacting our financial results include market structure and prices for electric energy, capacity and ancillary services, including pricing at our plant locations relative to pricing at their respective trading hubs, the volatility of fuel and electricity prices, transportation and transmission logistics, weather conditions and plant performance.

        The relationship between electricity prices and prices for natural gas and coal, commonly referred to as the "spark spread" and "dark spread," respectively, impacts the margin we earn on the electricity we generate. In particular, we benefit from rising commodity prices. For example, an increase in natural gas prices of $1/MMBTu (net of heat rate contraction) can have a positive material impact on our earnings, as can rising power prices and spark spreads.

        Since the announcement of the Acquisitions, power prices and spark spreads have increased in 2015 and 2016, by approximately 8% to 31% in ISO-NE, by approximately 4% to 11% in PJM and by approximately 3% to 5% in MISO, although there can be no assurances as to how long these price increases may be maintained, if at all. In the six months ended June 30, 2014, and for the year ended December 31, 2013, we, the Duke Midwest Assets and the ECP Assets generated 6.7 million MWh and 11.3 million MWh in ISO-NE, 23.0 million MWh and 45.0 million MWh in PJM and 22.1 million MWh and 45.7 million MWh in MISO, in each case, respectively.

Financing Transactions

        In addition to this offering, we expect to obtain additional financing for the Acquisitions as described below. We cannot assure you that we will complete any of the Financing Transactions on the terms contemplated by this prospectus supplement or at all.

 

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Mandatory Convertible Preferred Stock Offering

        Concurrently with this offering, we are offering, by means of a separate prospectus supplement, 4,000,000 shares of our Mandatory Convertible Preferred Stock, plus up to 600,000 additional shares of Mandatory Convertible Preferred Stock that the underwriters of the Mandatory Convertible Preferred Stock Offering have the option to purchase from us, in each case, at a public offering price of $100.00 per share. For a description of certain of the expected terms of the Mandatory Convertible Preferred Stock, see "Description of Certain Indebtedness and Other Obligations—Dynegy's Mandatory Convertible Preferred Stock". This prospectus supplement is not an offer to sell or a solicitation of an offer to buy the shares of the Mandatory Convertible Preferred Stock.

Debt Financing

        Subsequent to this offering and the Mandatory Convertible Preferred Stock Offering, we expect to obtain approximately $5.1 billion of debt financing in connection with the financing of the Acquisitions. See "The Transactions" and "Description of Indebtedness and Other Obligations," included in this prospectus supplement. This prospectus supplement is not an offer to sell or a solicitation of an offer to buy any debt being sold or placed in the Debt Financing.

        The completion of this offering is not contingent on the completion of the Debt Financing, and the Debt Financing is not contingent on the completion of this offering or the consummation of either or both of the Acquisitions. Accordingly, even if one or both of the Acquisitions or Financing Transactions are not completed, the common stock sold in this offering will remain outstanding.

        We will be required to redeem all of the debt borrowed if neither of the Acquisitions is consummated. If one or the other of the Acquisitions is not consummated, we will be required to redeem the debt borrowed in connection with such contemplated but unconsummated Acquisition.

        In the event we are unable to obtain such debt financing prior to the closing of the Acquisitions, we have obtained committed financing in the form of senior unsecured bridge loans as described below.

        In connection with entering into each of the Duke Midwest Purchase Agreement and the ERC Purchase Agreements, we obtained $2.8 billion and $3.55 billion, respectively, bridge loan commitments to ensure financing for the Acquisitions. Although we do not expect to make any borrowings under the bridge loan commitments, there can be no assurance that such borrowings will not be made. In that regard, we may be required to borrow under the bridge loan commitments if any of the other Financing Transactions is not completed or generates significantly less net proceeds than contemplated by this prospectus supplement. See "Description of Certain Indebtedness and Other Obligations," included in this prospectus supplement.

Strategic Rationale for the Acquisitions

        We believe that the Acquisitions will create significant value for stockholders and offer numerous strategic benefits, including:

 

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        We believe that these strategic benefits significantly enhance our competitive profile as a leading U.S. independent power producer and should drive increased profitability while simultaneously reducing the risk profile of the company. We believe the diversity of our portfolio should reduce our operating risk profile and reliance on any single market because it provides a balanced mix of both intrinsic and extrinsic value throughout different market cycles, weather patterns and commodity environments. The breadth of our fleet will also mitigate asset concentration risk by reducing the reliance on any single asset for our overall financial performance. Furthermore, we believe our scale and employment of best practices improve our business development opportunities through well-established industry relationships, and a deep understanding of regional power market dynamics.

Competitive Strengths

        We will have the following competitive strengths following the closing of the Acquisitions:

        Strong Portfolio Balance.    The Combined Company will have a well-diversified portfolio of assets with approximately 51%, 48% and 1% of total generation being fueled by natural gas, coal and oil, respectively, in multiple markets, including MISO, PJM, NYISO, ISO-NE and CAISO. The balance of the portfolio not only provides significant earnings potential and earnings diversity, but also risk mitigation as a greater proportion of the company's earnings are driven by visible capacity payments and the coal and gas fleets tend to partially hedge one another as power and fuel prices change.

        Strong Cash Flow Profile.    The high quality of the acquired assets, their favorable locations and strong capacity factors are expected to result in significant earnings and cash flows which may be used to further strengthen the Combined Company's balance sheet and liquidity position, make investments in existing assets, fund growth opportunities or support other high value capital allocation initiatives.

        Structured Markets.    The Acquisitions will increase our market share in the highly desirable PJM and ISO-NE markets. Both of these markets feature forward capacity, liquid energy and ancillary services markets that provide competitive pricing. Each of our markets benefits from mature regulatory frameworks supportive of existing generation, increasingly attractive market fundamentals and significant challenges to new construction including rising construction costs, more stringent siting and permitting processes and greater scrutiny of environmental impacts. Of the approximately 12,500 MW being acquired, 5,053 MW are modern combined cycle natural gas plants and 3,793 MW are environmentally compliant coal generation plants.

        Improved Scale.    The Acquisitions complement the current size and scale of our existing power generation platform. After the Acquisitions, we expect to be among the largest domestic publicly traded independent power producers, with approximately 26,000 MW of capacity, and benefit from significant diversification in terms of technology, fuel type and dispatch. The Combined Company generation fleet is geographically diversified with assets located in several power markets that feature forward capacity markets, mature regulatory frameworks supportive of existing generation, increasingly attractive market fundamentals, and low risk of becoming overbuilt because of the significant challenges to new construction. Our fleet also has a high degree of dispatch diversity consisting of baseload coal operations, some of the most efficient combined cycle assets that effectively operate in baseload mode because they are located in capacity-constrained regions, load-following capacity and peaking units. Further, the addition of Duke Energy Retail Sales will expand our retail business into three new competitive retail markets (Ohio,

 

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Pennsylvania and Michigan). The ECP Assets and Duke Midwest Assets will provide load following generation to support the retail business.

Business Strategies

        Our business strategy is to create value through the optimization of our generation facilities, cost structure and financial resources.

        Customer Focus.    Our commercial outreach focuses on the needs of the customers and constituents we serve, the end-use and wholesale customer, our market channel partners and the government agencies and regulatory bodies that represent the public interest. The insight provided through these relationships will drive decisions that meet customer needs while optimizing the value of our business.

        Currently, our commercial strategy seeks to optimize the value of our assets by locking in near-term cash flow while preserving the ability to capture higher values long-term as power markets improve. We may hedge portions of the expected output from our facilities with the goal of stabilizing near-term earnings and cash flow while preserving upside potential should commodity prices or market factors improve. Our wholesale origination and trading and retail marketing teams are responsible for implementation of this strategy. These teams provide access to a broad portfolio of customers with varying energy and capacity requirements. There is a significant risk reduction effect from linking our generation to our customer load which reduces the need to purchase financial hedging products in the market.

        Our wholesale origination efforts focus on marketing energy and services through structured transactions that are designed to meet our customers' operating, financial and risk requirements while simultaneously compensating Dynegy appropriately for the products and services delivered. Additionally, we seek to capture the intrinsic and extrinsic value of our generation portfolios. We utilize a wide range of products and contracts such as tolling agreements, fuel supply contracts, capacity auctions, bilateral capacity contracts, power and natural gas swap agreements, power and natural gas options and other financial instruments. The retail marketing effort focuses on offering end-use customers energy products that range from fixed price and full requirements to flexible price and volume structures. Our goal is to deliver value beyond price by leveraging our experience in the energy markets and sharing our expertise to help customers make sound energy decisions. Establishing and maintaining strong relationships with retail energy channel partners is another key focus where personal service and transparent communication further build our current and future retail brands as trusted suppliers. Our objective is to maximize the benefit to both Dynegy and our current and future customers by linking our generation to the load we serve.

        Dynegy operates in a complex and highly-regulated environment with multiple federal, state and local stakeholders, such as legislators, government agencies, industry groups, consumers and environmentalists. These stakeholders are important partners and exhibit influence over regulators and their decisions. Dynegy works with these stakeholders to encourage reasonable regulations that increase shareholder value through driving revenue and containing costs. Our regulatory strategy includes a continuous process of advocacy, visibility, education and building alliances. We also focus on the key issues that most affect our business. The ultimate goal is to find solutions that provide adequate cost recovery and incentivize investment, while providing safe, reliable, cost-effective and environmentally-compliant generation for the communities in which we operate.

        Continuous Improvement.    We have strong plant operations and are committed to operating all of our facilities in a safe, reliable, cost-efficient and environmentally compliant manner. We have dedicated significant resources toward these priorities with approximately $1 billion invested since 2005 in our Coal segment for environmental compliance initiatives to meet contractual obligations and state and federal environmental standards. In addition, we continue to invest across all segments to maintain and improve the safety, reliability and efficiency of the fleet. The Acquisitions highlight our commitment to operating safe, reliable, cost efficient and environmentally compliant power generation facilities. The facilities

 

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comprising the Duke Midwest Assets and the ECP Assets have benefited from regular investment, preventative maintenance and rigorous inspection programs. In addition, we will continue to capitalize on our centralized operations support function with the primary focus of instilling various cost and operating best practices across the fleets in the areas of safety procurement, engineering and outage management.

        We continue to employ our cost and performance improvement initiative, known as PRIDE, which is designed to drive recurring cash flow benefits by optimizing our cost structure, implementing company-wide process and operating improvements, and improving balance sheet efficiency. Our PRIDE program has targeted $135 million in earnings and improvements and $165 million in balance sheet improvements during the 2014-2016 timeframe.

        Capital Structure Management and Allocation.    The power industry is a cyclical commodity business with significant price volatility requiring considerable ongoing capital investment. As such, it is imperative to build and maintain a balance sheet with manageable debt levels supported by a flexible and diverse liquidity program. Our ongoing capital allocation priorities, first and foremost, are to maintain an appropriate leverage and liquidity profile and to make the necessary capital investments to maintain the safety and reliability of our fleet and to comply with environmental rules and regulations. Additional capital allocation options that are evaluated include investments in our existing portfolio, potential acquisitions and returning capital to shareholders. Capital allocation decisions are based on the alternatives that provide the highest risk-adjusted rates of return.

        We continue to focus on building a diverse liquidity program to support our ongoing operations and commercial activities. This includes maintaining adequate cash balances, expanding our first lien collateral program to include additional hedging counterparties and having in place sufficient committed lines of credit to support our ongoing liquidity needs. We will continue to evaluate other measures to best manage our balance sheet as well as seek additional sources of liquidity.

Industry Overview

        The power industry is one of the largest industries in the United States and impacts nearly every aspect of our economy, with an estimated end-user market of approximately $372 billion in power sales in 2013. In 2013, total generation in the United States reached approximately 4 million Gigawatt hours ("GWh"), composed of 27.4% natural gas, 39.1% coal, 19.4% nuclear, 12.8% renewables, and 1.3% other. Historically, the power generation industry has been largely characterized by electric utility monopolies producing electricity from old, less efficient, high-cost generating facilities selling to a captive customer base. Over the last 25 years, however, industry trends and regulatory initiatives, culminating with deregulation in the late 1990s and early 2000s, have transformed the market into a more competitive one where end-users purchase electricity from a variety of suppliers, including non-utility generators, power marketers, public utilities and others. Although models and rules for competition differ from state to state, all markets in which we operate have some form of wholesale market competition.

        The advancing age of the U.S. power generation fleet could present system reliability challenges as the economic efficiency of operating older plants declines over time. More than half of the U.S. power generation fleet is at least 30 years old, with the average age of the U.S. coal fleet being approximately 44 years old. Retirement decisions may also be affected by the cost of compliance with anticipated and existing state and federal environmental regulations. Further, although coal and oil generation assets currently comprise a large portion of planned retirements, baseload nuclear generation has also come under increased pressure. Since 2010, 4.8 GW of nuclear capacity has been retired or is in the process of retiring in the United States and there is a potential for further retirements as several nuclear generators have expressed concerns over maintenance and repair costs, declining profitability in a lower gas price environment and increasing regulatory compliance costs. The anticipated retirement of power generation resources would significantly alter the composition of the existing power supply. As resources are retired,

 

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higher cost units will be dispatched earlier and more often to meet demand, leading to higher power prices, particularly during winter and summer months when the demand for power is greatest.

        We believe that increasing demand and the need to replace old and less efficient generation facilities will create a significant need for additional power generating capacity throughout the United States. In our view, these factors combined with recent restructuring legislation provide an attractive environment in the United States for an independent power producer like us with existing generation assets and a history of successfully developing, acquiring and operating power generation facilities.

Our Markets and Segments

        Currently, Dynegy's largest market is MISO. The Acquisitions will significantly increase our geographic diversity in the PJM and ISO-NE markets.

 

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        Our existing generation assets are divided into Coal, IPH and Gas segments. Our coal segment is comprised of four operating coal-fired power generation facilities in Illinois with a total generating capacity of 2,980 MW. Our IPH segment is comprised of five operating coal-fired power generation facilities located in Illinois with a total owned generating capacity of 4,062 MW. Our Coal and IPH segments are generally concentrated within the MISO market. The Duke Midwest Assets include partial interests in five coal-fired power generation facilities with a total net generating capacity of 2,701 MW. The ECP Assets include two coal facilities with a total net generating capacity of 2,601 MW, of which 1,493 MW relate to Brayton Point which is scheduled to be retired from service in June 2017.

        Our Gas segment is comprised of six operating natural gas-fired power generation facilities located in California, Illinois, Pennsylvania, New York, and Maine and one fuel-oil fired power generation facility located in California, totaling 6,078 MW of electric generating capacity. Our Gas segment operates in the PJM, NYISO, ISO-NE and CAISO markets. The Duke Midwest Assets include 100% interests in six natural gas/oil-fired facilities with a total net generating capacity of 3,538 MW. The ECP Assets include five natural gas-fired power generation facilities, two natural gas and oil facilities in Ohio, and partial interests in one gas-fired power generation facility in Illinois, with a total net generating capacity of 3,748 MW.

Corporate Information

        Our principal executive offices are located at 601 Travis, Suite 1400, Houston, Texas 77002. Our telephone number is (713) 507-6400 and we have a website accessible at www.dynegy.com. The information posted on our website is not incorporated into this prospectus supplement and is not part of this prospectus supplement.

 

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THE OFFERING

        The summary below contains basic information about this offering. It does not contain all of the information that is important to you. You should read this prospectus supplement and the accompanying prospectus and the documents incorporated and deemed to be incorporated by reference in this prospectus supplement and the accompanying prospectus carefully before making an investment decision.

Issuer

  Dynegy Inc., a Delaware corporation

Common Stock Offered

 

22,500,000 shares

Common Stock to be Outstanding After this Offering

 

122,882,015 shares (excluding shares of common stock that the underwriters have the option to purchase as described below)

New York Stock Exchange Symbol for Common Stock

 

DYN

Underwriters' Purchase Option

 

We have granted the underwriters an option for a period of 30 days to purchase up to an additional 3,375,000 shares of common stock.

Use of Proceeds

 

We estimate that the net proceeds from this offering, after deducting underwriting discounts and commissions and before estimated offering expenses, will be approximately $680.5 million (or approximately $782.6 million if the underwriters exercise their option in full). We intend to use the net proceeds from this offering, together with the net proceeds of the Mandatory Convertible Preferred Stock Offering and the Debt Financings, the common stock placement to ECP and cash on hand to finance the Acquisitions and to pay related fees and expenses. If we consummate only one of the Acquisitions, we will use some or all of the net proceeds of this offering to fund the Acquisition that is consummated and any remaining amount for general corporate purposes. If we do not consummate either of the Acquisitions, we will use all of the net proceeds from this offering for general corporate purposes. See "Use of Proceeds."

 

A $1.00 increase (decrease) in the public offering price of our common stock would increase (decrease) the estimated net proceeds received by us from this offering by approximately $21.8 million (or approximately $25.1 million if the underwriters' option to purchase additional shares of common stock is exercised in full), after deducting estimated underwriting discounts and commissions and before estimated offering expenses payable by us.

 

For a sensitivity analysis related to the Acquisitions, see "Use of Proceeds" and "Summary Unaudited Pro Forma Condensed Combined Financial Information" included in this prospectus supplement.

 

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Concurrent Mandatory Convertible Preferred Stock Offering

 

Concurrently with this offering, we are offering, by means of a separate prospectus supplement, 4,000,000 shares of our Series A Mandatory Convertible Preferred Stock, plus up to an additional 600,000 shares of such Mandatory Convertible Preferred Stock that the underwriters of such offering have the option to purchase from us, exercisable within 30 days from the date of the prospectus supplement for the Mandatory Convertible Preferred Stock Offering. We will have the option to redeem, in whole but not in part, all of the Mandatory Convertible Preferred Stock (in cash, by delivery of shares of our common stock, or by delivery of any combination of cash and common stock) if either or both of the Acquisitions is terminated. The completion of this offering is not contingent on the completion of the Mandatory Convertible Preferred Stock Offering, and the Mandatory Convertible Preferred Stock Offering is not contingent on the completion of this offering. For additional information, see "The Transactions" and "Description of Certain Indebtedness and Obligations—Our Mandatory Convertible Preferred Stock," included in this prospectus supplement.

Debt Financings

 

Subsequent to this offering and the Mandatory Convertible Preferred Stock Offering, we expect to obtain Debt Financing in connection with the financing of the Acquisitions. We will be required to redeem all of the debt borrowed if neither of the Acquisitions is consummated. If one or the other of the Acquisitions is not consummated, we will be required to redeem the debt borrowed in connection with such contemplated but unconsummated Acquisition. The completion of this offering is not contingent on the completion of the Debt Financing, and the Debt Financing is not contingent on the completion of this offering. For additional information, see "The Transactions" and "Description of Certain Indebtedness and Obligations—Debt Financing," included in this prospectus supplement.

NYSE Trading Symbol

 

Our common stock is listed on the New York Stock Exchange under the symbol "DYN."

Risk Factors

 

See "Risk Factors" beginning on page S-23 of this prospectus supplement and page S-2 of the accompanying prospectus for a discussion of the factors you should carefully consider before deciding to invest in the common stock.

        The number of shares of our common stock to be outstanding immediately after this offering is based on 22,500,000 shares to be issued in this offering and 100,382,015 shares outstanding as of October 2, 2014, and excludes:

 

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        Unless otherwise specified or the context requires otherwise, information in this prospectus supplement assumes that (1) the option we have granted to the underwriters in this offering to purchase 3,375,000 additional shares of common stock and the option we have granted to the underwriters in the Mandatory Convertible Preferred Stock Offering to purchase 600,000 additional shares of Mandatory Convertible Preferred Stock, in each case, are not exercised, (2) the Mandatory Convertible Preferred Stock will not be redeemed if either or both of the Acquisitions are not consummated and (3) we elect to pay any and all dividends with respect to the Mandatory Convertible Preferred Stock in cash.

 

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SUMMARY HISTORICAL CONSOLIDATED FINANCIAL DATA OF DYNEGY

        The selected financial information presented below as of December 31, 2012 and 2013 and for the year ended December 31, 2011, the period from January 1 through October 1, 2012, the period from October 2, 2012 through December 31, 2012, and the year ended December 2013 was derived from, and is qualified by reference to, our audited consolidated financial statements, including the notes thereto, which are incorporated by reference in this prospectus supplement. The selected financial information presented below for the years ended December 31, 2009 and 2010 was derived from, and is qualified by reference to, our audited consolidated financial statements, including the notes thereto, which are not incorporated by reference in this prospectus supplement. The selected financial information as of June 30, 2014 and for the six months ended June 30, 2013 and 2014, was derived from, and is qualified by reference to, our consolidated financial statements, including the notes thereto, which are incorporated by reference in this prospectus supplement.

        This information is only a summary. You should read the data set forth in the table below in conjunction with the section entitled "Selected Financial Data" in our Annual Report on Form 10-K for the fiscal year ended December 31, 2013 and the section entitled "Part I. Financial Information" in our Quarterly Report on Form 10-Q for the quarter ended June 30, 2014, which are incorporated by reference in this prospectus supplement. As a result of the application of fresh-start accounting as of the October 1, 2012, following our reorganization, the financial statements on or prior to October 1, 2012 are not comparable with the financial statements after October 1, 2012. References to "Successor" refer to Dynegy after October 1, 2012, after giving effect to the application of fresh-start accounting. References to "Predecessor" refer to Dynegy on or prior to October 1, 2012.

 
  Predecessor    
  Successor  
 
   
   
   
   
   
   
   
  Six Months
Ended
June 30,
 
 
  Year Ended December 31,   January 1
Through
October 1,
2012(2)(3)
   
  October 2
Through
December 31,
2012
   
 
 
   
  Year Ended
December 31,
2013
 
 
  2009   2010   2011(1)    
  2013   2014  
 
   
 
 
   
   
   
   
   
  (in millions)
 
 
  (in millions)
   
   
   
  (unaudited)
 

Statement of Operations Data:

                                                     

Revenues

  $ 2,195   $ 2,059   $ 1,333   $ 981       $ 312   $ 1,466   $ 619   $ 1,283  

Depreciation expense

    (327 )   (397 )   (295 )   (110 )       (45 )   (216 )   (103 )   (124 )

Goodwill impairment

    (433 )                                

Impairment and other charges, exclusive of goodwill impairment shown separately above

    (326 )   (146 )   (5 )                        

General and administrative expense

    (159 )   (158 )   (102 )   (56 )       (22 )   (97 )   (47 )   (55 )

Operating income (loss)

    (632 )   (32 )   (189 )   5         (104 )   (318 )   (226 )   (53 )

Bankruptcy reorganization items, net

            (52 )   1,037         (3 )   (1 )        

Interest expense and debt extinguishment costs(4)

    (461 )   (363 )   (369 )   (120 )       (16 )   (108 )   (56 )   (72 )

Income tax benefit

    235     194     144     9             58         1  

Income (loss) from continuing operations

    (920 )   (259 )   (431 )   130         (113 )   (359 )   (292 )   (159 )

Income (loss) from discontinued operations, net of taxes(5)

    (348 )   17     (509 )   (162 )       6     3     5      

Net income (loss)

    (1,268 )   (242 )   (940 )   (32 )       (107 )   (356 )   (287 )   (159 )

Cash Flow Data:

                                                     

Net cash provided by (used in) operating activities

  $ 152   $ 423   $ (1 ) $ (37 )     $ (44 ) $ 175   $ (10 ) $ 163  

Net cash provided by (used in) investing activities

    790     (520 )   (229 )   278         265     474     283     (55 )

Net cash provided by (used in) financing activities

    (1,193 )   (69 )   375     (184 )       (328 )   (154 )   (160 )   (3 )

Capital expenditures, acquisitions and investments

    (596 )   (517 )   (21 )   193         (46 )   136     (55 )   (69 )

 

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  Successor  
 
  As of
December 31,
   
 
 
  As of
June 30,
2014
 
 
  2012   2013  
 
   
   
  (unaudited)
 
 
  (in millions)
 

Balance Sheet Data:

                   

Current assets

  $ 1,043   $ 1,685   $ 1,699  

Current liabilities

    347     721     753  

Property, plant and equipment, net

    3,022     3,315     3,260  

Total assets

    4,535     5,291     5,188  

Notes payable and current portion of long-term debt

    29     13     37  

Long-term debt (excluding current portion)(6)

    1,386     1,979     1,971  

Capital leases not already included in long-term debt

             

Total stockholders'/member's equity

    2,503     2,207     2,052  

(1)
We completed the DMG Transfer effective September 1, 2011; therefore, the results of our coal segment are only included through August 31, 2011. See Note 23—Dispositions and Discontinued Operations to our audited consolidated financial statements incorporated by reference in this prospectus supplement for further discussion.

(2)
We completed the DMG Acquisition effective June 5, 2012; therefore, the results of our Coal segment are only included subsequent to June 5, 2012. See Note 3—Merger and Acquisition to our audited consolidated financial statements incorporated by reference in this prospectus supplement for further discussion.

(3)
The results of operations for the period January 1, 2012 through October 1, 2012 includes the effects of the plan of reorganization ("Plan") and impacts of fresh-start accounting related to the DH bankruptcy. See "Selected Financial Data" in the 10-K for the period ended December 31, 2012, incorporated by reference in this prospectus supplement.

(4)
Includes $46 million, $21 million and $11 million of debt extinguishment costs for the years ended December 31, 2009, 2011 and 2013 respectively.

(5)
Discontinued operations include the results of operations from the following businesses:

The DNE Debtor Entities (see Note 23—Dispositions and Discontinued Operations to our audited consolidated financial statements incorporated by reference in this prospectus supplement for further discussion);

The Arlington Valley and Griffith power generation facilities (sold fourth quarter 2009);

Bluegrass power generating facility (sold fourth quarter 2009); and

Heard County power generating facility (sold second quarter 2009).

(6)
As a result of the DH Chapter 11 Cases, we reclassified approximately $3.6 billion in long-term debt to liabilities subject to compromise as of December 31, 2011. These liabilities were settled upon our emergence from bankruptcy on October 1, 2012. See Note 21—Emergence from Bankruptcy and Fresh-Start Accounting to our audited consolidated financial statements incorporated by reference in this prospectus supplement for further discussion.

 

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SUMMARY HISTORICAL CONSOLIDATED FINANCIAL DATA OF DUKE MIDWEST ASSETS

        The following table sets forth summary historical consolidated financial data for the Duke Midwest Assets as of and for the periods ended on the dates indicated below. We have derived the summary consolidated financial data as of and for the years ended December 31, 2011, 2012 and 2013 from the audited consolidated financial statements incorporated by reference into this prospectus supplement. We have derived the summary consolidated financial data as of June 30, 2014 and for the six-months ended June 30, 2013 and 2014, from the unaudited financial statements incorporated by reference into this prospectus supplement. The unaudited financial statements were prepared on the same basis as the audited financial statements and, in the opinion of management, include all adjustments, consisting only of normal, recurring adjustments necessary for a fair statement of the information set forth therein.

 
  Year Ended December 31,   Six Months
Ended June 30,
 
 
  2011   2012   2013   2013   2014  
 
   
   
   
  (unaudited)
 
 
  (in millions)
 

Statement of Operations Data:

                               

Operating revenues

  $ 2,299   $ 1,874   $ 1,951   $ 907   $ 622  

Operating expenses:

                               

Plant operating expense

    1,746     1,550     1,718     818     787  

Depreciation and amortization expense

    154     151     146     74     77  

Impairment charges

    79                  

Other operating expenses

    27     27     28     18     18  

Total operating expenses

    2,006     1,728     1,892     910     882  

Gain on sale of assets, net

    4     6         1     1  

Income from operations

    297     152     59     (2 )   (259 )

Interest expense

    2     3     2     1     5  

Other income, net

    3     1             1  

Income (loss) before income taxes and discontinued operations

    298     150     57     (3 )   (263 )

Income tax expense (benefit)

    103     54     20     (1 )   (93 )

Net income (loss)

    195     96     37     (2 )   (170 )

 

 
  As of
December 31,
   
 
 
  As of
June 30, 2014
 
 
  2012   2013  
 
   
   
  (unaudited)
 
 
  (in millions)
 

Balance Sheet Information:

                   

Cash and cash equivalents

  $ 2   $ 5   $ 5  

Total assets

    3,936     3,924     3,879  

Total debt

    402     402      

Total liabilities

    1,457     1,481     1,078  

Total stockholders' equity

    2,479     2,443     2,801  

 

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SUMMARY HISTORICAL COMBINED FINANCIAL DATA OF ECP ASSETS

        The following table sets forth summary historical combined financial data for the ECP Assets as of and for the periods ended on the dates indicated below. We have derived the summary combined financial data as of and for the years ended December 31, 2011, 2012 and 2013 from the audited combined financial statements incorporated by reference into this prospectus supplement. We have derived the summary unaudited combined interim financial data as of June 30, 2014 and for the six-months ended June 30, 2013 and 2014, from the unaudited combined financial statements incorporated by reference into this prospectus supplement. The unaudited combined financial statements were prepared on the same basis as the audited combined financial statements and, in the opinion of management, include all adjustments, consisting only of normal, recurring adjustments necessary for a fair statement of the information set forth therein.

 
  Year Ended
December 31,
  Six Months
Ended
June 30,
 
 
  2011   2012   2013   2013   2014  
 
   
   
   
  (unaudited)
 
 
  (in millions)
 

Combined Statements of Operations Data

                               

Operating revenues

  $ 562   $ 558   $ 870   $ 381   $ 876  

Operating expenses:

                               

Energy and fuel costs

    462     371     667     297     522  

Operations and maintenance

    47     68     101     23     97  

Depreciation and amortization

    31     52     65     28     46  

Taxes other than income taxes

    22     31     25     16     12  

Total operating expenses

    561     522     857     364     677  

Operating income

        36     13     18     199  

Other expense (income):

                               

Interest and fees on debt

    36     89     87     36     43  

Equity (income) loss in affiliates

            1         (2 )

Other income, net

        (4 )            

Mark-to-market on interest rate derivative contracts

    8     5     (4 )   (8 )   7  

Other expense, net

    44     89     84     28     48  

Gain on bargain purchase of business

            3          

Income (loss) before income tax expense (benefit)

    (44 )   (53 )   (68 )   (10 )   151  

Income tax expense (benefit)

    (16 )   (13 )   (27 )   (4 )   59  

Loss before preferred dividends

    (28 )   (40 )   (41 )   (7 )   92  

Preferred dividends

    1                  

Income (loss) from continuing operations

    (29 )   (40 )   (41 )   (7 )   92  

 

 
  As of
December 31,
   
 
 
  As of
June 30, 2014
 
 
  2012   2013  
 
   
   
  (unaudited)
 
 
  (in millions)
 

Combined Balance Sheets Data

                   

Cash and cash equivalents

  $ 21   $ 51   $ 71  

Restricted cash

    73     87     85  

Total assets

    1,679     2,562     2,531  

Total debt (includes inventory financing facility)

    923     1,538     1,548  

Total liabilities

    1,146     1,943     1,921  

Total equity

    533     613     610  

 

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SUMMARY UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

        The following summary unaudited pro forma condensed combined financial information (the "Summary Pro Forma Financial Information") sets forth selected historical consolidated financial information for Dynegy. The Summary Pro Forma Financial Information is derived from, and should be read in conjunction with, the Unaudited Pro Forma Condensed Combined Financial Information and related notes filed as Exhibit 99.1 to our Current Report on Form 8-K, filed October 6, 2014 (the "Pro Forma 8-K"), which is incorporated by reference into this prospectus supplement. The Summary Pro Forma Financial Information is provided for informational and illustrative purposes only and should be read in conjunction with "Management's Discussion and Analysis of Financial Condition and Results of Operations" and the consolidated financial statements and related notes in Dynegy's Annual Report on Form 10-K for the year ended December 31, 2013 and Dynegy's audited annual consolidated financial statements and unaudited interim condensed consolidated financial statements, which are incorporated by reference into this prospectus supplement.

        The pro forma adjustments, as described in the notes to the Unaudited Pro Forma Condensed Combined Financial Information filed as an exhibit to the Pro Forma 8-K, which is incorporated by reference into this prospectus supplement, are based on currently available information. Management believes such adjustments are reasonable, factually supportable and directly attributable to the events and transactions described therein. The unaudited pro forma condensed combined balance sheet reflects the impact of the AER Acquisition, this offering, the Mandatory Convertible Preferred Stock Offering, the Debt Financing, the Duke Midwest Acquisition, the ERC and Brayton Acquisitions, and the two incremental revolving credit facilities discussed elsewhere in this prospectus supplement (see "Overview of Financial Condition, Liquidity and Capital Resources") as if they had been completed on June 30, 2014. The unaudited pro forma condensed combined statements of operations give effect to the events and transactions described in the previous sentence as if they had been completed on January 1, 2013, and only include adjustments which have an ongoing impact. The Summary Pro Forma Financial Information does not purport to represent what our actual consolidated results of operations or financial position would have been had the events and transactions occurred on the dates assumed, nor is it necessarily indicative of our future financial condition or consolidated results of operations.

 

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DYNEGY INC.
UNAUDITED PRO FORMA CONDENSED COMBINED BALANCE SHEET

 
  As of June 30, 2014  
 
  Dynegy
As Reported
  Equity
Offerings
  Debt
Financing
and
Revolver
  Duke
Midwest
Acquisition
  EquiPower
Acquisition
  Dynegy
Pro Forma
As Adjusted
 
 
  (in millions)
 

ASSETS

                                     

Current Assets

                                     

Cash and cash equivalents

  $ 948   $ 1,068   $ 4,977   $ (2,849 ) $ (3,180 ) $ 964  

Restricted cash

                         

Accounts receivable, net

    367             146     54     567  

Inventory

    206             130     181     517  

Assets from risk management activities

    10             9     5     24  

Intangible assets

    60                     60  

Prepayments and other current assets

    108             140     80     328  
                           

Total Current Assets

    1,699     1,068     4,977     (2,424 )   (2,860 )   2,460  
                           

Property, plant, and equipment, net

    3,260             2,695     4,252     10,207  

Investment in affiliates

                    152     152  

Assets from risk management activities

    11             8     1     20  

Intangible assets

    50                     50  

Goodwill

                         

Deferred income taxes

    65                 (20 )   45  

Other long-term assets

    103         75     14     70     262  
                           

Total Assets

  $ 5,188   $ 1,068   $ 5,052   $ 293   $ 1,595   $ 13,196  
                           
                           

LIABILITIES AND STOCKHOLDERS' EQUITY

                                     

Current Liabilities

                                     

Accounts payable

    305             143     106     554  

Accrued interest

    13                     13  

Deferred income taxes

    65                 (20 )   45  

Intangible liabilities

    57                     57  

Accrued liabilities and other current liabilities

    166             36     68     270  

Liabilities from risk management activities

    110             49     57     216  

Debt, current portion

    37                     37  
                           

Total Current Liabilities

    753             228     211     1,192  

Debt, long-term portion

    1,971         5,100             7,071  

Other Liabilities

                                     

Liabilities from risk management activities

    40             56     17     113  

Asset retirement obligations

    160             4     59     223  

Other long-term liabilities

    212             23     59     294  
                           

Total Liabilities

    3,136         5,100     311     346     8,893  
                           

Commitments and contingencies

                                     

Total Equity

    2,052     1,068     (48 )   (18 )   1,249     4,303  
                           

Total Liabilities and Equity

  $ 5,188   $ 1,068   $ 5,052   $ 293   $ 1,595   $ 13,196  
                           
                           

 

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DYNEGY INC.
UNAUDITED PRO FORMA CONDENSED COMBINED STATEMENT OF OPERATIONS

 
  Year Ended December 31, 2013  
 
  Dynegy
As Reported
  AER
Acquisition
  Debt
Financing,
Revolver,
and
Equity
Offerings
  Duke
Midwest
Acquisition
  EquiPower
Acquisition
  Dynegy
Pro Forma
As Adjusted
 
 
  ($ in millions, except per share amounts)
 

Revenues

  $ 1,466   $ 1,096   $   $ 1,893   $ 870   $ 5,325  

Cost of sales, excluding depreciation expense

    (1,145 )   (831 )       (1,344 )   (667 )   (3,987 )
                           

Gross margin

    321     265         549     203     1,338  

Operating and maintenance expense

    (308 )   (204 )       (261 )   (119 )   (892 )

Depreciation and amortization expense

    (216 )   (22 )       (108 )   (170 )   (516 )

Gain on sale of assets

    2                     2  

Impairment

                         

General and administrative expense

    (97 )   (26 )       (79 )       (202 )

Acquisition and integration costs

    (20 )   20                  
                           

Operating (loss) income

    (318 )   33         101     (86 )   (270 )

Bankruptcy reorganization items, net

    (1 )                   (1 )

Earnings from unconsolidated investments

    2                     2  

Interest expense

    (97 )   (55 )   (348 )       (1 )   (501 )

Loss on extinguishment of debt

    (11 )                   (11 )

Other income and expense, net

    8                 2     10  
                           

(Loss) income from continuing operations before income taxes

    (417 )   (22 )   (348 )   101     (85 )   (771 )

Income tax benefit (expense)

    58                     58  
                           

(Loss) income from continuing operations

    (359 )   (22 )   (348 )   101     (85 )   (713 )

Less: Income (loss) attributable to noncontrolling interest

        3                 3  
                           

Net (loss) income attributable to Dynegy Inc. (excluding discontinued operations)

    (359 )   (25 )   (348 )   101     (85 )   (716 )

Less: Preferred stock dividends

            (22 )           (22 )
                           

Net (loss) income attributable to Dynegy Inc. common shareholders (excluding discontinued operations)

  $ (359 ) $ (25 ) $ (370 ) $ 101   $ (85 ) $ (738 )
                           
                           

Basic loss per share from continuing operations excluding discontinued operations available to common shareholders

  $ (3.59 )                         $ (5.72 )

Diluted loss per share from continuing operations excluding discontinued operations available to common shareholders

  $ (3.59 )                         $ (5.72 )

Basic shares outstanding

    100                             129  

Diluted shares outstanding

    100                             129  

 

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DYNEGY INC.
UNAUDITED PRO FORMA CONDENSED COMBINED STATEMENT OF OPERATIONS

 
  Six Months Ended June 30, 2014  
 
  Dynegy
As Reported
  Debt
Financing,
Revolver,
and
Equity
Offerings
  Duke
Midwest
Acquisition
  EquiPower
Acquisition
  Dynegy
Pro Forma
As Adjusted
 
 
  ($ in millions, except per share amounts)
 

Revenues

  $ 1,283   $   $ 575   $ 876   $ 2,734  

Cost of sales, exclusding depreciation expense

    (917 )       (605 )   (522 )   (2,044 )
                       

Gross margin

    366         (30 )   354     690  

Operating and maintenance expense

    (246 )       (140 )   (109 )   (495 )

Depreciation and amortization expense

    (124 )       (54 )   (85 )   (263 )

Gain on sale of assets, net

    14         1         15  

General and administrative expense

    (55 )       (32 )       (87 )

Acquisition and integration costs

    (8 )               (8 )
                       

Operating (loss) income

    (53 )       (255 )   160     (148 )

Earnings from unconsolidated investments

    10                 10  

Interest expense

    (72 )   (174 )       (1 )   (247 )

Other income and expense, net

    (45 )       1     2     (42 )
                       

(Loss) income from continuing operations before income taxes

    (160 )   (174 )   (254 )   161     (427 )

Income tax benefit (expense)

    1                 1  
                       

Net (loss) income from continuing operations

    (159 )   (174 )   (254 )   161     (426 )

Less: Net income attributable to noncontrolling interest

    5                 5  
                       

Net (loss) income attributable to Dynegy Inc. 

    (164 )   (174 )   (254 )   161     (431 )

Less: Preferred stock dividends

        (11 )           (11 )
                       

Net (loss) income attributable to Dynegy Inc. common shareholders

  $ (164 ) $ (185 ) $ (254 ) $ 161   $ (442 )
                       
                       

Basic loss per share from continuing operations available to common shareholders

  $ (1.64 )                   $ (3.43 )

Diluted loss per share from continuing operations available to common shareholders

  $ (1.64 )                   $ (3.43 )

Basic shares outstanding

    100                       129  

Diluted shares outstanding

    100                       129  

 

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RISK FACTORS

        Any investment in our common stock involves a high degree of risk. You should carefully consider the risks described below and all of the information contained in or incorporated by reference into this prospectus supplement and the accompanying prospectus before deciding whether to purchase our common stock. In addition, you should carefully consider, among other things, the matters discussed under "Risk Factors" in our Annual Report on Form 10-K for the fiscal year ended December 31, 2013 and in other documents that we subsequently file with the SEC, all of which are incorporated by reference into this prospectus supplement. The risks and uncertainties described in such incorporated documents and described below are not the only risks and uncertainties we face. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also impair our business operations. If any of those risks actually occurs, our business, financial condition and results of operations would suffer. In that event, the trading price of our common stock could decline, and you may lose all or part of your investment. The risks discussed below also include forward-looking statements and our actual results may differ substantially from those discussed in these forward-looking statements. See "Forward-Looking Statements."

Risks Related to the Proposed Acquisitions

We may be unable to obtain the regulatory approvals required to complete one or both of the Acquisitions or, in order to do so, we may be required to comply with material restrictions on our conduct or satisfy other material conditions required by various regulatory authorities.

        Consummation of the Acquisitions is subject to conditions and governmental approvals, including FERC approval and review by the U.S. Department of Justice Antitrust Division, referred to as the Antitrust Division, and the Federal Trade Commission, referred to as the FTC, under the HSR. We, Duke and ECP are currently responding to preliminary inquiries by the Antitrust Division. The expiration or termination of the waiting period (and any extension of the waiting period) applicable to an Acquisition under the HSR Act is a condition to closing such Acquisition. The closing of the Acquisitions are also subject to the condition that there be no injunction or order issued by a court of competent jurisdiction that prevents the consummation of the transactions contemplated by the acquisition agreements. We can provide no assurance that all required regulatory approvals will be obtained. There can also be no assurance as to the cost, scope or impact of the actions that may be required to obtain the required regulatory approvals. Furthermore, these actions could have the effect of delaying or preventing completion of the proposed transactions or imposing additional costs, conditions or restrictions on our business and operations, some of which could be material and adversely affect our revenues and profitability following the consummation of the transactions.

        Furthermore, the FERC, the Department of Justice or other governmental authorities could seek to block or challenge the Acquisitions as they deem necessary or desirable in the public interest at any time, including after completion of the transactions. In addition, in some circumstances, a competitor, customer or other third party could initiate a private action under antitrust laws challenging or seeking to enjoin either or both Acquisitions, before or after either or both of them are consummated. We may not prevail and may incur significant costs in defending or settling any action under the antitrust laws.

If one or both of the Acquisitions are consummated, we may be unable to successfully integrate the operations of the relevant Target Companies with each other or with our existing operations or to realize targeted cost savings, revenues and other anticipated benefits of the Acquisitions.

        The success of the proposed Acquisitions will depend, in part, on our ability to realize the anticipated benefits and synergies from integrating the Duke Midwest Assets and/or the ECP Assets with each other or with our existing generation business. To realize these anticipated benefits, the businesses must be successfully combined.

        We may be required to make unanticipated capital expenditures or investments in order to maintain, integrate, improve or sustain the Duke Midwest Assets' and/or the ECP Assets' operations, or take

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unexpected write-offs or impairment charges resulting from the Acquisitions. Further, we may be subject to unanticipated or unknown liabilities relating to the Target Companies. If any of these factors occur or limit our ability to integrate the businesses successfully or on a timely basis, the expectations of our future financial conditions and results of operations following the Acquisitions might not be met.

        In addition, we, the Duke Midwest Assets and the ECP Assets have operated and, until the consummation of the Acquisitions, will continue to operate independently. It is possible that the integration process could result in the loss of key employees, the disruption of each company's ongoing businesses, inefficiencies, or inconsistencies in standards, controls, information technology systems, procedures and policies, any of which could adversely affect our ability to achieve the anticipated benefits of the Acquisitions and could harm our financial performance. Further, because ECP is a private company, we may be required to implement or improve the internal controls, procedures and policies of the ECP Assets to meet standards applicable to public companies, which may be time-consuming and more expensive than anticipated.

        In addition, we continue to evaluate our estimates of synergies to be realized from, and the fair value accounting allocations associated with, the Acquisitions and refine them, so that our actual cost-savings could differ materially from our current estimates. Actual cost-savings, the costs required to realize the cost-savings and the source of the cost-savings could differ materially from our estimates, and we cannot assure you that we will achieve the full amount of cost-savings on the schedule anticipated or at all.

        Finally, we may not be able to achieve the targeted operating or long-term strategic benefits of the Acquisitions. If the combined businesses are not able to achieve our objectives, or are not able to achieve our objectives on a timely basis, the anticipated benefits of the Acquisitions may not be realized fully or at all. An inability to realize the full extent of, or any of, the anticipated benefits of the Acquisitions, as well as any delays encountered in the integration process, could have an adverse effect on our financial condition, results of operations and cash flows.

This offering is not contingent upon the consummation of the Acquisitions. If either or both of the Acquisitions are not consummated, we will have broad discretion to use the net proceeds of this offering and our concurrent Mandatory Convertible Preferred Stock Offering for general corporate purposes. Even if the Acquisitions are consummated, they may not be consummated in the time frame, or on the terms or in the manner contemplated, which could have a negative impact on our business.

        This offering is not contingent upon the consummation of the Acquisitions. Accordingly, your purchase of our common stock in this offering may be an investment in Dynegy on a stand-alone basis without any of the assets of the Duke Midwest Assets or the ECP Assets, or anticipated benefits of the Acquisitions. We will have broad discretion to use the net proceeds of this offering if either or both of the Acquisitions do not occur. General corporate purposes may include strategic investments and acquisitions.

        There are a number of risks and uncertainties relating to the Acquisitions. For example, the Acquisitions may not be consummated, or may not be consummated in the time frame, on the terms or in the manner currently anticipated, as a result of a number of factors, including, among other things, the failure of one or more of the conditions to closing to be satisfied. There can be no assurance that the conditions to closing of the Acquisitions will be satisfied or waived or that other events will not intervene to delay or result in the failure to close the Acquisitions. Any delay in closing or a failure to close could have a negative impact on our business and the trading prices of our securities, including our common stock. Likewise, the Transactions may be completed on terms that differ, perhaps substantially, from those described in this prospectus supplement.

We will incur significant transaction and acquisition-related costs in connection with the proposed Acquisitions.

        We expect to incur significant costs associated with the Acquisitions and combining the operations of our company with the Target Companies, including costs to achieve targeted cost-savings. The substantial majority of the expenses resulting from the Acquisitions will be composed of transaction costs, systems

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consolidation costs, and business integration and employment-related costs, including costs for severance, retention and other restructuring. We may also incur transaction fees and costs related to formulating integration plans. Additional unanticipated costs may be incurred in the integration of our and the Target Companies' businesses. Although we expect that the elimination of duplicative costs, as well as the realization of other efficiencies related to the integration of the businesses, should allow us to offset incremental transaction and acquisition-related costs over time, this net benefit may not be achieved in the near term, or at all.

The announcement and pendency of the Acquisitions could impact or cause disruptions in our, Duke Midwest Assets' and ECP Assets' operations.

        The announcement and pendency of the Acquisitions could impact or cause disruptions in our, Duke's and ECP's operations. Specifically:

Any of the above disruptions could have an adverse effect on our business, results of operations and financial condition.

The Duke Midwest Assets and ECP Assets have no operating history as a stand-alone provider of electric energy, capacity and ancillary services. Therefore, each of the Target Companies' historical financial information and the pro forma financial information do not reflect the results we would have achieved during the periods presented as a stand-alone company and may not be a reliable indicator of our future results.

        The historical and pro forma financial information included or incorporated by reference in this prospectus supplement does not reflect the financial condition, results of operations or cash flows we would have achieved during the periods presented or those results we will achieve in the future as a stand-alone provider of electric energy, capacity and ancillary services.

        The audited combined financial statements included in this prospectus supplement have been derived from the books and records of Duke and Duke Ohio on the one hand and ERC and Brayton on the other hand. Preparing the audited combined financial statements required management of Duke and Duke Ohio and ERC and Brayton to assign certain assets, liabilities, revenues and expenses using the historical results of operations and cost basis of the Duke Midwest Assets and ECP Assets, respectively, during the periods presented. The financial statements of the Duke Midwest Assets also include income and expense allocations from Duke and its subsidiaries, including Duke Ohio. These assignments are based on certain assumptions, and, as a result, the audited combined financial statements may not reflect what our results of operations, financial position or cash flow would have been if we had operated as a stand-alone provider of electric energy, capacity and ancillary services.

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The unaudited pro forma condensed combined financial information included and incorporated by reference into this prospectus supplement is presented for illustrative purposes only and does not represent what the financial position or results of operations of the Combined Company would have been had the Acquisitions been consummated on the dates assumed for purposes of that pro forma information nor does it represent the actual financial position or results of operations of the Combined Company following the Acquisitions.

        The unaudited pro forma condensed combined financial information included and incorporated by reference into this prospectus supplement is presented for illustrative purposes only, contains a variety of adjustments, assumptions and preliminary estimates, is subject to numerous other uncertainties and does not reflect what the Combined Company's financial position or results of operations would have been had the Acquisitions been consummated as of the dates assumed for purposes of that pro forma financial information nor does it reflect the financial position or results of operations of the combined company following the Acquisitions. The pro forma adjustments are based on the preliminary information available at the time of the preparation of this document. For purposes of the unaudited pro forma condensed combined financial information, the estimated Acquisitions consideration has been preliminarily allocated to the assets acquired and liabilities assumed based on limited information presently available to us to estimate fair values. The Acquisitions consideration will be allocated among the relative fair values of the assets acquired and liabilities assumed based on their estimated fair values as of the respective dates of the Acquisitions. The final allocation is dependent upon certain valuations and other analyses that cannot be completed prior to the Acquisitions and are required to make a definitive allocation. The actual amounts recorded may differ materially from the information presented in the unaudited pro forma condensed combined financial information.

        Additionally, the unaudited pro forma condensed combined financial information does not reflect the cost of any integration activities or benefits from synergies that may be derived from any integration activities nor does it include any other items not expected to have a continuing impact on the consolidated results of operations. The unaudited pro forma condensed combined financial information has also been prepared on the assumption that the Acquisitions and the Financing Transactions will be completed on the terms and in accordance with the assumptions set forth under "Summary Unaudited Pro Forma Condensed Combined Financial Information" and in the Unaudited Pro Forma Condensed Combined Financial Information filed as an exhibit to the Pro Forma Form 8-K, which is incorporated by reference into this prospectus supplement. The purchase price and other terms of the Acquisitions and the terms of the Financing Transactions may change, perhaps substantially, and, because none of the Financing Transactions are contingent upon completion of any of the other Financing Transactions, it is possible that one or more of the Financing Transactions will not be completed. In particular, it is possible that the Financing Transactions will not generate the anticipated amount of net proceeds, which may require us to obtain additional financing or utilize cash on hand in order to effect the Acquisitions. See "Summary Unaudited Pro Forma Condensed Combined Financial Information" in this prospectus supplement, our and the Target Companies' consolidated financial statements incorporated by reference in this prospectus supplement and the Pro Forma Form 8-K, which is incorporated by reference into this prospectus supplement.

Risks Related to the Operation of Our Business

Because wholesale and retail power prices are subject to significant volatility and because many of our power generation facilities, including certain of the Target Companies' facilities, operate without long-term power sales agreements, our revenues and profitability are subject to wide fluctuations.

        Because we largely sell electric energy, capacity and ancillary services into the wholesale energy spot market or into other wholesale and retail power markets on a short term basis, we are not guaranteed any rate of return on our capital investments. Rather, our financial condition, results of operations and cash flows will depend, in large part, upon prevailing market prices for power and the fuel to generate such power. Wholesale and retail power markets are subject to significant price fluctuations over relatively short

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periods of time and can be unpredictable. Factors that may materially impact the power markets and our financial results include:

        The majority of our facilities and certain of the Target Companies' facilities operate as "merchant" facilities without long-term power sales agreements. Consequently, there can be no assurance that we will be able to sell any or all of the electric energy, capacity or ancillary services from those facilities at commercially attractive rates or that our facilities will be able to operate profitably. This could lead to less favorable financial results as well as future impairments of our property, plant and equipment or to the retirement of certain of our facilities resulting in economic losses and liabilities.

        Given the volatility of commodity power prices, to the extent we do not secure long-term power sales agreements for the output of our power generation facilities including the Target Companies' facilities, our revenues and profitability will be subject to increased volatility, and our financial condition, results of operations and cash flows could be materially adversely affected.

Our commercial strategies for our wholesale and retail businesses may not be executed as planned, may result in lost opportunities or adversely affect financial performance.

        We seek to commercialize our assets through sales arrangements of various types. In doing so, we attempt to balance a desire for greater predictability of earnings and cash flows in the short- and medium-terms with our expectation that commodity prices will rise over the longer term, creating upside opportunities for those with unhedged generation volumes. Our ability to successfully execute this strategy is dependent on a number of factors, many of which are outside our control, including market liquidity and design, correlation risk, commodity cycles, the availability of counterparties willing to transact with us or to transact with us at prices we think are commercially acceptable, the availability of liquidity to post collateral in support of our derivative instruments and the reliability of the systems and models comprising our commercial operations function. The availability of market liquidity and willing counterparties could be negatively impacted by poor economic and financial market conditions, including impacts on financial institutions and other current and potential counterparties as well as counterparties' views of our creditworthiness. If we are unable to transact in the short- and medium-terms, our financial condition, results of operations and cash flows will be subject to significant uncertainty and volatility. Alternatively,

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significant contract execution for any such period may precede a run-up in commodity prices, resulting in lost up-side opportunities.

        Further, financial performance may be adversely affected if we are unable to effectively manage our power portfolio. A portion of the generation power portfolio is used to provide power under contracts with wholesale and retail customers. To the extent portions of the power portfolio are not needed for that purpose, generation output is sold in the wholesale market. To the extent our power portfolio is not sufficient to meet the requirements of our customers, we must purchase power in the wholesale power markets. Our financial results may be negatively affected if we are unable to manage the power portfolio and cost-effectively meet the requirements of our customers.

A decline in market liquidity and our ability to manage our counterparty credit risk could adversely affect us.

        Our supplier counterparties may experience deteriorating credit. These conditions could cause counterparties in the natural gas and power markets, particularly in the energy commodity derivative markets that we rely on for our hedging activities, to withdraw from participation in those markets. If multiple parties withdraw from those markets, market liquidity may be threatened, which in turn could adversely impact our business. Additionally, these conditions may cause our counterparties to seek bankruptcy protection under Chapter 11 or liquidation under Chapter 7 of the Bankruptcy Code. Our credit risk may be exacerbated to the extent collateral held by us cannot be realized or is liquidated at prices not sufficient to recover the full amount of the exposure due to us. There can be no assurance that any such losses or impairments to the carrying value of our financial assets would not materially and adversely affect our financial condition, results of operations and cash flows. In addition, retail sales subject us to credit risk through competitive electricity supply activities to serve commercial and industrial companies and governmental entities. Retail credit risk results when customers default on their contractual obligations. This risk represents the loss that may be incurred due to the nonpayment of a customer's account balance, as well as the loss from the resale of energy previously committed to serve that customer, which could have a material adverse effect on our financial condition, results of operations and cash flows.

We are exposed to the risk of fuel and fuel transportation cost increases and interruptions in fuel supplies.

        We purchase the fuel requirements for many of our power generation facilities, primarily those that are natural gas-fired, under short-term contracts or on the spot market. As a result, we face the risks of supply interruptions and fuel price volatility, as fuel deliveries may not exactly match those required for energy sales.

        Moreover, profitable operation of many of our coal-fired generation facilities is highly dependent on coal prices and coal transportation rates. We monitor our price exposure by entering into term contracts for PRB coal, which we use for our Coal and IPH facilities in the Midwest. Our coal transportation requirements for the Coal and IPH facilities are fully contracted and priced for the next several years. Transportation of PRB coal can also be affected by extreme weather, slowing or stopping the delivery from the mine to the facility. Brayton Point sources some of its coal requirements from South America. The ability to procure South American coal is subject to local political and other factors that could have a negative impact on our coal deliveries regardless of any contracts.

        We continue to explore various alternative contractual commitments and financial options, as well as facility modifications, to ensure stable and competitive fuel supplies and to mitigate further supply risks for near- and long-term coal supplies.

        Further, any changes in the costs of coal, fuel oil, natural gas or transportation rates and changes in the relationship between such costs and the market prices of power will affect our financial results. If we are unable to procure fuel for physical delivery at prices we consider favorable, our financial condition, results of operations and cash flows could be materially adversely affected.

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If one or both of the Acquisitions are not consummated, the concentration of our business in Illinois and the MISO may increase the effects of adverse trends in that market and any disruption of production at the Kendall, Ontelaunee, Independence or Moss Landing facilities could have a material adverse effect on our financial condition, results of operations and cash flows.

        A substantial portion of our business is located in Illinois and the MISO where more than 50% of our plant capacity is currently located. Further, natural disasters in Illinois and changes in economic conditions in MISO, including changing demographics, congestion, or oversupply of or reduced demand for power, could have a material adverse effect on our financial condition, results of operations and cash flows.

        In addition, a substantial portion of our gross margin is derived from four of our Gas facilities, Kendall, Ontelaunee, Independence and Moss Landing. Consequently, if one or both of the Acquisitions are not consummated, then any disruption of production at these facilities could have a material adverse effect on our financial condition, results of operations and cash flows.

Operation of power generation facilities involves significant risks customary to the power industry that could have a material adverse effect on our financial condition, results of operations and cash flows.

        The ongoing operation of our facilities involves risks customary to the power industry that include the breakdown or failure of equipment or processes, performance below expected levels of output or efficiency and the inability to transport our product to customers in an efficient manner due to a lack of transmission capacity. Unplanned outages of generating units, including extensions of scheduled outages due to mechanical failures or other problems, occur from time to time and are an inherent risk of our business. Further, several of our facilities and the Target Companies' facilities are old and require periodic upgrading and improvement. Any unexpected failure, including failure associated with breakdowns, forced outages or any unanticipated capital expenditures, could result in reduced profitability. Unplanned outages typically increase our operation and maintenance expenses and may reduce our revenues as a result of selling fewer MW or require us to incur significant costs as a result of running one of our higher cost units or obtaining replacement power from third parties in the open market to satisfy our forward power sales obligations. If we are unsuccessful in operating the facilities efficiently, such inefficiency could have a material adverse effect on our results of operations, financial condition and cash flows.

Our costs of compliance with existing environmental requirements are significant, and costs of compliance with new environmental requirements or factors could materially adversely affect our financial condition, results of operations and cash flows.

        Our business is subject to extensive and frequently changing environmental regulation by federal, state and local authorities. Such environmental regulation imposes, among other things, restrictions, liabilities and obligations in connection with the generation, handling, use, transportation, treatment, storage and disposal of hazardous substances and waste and in connection with spills, releases and emissions of various substances (including GHG) into the environment, and in connection with environmental impacts associated with cooling water intake structures. Existing environmental laws and regulations may be revised or reinterpreted, new laws and regulations may be adopted or may become applicable to us or our facilities, and litigation or enforcement proceedings could be commenced against us. Proposals being considered by federal and state authorities (including proposals regarding regulation of coal combustion byproducts, ash ponds, cooling water intake structures and GHGs) could, if and when adopted or enacted, require us to make substantial capital and operating expenditures or consider retiring certain of our facilities. If any of these events occur, our financial condition, results of operations and cash flows could be materially adversely affected.

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        Many environmental laws require approvals or permits from governmental authorities before construction, modification or operation of a power generation facility may commence. Certain environmental permits must be renewed periodically in order for us to continue operating our facilities. The process of obtaining and renewing necessary permits can be lengthy and complex and can sometimes result in the establishment of permit conditions that make the project or activity for which the permit was sought unprofitable or otherwise unattractive. Even where permits are not required, compliance with environmental laws and regulations can require significant capital and operating expenditures. We are required to comply with numerous environmental laws and regulations, and to obtain numerous governmental permits when we modify and operate our facilities. If there is a delay in obtaining any required environmental regulatory approvals or permits, if we fail to obtain any required approval or permit, or if we are unable to comply with the terms of such approvals or permits, the operation of our facilities may be interrupted or become subject to additional costs and/or legal challenges. Further, changed interpretations of existing regulations may subject historical maintenance, repair and replacement activities at our facilities to claims of noncompliance. As a result, our financial condition, results of operations and cash flows could be materially adversely affected. With the continuing trend toward stricter environmental standards and more extensive regulatory and permitting requirements, our capital and operating environmental expenditures are likely to be substantial and may significantly increase in the future.

Our business is subject to complex government regulation. Changes in these regulations or in their implementation may affect costs of operating our facilities or our ability to operate our facilities, or increase competition, any of which would negatively impact our results of operations.

        We are subject to extensive federal, state and local laws and regulations governing the generation and sale of energy commodities in each of the jurisdictions in which we have operations. Compliance with these ever-changing laws and regulations requires expenses (including legal representation) and monitoring, capital and operating expenditures. Potential changes in laws and regulations that could have a material impact on our business include: the introduction, or reintroduction, of rate caps or pricing constraints; increased credit standards, collateral costs or margin requirements, as well as reduced market liquidity, as a result of potential OTC market regulation; or a variation of these. Furthermore, these and other market-based rules and regulations are subject to change at any time, and we cannot predict what changes may occur in the future or how such changes might affect any facet of our business.

        The costs and burdens associated with complying with the increased number of regulations may have a material adverse effect on us if we fail to comply with the laws and regulations governing our business or if we fail to maintain or obtain advantageous regulatory authorizations and exemptions. Failure to comply with such requirements could result in the shutdown of any noncompliant facility, the imposition of liens or fines, or civil or criminal liability. Moreover, increased competition within the sector resulting from potential legislative changes, regulatory changes or other factors may create greater risks to the stability of our power generation earnings and cash flows generally.

Availability and cost of emission allowances could materially impact our costs of operations.

        We are required to maintain, either through allocation or purchase, sufficient emission allowances to support our operations in the ordinary course of operating our power generation facilities. These allowances are used to meet our obligations imposed by various applicable environmental laws, and the trend toward more stringent regulations (including regulations regarding GHG emissions) will likely require us to obtain new or additional emission allowances. If our operational needs require more than our allocated quantity of emission allowances, we may be forced to purchase such allowances on the open market, which could be costly. If we are unable to maintain sufficient emission allowances to match our operational needs, we may have to curtail our operations so as not to exceed our available emission allowances, or install costly new emissions controls. As we use the emissions allowances that we have

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purchased on the open market, costs associated with such purchases will be recognized as an operating expense. If such allowances are available for purchase, but only at significantly higher prices, their purchase could materially increase our costs of operations in the affected markets and materially adversely affect our financial condition, results of operations and cash flows.

Competition in wholesale and retail power markets, together with the age of certain of our generation facilities and the Target Companies' facilities, may have a material adverse effect on our financial condition, results of operations and cash flows.

        Our power generation business competes with other non-utility generators, regulated utilities, unregulated subsidiaries of regulated utilities, other energy service companies and financial institutions in the sale of electric energy, capacity and ancillary services, as well as in the procurement of fuel, transmission and transportation services. Moreover, aggregate demand for power may be met by generation capacity based on several competing technologies, as well as power generating facilities fueled by alternative or renewable energy sources, including hydroelectric power, synthetic fuels, solar, wind, wood, geothermal, waste heat and solid waste sources. Regulatory initiatives designed to enhance and/or subsidize renewable generation could increase competition from these types of facilities.

        We also compete against other energy merchants on the basis of our relative operating skills, financial position and access to credit sources. Electric energy customers, wholesale energy suppliers and transporters often seek financial guarantees, credit support such as letters of credit, and other assurances that their energy contracts will be satisfied. Companies with which we compete may have greater resources in these areas. In addition, certain of our current facilities and the Target Companies' facilities are relatively old. Newer plants owned by competitors may be more efficient than some of our plants, which may put these plants at a competitive disadvantage. Over time, some of our plants may become unable to compete because of the construction of new plants, and such new plants could have a number of advantages including: more efficient equipment, newer technology that could result in fewer emissions or more advantageous locations on the electric transmission system. Additionally, these competitors may be able to respond more quickly to new laws and regulations because of the newer technology utilized in their facilities or the additional resources derived from owning more efficient facilities. Taken as a whole, the potential disadvantages of our aging fleet could result in lower run-times or even early asset retirement.

        Other factors may contribute to increased competition in wholesale power markets. New forms of capital and competitors have entered the industry, including financial investors who perceive that asset values are at levels below their true replacement value. As a result, a number of generation facilities in the U.S. are now owned by lenders and investment companies. Furthermore, mergers and asset reallocations in the industry could create powerful new competitors. Under any scenario, we anticipate that we will face competition from numerous companies in the industry.

        In addition, the retail marketing activities compete for customers in a competitive environment, which impacts the margins that we can earn on the volumes we are able to serve. Further, with retail competition, residential customers where we serve load can switch to and from competitive electric generation suppliers for their energy needs. If fewer customers switch to another supplier than anticipated, the load we must serve will be greater and, if market prices have increased, our costs will increase due to the need to go to the market to cover the incremental supply obligation. If more customers switch to another supplier than anticipated, the load we must serve will be lower and, if market prices have decreased, we could lose opportunities in the market.

        Moreover, many companies in the regulated utility industry, with which the wholesale power industry is closely linked, are also restructuring or reviewing their strategies. Several of those companies have discontinued or are discontinuing their unregulated activities and seeking to divest or spin-off their unregulated subsidiaries. This may lead to increased competition between the regulated utilities and the

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unregulated power producers within certain markets. To the extent that competition increases, our financial condition, results of operations and cash flows may be materially adversely affected.

With the exception of Joppa, we do not own or control transmission facilities required to sell the wholesale power from our generation facilities. If the transmission service is inadequate, our ability to sell and deliver wholesale power may be materially adversely affected. Furthermore, RTOs and ISOs administer the transmission infrastructure and market, which are subject to changes in structure and operation and impose various pricing limitations. These changes and pricing limitations may affect our ability to deliver power to the market that would, in turn, adversely affect the profitability of our generation facilities.

        Other than for Joppa, which owns and controls transmission lines interconnecting the EEI control area to MISO, TVA and LGE, we do not own or control the transmission facilities required to sell the wholesale power from most of our generation facilities. If the transmission service from these facilities is unavailable or disrupted, or if the transmission capacity infrastructure is inadequate, our ability to sell and deliver wholesale power may be materially adversely affected. RTOs and ISOs provide transmission services, administer transparent and competitive power markets and maintain system reliability. Many of these RTOs and ISOs operate in the real-time and day-ahead markets in which we sell energy. The RTOs and ISOs that oversee most of the wholesale power markets impose, and in the future may continue to impose, offer caps and other mechanisms to guard against the potential exercise of market power in these markets as well as price limitations. These types of price limitations and other regulatory mechanisms may adversely affect the profitability of our generation facilities that sell energy and capacity into the wholesale power markets. Problems or delays that may arise in the formation and operation of maturing RTOs and similar market structures, or changes in geographic scope, rules or market operations of existing RTOs, may also affect our ability to sell, the prices we receive or the cost to transmit power produced by our generating facilities. Market design as well as rules governing the various regional power markets may also change from time to time, which could affect our costs or revenues. Additionally, if the transmission service from these facilities is unavailable or disrupted, or if the transmission capacity infrastructure is inadequate, our ability to sell and deliver wholesale power may be materially adversely affected. Furthermore, the rates for transmission capacity from these facilities are set by others and thus are subject to changes, some of which could be significant. As a result, our financial condition, results of operations and cash flows may be materially adversely affected.

Our Retail business is subject to the risk that sensitive customer data may be compromised, which could result in an adverse impact to our reputation and/or the results of operations of the Retail business.

        The Retail business requires access to sensitive customer data in the ordinary course of business. Examples of sensitive customer data are names, addresses, account information, historical electricity usage, expected patterns of use, payment history, credit bureau data and bank account information. The Retail business may need to provide sensitive customer data to vendors and service providers who require access to this information in order to provide services, such as call center operations, to the Retail business. If a significant breach occurred, our reputation and that of Homefield Energy may be adversely affected, customer confidence may be diminished or we may be subject to legal claims, any of which may contribute to the loss of customers and have a negative impact on our business and/or financial condition, results of operations and cash flows.

Unauthorized hedging and related activities by our employees could result in significant losses.

        We intend to continue our commercial strategy, which emphasizes forward power sales opportunities intended to reduce the market price exposure of the Company to power price declines. We have various internal policies and procedures designed to monitor hedging activities and positions. These policies and procedures are designed, in part, to prevent unauthorized purchases or sales of products by our employees. We cannot assure, however, that these steps will detect and prevent all violations of our risk management

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policies and procedures, particularly if deception or other intentional misconduct is involved. A significant policy violation that is not detected could result in a substantial financial loss for us.

Our risk management policies cannot fully eliminate the risk associated with our commodity trading activities.

        Our asset-based power position as well as our power marketing, fuel procurement and other commodity trading activities expose us to risks of commodity price movements. We attempt to manage this exposure through enforcement of established risk limits and risk management procedures. These risk limits and risk management procedures may not work as planned and cannot eliminate all risks associated with these activities. Even when our policies and procedures are followed, and decisions are made based on projections and estimates of future performance, results of operations may be diminished if the judgments and assumptions underlying those decisions prove to be incorrect. Factors, such as future prices and demand for power and other energy-related commodities, become more difficult to predict and the calculations become less reliable the further into the future estimates are made. As a result, we cannot predict the impact that our commodity trading activities and risk management decisions may have on our business and/or financial condition, results of operations and cash flows.

Our financial condition, results of operations and cash flows would be adversely impacted by strikes or work stoppages by our unionized employees.

        A majority of the employees at our facilities and the Target Companies' facilities are subject to collective bargaining agreements with various unions. Additionally, unionization activities, including votes for union certification, could occur at our non-union generating facilities in our fleet. If union employees strike, participate in a work stoppage or slowdown or engage in other forms of labor strike or disruption, we could experience reduced power generation or outages if replacement labor is not procured. The ability to procure such replacement labor is uncertain. Strikes, work stoppages or an inability to negotiate future collective bargaining agreements on commercially reasonable terms could have a material adverse effect on our financial condition, results of operations and cash flows.

The IPH segment's ring-fencing structure may not work as planned and Dynegy may be subject to the claims of the creditors of IPH and its subsidiaries.

        In connection with the AER Acquisition, IPH and its direct and indirect subsidiaries were organized into ring-fenced groups. The entities within the IPH ring-fenced structure maintain corporate separateness from our other current legal entities. This structure was implemented, in part, to minimize the risk that creditors of IPH, or a bankruptcy trustee if any entity of the IPH segment were to become a debtor in a bankruptcy case, would attempt to assert claims against Dynegy for payment of IPH's obligations. We believe the ring-fenced structure should preclude any corporate veil-piercing or other similar claims of IPH's creditors but, if any such claims were successful, it could have a material adverse effect on our financial position, results of operations and cash flows. We also believe the ring-fenced structure should preclude any bankruptcy court from ordering the substantive consolidation of Dynegy's assets and liabilities with the assets and liabilities of any IPH debtor in bankruptcy. However, bankruptcy courts have broad equitable powers, and as a result, outcomes in bankruptcy proceedings are inherently difficult to predict. To the extent a bankruptcy court were to determine that substantive consolidation was appropriate under the facts and circumstances, it could have a material adverse effect on our financial position, results of operations and cash flows.

Terrorist attacks and/or cyber-attacks may result in our inability to operate and fulfill our obligations, and could result in material repair costs.

        As a power generator, we face heightened risk of terrorism, including cyber terrorism, either by a direct act against one or more of our generating facilities or an act against the transmission and distribution infrastructure that is used to transport our power. We rely on information technology networks

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and systems to operate our generating facilities, engage in asset management activities and process, transmit and store electronic information. Security breaches of this information technology infrastructure, including cyber-attacks and cyber terrorism, could lead to system disruptions, generating facility shutdowns or unauthorized disclosure of confidential information related to our employees, vendors and counterparties.

        Systemic damage to one or more of our generating facilities and/or to the transmission and distribution infrastructure could result in our inability to operate in one or all of the markets we serve for an extended period of time. If our generating facilities are shut down, we would be unable to respond to the ISOs and RTOs or fulfill our obligations under various energy and/or capacity arrangements, resulting in lost revenues and potential fines, penalties and other liabilities. Pervasive cyber-attacks across our industry could affect the ability of ISOs and RTOs to function in some regions. The cost to restore our generating facilities after such an occurrence could be material.

Risks Related to Investing

Our indebtedness could adversely affect our ability to raise additional capital to fund our operations. It could also expose us to the risk of increased interest rates and limit our ability to react to changes in the economy or our industry as well as impact our cash available for distribution.

        As of June 30, 2014, we had approximately $2.1 billion of total indebtedness and approximately $1.2 billion of indebtedness net of cash. Following the completion of this offering, on a pro forma basis to give effect to the Acquisitions, the Debt Financings, the Mandatory Convertible Preferred Stock Offering and this offering, we expect to have approximately $7.2 billion of total indebtedness and approximately $6.2 billion of indebtedness net of cash. We have secured commitments for two incremental revolving credit facilities totaling $950 million, each of which is expected to close upon consummation of the respective Acquisition. We expect to have approximately $600 million available, net of expected letters of credit outstanding, for future borrowings under our revolving credit facility immediately following the completion of the Acquisitions. Our debt could have important negative consequences for our financial condition including:

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        We may not be successful in obtaining additional capital for these or other reasons. Furthermore, we may be unable to refinance or replace our existing indebtedness on favorable terms or at all upon the expiration or termination thereof. Our failure to obtain additional capital or enter into new or replacement financing arrangements when due may constitute a default under such existing indebtedness and may have a material adverse effect on our business, financial condition, results of operations and cash flows.

Our existing credit facilities contain, and agreements we enter into in the future may contain, covenants that significantly restrict our operations and our ability to redeem our Mandatory Convertible Preferred Stock.

        Our existing credit facilities contain covenants imposing financial and operating restrictions on our business. These restrictions may affect our ability to operate our business, may limit our ability to take advantage of potential business opportunities as they arise and may adversely affect the conduct of our current business, including restricting our ability to finance future operations and capital needs and limiting our ability to engage in other business activities. These covenants will place restrictions on our ability and the ability of our operating subsidiaries to, among other things:

        These restrictions may also limit our ability to obtain future financings, withstand a future downturn in our business or the economy in general, or otherwise conduct necessary corporate activities. We may also be prevented from taking advantage of business opportunities that arise because of the limitations that the restrictive covenants under our existing credit facilities impose on us. Agreements we enter into in the future may also have covenants that restrict our operations. A breach of any covenant in the existing credit facilities or the agreements governing our other indebtedness would result in a default. A default, if not waived, could result in acceleration of the debt outstanding under any such agreement and in a default with respect to, and acceleration of, the debt outstanding under any other debt agreements. The accelerated debt would become due and payable immediately. If that should occur, we may not be able to make all of the required payments or borrow sufficient funds to refinance it. Even if new financing were then available, it may not be on terms that are acceptable to us.

Risks Related to this Offering and Ownership of Our Common Stock

The market price of our common stock may be volatile, which could cause the value of your investment to decline.

        The prevailing price of our common stock on the NYSE after this offering and the Mandatory Convertible Preferred Stock Offering may fluctuate substantially and may be higher or lower than the price you have paid in this offering. Numerous factors, including many over which we have no control, may have a significant impact on the market price of our common stock. These risks include those described or

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referred to in this "Risk Factors" section and in the other documents incorporated herein by reference as well as, among other things:

        In addition, investors in the Mandatory Convertible Preferred Stock may employ a convertible arbitrage strategy with respect to the Mandatory Convertible Preferred Stock by selling short the common stock underlying the Mandatory Convertible Preferred Stock or by entering into cash-settled over-the-counter derivative transactions with respect to the underlying common stock that have the same economic effect. Short sales of our common stock or derivative actions having the same economic effect could adversely impact the market price of our common stock.

Sales of substantial amounts of our common stock in the public market and the conversion of our Mandatory Convertible Preferred Stock or the payment of dividends thereon in the form of stock, or the perception that these events may occur, could cause the market price of our common stock to decline.

        Sales of substantial amounts of our common stock in the public market, or the perception that these sales may occur, could cause the market price of our common stock to decline. In particular, pursuant to a registration rights agreement with Franklin Advisers, Inc. ("Franklin"), on October 2, 2013, we filed a registration statement with the SEC which permits Franklin to publicly offer and sell from time to time an aggregate of up to 31,459,816 shares of our common stock owned by it. As of August 14, 2014, Franklin was the beneficial owner of 18,927,023 shares of our common stock. We do not know when or in what amounts Franklin may offer these shares of common stock for sale. Any such sales could impact the market price of our common stock. An increase in the number of available shares of our common stock may make it more difficult for us to sell equity securities in the future at a time and price we deem appropriate.

        In addition, the market price of our common stock could also decline as a result of the conversion of our Mandatory Convertible Preferred Stock or the payment of dividends on the Mandatory Convertible Preferred Stock in the form of shares of our common stock, or the perception that such conversions or dividends could occur.

Our common stock will rank junior to the Mandatory Convertible Preferred Stock with respect to dividends and amounts payable in the event of our liquidation and ranks junior to our indebtedness.

        Our common stock will rank junior to the Mandatory Convertible Preferred Stock with respect to the payment of dividends and amounts payable in the event of our liquidation, dissolution or winding-up. This means that, unless accumulated dividends have been paid or set aside for payment on all outstanding Mandatory Convertible Preferred Stock for all completed dividend periods, no dividends may be declared or paid on our common stock. Likewise, in the event of our voluntary or involuntary liquidation, dissolution or winding-up, no distribution of our assets may be made to holders of our common stock until

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we have paid to holders of the Mandatory Convertible Preferred Stock a liquidation preference equal to $100.00 per share plus accrued and unpaid dividends.

        Additionally, in the event of our liquidation, dissolution or winding up, our common stock would rank below all debt claims against us. As a result, holders of our common stock will not be entitled to receive any payment or other distribution of assets upon our liquidation, dissolution or winding up until after all of our obligations to our debt holders have been satisfied.

Our board of directors may, without stockholder approval, cause the issuance of shares of preferred stock with rights which could adversely affect the right of holders of our common stock or could discourage, delay or prevent a change of control of us.

        Our third amended and restated certificate of incorporation provides for the issuance of up to 20,000,000 shares of preferred stock with such designations, rights and preferences as may be determined from time to time by our board of directors. A portion of this preferred stock will be issued pursuant to the Mandatory Convertible Preferred Stock Offering. However, after the consummation of the Mandatory Convertible Preferred Stock Offering, we will still have a significant amount of authorized but unissued shares of preferred stock. Our board of directors may, without further stockholder approval, cause the issuance of preferred stock with dividend, liquidation, conversion, voting or other rights which could adversely affect the voting power or other rights of the holders of our common stock. If issued, the preferred stock could also dilute the holders of our common stock and could discourage, delay or prevent a change of control of us, including transactions in which stockholders might receive a premium for their shares.

We do not currently anticipate paying cash dividends on our common stock in the foreseeable future.

        We have paid no cash dividends on our common stock and have no current intention of doing so. Any future determination to pay cash dividends will be at the discretion of our Board, subject to applicable limitations under Delaware law, and will be dependent upon our results of operations, financial condition, contractual restrictions and other factors deemed relevant by our Board.

The ownership position of Franklin limits other stockholders' ability to influence corporate matters and could affect the price of our common stock.

        As of August 14, 2014, Franklin had sole dispositive power over 18% of our outstanding common stock, or 15% immediately after giving effect to this offering. As a result, it, or any entity to which it sells our common stock, may be able to exercise significant control over matters requiring stockholder approval. Further, the sale of our common stock by a large shareholder may have an adverse effect on the market price for our common stock.

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SPECIAL NOTE ON FORWARD-LOOKING STATEMENTS

        In addition to historical information, this prospectus supplement contains, and the accompanying prospectus and any documents incorporated by reference herein and therein may contain, "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995, Section 27A of the Securities Act, and Section 21E of the Exchange Act. We use words such as "believe," "intend," "expect," "anticipate," "plan," "may," "will," "should," "estimate," "potential," "project" and similar expressions to identify forward-looking statements. Such statements include, among others, those concerning our expected financial performance and strategic and operational plans, as well as all assumptions, expectations, predictions, intentions or beliefs about future events. You are cautioned that any such forward-looking statements are not guarantees of future performance and that a number of risks and uncertainties could cause actual results to differ materially from those anticipated in the forward-looking statements. Such risks and uncertainties include, but are not limited to:

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        This discussion of uncertainties is by no means exhaustive but is designed to highlight important factors that may impact our outlook. We disclaim any obligation or intent to update forward-looking statements made by us in order to reflect new information, events or circumstances after the date they are made.

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USE OF PROCEEDS

        We estimate that the net proceeds from this offering, after deducting underwriting discounts, commissions and before estimated offering expenses, will be approximately $680.5 million (or approximately $782.6 million if the underwriters exercise their option to purchase additional shares of common stock in full), in each case based on the assumed public offering price per share of common stock set forth below. We intend to use the net proceeds from this offering, together with the net proceeds of the concurrent Mandatory Convertible Preferred Stock Offering and the Debt Financings, the common stock placement to ECP and cash on hand to finance the Acquisitions and to pay related fees and expenses. If we consummate only one of the Acquisitions, we will use some or all of the net proceeds of this offering to fund the Acquisition that is consummated and any remaining amount for general corporate purposes. If neither of the Acquisitions are consummated, we will use all of the net proceeds of this offering for general corporate purposes.

        The following table outlines the sources and uses of funds for the Transactions. The table assumes that the Acquisitions and the Financing Transactions are completed simultaneously, although the Financing Transactions are expected to occur before consummation of the Acquisitions. The table also assumes that we complete the Transactions on the terms and in accordance with the assumptions set forth under "Summary Unaudited Pro Forma Condensed Combined Financial Information" and in the Pro Forma Form 8-K, which is incorporated by reference into this prospectus supplement.

        All of the amounts in the following table are estimated. The actual amount of net proceeds from this offering will likely be different from the amount reflected in the following table, and other actual amounts may vary from the estimated amounts set forth below.

Source of Funds   Use of Funds  
(Dollars in millions)
 

Common Stock Offering

  $ 680.5  

Duke Midwest Acquisition consideration

  $ 2,800.0  

Mandatory Convertible Preferred Stock Offering

    388.0  

ERC and Brayton Acquisitions consideration

    3,450.0  

Debt Financing

    5,100.0  

Transaction expenses

    160.0  
                 

Common Stock Placement to ECP(1)

    200.0  

 

       

Cash on hand

    41.5            
                 

Total sources of funds

  $ 6,410  

Total uses of funds

  $ 6,410  
               
               

(1)
In accordance with the ERC Purchase Agreements, the purchase price for the EquiPower Acquisition is $3.25 billion of cash and $200.0 million of our common stock issued in a transaction exempt from registration under the Securities Act. The final number of shares issued for the EquiPower Acquisition will be based on the weighted average trading price of the 10 day trading period ending on the second business day immediately preceding the closing of the EquiPower Acquisition. In certain circumstances, we will have the option to pay some or all of this amount in cash. For additional information, see the ERC purchase agreement, a copy of which is attached as Exhibit 2.2 on our Current Report on Form 8-K, filed on August 26, 2014, and the terms of which are incorporated by reference herein.

        For more information, see "Summary Unaudited Pro Forma Condensed Combined Financial Information" included in this prospectus supplement and in the Unaudited Pro Forma Condensed Combined Financial Information filed as an exhibit to the Pro Forma Form 8-K, which is incorporated by reference into this prospectus supplement.

        The estimated net proceeds from this offering reflected in this section have been calculated by assuming a public offering price of $31.27 per share of common stock, which is equal to the last reported

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sale price of the common stock on the New York Stock Exchange on October 3, 2014. A $1.00 increase (decrease) in the public offering price per share of common stock would increase (decrease) the estimated net proceeds received by us from this offering by approximately $21.8 million (or approximately $25.1 million if the underwriters' option to purchase additional shares of common stock is exercised in full), after deducting estimated underwriting discounts and commissions and before estimated offering expenses payable by us.

        The estimated net proceeds from the Mandatory Convertible Preferred Stock Offering have been calculated by assuming a public offering price of $100.00 per Mandatory Convertible Preferred Stock. In addition, we will have the option to redeem, in whole but not in part, all of the Mandatory Convertible Preferred Stock (in cash, by delivery of our common stock, or by delivery of any combination of cash and common stock) if either or both of the Acquisitions is terminated.

        If one or the other of the Acquisitions is not consummated, we will be required to redeem the Debt Financing in connection with such contemplated but unconsummated Acquisition.

        To the extent that the aggregate net proceeds from this offering and the Mandatory Convertible Preferred Stock Offering are less than the aggregate amount assumed in the above table (whether due to a change in the respective public offering prices or number of shares issued or sold), we intend to increase the amount of debt borrowed in the Debt Financing to effect the Acquisitions by a similar amount. However, if any of the Financing Transactions is not completed or the aggregate net proceeds from the Financing Transactions are less than the amount we have assumed for purposes of the above table, we may be required to obtain additional financing or utilize cash on hand in order to effect the Acquisitions.

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CAPITALIZATION

        The following table sets forth our consolidated cash and cash equivalents and our consolidated capitalization as of June 30, 2014:

        The as adjusted data in the following table assumes that the applicable transactions had been completed as of June 30, 2014, on the terms and in accordance with the assumptions set forth under "Summary Unaudited Pro Forma Condensed Combined Financial Information" included in this prospectus supplement and in the Unaudited Pro Forma Condensed Combined Financial Information filed as an exhibit to the Financial Statement Form 8-K, which is incorporated by reference into this prospectus supplement. You should read the following information in conjunction with the sections entitled "Risk Factors," "Summary Unaudited Pro Forma Condensed Combined Financial Information" included in this prospectus supplement, the Unaudited Pro Forma Condensed Combined Financial Information filed as an exhibit to the Pro Forma Form 8-K and the sections entitled "Management's Discussion and Analysis of Financial Condition and Results of Operations" contained in our Annual Report on Form 10-K for the year ended December 31, 2013, and in our Quarterly Report on Form 10-Q for the quarters ended March 31, 2014 and June 30, 2014, each incorporated by reference in this prospectus supplement, and the financial statements of Dynegy, AER, the Duke Midwest Assets and the ECP Assets and the related notes incorporated by reference into this prospectus supplement. The data presented in the following table is for illustrative purposes only, does not purport to reflect what our actual financial position would have been had this offering (and the use of proceeds contemplated hereby)

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actually taken place on such date and is not necessarily indicative of our financial position as of the specified date or in the future.

 
  As of June 30, 2014  
 
   
   
  As Further Adjusted    
 
 
  Actual   Adjusted
for this
Offering
  For the
Mandatory
Convertible
Preferred
Stock
Offering
  For the
Debt
Financing
  For the
Duke
Midwest
Acquisition
  For the
ERC and
Brayton
Acquisitions
  Total, as
Adjusted
 
 
  (in millions)
 

Cash and cash equivalents

  $ 948   $ 680   $ 388   $ 4,977   $ (2,849 ) $ (3,180 ) $ 964  
                               
                               

Long-term debt (including current portion):

                                           

Revolving Credit Facility(1)(2)

  $   $   $   $   $   $   $  

Tranche B-2 Term Loan Agreement

    792                         792  

5.875% Senior Notes due 2023

    500                         500  

7.95% Senior Notes due 2032

    275                         275  

7.00% Senior Notes due 2018

    300                         300  

6.30% Senior Notes due 2020

    250                         250  

Debt financing

                5,100             5,100  

Emissions Repurchase Agreements

    29                         29  

Unamortized discount on debt, net

    (138 )                       (138 )
                               

Total long-term debt (including current portion)

  $ 2,008   $   $   $ 5,100   $   $   $ 7,108  

Stockholders' equity

                                           

Common stock, $0.01 par value, 420,000,000 shares authorized at June 30, 2014 and December 31, 2013; 100,363,958 shares and 100,202,036 shares issued and outstanding at June 30, 2014 and December 31, 2013, respectively

    1                         1  

Additional paid-in capital

    2,623     680     388             200     3,891  

Accumulated other comprehensive income, net of tax

    54                         54  

Accumulated deficit

    (627 )           (48 )   (18 )   1,049     356  
                               

Total Dynegy stockholders' equity

  $ 2,051   $ 680   $ 388   $ (48 ) $ (18 ) $ 1,249   $ 4,302  

Noncontrolling interest

    1                         1  
                               

Total equity

    2,052     680     388     (48 )   (18 )   1,249     4,303  
                               

Total capitalization

  $ 4,060   $ 680   $ 388   $ 5,052   $ (18 ) $ 1,249   $ 11,411  
                               
                               

(1)
Dynegy has a $1.275 billion credit agreement that consists of (i) an $800 million seven-year senior secured term loan B facility and (ii) a $475 million five-year senior secured revolving credit facility. In addition, we have secured commitments for two incremental revolving credit facilities totaling $950 million, each of which is expected to close upon consummation of the respective Acquisition.

(2)
At June 30, 2014, there were no amounts drawn on the Revolving Credit Facility; however, we had outstanding letters of credit of approximately $181 million, which reduces the amount available under the Revolving Credit Facility.

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PRICE RANGE OF OUR COMMON STOCK

        Our common stock is listed on the NYSE under the symbol "DYN" and has been trading since October 3, 2012. No prior established public trading market existed for our common stock prior to that date. The following table sets forth the per share high and low closing prices for our common stock as reported on the NYSE for the periods presented.

 
  High   Low  

2014:

             

Fourth Quarter through October 3, 2014

  $ 31.27   $ 30.00  

Third Quarter

  $ 34.28   $ 26.55  

Second Quarter

  $ 36.14   $ 24.80  

First Quarter

  $ 22.70   $ 19.57  

2013:

             

Fourth Quarter

  $ 21.93   $ 18.50  

Third Quarter

  $ 22.79   $ 19.09  

Second Quarter

  $ 24.76   $ 22.00  

First Quarter

  $ 23.99   $ 19.39  

2012

             

Fourth Quarter

  $ 19.35   $ 17.35  

        The closing price of our common stock on the NYSE on October 3, 2014 was $31.27 per share.

        As of October 2, 2014, we had approximately 2,666 holders of record of our common stock, based on information provided by our transfer agent.




DIVIDEND POLICY

        We have paid no cash dividends on our common stock and have no current intention of doing so. Any future determination to pay cash dividends will be at the discretion of our Board, subject to applicable limitations under Delaware law, and will be dependent upon our results of operations, financial condition, contractual restrictions and other factors deemed relevant by our Board.

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THE TRANSACTIONS

        The following is a description of some of the terms of the Transactions. For information concerning our existing indebtedness, see "Management's Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources—Financing Activities" in our Annual Report on Form 10-K for the year ended December 31, 2013, incorporated by reference in this prospectus supplement and note 12 to our consolidated financial statements included in such Form 10-K.

Overview

        In August 2014, we entered into agreements with Duke to purchase certain of its facilities located in the Midwest and its retail energy business for a purchase price of $2.8 billion in cash (subject to certain adjustments), and with ECP to purchase ERC and Brayton for a purchase price of approximately $3.25 billion in cash and $200 million of our common stock (subject to certain adjustments). The Acquisitions will increase our generation capacity by approximately 12,500 MW to nearly 26,000 MW.

        The Financing Transactions are expected to occur in connection with, but prior to, the Acquisitions. Because none of the Financing Transactions is contingent on any of the other Financing Transactions, it is possible that one or more of the Financing Transactions will not be completed. We intend to use the net proceeds from this offering, together with the net proceeds of the concurrent Mandatory Convertible Preferred Stock Offering and the Debt Financings, to finance the Acquisitions and to pay related fees and expenses. To the extent that the aggregate net proceeds from this offering and the Mandatory Convertible Preferred Stock Offering are less than the aggregate amount assumed in the table under the heading "Use of Proceeds" in this prospectus supplement (whether due to a change in the respective public offering prices or number of shares issued or sold), we intend to increase the amount of debt borrowed in the Debt Financing to effect the Acquisitions by a similar amount. However, if any of the Financing Transactions is not completed or the aggregate net proceeds from the Financing Transactions are less than the amount we have assumed for purposes of the such table, we may be required to obtain additional financing or utilize cash on hand in order to consummate the Acquisitions. If we consummate only one of the Acquisitions, we will use some or all of the net proceeds of this offering to fund the Acquisition that is consummated and any remaining amount for general corporate purposes. If we do not consummate either of the Acquisitions, we will use all of the net proceeds from this offering for general corporate purposes. See "Use of Proceeds," included in this prospectus supplement.

        We anticipate that the Duke Midwest Acquisition and ERC and Brayton Acquisitions will each close by the end of the first quarter of 2015. However, we cannot assure you that the Acquisitions will be consummated or, if consummated, that they will be consummated at the price, within the time period or on the terms and with the anticipated benefits contemplated by this prospectus supplement. The closing of one Acquisition is not contingent upon the closing of the other Acquisition and this offering is not contingent on either or both of the Acquisitions occurring on a timely basis or at all. See "Risk Factors—Risks Relating to Our Proposed Acquisitions," included in this prospectus supplement.

Duke Midwest Purchase Agreement

        On August 21, 2014, Dynegy Inc.'s wholly-owned subsidiary, Dynegy Resource I, LLC ("DRI"), a Delaware limited liability company, entered into the Duke Midwest Purchase Agreement with Duke Energy SAM, LLC ("Duke Energy SAM"), a Delaware limited liability company, and Duke Energy Commercial Enterprises, Inc., an Indiana corporation ("Duke Energy CE" and, together with Duke Energy SAM, "Duke Energy"), pursuant to which DRI will, subject to the terms and conditions in the Duke Midwest Purchase Agreement, purchase from Duke Energy 100% of the membership interests in Duke Energy Commercial, an Ohio limited liability company, and Duke Energy Retail Sales, a Delaware limited liability company, thereby acquiring (i) five natural gas-fired power facilities located in Ohio, Pennsylvania and Illinois, (ii) one oil-fired power facility located in Ohio, (iii) partial interests in five

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coal-fired power facilities located in Ohio and (iv) a retail energy business for a base purchase price of $2.8 billion in cash, subject to certain adjustments, including, among others, Duke Energy's (A) level of working capital at closing relative to target working capital and (B) actual capital expenditures relative to budgeted capital expenditures through the closing date. The closing of the Duke Midwest Acquisition is expected to occur by the end of the first quarter of 2015.

        The Duke Midwest Purchase Agreement includes customary representations, warranties and covenants by the parties, and is subject to various closing conditions, including (i) obtaining approval of the FERC under Section 203 of the Federal Power Act, as amended, and other required governmental consents and approvals; (ii) no injunction or other orders preventing the consummation of the transactions contemplated under the Duke Midwest Purchase Agreement; (iii) the continuing accuracy of each party's representations and warranties; and (iv) the satisfaction of other customary conditions.

        Each party has agreed to indemnify the other for breaches of representations and warranties, breaches of covenants and certain other matters, subject to certain exceptions and limitations.

        The Duke Midwest Purchase Agreement contains certain termination rights for both DRI and Duke Energy, including if the closing does not occur within nine months following the date of the Duke Midwest Purchase Agreement (subject to extension to 12 months, if necessary to obtain applicable governmental approvals).

        The foregoing description of the Duke Midwest Purchase Agreement and the transactions contemplated thereby is subject to and qualified in its entirety by reference to the full text of the Duke Midwest Purchase Agreement, a copy of which is attached as Exhibit 2.1 to our Current Report on Form 8-K, filed on August 26, 2014, which is incorporated herein by reference. The Duke Midwest Purchase Agreement has been incorporated by reference into this prospectus supplement to provide investors with information regarding the terms of the Duke Midwest Acquisition and is not intended to provide any factual information about us, Duke or their respective subsidiaries or affiliates. The Duke Midwest Purchase Agreement contains representations and warranties that the parties made to each other as of specific dates. The assertions embodied in those representations and warranties were made solely for purposes of the contracts between the parties to the Duke Midwest Purchase Agreement and may be subject to important qualifications and limitations agreed by the parties in connection with negotiating the terms of the contracts. Moreover, some of those representations and warranties may not be accurate or complete as of any specified date, may be subject to a contractual standard of materiality different from those generally applicable to stockholders, or may have been used for the purpose of allocating risk between the parties rather than establishing matters as facts. For the foregoing reasons, investors should not rely on the representations and warranties as statements of factual information. The representations and warranties in the Duke Midwest Purchase Agreement and the description of them in this prospectus supplement should not be read alone but instead should be read in conjunction with the other information contained in our reports, statements and filings publicly filed with the SEC. Such information can be found elsewhere in this prospectus supplement and in the public filings we make with the SEC, as described in the sections entitled "Where You Can Find More Information" and "Incorporation by Reference," included in this prospectus supplement.

ERC Purchase Agreements

        Also on August 21, 2014, Dynegy's wholly-owned subsidiary, Dynegy Resource II, LLC, a Delaware limited liability company (the "ERC Purchaser"), entered into a stock purchase agreement with Energy Capital Partners II, LP, a Delaware limited partnership ("ECP II"), Energy Capital Partners II-A, LP, a Delaware limited partnership ("ECP II-A"), Energy Capital Partners II-B, LP, a Delaware limited partnership ("ECP II-B"), Energy Capital Partners II-C (Direct IP), LP, a Delaware limited partnership ("ECP II-C"), Energy Capital Partners II-D, LP, a Delaware limited partnership ("ECP II-D"), and Energy Capital Partners II (ERC Co-Invest), LP, a Delaware limited partnership ("ECP Coinvest" and,

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collectively with ECP II, ECP II-A, ECP II-B, ECP II-C and ECP II-D, the "ERC Sellers"), ERC, a Delaware corporation, and, solely for certain limited purposes set forth therein, each of Energy Capital Partners II-C, LP, a Delaware limited partnership ("ECP II-C Fund"), and Dynegy, pursuant to which the ERC Purchaser will, subject to the terms and conditions in the stock purchase agreement, purchase from the ERC Sellers 100% of the equity interests in ERC, thereby acquiring (i) five combined cycle gas turbines in Connecticut, Massachusetts and Pennsylvania, (ii) a partial interest in one natural gas-fired peaking facility in Illinois, (iii) two gas- and oil-fired peaking facilities in Ohio and (iv) one coal-fired facility in Illinois.

        On August 21, 2014, in a related transaction, Dynegy's wholly-owned subsidiaries, Dynegy Resource III, LLC, a Delaware limited liability company (the "Brayton Purchaser" and, together with the ERC Purchaser, the "ECP Purchasers"), and Dynegy Resources III-A, LLC, a Delaware limited liability company ("Merger Sub"), entered into a stock purchase agreement and agreement and plan of merger with Energy Capital Partners GP II, LP, a Delaware limited partnership ("ECP GP"), ECP II, ECP II-A, ECP II-B, ECP II-D, and Energy Capital Partners II-C (Cayman), L.P., a Cayman Islands limited partnership ("ECP II-C (Cayman)" and, collectively with ECP GP, ECP II, ECP II-A, ECP II-B and ECP II-D, the "Brayton Sellers" and, together with the ERC Sellers, the "ECP Sellers"), Brayton, a Delaware limited liability company, and, solely for certain limited purposes set forth therein, each of ECP II-C Fund and Dynegy, pursuant to which Brayton Purchaser will, subject to the terms and conditions in the agreement, acquire from the Brayton Sellers and other holders of equity interests in Brayton, through a stock purchase and the related merger of Merger Sub with and into Brayton, 100% of the equity interests in Brayton. The closing of each of the ERC and Brayton Acquisitions is contingent on the simultaneous closing of the other acquisition, and such closings are expected to occur by the end of the first quarter of 2015. The aggregate base purchase price for the ERC and Brayton Acquisitions is $3.25 billion in cash plus $200 million in common stock of Dynegy, subject to certain adjustments, including, among others, the level of working capital, indebtedness, and emission allowances at closing.

        Each ERC Purchase Agreement includes customary representations, warranties and covenants by the respective parties thereto, and is subject to various closing conditions, including (i) obtaining FERC Approval and other required governmental approvals; (ii) no injunction or other legal prohibition preventing the closing under the applicable ERC Purchase Agreement; (iii) the continuing accuracy of each applicable party's representations and warranties; and (iv) the satisfaction of other customary conditions.

        Under each ERC Purchase Agreement, the applicable parties have agreed to indemnify the other applicable parties for breaches of representations and warranties, breaches of covenants and certain other matters, subject to certain exceptions and limitations. The ECP Purchasers shall, in the aggregate, not be entitled to indemnification in excess of $276.0 million, and a portion of the purchase price will be held in escrow for one year after closing to support the indemnification obligations of the ECP Sellers.

        Each ERC Purchase Agreement contains certain termination rights for the respective ECP Purchasers and ECP Sellers, including if the closing of the applicable ERC Purchase Agreement does not occur by May 8, 2015. Each ERC Purchase Agreement provides for the payment of a termination fee by Dynegy under specific circumstances, including where the applicable ERC Purchase Agreement is terminated because of a breach of the representations, warranties or covenants by the applicable ECP Purchaser.

        The foregoing description of the ERC Purchase Agreements and the transactions contemplated thereby is subject to and qualified in its entirety by reference to the full text of the ERC Purchase Agreements, copies of which are attached as Exhibit 2.2 and 2.3 to our Current Report on Form 8-K, filed on August 26, 2014, respectively, which is incorporated herein by reference. The ERC Purchase Agreements have been incorporated by reference into this prospectus supplement to provide investors with information regarding the terms of the ERC and Brayton Acquisitions and is not intended to provide any factual information about us, ERC or their respective subsidiaries or affiliates. The ERC Purchase

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Agreements contain representations and warranties that the parties made to each other as of specific dates. The assertions embodied in those representations and warranties were made solely for purposes of the contracts between the parties to the ERC Purchase Agreements and may be subject to important qualifications and limitations agreed by the parties in connection with negotiating the terms of the contracts. Moreover, some of those representations and warranties may not be accurate or complete as of any specified date, may be subject to a contractual standard of materiality different from those generally applicable to stockholders, or may have been used for the purpose of allocating risk between the parties rather than establishing matters as facts. For the foregoing reasons, investors should not rely on the representations and warranties as statements of factual information. The representations and warranties in the ERC Purchase Agreements and the description of them in this prospectus supplement should not be read alone but instead should be read in conjunction with the other information contained in our reports, statements and filings publicly filed with the SEC. Such information can be found elsewhere in this prospectus supplement and in the public filings we make with the SEC, as described in the sections entitled "Where You Can Find More Information" and "Incorporation by Reference," included in this prospectus supplement.

The Financing Transactions

        We are using the proceeds of the Financing Transactions to finance the Acquisitions and pay related fees and expenses. This offering and the Mandatory Convertible Preferred Stock Offering are being made concurrently, each pursuant to a separate prospectus supplement. Subsequent to this offering and the Mandatory Convertible Preferred Stock Offering, we expect to obtain the Debt Financing. The completion of this offering is not contingent on the completion of the Mandatory Convertible Preferred Stock Offering or the Debt Financing, and neither the Mandatory Convertible Preferred Stock Offering nor the Debt Financing is contingent on the completion of this offering. In addition, none of this offering, the Mandatory Convertible Preferred Stock Offering or the Debt Financing is or will be contingent on the consummation of the Acquisitions. This prospectus supplement is not an offer to sell or a solicitation of an offer to buy any securities being offered in the Mandatory Convertible Preferred Stock Offering or the Debt Financing.

        Mandatory Convertible Preferred Stock Offering.    Concurrently with this offering, we are offering, by means of a separate prospectus supplement, 4,000,000 of our Series A Mandatory Convertible Preferred Stock, par value $0.01 per share, plus up to an additional 600,000 shares of such Mandatory Convertible Preferred Stock that the underwriters of such offering have the option to purchase from us, exercisable within 30 days from the date of the prospectus supplement for the Mandatory Convertible Preferred Stock Offering, in connection with the financing of the Acquisitions. We will have the option to redeem, in whole but not in part, all of the Mandatory Convertible Preferred Stock (in cash, by delivery of our common stock, or by delivery of any combination of cash and common stock) if either or both of the Acquisitions is terminated. For additional information, see "Description of Certain Indebtedness and Obligations—Our Mandatory Convertible Preferred Stock," included in this prospectus supplement.

        Debt Financing.    Subsequent to this offering and the Mandatory Convertible Preferred Stock Offering, we expect to obtain Debt Financing in connection with the financing of the Acquisitions. We will be required to redeem all of the debt borrowed if neither of the Acquisitions are consummated. If one or the other of the Acquisitions is not consummated, we will be required to redeem the debt borrowed in connection with such contemplated but unconsummated Acquisition. For additional information, see "Description of Certain Indebtedness and Obligations," included in this prospectus supplement.

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RATIO OF EARNINGS TO FIXED CHARGES

        The following table presents our ratio of earnings to fixed charges for the periods indicated:

 
   
   
   
   
 
Predecessor
 
 
  Successor    
 
 
   
   
  Year Ended
December 31,
 
 
   
   
  October 2
Through
December 31,
2012
   
  January 1
Through
October 1,
2012
 
 
  Six Months
Ended
June 30, 2014
  Year Ended
December 31,
2013
   
 
 
   
  2011   2010   2009  
 
   
 

Ratio of earnings to fixed charges(1)(2)

    (3)   (3)   (3)       2.13     (3)   (3)   (3)

(1)
For purposes of computing the ratio of earnings to fixed charges, "earnings" are defined as pre-tax income from continuing operations before adjustment for earnings from equity investments plus fixed charges. "Fixed charges" consist of interest, whether capitalized or expensed, amortization of debt expense and the estimated interest component of rent expense.

(2)
For the periods presented, we had no preferred stock outstanding. Therefore, the ratios of earnings to combined fixed charges and preferred share dividends for the periods indicated equal the ratios of earnings to fixed charges for the same periods.

(3)
For the six months ended June 30, 2014, the year ended December 31, 2013, the period from October 2 through December 31, 2012 and the years ended December 31, 2011, 2010 and 2009 earnings were insufficient to cover fixed charges by $175 million, $419 million, $113 million, $587 million, $406 million and $1,107 million, respectively.

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OVERVIEW OF FINANCIAL CONDITION, LIQUIDITY AND CAPITAL RESOURCES

        You should read the following overview in conjunction with "Summary Unaudited Pro Forma Condensed Combined Financial Information," "Capitalization" and "Use of Proceeds," included elsewhere in this prospectus supplement. Ours, AER's and the Target Companies' consolidated financial statements and accompanying notes are incorporated by reference in this prospectus supplement, as well as the Pro Forma Form 8-K, Items 7 (Management's Discussion and Analysis of Financial Condition and Results of Operations) and 7A (Quantitative and Qualitative Disclosures About Market Risk) in our Annual Report on Form 10-K for the fiscal year ended December 31, 2013. See "Where You Can Find More Information."

Overview

        We expect to incur significant debt in connection with the Acquisitions. As of June 30, 2014, on a pro forma basis giving effect to the Transactions, we had approximately $7.1 billion of total indebtedness, as well as approximately $600 million, net expected letters of credit outstanding, available for borrowing under our current and incremental revolving credit facilities. We have secured commitments for two incremental revolving credit facilities totaling $950 million, each of which is expected to close upon consummation of the respective Acquisition. We intend to use the net proceeds from this offering, together with the net proceeds of the concurrent Mandatory Convertible Preferred Stock Offering and the Debt Financing, the common stock placement to ECP and cash on hand to finance the Acquisitions and to pay related fees and expenses. If we consummate only one of the Acquisitions, we will use some or all of the net proceeds of this offering to fund the Acquisition that is consummated and any remaining amount for general corporate purposes. If neither of the Acquisitions are consummated, we will use all of the net proceeds of this offering for general corporate purposes. For a description of certain of our indebtedness, including the credit facilities, see "Description of Certain Indebtedness and Obligations."

        Our liquidity and capital requirements are primarily a function of our debt maturities and debt service requirements, fixed capacity payments and contractual obligations, capital expenditures (including required environmental expenditures) and working capital needs. Examples of working capital needs include purchases and sales of commodities and associated margin and collateral requirements, facility maintenance costs and other costs such as payroll. Our primary sources of liquidity are cash flows from operations, cash on hand and amounts available under the revolver. Our future operating cash flows will vary based on a number of factors, many of which are beyond our control, including the price of power, the prices of natural gas, coal and fuel oil and their correlation to power prices, collateral requirements, the value of capacity and ancillary services, the run time of our generating facilities, the effectiveness of our commercial strategy, legal, environmental and regulatory requirements, changes to the design of the markets in which we operate and our ability to achieve the cost savings contemplated in our PRIDE improvement programs.

Cash Balances

        As of June 30, 2014, on a pro forma basis giving effect to the Transactions, we had cash and cash equivalents of $1.0 billion and $1.2 billion of total current liabilities.

Synergies

        We believe that the Acquisitions will provide opportunities for meaningful synergies, including at least $40 million in cost reductions per year, $200 million in balance sheet efficiencies and nearly $500 million in present value cash tax savings. In order to achieve these synergies, we expect to incur a cost of approximately $40 million.

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DESCRIPTION OF THE OPERATIONS OF THE DUKE MIDWEST ASSETS AND
THE ECP ASSETS

The Duke Midwest Assets

        The Duke Midwest Assets are part of Duke's commercial power segment, which owns, operates and manages power plants and engages in the wholesale marketing and procurement of electric power, fuel and emission allowances related to these plants as well as other contractual positions. Consisting of approximately 6,200 MW of net generating capacity across 11 facilities which operate in the PJM wholesale market, the Duke Midwest Assets have a diversified fuel mix with baseload coal-fired units as well as combined cycle and peaking natural gas-fired units.

        Generation from the coal-fired and gas-fired assets is dispatched into the PJM wholesale market. These assets earn energy and capacity revenue at market prices. The Duke Midwest Assets have economically hedged its forecasted coal-fired generation and a significant portion of its forecasted gas-fired generation for 2014. The Duke Midwest Assets also have long-term economic hedges in place for a portion of expected coal and gas generation through 2017 and 2018, respectively. Capacity revenues are 100% fixed in PJM through May 2017.

        Duke Energy Retail Sales, which is certified by the PUCO as a Competitive Retail Electric Supplier (CRES) provider in Ohio, serves retail electric and gas customers in Ohio with energy and other energy services at competitive rates.

        The following table sets forth certain information with respect to the generating facilities:

Facility
  Net
Generating
Capacity
(MW)(1)
  Primary
Fuel Type
  Dispatch Type   Location   Region   Interest
to be
Acquired
 

Dicks Creek

    153   Gas   Peaking   Middleton, OH   PJM     100.0 %

Fayette

    649   Gas   Intermediate   Masontown, PA   PJM     100.0 %

Hanging Rock

    1,296   Gas   Intermediate   Ironton, OH   PJM     100.0 %

Lee

    712   Gas   Intermediate   Dixon, IL   PJM     100.0 %

Washington

    648   Gas   Intermediate   Beverly, OH   PJM     100.0 %

Killen

    204   Coal   Baseload   Wrightsville, OH   PJM     33.0 %

Stuart

    904   Coal   Baseload   Aberdeen, OH   PJM     39.0 %

Conesville

    312   Coal   Baseload   Conesville, OH   PJM     40.0 %

Zimmer

    628   Coal   Baseload   Moscow, OH   PJM     46.5 %

Miami Fort (Units 7 and 8)

    653   Coal   Baseload   North Bend, OH   PJM     64.0 %

Miami Fort (CT)

    80   Oil   Peaking   North Bend, OH   PJM     100.0 %
                             

Total

    6,239                        
                             
                             

(1)
Unit capabilities are based on winter capacity.

The ECP Assets

        Consisting of approximately 6,300 MW of net generating capacity across ten facilities, the ECP Assets primarily include highly efficient and clean-burning natural gas-fired facilities. The ECP Assets' natural gas fleet consists of eight facilities including five modern, efficient combined cycle gas turbine ("CCGT") facilities, two gas-fired peaking facilities and one oil-fired peaking facility. The ECP Assets' CCGT fleet was recently constructed, with 13 years of operations on average, and consists of highly efficient assets, with an average heat rate of approximately 7,100 Btu/kWh. While all of the ECP CCGT facilities serve as intermediate facilities, Lake Road and Milford each operate with a high capacity factor and contribute substantially to the ECP Assets' energy margin as a result of extended run time and profitability. The

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Dighton and MASSPOWER facilities tend to be load following resources, meaning they supply energy to the market more opportunistically in a higher power price environment. All of the ECP Assets' CCGTs have a high degree of operating flexibility which allows them to start and ramp up quickly in response to favorable market pricing and reduce their generation output to minimize losses when that is preferable to temporarily shutting down. The ECP Assets own a 49.5% interest in, and operate, the largest natural gas-fired peaking plant in the western PJM, Elwood Generating Station. The ECP Assets currently expect to acquire an additional 0.5% ownership interest in Elwood from Dominion Energy, Inc. in the fourth quarter of 2014. Additionally, the ECP Assets own two gas- and oil-fired peaking facilities in the ATSI zone of PJM, Richland and Stryker Generating facilities. Peaking facilities are designed to turn on and off quickly to capture high price opportunities, making starting reliability one of the most important operating metrics for a facility of this type. The ECP Assets' natural gas peaking facilities demonstrated 99% start reliability across the ECP Assets' fleet in 2013, allowing them to capture energy margin opportunities during valuable hours of the year.

        The ECP Assets' coal fleet consists of two plants, Kincaid Generating Station in PJM and Brayton Point Generating Station in ISO-NE. Both facilities have environmental controls that meet current regulations codified under a consent decree with the EPA. Kincaid is well-positioned on the PJM dispatch curve, ensuring competitive and long-term operation. In 1998 and 1999, $166 million was invested in refurbishing and converting Kincaid to burn low-cost and low sulfur PRB coal. Since then, $157 million has been invested in Kincaid's back-end environmental controls. Kincaid also benefits from rail transportation alternatives resulting in competition that contributes to low transportation costs of PRB coal from the mines to the facility. Additionally, until its expected retirement in June 2017, Brayton Point will sell capacity, energy and ancillary services to the ISO-NE market. The facility serves the New England marketplace primarily during peak demand seasons. Brayton Point is currently in a position to capture power demand in the winter at a lower cost than its natural gas-fired generation competitors because demand for natural gas is higher in the Northeast during the winter months, in particular due to high heating demand, leading to natural gas price increases. Because natural gas represents the marginal fuel in ISO-NE approximately 70% of the time, high demand for natural gas typically results in higher day-ahead and real-time power prices, which increase Brayton Point's energy margin opportunities. Brayton Point is also able to serve the New England marketplace in the summer when electricity demand is greatest.

        On February 28, 2014, ISO-NE filed with FERC the results of its eighth forward capacity auction, or FCA-8. Certain parties, including Utility Workers Union of America Local 464, Public Citizen and the Attorney General for the State of Connecticut, filed protests alleging, inter alia, that ECP, ERC and Brayton Point Energy had intentionally withheld the Brayton Point facility's capacity from FCA-8 to benefit affiliated resources in the region and requesting that FERC reject the prices resulting from the auction. On September 16, 2014, the ISO-NE filing, including the disputed auction results, was accepted by FERC by operation of law. This proceeding is currently pending, and we cannot predict the outcome of this proceeding or the potential consequences of an adverse finding.

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        The following table sets forth certain information with respect to the generating facilities:

Facility
  Net
Generating
Capacity
(MW)(1)
  Primary
Fuel Type
  Dispatch Type   Location   Region   Interest
to be
Acquired
 

Brayton Point(2)

    1,493   Coal   Baseload   Somerset, MA   ISO-NE     100.0 %

Kincaid(3)

    1,108   Coal   Baseload   Kincaid, IL   PJM     100.0 %

Milford

    579   Gas   Intermediate   Milford, CT   ISO-NE     100.0 %

Lake Road

    856   Gas   Intermediate   Killingly, CT   ISO-NE     100.0 %

Dighton

    187   Gas   Intermediate   Dighton, MA   ISO-NE     100.0 %

MASSPOWER

    280   Gas   Intermediate   Indian Orchard, MA   ISO-NE     100.0 %

Liberty

    600   Gas   Intermediate   Eddystone, PA   PJM     100.0 %

Richland

    447   Gas   Peaking   Defiance, OH   PJM     100.0 %

Stryker

    19   Oil   Peaking   Stryker, OH   PJM     100.0 %

Elwood(4)

    780   Gas   Peaking   Elwood, IL   PJM     49.5 %
                             

Total

    6,349                        
                             
                             

(1)
Unit capabilities are based on winter capacity.

(2)
Brayton Point is scheduled to be retired from service in June 2017.

(3)
Kincaid is physically located within the MISO market, but is interconnected to the PJM market and sells both energy and capacity in the PJM market only.

(4)
In addition, ERC expects to acquire an additional 0.5% interest in Elwood from Dominion Energy, Inc. in the fourth quarter of 2014, which additional interest we would receive in connection with the ERC and Brayton Acquisitions.

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INDUSTRY OVERVIEW

        The power industry is one of the largest industries in the United States. In 2013, total generation in the United States reached approximately 4 million GWh, composed of 27.4% natural gas, 39.1% coal, 19.4% nuclear, 12.8% renewables, and 1.3% other.

        Sub-sectors of the power industry include:

Industry Drivers

        Age and Retirement of Assets:    According to data from the Energy Information Administration (EIA), the average age of the U.S. power generation fleet is approximately 32 years old and approximately 51% of all U.S. power generation capacity is at least 30 years old. Capacity additions in recent years include renewable units, primarily wind, coming online in the late 2000s, reducing the overall average age of the fleet. The anticipated retirement of baseload power generation resources would significantly alter the composition of the existing supply stack.

        Reserve Margin:    Each of the MISO, ISO-NE, PJM and NYISO markets has a centrally administered, formal capacity market, where tighter reserve margins should lead to increased revenues paid to power generation resources participating in capacity auctions. In the energy market, tightening reserve margins typically lead to higher power prices since the marginal cost resource is the least efficient resource dispatched and requires the highest power price to compensate it for its output. In addition, a market with tighter reserve margins can lead to increased power price spikes during periods of surging demand due to weather volatility or other extraneous factors.

        System Reliability and the Changing Nature of Power Generation Supply Resources:    With a low variable cost, renewable generation resources can lower energy margins; however, the intermittent nature of some renewable generation resources creates challenges for grid reliability and a greater need for flexible, reliable sources of conventional generation that have quick start capabilities.

        Growing Role of Demand Response:    Demand response refers to end use customers agreeing to reduce their consumption of electricity in response to power grid needs, economic signals from a competitive wholesale market or special retail rates. Demand response is typically called upon to provide capacity during peak demand periods and is brought on and off-line quickly for short periods of time throughout the year. It is unclear if demand response can perform as well as other capacity assets and to our knowledge it has not been tested to a meaningful extent in any market to date.

        Natural Gas/Regional Dynamics:    Limited gas supply can affect regional power prices due to the curtailment of certain gas-fired power plants that would otherwise be dispatched. While gas prices have generally remained at or near historic lows over the past few years, significant regional price differences have emerged and persisted due to limited gas pipeline transport capacity in some areas and the proliferation of shale gas.

        Rising Cost of Environmental Compliance:    The power generation industry is subject to extensive federal, state and local laws and regulations concerning emissions, water quality, land use, greenhouse gas and other environmental matters. The cost of compliance with current and future regulation at both the state and federal levels may increase the operating costs of power generation assets, particularly older, less efficient fossil-fuel power plants.

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        Rising Cost of New Entry:    Rising costs of labor and raw materials, as well as more restrictive siting, permitting and environmental requirements, have all contributed to significant increases in construction and development costs for electric generation facilities over the last several years.

        Regulatory Constructs and Market Design Initiatives.    RTOs and ISOs are the primary regulatory bodies charged with administering wholesale power markets and transmission infrastructure in regions across the U.S. Specifically, RTOs and ISOs are responsible for dispatching all generation facilities in their respective footprints and for maximizing utilization and efficient operation of the transmission system. In RTOs and ISOs with centrally dispatched market structures, including ISO-NE, PJM and NYISO, all generators selling into the centralized market receive the same price for energy sold based on the marginal cost for power production needed to balance supply with demand at a given location, with adjustments then made for location specific congestion and transmission line losses. These adjustments are referred to as power basis. In addition to their role in energy markets, some RTOs and ISOs, including MISO, ISO-NE, PJM and NYISO, also administer centralized markets for capacity to attract new investment in power generation when and where that capacity is needed most. The actual market design and rules and regulations implemented by the RTOs and ISOs impact prices realized in both capacity and energy markets. We believe that supportive regulatory developments, resulting in more transparent and stable energy and capacity price signals, have continued to play out across power markets in the U.S. and that regulators in our key markets remain committed to the competitive wholesale power model reflecting a level playing field for all generators.

        Demand Growth and Energy Efficiency:    Demand fundamentals in many U.S. power markets have been negatively affected by a general decline in weather normalized load growth rates due to the economic recession and emerging energy efficiency measures.

RTOs and ISOs

        The NERC and its regional reliability entities were formed to ensure the reliability and security of the electricity system. NERC was established to ensure that the electricity grid in the United States is reliable, adequate and secure. The regional reliability entities set standards for reliable operation and maintenance of power generation facilities and transmission systems. Some NERC members have formed regional organizations with similar missions. These organizations are referred to as RTOs and ISOs. They are part of a national standard design advocated by FERC.

        The RTOs and ISOs administer the transmission infrastructure and markets across a regional footprint in most of the markets in which we operate. They are responsible for dispatching all generation facilities in their respective footprints and are responsible for both maximum utilization and reliable and efficient operation of the transmission system. RTOs and ISOs administer energy and ancillary service markets in the short term, usually day-ahead and real-time markets. Several RTOs and ISOs also ensure long-term planning reserves through monthly, semi-annual, annual and multi-year capacity markets. The RTOs and ISOs that oversee most of the wholesale power markets in which we operate currently impose, and will likely continue to impose, both bid and price limits. They may also enforce caps and other mechanisms to guard against the exercise of market dominance in these markets. NERC regions and RTOs/ISOs often have different geographic footprints, and while there may be geographic overlap between NERC regions and RTOs/ISOs, their respective roles and responsibilities do not generally overlap.

        RTOs and ISOs are required to meet NERC planning and resource adequacy standards. The reserve margin, which is the amount of generation resources in excess of peak load, is a measure of resource adequacy and is also used to assess the supply-demand balance of a region. RTOs and ISOs use various mechanisms to help market participants meet their planning reserve margin requirements. Mechanisms range from centralized capacity markets administered by the ISO to unstructured markets where entities

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fulfill their requirements through a combination of long and short-term bilateral contracts between individual counterparties and self-generation.

Dynegy's Markets

        We operate in the MISO, PJM, NYISO, ISO-NE and CAISO markets, which are responsible for ensuring system reliability in their respective markets.

        MISO Market.    The MISO market includes all of Wisconsin and portions of Michigan, Kentucky, Indiana, Illinois, Missouri, Arkansas, Mississippi, Texas, Louisiana, Iowa, Minnesota, North Dakota, South Dakota, Montana and Manitoba, Canada. MISO, as an independent RTO, maintains functional control over the use of the transmission system to ensure transmission circuits do not exceed their secure operating limits and become overloaded. MISO operates day-ahead and real-time energy markets using a LMP system which calculates a price for every generator and load point within MISO.

        PJM Market.    The PJM market includes all or parts of Delaware, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia and the District of Columbia. PJM administers markets for wholesale electricity and provides transmission planning for the region. PJM, like MISO, dispatches power plants to meet system energy and reliability needs, and settles physical power deliveries at LMPs. Prices paid in these LMP energy markets are affected by (1) market mitigation measures, which can result in lower prices associated with certain generating units that are mitigated because they are deemed to have the potential to exercise locational market power and (2) the existing $1,000/MWh energy market price caps that are in place.

        NYISO.    The NYISO market includes the entire state of New York. Capacity pricing is calculated as a function of NYISO's annual required reserve margin, the estimated net cost of "new entrant" generation, estimated peak demand and the actual amount of capacity bid into the market at or below the demand curve. Due to transmission constraints, energy prices vary across New York and are generally higher in the Southeastern part of New York, New York City and Long Island. Our Independence facility is located in the Northwestern part of the state.

        ISO-NE.    The ISO-NE market includes the six New England states of Vermont, New Hampshire, Massachusetts, Connecticut, Rhode Island and Maine. ISO-NE also dispatches power plants to meet system energy and reliability needs and settles physical power deliveries at LMPs. On October 17, 2013, ISO-NE issued a memorandum to market participants noting a potential resource shortfall based on submitted retirement requests. FCA-8 occurred on February 3, 2014. The auction cleared at a price of $15/kilowatt (kW)-month. However, due to recent capacity retirements, the "insufficient competition" clause in the ISO-NE tariff was triggered. Under the insufficient competition clause, existing generation in rest-of-pool (including Casco Bay) received an administrative cap price of $7.025/kW-month. Two rule changes have recently been approved for FCA-9 covering the 2018-2019 planning year. These rules include a sloped demand curve and performance incentives. The sloped demand curve is replacing administrative pricing rules for the entire region while the performance incentives rules have the potential to increase capacity payments for those resources that are providing excess energy or reserves during a shortage event, while penalizing those that produce less than the required level.

        CAISO.    CAISO covers approximately 90% of the State of California and operates a centrally cleared market for energy and ancillary services. Energy is priced at each location utilizing the LMP system described above. This market structure was implemented in April 2009 as part of the MRTU. Currently the CAISO has a mandatory resource adequacy requirement but no centrally-administered capacity market. The Oakland facility has been designated as an RMR unit by the CAISO for 2014.

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Reserve Margins

        MISO.    For the 2013-2014 planning year, capacity cleared at $1.05 per MW-day for all zones. On April 14, 2014, MISO released the results of the 2014-2015 planning year capacity auction. Local Resource Zone 4, in which our assets are located, cleared at $16.75 per MW-day, compared to $1.05 per MW-day for the previous 2013-2014 planning year capacity auction. In the future, the potential retirement of marginal MISO coal capacity due to poor economics or expected environmental mandates and confirmed future capacity exports from MISO to PJM could also increase MISO capacity and energy pricing.

        PJM.    The installed reserve margin requirement is reviewed by PJM on an annual basis and has been in the 15.6% to 15.9% range for the planning years 2012-2013 to 2013-2014. The actual reserve margin based on deliverable capacity was 29.4% for planning year 2013-2014, which is 13.5 percentage points above the required installed reserve margin. The latest RPM auction was for the 2017-2018 planning year, which cleared at $3.65 per kW-month for both Kendall and Ontelaunee. The next RPM auction for the 2018-2019 planning year will be conducted in May 2015.

        NYISO.    A reserve margin of 17% has been accepted by FERC for the New York Control Area for the period beginning May 1, 2013 and ending April 30, 2014. A reserve margin of 17% for the period beginning May 1, 2014 and ending April 30, 2015 has been filed and is being reviewed at FERC. The actual amount of installed capacity is approximately 3 percentage points above NYISO's current required reserve margin. The most recent summer and winter auctions have cleared higher than the previous auctions with summer 2014 at $5.15 per kW-month and winter 2013-2014 at $2.58 per kW-month for the rest of state market.

        ISO-NE.    Similar to PJM, ISO-NE will publish on an annual basis the required reserve margin which is called Installed Capacity Requirement ("ICR"). For the 2014-2015 planning period, it is 18.7%, including capacity imported from Hydro Quebec (HQICC). This is approximately 1.5% higher than the previous planning period, which indicates a growing need for reserves. Actual installed reserve margin is approximately 36.6%, which is 17.9 percentage points above the ICR. Recommended improvements and modifications to the forward capacity market design are currently in litigation at FERC, and discussions to address improvements to the forward capacity market design are currently underway by the ISO and its stakeholders. Beginning with the 2017-2018 commitment year, the floor price in the capacity market was removed. Recent retirement announcements, as well as the reduction in demand response, have resulted in higher capacity prices. ISO-NE is developing additional changes to the forward capacity market including performance incentives and a sloped demand curve which are expected to be in place for the ninth forward capacity auction in 2015.

        CAISO.    CPUC requires a resources adequacy margin of 15% to 17%. The CAISO capacity market is a bilateral market in which LSEs are required to procure sufficient resources to meet their peak load plus a 15% reserve margin. The CAISO faces challenges to ensure system reliability and the ability to integrate renewables into the system given the state's mandate to have 33% renewable resources by 2020. The CAISO and CPUC recently approved the Joint Reliability Plan in which the CAISO and CPUC will collaborate on several initiatives: (i) the determination of multi-year resource adequacy procurement obligations for CPUC jurisdictional LSEs; (ii) the development of a joint long-term planning assessment and (iii) the development of a market-based reliability backstop mechanism to replace CPM (Capacity Procurement Mechanism), which is the administratively-priced mechanism currently used by CAISO. A flexible capacity requirement to support renewable integration has been imposed on CPUC jurisdictional LSEs and will be mandatory starting in 2015. The CAISO board recently approved the methodology and "must-offer" obligations for flexible capacity developed through a stakeholder process. Additionally, CAISO studies on flexible capacity needs appear to show ample supplies through 2018.

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The Duke Midwest Assets' Markets

        The Duke Midwest Assets operate in markets similar to those in which Dynegy operates. The Duke Midwest Assets are located in the PJM power market. PJM administers centrally-dispatched day-ahead and real-time energy, capacity and ancillary services markets. The market price of commodities and services, along with the quality and reliability of services provided, drive competition in the wholesale energy business. The main competitors for the Duke Midwest Assets include other nonregulated generators and wholesale power providers. Capacity prices in PJM are set through ISO-administered auctions more than three years in advance. Recent favorable industry trends in these markets, including the retirement of older generation and environmentally disadvantaged coal plants, tightening reserve margins and limitations on imports and demand response resources, are leading to positive and persistent supply and demand dynamics.

        The Duke Midwest Assets rely on coal and natural gas for their generation of electric energy. The Duke Midwest Assets meet coal demands through a portfolio of purchase supply contracts and spot agreements. Large amounts of coal are purchased under supply contracts with mining operators who mine both underground and at the surface. Expiration dates for its supply contracts, which have various price adjustment provisions and market re-openers, range through 2018. The Duke Midwest Assets expect to renew these contracts or enter into similar contracts with other suppliers for the quantities and quality of coal required as existing contracts expire, though prices will fluctuate over time as coal markets change. The majority of the Duke Midwest Assets' coal is sourced from mines in the Northern Appalachian and Illinois basins, and utilizes cost effective barge transportation on the Ohio River. The Duke Midwest Assets have an adequate supply of coal to fuel projected 2014 operations. The majority of Duke Midwest Assets' coal-fired generation is equipped with environmental controls. As a result, the Duke Midwest Assets are able to satisfy the current emission limitations for SO2 for existing facilities.

        The Duke Midwest Assets hedge their natural gas requirements using physical and financial contracts. Physical gas is purchased in the spot market and under long-term contracts to meet generation needs.

The ECP Assets' Markets

        The ECP Assets' facilities also operate in markets similar to those in which Dynegy operates. The ECP Assets are located mainly in ISO-NE, with some assets located in the PJM power market. Both PJM and ISO-NE administer centrally-dispatched day-ahead and real-time energy, capacity and ancillary services markets. These are two of the most active forward energy commodities markets in the United States, which provides the ECP Assets with the ability to proactively manage commodity price risk exposure while opportunistically positioning the ECP Assets to benefit from tightening energy fundamentals. Capacity prices in ISO-NE and PJM are set through ISO-administered auctions more than three years in advance. Recent favorable industry trends in these markets, including the retirement of older generation and environmentally disadvantaged coal plants, tightening reserve margins and limitations on imports and demand response resources, are leading to positive and persistent supply and demand dynamics.

        The ECP Assets rely on coal and natural gas for their generation of electric energy. The Kincaid coal-fried facility procures all of its coal from the PRB region and meets its coal demand through a portfolio of short-and-medium-term purchase supply contracts and spot agreements. All coal is delivered to the facility through rail transportation contracts. The Brayton Point facility utilizes Central Appalachian and South American coal for its coal units, and natural gas or No. 6 fuel oil for its peaking unit. Coal for Brayton Point is procured through relatively short-term or spot agreements. Transportation to the facility is done by vessel.

        The ECP Assets hedge their natural gas requirements by using physical and financial contracts. Physical gas is purchased in the spot market and under long-term contracts to meet generation needs.

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Market-Based Rates

        Our ability to charge market-based rates for wholesale sales of electricity, as opposed to cost-based rates, is governed by FERC. We have been granted market-based rate authority for wholesale power sales from our Exempt Wholesale Generator (EWG) facilities, as well as wholesale power sales by our power marketing entities, DYPM, DMT and IPM. The Dynegy EWG facilities include all of our facilities.

        Every three years, FERC conducts a review of our market-based rates and potential market power on a regional basis (known as the triennial market power review). In 2013, we filed a market power update with FERC for our CAISO assets.

The Dodd-Frank Act

        The CFTC has regulatory oversight authority over the trading of electricity and gas commodities, including financial products and derivatives, under the Commodity Exchange Act. On July 21, 2010, President Obama signed the Dodd-Frank Wall Street Reform and Consumer Protection Act, which, among other things, aims to improve transparency in derivative markets. The Dodd-Frank Act increased the CFTC's regulatory authority on matters related to over-the-counter derivatives, market clearing, position reporting and capital requirements. On April 10, 2013, certain record-keeping and reporting requirements went into effect for Non-Swap Dealers/Non-Major Swap Participants, as defined by the CFTC. Beginning on April 5, 2013, the CFTC Staff issued various materials, including "No Action" letters, which delayed the effectiveness or otherwise altered many of these requirements. Dynegy has systems in place in order to monitor our swap activity and comply with Non-Swap Dealer/Major Swap Participant reporting requirements. As required, Dynegy is meeting its reporting obligations under Parts 43, 45 and 46 of the CFTC's regulations, which cover real-time public reporting of swap transaction data, reporting of swap transaction data to a registered swap data repository and reporting of historical swaps. We continue to monitor the CFTC's releases for guidance on these rules and any other clearing and reporting requirements that will be required of our business or impact current operations. On November 5, 2013, the CFTC voted in favor of putting new proposals on position limits and aggregation out for public comment. The two new notices of proposed rulemaking constitute the re-proposal of federal aggregate position limits rules that were previously finalized under Dodd-Frank and vacated by a federal court in September 2012.

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DESCRIPTION OF COMMON STOCK

        The following summary of the terms of our capital stock is not meant to be complete and is qualified in its entirety by reference to our third amended and restated certificate of incorporation, our sixth amended and restated bylaws and the provisions of applicable law. For a description of certain of the expected terms of the Mandatory Convertible Preferred Stock, which will be a series of our preferred stock and will impact the rights of holders of our common stock, see "Description of Certain Indebtedness—Description of Mandatory Convertible Preferred Stock". For additional information, see "Risk Factors—Risks Relating to this Offering and Ownership of Our Common Stock—Our common stock will rank junior to the Mandatory Convertible Preferred Stock with respect to dividends and amounts payable in the event of our liquidation and ranks junior to our indebtedness." You should read the following description of our common stock in light of this information and the other information under "Risk Factors" in this prospectus supplement.

Authorized Capital Stock

        We have the authority to issue a total of 440,000,000 shares of capital stock, consisting of:

Common Stock

        The rights, preferences and privileges of holders of our common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of our preferred stock which we may designate and issue in the future.

        Dividend Rights.    Subject to the rights of holders of preferred stock of any series that may be issued from time to time, and as otherwise provided by the third amended and restated certificate of incorporation, holders of common stock shall be entitled to receive such dividends and other distributions in cash, stock of any corporation or of our property as may be declared by the Board from time to time out of assets or funds of Dynegy legally available for dividends and other distributions, and shall share equally on a per share basis in all such dividends and other distributions.

        Liquidation Rights.    In the event of any liquidation, dissolution or winding up of Dynegy, the holders of our common stock will be entitled to share in the net assets of Dynegy available after the payment of all debts and other liabilities and subject to the prior rights of any outstanding class of our preferred stock.

        Preemptive Rights.    Pursuant to our third amended and restated certificate of incorporation, the holders of our common stock have no preemptive rights.

        Conversion Rights.    Shares of our common stock are not convertible.

        Voting Rights.    Subject to the rights of the holders of any series of our preferred stock, each outstanding share of our common stock is entitled to one vote on all matters submitted to a vote of stockholders.

        Board of Directors.    Holders of common stock do not have cumulative voting rights with respect to the election of directors. At any meeting to elect directors by holders of our common stock, the presence, in person or by proxy, of the holders of a majority of the voting power of shares of capital stock then outstanding shall constitute a quorum for such election. Directors shall be elected by a plurality of the votes of the shares present and entitled to vote on the election of directors, except for directors whom the holders of preferred stock have the right to elect, if any.

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Warrants to Purchase Common Stock

        Pursuant to the Plan, Dynegy issued warrants to purchase shares of new common stock to holders of shares of its old common stock, which were cancelled pursuant to the Plan. The warrants became exercisable at any time after the date of issuance and have an exercise price of $40.00 per share. Each of the warrants expires on October 2, 2017. The warrants provide for a cashless exercise by the warrant holder. The exercise price of the warrants and the number of shares issuable upon exercise of the warrants are subject to adjustment upon certain events including: stock subdivisions, combinations, splits, stock dividends, capital reorganizations, or capital reclassifications of common stock and in connection with certain distributions of cash, assets or securities. The warrants are not redeemable.

Preferred Stock

        Under the terms of our third amended and restated certificate of incorporation, the Board is authorized to issue from time to time up to an aggregate of 20,000,000 shares of preferred stock and to fix or alter the designations, preferences, rights and any qualifications, limitations or restrictions of the shares of each series, including the dividend rights, dividend rates, conversion rights, voting rights, rights and terms of redemption (including sinking fund provisions), redemption price or prices, liquidation preferences and the number of shares constituting any series. These additional shares may be used for a variety of corporate purposes, including future public offerings, to raise additional capital or to facilitate acquisitions. If the Board decides to issue shares of preferred stock to persons supportive of current management, this could render it more difficult or discourage an attempt to obtain control of Dynegy by means of a merger, tender offer, proxy contest or otherwise. Authorized but unissued shares of preferred stock also could be used to dilute the stock ownership of persons seeking to obtain control of Dynegy. To the extent required by 11 U.S.C. § 1123(a)(6), Dynegy is prohibited from issuing shares of nonvoting equity securities (within the meaning of such statute).

Certain Anti-Takeover Effects

        Provisions of Delaware Law.    We are a Delaware corporation. In our third amended and restated certificate of incorporation, we elected not to be subject to the provisions of Section 203 of the Delaware General Corporation Law ("DGCL") regulating corporate takeovers. In general, Section 203 prohibits Delaware corporations, including those whose securities are listed for trading on the NYSE, from engaging in any business combination with any interested stockholder for a period of three years following the date that the stockholder became an interested stockholder, unless:

Under certain circumstances, Section 203 makes it more difficult for a person who would be an "interested stockholder" to effect various business combinations with a corporation for a three-year period. However, Section 203 is not applicable to us.

        Advance Notice Procedures.    Our sixth amended and restated bylaws establish an advance notice procedure for stockholder proposals to be brought before an annual meeting of stockholders, including proposed nominations of persons for election to the Board. Stockholders at an annual meeting will only be able to consider proposals or nominations specified in the notice of meeting or brought before the meeting

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by or at the direction of the Board or by a stockholder who was a stockholder of record on the record date for the meeting, who is entitled to vote at the meeting and who has given our corporate secretary timely written notice, in proper form, of the stockholder's intention to bring that business before the meeting. Although the bylaws will not give the Board the power to approve or disapprove stockholder nominations of candidates or proposals regarding other business to be conducted at a special or annual meeting, the bylaws may have the effect of precluding the conduct of certain business at a meeting if the proper procedures are not followed or may discourage or deter a potential acquiror from conducting a solicitation of proxies to elect its own slate of directors or otherwise attempting to obtain control of the company.

        Action by Written Consent; Special Meetings of Stockholders.    Our sixth amended and restated bylaws provide that stockholder action can be taken at an annual or special meeting of stockholders or by written consent in lieu of a meeting. Our third amended and restated certificate of incorporation and the bylaws provide that, except as otherwise required by law, special meetings of the stockholders can only be called by the chairman of the board, the chief executive officer, the president, a majority of the Board, or the holders of at least 20% of all the outstanding shares entitled to vote on the matter for which the meeting is being held. The Board may postpone or reschedule any meeting previous scheduled by the chairman of the Board, the Board, chief executive officer, or president.

        Authorized but Unissued Shares.    Our authorized but unissued shares of common stock and preferred stock will be available for future issuance without stockholder approval, subject to the rules and regulations of the NYSE or any applicable exchange. These additional shares may be utilized for a variety of corporate purposes, including future public offerings to raise additional capital, corporate acquisitions and employee benefit plans. The existence of authorized but unissued shares of common stock and preferred stock could render more difficult or discourage an attempt to obtain control of a majority of our common stock by means of a proxy contest, tender offer, merger or otherwise.

Transfer Agent and Registrar

        Computershare Shareholder Services LLC is the transfer agent and registrar for our common stock.

Listing of Our Common Stock

        Currently, our common stock is listed on the NYSE under the trading symbol "DYN."

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DESCRIPTION OF CERTAIN INDEBTEDNESS AND OTHER OBLIGATIONS

Dynegy's Debt

        For information concerning our existing indebtedness, see "Management's Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources—Financing Activities" in our Annual Report on Form 10-K for the year ended December 31, 2013, incorporated by reference in this prospectus supplement and note 12 to our consolidated financial statements included in such Form 10-K. You should read this information in conjunction with (1) the sections entitled "Risk Factors", "Capitalization", and "Summary Unaudited Pro Forma Condensed Combined Financial Information" included in this prospectus supplement, (2) the Unaudited Pro Forma Condensed Combined Financial Information filed as an exhibit to the Pro Forma Form 8-K, which is incorporated by reference into this prospectus supplement , (3) "Management's Discussion and Analysis of Financial Condition and Results of Operations" contained in our Annual Report on Form 10-K for the year ended December 31, 2013, and in our Quarterly Report on Form 10-Q for the quarter ended June 30, 2014, each incorporated by reference in this prospectus supplement, and (4) the consolidated financial statements of Dynegy and the related notes incorporated by reference into this prospectus supplement.

        We expect to borrow additional debt in the Debt Financing to finance the Acquisitions. Such debt will be borrowed pursuant to separate offering or borrowing documents and not this prospectus supplement. We expect such debt to have terms consistent with certain of our existing debt. However, in the event we are unable to obtain such debt financing prior to the closing of the Acquisitions, we have obtained committed financing in the form of senior unsecured bridge loans as described below.

        In connection with entering into each of the Duke Midwest Purchase Agreement and the ERC Purchase Agreements, we obtained $2.8 billion and $3.55 billion, respectively, bridge loan commitments to ensure financing for the Acquisitions. Although we do not expect to make any borrowings under the bridge loan commitments, there can be no assurance that such borrowings will not be made. In that regard, we may be required to borrow under the bridge loan commitments if any of the other Financing Transactions is not completed or generates significantly less net proceeds than contemplated by this prospectus supplement.

Dynegy's Mandatory Convertible Preferred Stock

        Concurrently with this offering of shares of our common stock, pursuant to a separate prospectus supplement, we are offering 4,000,000 shares of our Mandatory Convertible Preferred Stock (or 4,600,000 shares, if the underwriters in the Mandatory Convertible Preferred Stock Offering exercise their option to purchase additional shares in full). The Mandatory Convertible Preferred Stock will be a series of our preferred stock, par value $0.01 per share, described in the accompanying prospectus. Each share of the Mandatory Convertible Preferred Stock will have a liquidation preference of $100.00 per share.

        Dividends on the Mandatory Convertible Preferred Stock will be payable on a cumulative basis when, as and if declared by our board of directors. We may pay declared dividends in cash or, subject to certain limitations, in shares of our common stock or by delivery of any combination of cash and shares of our common stock on February 1, May 1, August 1 and November 1 of each year, commencing on February 1, 2015, and to, and including, November 1, 2017.

        Each share of Mandatory Convertible Preferred Stock will, unless previously converted, automatically convert on November 1, 2017, into between      and       shares of our common stock, subject to anti-dilution and other adjustments.

        We will have the option to redeem the Mandatory Convertible Preferred Stock, in whole but not in part, if (i) on the date that is nine months after the date of issuance of the Mandatory Convertible Preferred Stock (the "Outside Date"), the consummation of either or both of the Acquisitions has not occurred, or (ii) an Acquisition Termination Event (as defined herein) occurs prior to the Outside Date, at

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a redemption price equal to $101.00 per share of Mandatory Convertible Preferred Stock plus accumulated and unpaid dividends to the date of redemption or, in certain circumstances, at an early redemption price that includes a make-whole adjustment.

        The holders of the Mandatory Convertible Preferred Stock will not have voting rights except as described below and as specifically required by Delaware law from time to time.

        Whenever dividends on any shares of the Mandatory Convertible Preferred Stock have not been paid in the aggregate amount equivalent to at least six or more dividend payments, whether or not for consecutive dividend periods (a "Nonpayment"), the authorized number of directors on our board of directors will, at the next annual meeting of stockholders or at a special meeting of stockholders as provided below, automatically be increased by two and the holders of such shares of the Mandatory Convertible Preferred Stock, voting together as a single class with holders of any and all other series of Voting Preferred Stock (as defined below) then outstanding, will be entitled, at our next annual or at a special meeting of stockholders, to fill such newly created directorships by electing two additional directors (the "Preferred Stock Directors"); provided that if the election of any such Preferred Stock Directors will cause us to violate the corporate governance requirements of the NYSE (or any other exchange or automated quotation system on which our securities may be listed or quoted) that requires listed or quoted companies to have a majority of independent directors, we will take such action as is necessary to ensure compliance with such requirements; and provided further that our board of directors shall, at no time, include more than two preferred stock directors.

        In the event of a Nonpayment, the holders of at least 25% of the shares of the Mandatory Convertible Preferred Stock and any other series of Voting Preferred Stock (as defined below) may request that a special meeting of stockholders be called to elect such Preferred Stock Directors (provided, however, that if our next annual or a special meeting of stockholders is scheduled to be held within 90 days of the receipt of such request, the election of such Preferred Stock Directors will be included in the agenda for and will be held at such scheduled annual or special meeting of stockholders). The Preferred Stock Directors will stand for reelection annually, at each subsequent annual meeting of the stockholders, so long as the holders of the Mandatory Convertible Preferred Stock continue to have such voting rights.

        At any meeting at which the holders of the Mandatory Convertible Preferred Stock are entitled to elect Preferred Stock Directors, the holders of a majority of the then outstanding shares of the Mandatory Convertible Preferred Stock and all other series of Voting Preferred Stock, present in person or represented by proxy, will constitute a quorum and the vote of the holders of a majority of such shares of the Mandatory Convertible Preferred Stock and other Voting Preferred Stock so present or represented by proxy at any such meeting at which there shall be a quorum shall be sufficient to elect the Preferred Stock Directors.

        As used in this prospectus supplement, "Voting Preferred Stock" means any series of our preferred stock, in addition to the Mandatory Convertible Preferred Stock, ranking equally with the Mandatory Convertible Preferred Stock either as to dividends or to the distribution of assets upon liquidation, dissolution or winding up and upon which like voting rights for the election of directors have been conferred and are exercisable. Whether a plurality, majority or other portion in voting power of the Mandatory Convertible Preferred Stock and any other Voting Preferred Stock have been voted in favor of any matter shall be determined by reference to the respective liquidation preference amounts of the Mandatory Convertible Preferred Stock and such other Voting Preferred Stock voted.

        If and when all accumulated and unpaid dividends have been paid in full, or declared and a sum (which may include shares of our common stock) sufficient for such payment shall have been set aside (a "Nonpayment Remedy"), the holders of the Mandatory Convertible Preferred Stock shall immediately and, without any further action by us, be divested of the foregoing voting rights, subject to the revesting of such rights in the event of each subsequent nonpayment. If such voting rights for the holders of the Mandatory Convertible Preferred Stock and all other holders of Voting Preferred Stock have terminated,

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the term of office of each Preferred Stock Director so elected will terminate at such time and the authorized number of directors on our board of directors shall automatically decrease by two.

        Any Preferred Stock Director may be removed at any time, with cause as provided by law or without cause by the holders of record of a majority in voting power of the outstanding shares of the Mandatory Convertible Preferred Stock and any other series of Voting Preferred Stock then outstanding (voting together as a single class) when they have the voting rights described above. In the event that a nonpayment shall have occurred and there shall not have been a Nonpayment Remedy, any vacancy in the office of a Preferred Stock Director (other than prior to the initial election after a nonpayment) may be filled by the written consent of the Preferred Stock Director remaining in office or, if none remains in office, by a vote of the holders of record of a majority in voting power of the outstanding shares of the Mandatory Convertible Preferred Stock and any other series of Voting Preferred Stock then outstanding (voting together as a single class) when they have the voting rights described above; provided that if the election of any such Preferred Stock Directors will cause us to violate the corporate governance requirements of the NYSE (or any other exchange or automated quotation system on which our securities may be listed or quoted) that requires listed or quoted companies to have a majority of independent directors, we will take such action as is necessary to ensure compliance with such requirements. The Preferred Stock Directors will each be entitled to one vote per director on any matter.

        The Mandatory Convertible Preferred Stock will have certain other voting rights with respect to certain amendments to our Charter and certain other transactions as described in the certificate of designations establishing the terms of the Mandatory Convertible Preferred Stock.

        The foregoing information concerning the Mandatory Convertible Preferred Stock is not complete and is subject to, and qualified in its entirety by reference to, the provisions of the certificate of designations establishing the terms of the Mandatory Convertible Preferred Stock, a copy of which has been or will be incorporated by reference as an exhibit into the registration statement of which this prospectus supplement and the accompanying prospectus form a part and which may be obtained as described under "Where You Can Find More Information". In addition, a description of the proposed Mandatory Convertible Preferred Stock is set forth in the separate prospectus supplement pursuant to which such preferred stock is being offered.

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MATERIAL U.S. FEDERAL TAX CONSIDERATIONS

        The following discussion describes the material U.S. federal income tax considerations associated with the purchase, ownership and disposition of our shares by U.S. Shareholders (as defined below) and non-U.S. Shareholders (as defined below). Except where noted, this discussion deals only with our shares held as capital assets by holders who acquired our shares in this issuance and does not address special situations, such as those of:

        Moreover, this description does not address the U.S. gift tax consequences of the acquisition, ownership, retirement or other disposition of shares. Furthermore, the discussion below is based upon the provisions of the Code, the Regulations and administrative and judicial interpretations thereof, all as of the date hereof, and such authorities may be repealed, revoked, modified or subject to differing interpretations, possibly on a retroactive basis, so as to result in U.S. federal income tax consequences different from those described below.

        A "U.S. Shareholder" of our shares means a beneficial owner of our shares that is, for U.S. federal income tax purposes:

        A "non-U.S. Shareholder" of our shares means a beneficial owner of our shares that is an individual, a corporation, an estate or a trust that is neither a U.S. holder nor a partnership (or other entity taxable as a partnership).

        If a partnership or other entity or arrangement treated as a partnership for U.S. federal income tax purposes holds our shares, the tax treatment of a partner will generally depend upon the status of the partner and the activities of the partnership. If you are a partner of a partnership holding our shares, we urge you to consult your own tax adviser.

        We cannot assure you that the IRS or the courts will agree with the tax consequences described herein. A different treatment from that described below could adversely affect the amount, timing and

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character of income, gain or loss in respect of an investment in our shares. If you are considering the purchase of our shares, we urge you to consult your own tax adviser concerning the particular U.S. federal income tax consequences to you of the purchase, ownership and disposition of our shares, as well as any consequences to you arising under the laws of any other taxing jurisdiction.

Taxation of U.S. Shareholders

        Distributions Generally.    Distributions of cash or property that we pay in respect of our shares will constitute dividends for U.S. federal income tax purposes to the extent they are paid from our current or accumulated earnings and profits (as determined under U.S. federal income tax principles) and will be includible in gross income upon receipt. Any such dividend will be eligible for the dividends received deduction if received by an otherwise qualifying corporation that meets the holding period and other requirements for the dividends received deduction. Dividends paid by us to certain non-corporate shareholders (including individuals) are eligible for U.S. federal income taxation at the rates generally applicable to long-term capital gains for individuals (at a maximum tax rate of 20%), provided that the recipient of such dividend satisfies the applicable holding period and other requirements. If the amount of a distribution exceeds our current and accumulated earnings and profits, such excess first will be treated as a tax-free return of capital to the extent of the shareholder's tax basis in our shares, and thereafter will be treated as capital gain (and thus treated in the manner described in "—Disposition of Shares" below).

        Disposition of Shares.    Upon a sale, exchange or other taxable disposition of our shares, a shareholder generally will recognize capital gain or loss equal to the difference between the amount realized on the sale, exchange or other taxable disposition and its adjusted tax basis in our shares. Such capital gain or loss will be long-term capital gain or loss if the shares had been held for more than one year at the time of disposition. Long-term capital gains of certain non-corporate shareholders (including individuals) are subject to U.S. federal income taxation at a maximum rate of 20%. The deductibility of capital losses is subject to limitations under the Code.

        Medicare Tax.    Certain U.S. Shareholders who are individuals, estates or trusts will be subject to a 3.8% Medicare tax on the lesser of (1) their "net investment income" for the relevant taxable year and (2) the excess of their modified adjusted gross income for the taxable year over a certain threshold (which, in the case of individuals will be between $125,000 and $250,000, depending on the individual's circumstances). A U.S. Shareholder's net investment income will generally include its dividend income and its gains from the disposition of our shares unless such dividend income or gains are derived in the ordinary course of the conduct of a trade or business (other than a trade or business that consists of certain passive or trading activities). If you are a U.S. Shareholder that is an individual, estate, or trust, you are urged to consult your own tax advisors regarding the applicability of the Medicare tax to your income and gains in respect of your investment in our shares.

Taxation of Non-U.S. Shareholders

        The following discussion is only a summary of the rules governing the Federal income taxation of non-U.S. Shareholders, such as nonresident alien individuals and foreign corporations. Prospective non-U.S. Shareholders should consult with their own tax advisors to determine the impact of Federal, state and local income tax laws with regard to an investment in our shares, including any reporting requirements.

        Distributions Generally.    Distributions of cash or property that we pay in respect of our shares will constitute dividends for U.S. federal income tax purposes to the extent paid from our current or accumulated earnings and profits (as determined under U.S. federal income tax principles). A non-U.S. Shareholder generally will be subject to U.S. federal withholding tax at a 30% rate, or at a reduced rate prescribed by an applicable income tax treaty, on any dividends received in respect of our shares. If the amount of a distribution exceeds our current and accumulated earnings and profits, such excess first will be treated as a tax-free return of capital to the extent of the non-U.S. Shareholder's tax basis in our shares,

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and thereafter will be treated as capital gain (and thus treated in the manner described in "—Dispositions" below). In order to obtain a reduced rate of U.S. federal withholding tax under an applicable income tax treaty, a non-U.S. Shareholder will be required to provide a properly executed IRS Form W-8BEN or IRS Form W-8BEN-E, as applicable, certifying its entitlement to benefits under the treaty. A non-U.S. Shareholder of our shares that is eligible for a reduced rate of U.S. federal withholding tax under an income tax treaty may obtain a refund or credit of any excess amounts withheld by filing an appropriate claim for a refund with the IRS. A non-U.S. Shareholder should consult its own tax advisor regarding its possible entitlement to benefits under an income tax treaty.

        The U.S. federal withholding tax described in the preceding paragraph does not apply to dividends that represent U.S. trade or business income of a non-U.S. Shareholder who provides a properly executed IRS Form W-8ECI, certifying that the dividends are effectively connected with the non-U.S. Shareholder's conduct of a trade or business within the United States.

        Dispositions.    Except as set forth below, a non-U.S. Shareholder generally will not be subject to U.S. federal income or withholding tax in respect of any gain on a sale, exchange or other taxable disposition of our shares unless:

        We have not determined whether we are a U.S. real property holding corporation, and no assurance can be given that we are not or will not become one in the future. If, however, we are or become a U.S. real property holding corporation, so long as our shares are regularly traded on an established securities market, generally only a non-U.S. Shareholder who holds or held directly or indirectly (at any time during the shorter of the five year period ending on the date of disposition or the non-U.S. Shareholder's holding period) more than five percent of our shares will be subject to United States federal income tax on the disposition of our shares. Non-U.S. Shareholders should consult their own advisors about the consequences that could result if we are, or become, a U.S. real property holding corporation.

        FATCA.    Pursuant to Sections 1471 to 1474 of the Code and the Regulations promulgated thereunder (the provisions commonly known as FATCA), dividends paid, and the gross proceeds from the sale or other disposition of our shares after December 31, 2016, to a foreign financial institution may be subject to withholding at a rate of 30% unless (x)(1) such institution enters into an agreement with the U.S. government to withhold on certain payments and to collect and provide to the U.S. tax authorities substantial information regarding U.S. account holders of such institution (which includes certain equity and debt holders of such institution, as well as certain account holders that are foreign entities with U.S. owners) or (2) such institution resides in a jurisdiction with which the United States has entered into an intergovernmental agreement to implement FATCA and (y) such foreign financial institution provides the withholding agent with a certification that it is eligible to receive payment free of FATCA withholding. The legislation also generally will impose a U.S. federal withholding tax of 30% on dividends paid on our shares or, in the case of gross proceeds from a sale or other disposition of our shares, December 31, 2016, to a non-financial foreign entity unless such entity provides the withholding agent with a certification (i) that such entity does not have any "substantial United States owners" or (ii) provides certain information regarding the entity's "substantial United States owners," which will in turn be provided to the U.S. tax authorities. A foreign financial institution or non-financial foreign entity can meet the certification requirements by providing a properly executed IRS Form W-8BEN, IRS Form W-8BEN-E or IRS

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Form W-8ECI, as applicable. Under certain circumstances, a shareholder might be eligible for refunds or credits of such taxes from the IRS. Prospective investors are encouraged to consult with their own tax advisors regarding the possible implications of this legislation on their investment in our shares.

        Federal Estate Tax.    Our Mandatory Convertible Preferred Stock or Common Shares beneficially owned by an individual who is not a citizen or resident of the U.S. (as defined for U.S. federal estate tax purposes) at the time of death will generally be includable in the decedent's gross estate for U.S. federal estate tax purposes, unless an applicable estate tax treaty provides otherwise.

Information Reporting Requirements and Backup Withholding Tax

        U.S. Shareholders.    In general, dividends on our shares and payments of the proceeds of a sale, exchange or other taxable disposition of our shares paid to a U.S. Shareholder are subject to information reporting and may be subject to backup withholding, currently at a rate of 28%, unless it (i) is a corporation or other exempt recipient, or (ii) provides an accurate taxpayer identification number and certifies that it is not subject to backup withholding.

        Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules will be refunded by the IRS or credited against the shareholder's U.S. federal income tax liability, if any, provided that the required information is furnished to the IRS.

        Non-U.S. Shareholders.    We must annually report to the IRS and to each non-U.S. Shareholder any dividend income that is subject to U.S. federal withholding tax, or that is exempt from such withholding tax pursuant to an income tax treaty. Copies of these information returns also may be made available under the provisions of a specific treaty or agreement to the tax authorities of the country in which the non-U.S. Shareholder resides. Under certain circumstances, the Code imposes a backup withholding obligation (currently at a rate of 28%) on certain reportable payments. Dividends paid to a non-U.S. holder of our shares generally will be exempt from backup withholding if the non-U.S. Shareholder provides a properly executed IRS Form W-8BEN or IRS Form W-8BEN-E, as applicable, or otherwise establishes an exemption.

        The payment of the proceeds from the disposition of our shares to or through the U.S. office of any broker, U.S. or foreign, will be subject to information reporting and possible backup withholding unless the owner certifies as to its non-U.S. status under penalties of perjury or otherwise establishes an exemption, provided that the broker does not have actual knowledge or reason to know that the holder is a U.S. person or that the conditions of any other exemption are not, in fact, satisfied. The payment of the proceeds from the disposition of our shares to or through a non-U.S. office of a non-U.S. broker will not be subject to information reporting or backup withholding unless the non-U.S. broker has certain types of relationships with the United States (a "U.S. related person"). In the case of the payment of the proceeds from the disposition of our shares to or through a non-U.S. office of a broker that is either a U.S. person or a U.S. related person, the Regulations require information reporting (but not backup withholding) on the payment unless the broker has documentary evidence in its files that the owner is a non-U.S. Shareholder and the broker has no knowledge to the contrary. Prospective investors should consult their own tax advisors on the application of information reporting and backup withholding to them in their particular circumstances (including upon their disposition of our shares).

        Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules will be refunded by the IRS or credited against the shareholder's U.S. federal income tax liability, if any, provided that the required information is furnished to the IRS.

        Prospective Investors are advised to consult their own tax advisers with respect to the particular tax consequences to them of an investment in us.

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UNDERWRITING

        Under the terms and subject to the conditions in an underwriting agreement to be dated the date of the final prospectus supplement, the underwriters named below, for whom Morgan Stanley & Co. LLC, Barclays Capital Inc., Credit Suisse Securities (USA) LLC, RBC Capital Markets, LLC and UBS Securities LLC are acting as representatives, have severally agreed to purchase, and we have agreed to sell to them, severally, the number of shares indicated below:

Name
  Number of
Shares
 

Morgan Stanley & Co. LLC

       

Barclays Capital Inc. 

       

Credit Suisse Securities (USA) LLC

       

RBC Capital Markets, LLC

       

UBS Securities LLC

       

BNP Paribas Securities Corp. 

       

Merrill Lynch, Pierce, Fenner & Smith

       

                      Incorporated

       

Credit Agricole Securities (USA)

       

Deutsche Bank Securities Inc. 

       

J.P. Morgan Securities LLC

       

Mitsubishi UFJ Securities (USA), Inc. 

       

SunTrust Robinson Humphrey, Inc. 

       
       

Total:

                  
       

        The underwriters and the representatives are collectively referred to as the "underwriters" and the "representatives," respectively. The underwriters are offering the shares of common stock subject to their acceptance of the shares from us and subject to prior sale. The underwriting agreement provides that the obligations of the several underwriters to pay for and accept delivery of the shares of common stock offered by this prospectus supplement are subject to, among other things, the approval of certain legal matters by their counsel and to certain other conditions. The underwriters are obligated to take and pay for all of the shares of common stock offered by this prospectus supplement if any such shares are taken. However, the underwriters are not required to take or pay for the shares covered by the underwriters' option to purchase additional shares described below.

        The underwriters initially propose to offer part of the shares of common stock directly to the public at the offering price listed on the cover page of this prospectus supplement and part to certain dealers. After the initial offering of the shares of common stock, the offering price and other selling terms may from time to time be varied by the representatives.

        We have granted to the underwriters an option, exercisable for 30 days from the date of this prospectus supplement, to purchase up to 3,375,000 additional shares of common stock at the public offering price listed on the cover page of this prospectus supplement, less underwriting discounts and commissions, and less an amount per share of common stock equal to any dividends or distributions that are paid or payable by us on the shares of common stock reflected in the preceding table but that are not payable on the shares of common stock purchased on exercise of that option. To the extent the option is exercised, each underwriter will become obligated, subject to certain conditions, to purchase about the same percentage of the additional shares of common stock as the number listed next to the underwriter's name in the preceding table bears to the total number of shares of common stock listed next to the names of all underwriters in the preceding table.

        The following table shows the per share and total public offering price, underwriting discounts and commissions, and proceeds before expenses to us. These amounts are shown assuming both no exercise

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and full exercise of the underwriters' option to purchase up to an additional 3,375,000 shares of common stock.

 
   
  Total  
 
  Per
Share
  No
Exercise
  Full
Exercise
 

Public offering price

  $            $            $           

Underwriting discounts and commissions to be paid by us

  $            $            $           

Proceeds, before expenses, to us

  $            $            $           

        The estimated offering expenses payable by us, exclusive of the underwriting discounts and commissions, are approximately $            .

        Our common stock is listed on the New York Stock Exchange under the trading symbol "DYN".

        We have agreed that, without the prior written consent of Morgan Stanley & Co. LLC on behalf of the underwriters, during the period ending 60 days after the date of the final prospectus supplement (the "Restricted Period"), we will not (i) offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend, or otherwise transfer or dispose of, directly or indirectly, any shares of common stock or any other securities convertible into or exercisable or exchangeable for common stock or (ii) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of the common stock, whether any such transaction described in (i) or (ii) is to be settled by delivery of common stock or such other securities, in cash or otherwise or (iii) file any registration statement with the SEC relating to the offering of any shares of common stock or any securities convertible into or exercisable or exchangeable for common stock, other than (a) the common stock to be sold hereunder, (b) the issuance of shares of common stock upon the exercise of an option or warrant or the conversion of a security outstanding on the date hereof or otherwise disclosed herein, (c) the offer and sale of shares of common stock in connection with the Mandatory Convertible Preferred Stock Offering described herein and the filing of a registration statement in connection therewith, (d) the issuance and sale of shares of common stock to ECP in a transaction exempt from registration under the Securities Act pursuant to the ERC Purchase Agreements, (e) the grant of awards or the issuance of securities upon the exercise of awards granted pursuant to any incentive compensation plan or arrangement disclosed herein (including in the exhibits to any documents incorporated by reference herein), (e) the filing of one or more registration statements on Form S-8 with respect to any of our incentive compensation plans, and (f) the issuance by us of up to 5.0% of the shares of common stock outstanding after this offering or any securities convertible into or exercisable or exchangeable for common stock in connection with mergers or acquisitions, joint ventures, commercial relationships or other strategic transactions if each person receiving shares pursuant to this clause (f) enters into a lock-up agreement, as described below, for the balance of the Restricted Period.

        Each of our directors and officers (as such term is defined in Section 16a-1(f) of the Exchange Act) have agreed that, without the prior written consent of Morgan Stanley & Co. LLC on behalf of the underwriters, during the Restricted Period, they will not (1) offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend, or otherwise transfer or dispose of, directly or indirectly, any shares of common stock beneficially owned (as such term is used in Rule 13d-3 of the Exchange Act), by such persons, or any other securities so owned convertible into or exercisable or exchangeable for shares of common stock, or (2) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of the shares of common stock, whether any such transaction described in (1) or (2) is to be settled by delivery of shares of common stock or such other securities, in cash or otherwise.

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        The restrictions described in the immediately preceding paragraph do not apply to:

        Morgan Stanley & Co. LLC, in its sole discretion, may release the common stock and other securities subject to the lock-up agreements described above in whole or in part at any time with or without notice.

        In order to facilitate the offering of the common stock, the underwriters may engage in transactions that stabilize, maintain or otherwise affect the price of the common stock. Specifically, the underwriters may sell more shares than they are obligated to purchase under the underwriting agreement, creating a short position. A short sale is covered if the short position is no greater than the number of shares available for purchase by the underwriters under the option. The underwriters can close out a covered short sale by exercising the option or purchasing shares in the open market. In determining the source of shares to close out a covered short sale, the underwriters will consider, among other things, the open market price of shares compared to the price available under the option. The underwriters may also sell shares in excess of the option, creating a naked short position. The underwriters must close out any naked short position by purchasing shares in the open market. A naked short position is more likely to be created if the underwriters are concerned that there may be downward pressure on the price of the common stock in the

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open market after pricing that could adversely affect investors who purchase in this offering. As an additional means of facilitating this offering, the underwriters may bid for, and purchase, shares of common stock in the open market to stabilize the price of the common stock. The underwriting syndicate may also reclaim selling concessions allowed to an underwriter or a dealer for distributing the shares of common stock in this offering if the syndicate repurchases previously distributed shares of common stock to cover syndicate short positions or to stabilize the price of the shares of common stock. These activities may raise or maintain the market price of the common stock above independent market levels or prevent or retard a decline in the market price of the common stock. The underwriters are not required to engage in these activities and may end any of these activities at any time.

        We and the underwriters have agreed to indemnify each other against certain liabilities, including liabilities under the Securities Act.

        A prospectus supplement in electronic format may be made available on websites maintained by one or more underwriters, or selling group members, if any, participating in this offering. The representatives may agree to allocate a number of shares of common stock to underwriters for sale to their online brokerage account holders. Internet distributions will be allocated by the representatives to underwriters that may make Internet distributions on the same basis as other allocations.

        The underwriters and their respective affiliates are full service financial institutions engaged in various activities, which may include securities trading, commercial and investment banking, financial advisory, investment management, investment research, principal investment, hedging, financing and brokerage activities. Certain of the underwriters and their respective affiliates have, from time to time, performed, and may in the future perform, various financial advisory and investment banking services for us and our subsidiaries, for which they have received and may in the future receive customary fees and expenses. In that regard, (i) some or all of the underwriters and/or their affiliates are lenders and/or agents under our $1,775,000,000 term and revolving credit facility, (ii) all of the underwriters and/or affiliates of such underwriters are acting as underwriters and/or representatives of the Mandatory Convertible Preferred Stock Offering, and (iii) in connection with the Debt Financing, some or all of the underwriters and/or affiliates of such underwriters have entered into commitments to provide the entire aggregate amount of the Debt Financing, which is conditional, in part, on the closing of the relevant Acquisition, including to (a) act as arrangers, lenders and agents under our proposed $950,000,000 incremental revolving credit facilities and (b) act as arrangers, lenders and agents under our proposed $6,350,000,000 bridge loan facilities, and/or to act as initial purchasers or placement agents for any debt securities or arrangers for other debt financings that may be borrowed to fund the Acquisitions (a "Securities Offering"), the proceeds of which, together the proceeds from the issuance of the shares of common stock pursuant to this prospectus supplement and the proceeds from the Mandatory Convertible Preferred Stock Offering, are expected to reduce the aggregate commitments of the underwriters and/or affiliates to provide the bridge loan facilities on a dollar for dollar basis. In addition, (i) Morgan Stanley & Co. LLC and Credit Suisse Securities (USA) LLC are acting as financial advisors to the Company in connection with the ERC and Brayton Acquisitions, (ii) Morgan Stanley & Co. LLC and Credit Suisse Securities (USA) LLC are acting as financial advisors to Duke in connection with the Duke Midwest Acquisition, (iii) Barclays Capital Inc. is acting as a financial advisor to ECP in connection with the ERC and Brayton Acquisitions, and (iv) Morgan Stanley Senior Funding, LLC, Credit Suisse Securities (USA) LLC and RBC Capital Markets, LLC have each been engaged separately in advisory roles with respect to financial and/or M&A structuring, provided that the fees for each of (i) - (iv) are contingent upon the closing of the relevant Acquisition.

        In addition, in the ordinary course of their various business activities, the underwriters and their respective affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative securities) and financial instruments (including bank loans) for their own account and for the accounts of their customers and may at any time hold long and short positions in such securities and instruments. Such investment and securities activities may involve securities and instruments

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of ours or our subsidiaries. Certain of the underwriters and/or their affiliates that have lending or other relationships with us or our subsidiaries may also choose to hedge their credit exposure to us or our subsidiaries, as the case may be, consistent with their customary risk management policies. Typically, those underwriters and their affiliates would hedge such exposure by entering into transactions, which may consist of either the purchase of credit default swaps or the creation of short positions in securities of ours or our subsidiaries, including potentially the shares of Common Preferred Stock offered hereby. Any such credit default swaps or short positions could adversely affect future trading prices of the shares of common stock offering hereby. The underwriters and their respective affiliates may also make investment recommendations or publish or express independent research views in respect of such securities or instruments and may at any time hold, or recommend to clients that they acquire, long or short positions in such securities and instruments.

Selling Restrictions

European Economic Area

        In relation to each Member State of the European Economic Area which has implemented the Prospectus Directive (each, a "Relevant Member State"), an offer to the public of any shares of our common stock may not be made in that Relevant Member State, except that an offer to the public in that Relevant Member State of any shares of our common stock may be made at any time under the following exemptions under the Prospectus Directive, if they have been implemented in that Relevant Member State:

For the purposes of this provision, the expression an "offer to the public" in relation to any shares of our common stock in any Relevant Member State means the communication in any form and by any means of sufficient information on the terms of the offer and any shares of our common stock to be offered so as to enable an investor to decide to purchase any shares of our common stock, as the same may be varied in that Member State by any measure implementing the Prospectus Directive in that Member State, the expression "Prospectus Directive" means Directive 2003/71/EC (and amendments thereto, including the 2010 PD Amending Directive, to the extent implemented in the Relevant Member State), and includes any relevant implementing measure in the Relevant Member State, and the expression "2010 PD Amending Directive" means Directive 2010/73/EU.

United Kingdom

        Each underwriter has represented and agreed that:

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Hong Kong

        The shares may not be offered or sold by means of any document other than (i) in circumstances which do not constitute an offer to the public within the meaning of the Companies Ordinance (Cap. 32, Laws of Hong Kong), or (ii) to "professional investors" within the meaning of the Securities and Futures Ordinance (Cap. 571, Laws of Hong Kong) and any rules made thereunder, or (iii) in other circumstances which do not result in the document being a "prospectus" within the meaning of the Companies Ordinance (Cap. 32, Laws of Hong Kong), and no advertisement, invitation or document relating to the shares may be issued or may be in the possession of any person for the purpose of issue (in each case whether in Hong Kong or elsewhere), which is directed at, or the contents of which are likely to be accessed or read by, the public in Hong Kong (except if permitted to do so under the laws of Hong Kong) other than with respect to shares which are or are intended to be disposed of only to persons outside Hong Kong or only to "professional investors" within the meaning of the Securities and Futures Ordinance (Cap. 571 Laws of Hong Kong) and any rules made thereunder.

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WHERE YOU CAN FIND MORE INFORMATION

        We file annual, quarterly and current reports, proxy statements and other information with the SEC. You may read and copy at prescribed rates any document that we file at the SEC's Public Reference Room located at 100 F Street, N.E., Washington, D.C. 20549. You may obtain information on the operation of the Public Reference Room by calling the SEC at 1-800-SEC-0330. Our filings are also available on the SEC's website at http://www.sec.gov.

        You may also obtain any of these filings incorporated by reference into this prospectus supplement from us without charge, excluding any exhibits to these documents unless the exhibit is specifically incorporated by reference in such filing, by requesting a copy in writing, or by telephoning, the office of the Investor Relations Department, Dynegy Inc., 601 Travis, Suite 1400, Houston, Texas 77002, telephone number (713) 507-6400, or through the "Investor Relations" section of our website at www.dynegy.com.



INCORPORATION BY REFERENCE

        The SEC allows us to incorporate by reference information into this prospectus supplement. This means that we can disclose important information to you by referring you to another document. Any information referred to in this way is considered part of this prospectus supplement from the date we file that document with the SEC.

        We incorporate by reference in this prospectus supplement the documents set forth below that have been previously filed with the SEC:

        Any reports filed by us with the SEC on or after the date of this prospectus supplement and before the termination of this offering will automatically update and, where applicable, supersede any information contained or incorporated by reference in this prospectus supplement. Notwithstanding the above, we are not incorporating any documents or information deemed to have been furnished rather than filed in accordance with SEC rules. To obtain copies of these filings, see "Where You Can Find More Information."

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LEGAL MATTERS

        The validity of the common stock will be passed upon for us by White & Case LLP, New York, New York. Certain legal matters with respect to this offering will be passed upon for the underwriters Paul Hastings LLP, New York, New York.

EXPERTS

        Ernst & Young LLP, independent registered public accounting firm, has audited our consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2013, and the effectiveness of our internal control over financial reporting as of December 31, 2013, as set forth in their reports, which are incorporated by reference in this prospectus and elsewhere in the registration statement. Our financial statements are incorporated by reference in reliance on Ernst & Young LLP's reports, given on their authority as experts in accounting and auditing.

        The audited historical consolidated financial statements of Ameren Energy Resources Company, LLC included on pages A-43 through A-107 in "Annex A: Financial Statements Relating to AER" of the Company's registration statement on Form S-3ASR dated October 2, 2013, have been so incorporated in reliance on the report of PricewaterhouseCoopers LLP, independent accountants, given on the authority of said firm as experts in auditing and accounting.

        The combined financial statements of the Midwest Generation Business of Duke Energy Corporation as of December 31, 2013 and 2012, and for each of the three years in the period ended December 31, 2013, appearing as Exhibit 99.1 in Dynegy Inc.'s Current Report on Form 8-K dated October 6, 2014, which is incorporated by reference in this prospectus supplement, have been audited by Deloitte & Touche LLP, independent auditors, as stated in their report (which report expresses an unqualified opinion and includes an emphasis-of-matter paragraph relating to certain income and expense allocations), which is incorporated herein by reference. Such combined financial statements have been so incorporated in reliance upon the report of such firm given upon their authority as experts in accounting and auditing.

        The combined financial statements of EquiPower Resources Corp. and Subsidiaries and Brayton Point Holdings, LLC and Subsidiary as of and for the years ended December 31, 2013, 2012, and 2011 appearing as Exhibit 99.3 in Dynegy Inc.'s Current Report on Form 8-K dated October 6, 2014, have been audited by Deloitte & Touche LLP, independent auditors, as stated in their report (which report expresses an unqualified opinion and includes an emphasis-of-matter paragraph relating to the sale of EquiPower Resources Corp. and Subsidiaries and Brayton Point Holdings, LLC and Subsidiary) which is incorporated by reference herein. Such financial statements have been so incorporated in reliance upon the report of such firm given upon their authority as experts in accounting and auditing.

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PROSPECTUS

GRAPHIC

Dynegy Inc.

Common Stock
Preferred Stock
Debt Securities
Guarantees of Debt Securities
Warrants
Units
Depositary Shares
Purchase Contracts



        We may offer from time to time common stock, preferred stock, debt securities, guarantees of debt securities, warrants, units, depositary shares or purchase contracts. In addition, certain selling securityholders to be identified in a prospectus supplement may offer and sell these securities from time to time, in amounts, at prices and on terms that will be determined at the time the securities are offered. The preferred stock and debt securities may be convertible into or exchangeable for our common stock or other securities. Specific terms of these securities will be provided in supplements to this prospectus. You should read this prospectus and any supplement carefully before you invest.

        Our common stock is listed on the New York Stock Exchange under the symbol "DYN."



        Investing in our securities involves risks. See "Risk Factors" beginning on page 2 of this prospectus and those contained or incorporated by reference herein or in any prospectus supplement or any free writing prospectus from time to time before making an investment decision.



        Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved these securities, or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.



        This prospectus may not be used to sell securities unless accompanied by a prospectus supplement.

The date of this prospectus is October 6, 2014


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TABLE OF CONTENTS

 
  Page

ABOUT THIS PROSPECTUS

  1

RISK FACTORS

  2

SPECIAL NOTE ON FORWARD-LOOKING STATEMENTS

  2

WHERE YOU CAN FIND MORE INFORMATION

  2

INCOPORATION BY REFERENCE

  3

DYNEGY INC. 

  4

USE OF PROCEEDS

  5

RATIO OF EARNINGS TO FIXED CHARGES

  6

DESCRIPTION OF SECURITIES

  7

PLAN OF DISTRIBUTION

  8

VALIDITY OF SECURITIES

  8

EXPERTS

  8




ABOUT THIS PROSPECTUS

        This prospectus is part of an automatically effective registration statement that we filed with the Securities and Exchange Commission, or the SEC, utilizing a "shelf" registration process. Under this shelf registration process, we and/or the selling securityholders may sell any combination of the securities described in this prospectus in one or more offerings and with prices and other terms to be determined. This prospectus provides you with a general description of the securities we and/or the selling securityholders may offer. Each time we and/or the selling securityholders sell securities pursuant to the registration statement of which this prospectus forms a part, we will provide a prospectus supplement that will contain specific information about the securities being offered and the terms of that offering. The prospectus supplement may also add, update or change information contained or incorporated by reference in this prospectus. If there is any inconsistency between this prospectus and the applicable prospectus supplement, you should rely on the information in the prospectus supplement. You should carefully read this prospectus, any applicable prospectus supplement and any related pricing supplement or free writing prospectus, together with the additional information incorporated by reference into this prospectus as described under the heading "Incorporation of Certain Information by Reference" before making an investment in our securities.

        We have not authorized anyone to provide any information other than that contained or incorporated by reference in this prospectus, any accompanying prospectus supplement or any free writing prospectus prepared by or on behalf of us or to which we have referred you. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. We are not making an offer of these securities in any jurisdiction where the offer is not permitted. You should not assume that the information contained in or incorporated by reference in this prospectus or any prospectus supplement or in any free writing prospectus is accurate as of any date other than their respective dates.

        In this prospectus, the terms "DYN," "we," "us," "our" and "Dynegy" refer to Dynegy Inc. and its subsidiaries.



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RISK FACTORS

        An investment in our securities involves risks. You should carefully consider the risk factors contained in Item 1A of our most recent Annual Report on Form 10-K and other subsequent filings with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act, each of which is incorporated by reference, and those risk factors that may be included or incorporated by reference under the caption "Risk Factors" in any applicable prospectus supplement, together with all of the other information included in this prospectus, any prospectus supplement or any free writing prospectus before making an investment decision. These risks could materially affect our business, results of operations or financial condition and cause the value of our securities to decline. In addition, new risks may emerge at any time and we cannot predict such risks or estimate the extent to which they may affect our financial performance.




SPECIAL NOTE ON FORWARD-LOOKING STATEMENTS

        Certain statements contained or incorporated by reference in this prospectus which are not statements of historical fact constitute "forward looking statements," which involve risks and uncertainties. All statements included or incorporated by reference into this prospectus, other than statements of historical fact, that address activities, events or developments that we believe or anticipate will or may occur in the future are forward-looking statements. These statements represent our reasonable judgment of the future based on various factors and using numerous assumptions and are subject to known and unknown risks, uncertainties and other factors that could cause our actual results and financial position to differ materially from those contemplated by the statements. You can identify these statements by the fact that they do not relate strictly to historical or current facts. They use words such as "anticipate," "estimate," "project," "forecast," "plan," "may," "will," "should," "expect" and other words of similar meaning.

        Although we believe the expectations reflected in the forward-looking statements are reasonable, we cannot guarantee future results, level of activity, performance or achievements. Moreover, neither we nor any other person assumes responsibility for the accuracy and completeness of any of these forward-looking statements. We are under no duty to update any of these forward-looking statements after the date of this prospectus to conform our prior statements to actual results or revised expectations.




WHERE YOU CAN FIND MORE INFORMATION

        We file annual, quarterly and current reports, proxy statements and other information with the SEC. You may read and copy at prescribed rates any document that we file at the SEC's Public Reference Room located at 100 F Street, N.E., Washington, D.C. 20549. You may obtain information on the operation of the Public Reference Room by calling the SEC at 1-800-SEC-0330. Our filings are also available on the SEC's website at http://www.sec.gov.

        You may also obtain any of these filings incorporated by reference into this prospectus from us without charge, excluding any exhibits to these documents unless the exhibit is specifically incorporated by reference in such filing, by requesting a copy in writing, or by telephoning, the office of the Investor Relations Department, Dynegy Inc., 601 Travis, Suite 1400, Houston, Texas 77002, telephone number (713) 507-6400, or through the "Investor Relations" section of our website at www.dynegy.com.



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INCOPORATION BY REFERENCE

        The SEC allows us to incorporate by reference the information we file with them, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is an important part of this prospectus. We incorporate by reference in this prospectus the documents listed below:

        Any reports filed by us with the SEC on or after the date of this prospectus and before the date that the offering of any securities by means of this prospectus and an accompanying prospectus supplement is terminated will automatically update and, where applicable, supersede any information contained or incorporated by reference into this prospectus. Notwithstanding the above, we are not incorporating any documents or information deemed to have been furnished rather than filed in accordance with SEC rules. To obtain copies of these filings, see "Where You Can Find More Information."

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DYNEGY INC.

        Our primary business is the production and sale of electric energy, capacity and ancillary services. We operate a portfolio of generation assets that is diversified in terms of dispatch profile, fuel type and geography. Our Coal and Illinois Power Holdings segments are fleets of baseload coal facilities, located in Illinois, that dispatch around the clock throughout the year. Our Gas segment operates both intermediate and peaking natural gas facilities, located in the Midwest, Northeast and California. In addition to generating power, our generating facilities also receive capacity revenues through structured markets or bilateral tolling agreements, as local utilities and independent system operators ("ISOs") seek to ensure sufficient generation capacity is available to meet future market demands.

        We sell electric energy, capacity and ancillary services on a wholesale basis from our power generation facilities. In connection with the acquisition of New Ameren Energy Resources, LLC and its subsidiaries on December 2, 2013, we began serving residential, municipal, commercial and industrial consumers through our Homefield Energy retail business in Illinois. Wholesale electricity customers will, for reliability reasons and to meet regulatory requirements, contract for rights to capacity from generating units. Ancillary services are the products of a power generation facility that support the transmission grid operation, follow real-time changes in load and provide emergency reserves for major changes to the balance of generation and load. Retail electricity customers purchase energy and these related services in the deregulated retail energy market. We sell these products individually or in combination to our customers for various lengths of time ranging from hourly to multi-year transactions.

        We do business with a wide range of customers, including: regional transmission organizations and ISOs, integrated utilities, municipalities, electric cooperatives, transmission and distribution utilities, power marketers, financial participants such as banks and hedge funds, and residential, commercial and industrial end-users. Some of our customers, such as municipalities or integrated utilities, purchase our products for resale in order to serve their retail, commercial and industrial customers. Other customers, such as some power marketers, may buy from us to serve their own wholesale or retail customers or as a hedge against power sales they have made.

        Our principal executive offices are located at 601 Travis, Suite 1400, Houston, Texas 77002. Our telephone number is (713) 507-6400 and we have a website accessible at www.dynegy.com. The information posted on our website is not incorporated into this prospectus and is not part of this prospectus.

        To find more information about us, please see the sections entitled "Where You Can Find More Information" and "Incorporation of Certain Documents by Reference."

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USE OF PROCEEDS

        Unless otherwise indicated in a prospectus supplement, the net proceeds from the sale of the securities will be used for general corporate purposes, including without limitation acquisitions, working capital, repayment of debt and capital expenditures. In the case of a sale by a selling securityholder, we will not receive any of the proceeds from such sale. Additional information on the use of the net proceeds may be provided in the applicable prospectus supplement.

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RATIO OF EARNINGS TO FIXED CHARGES

        The following table presents our ratio of earnings to fixed charges for the periods indicated:

 
   
   
   
   
  Year Ended December 31,  
 
  Successor   Predecessor  
 
  Six Months
Ended
June 30,
2014
  Year Ended
December 31,
2013
  October 2
Through
December 31,
2012
  January 1
Through
October 1,
2012
  2011   2010   2009  

Ratio of earnings to fixed charges(1), (2)

    (3)   (3)   (3)   2.13     (3)   (3)   (3)

(1)
For purposes of computing the ratio of earnings to fixed charges, "earnings" are defined as pre-tax income from continuing operations before adjustment for earnings from equity investments plus fixed charges. "Fixed charges" consist of interest, whether capitalized or expensed, amortization of debt expense and the estimated interest component of rent expense.

(2)
For the periods presented, we had no preferred shares outstanding. Therefore, the ratios of earnings to combined fixed charges and preferred share dividends for the periods indicated equal the ratios of earnings to fixed charges for the same periods.

(3)
For six months ended June 30, 2014, the year ended December 31, 2013, the period from October 2 through December 31, 2012 and the years ended December 31, 2011, 2010 and 2009 earnings were insufficient to cover fixed charges by $175 million, $419 million, $113 million, $587 million, $406 million and $1,107 million, respectively.

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DESCRIPTION OF SECURITIES

        We and/or the selling securityholders may sell, from time to time, in one or more offerings, the following securities:

        We will set forth in the applicable prospectus supplement or other offering material a description of the common stock, preferred stock, debt securities, guarantees of debt securities, warrants, units, depositary shares and purchase contracts, which may be offered under this prospectus. Any preferred stock or debt securities may be convertible into or exchangeable for our common stock or other securities. The terms of the offering of securities, including the initial offering price and the net proceeds to us, will be contained in the prospectus supplement or other offering material relating to such offer. You should carefully read this prospectus, any prospectus supplement or other offering material before you invest in any of our securities.

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PLAN OF DISTRIBUTION

        We and/or the selling securityholders may sell the securities from time to time (a) through underwriters or dealers; (b) through agents; (c) directly to one or more purchasers or other persons or entities; (d) through a combination of these methods of sale; or (e) through other means. We will identify the specific plan of distribution, including any underwriters, dealers, agents or other purchasers, persons or entities and any applicable compensation in any related amendment to the registration statement of which this prospectus is a part, any related prospectus supplement, or any documents incorporated by reference or deemed incorporated by reference into this prospectus.


VALIDITY OF SECURITIES

        The validity of the securities in respect of which this prospectus is being delivered will be passed on for us by White & Case LLP.


EXPERTS

        The consolidated financial statements of Dynegy Inc. appearing in Dynegy Inc.'s Annual Report (Form 10-K) for the year ended December 31, 2013, and the effectiveness of Dynegy Inc.'s internal control over financial reporting as of December 31, 2013, have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their reports thereon included therein, and incorporated herein by reference. Such financial statements are, and audited financial statements to be included in subsequently filed documents will be, incorporated herein in reliance upon the reports of Ernst & Young LLP pertaining to such financial statements and the effectiveness of internal control over financial reporting as of the respective dates (to the extent covered by consents filed with the Securities and Exchange Commission) given on the authority of such firm as experts in accounting and auditing.

        The audited historical consolidated financial statements of Ameren Energy Resources Company, LLC included on pages A-43 through A-107 in "Annex A: Financial Statements Relating to AER" of Dynegy Inc.'s registration statement on Form S-3ASR dated October 2, 2013, have been so incorporated in reliance on the report of PricewaterhouseCoopers LLP, independent accountants, given on the authority of said firm as experts in auditing and accounting.

        The combined financial statements of the Midwest Generation Business of Duke Energy Corporation as of December 31, 2013 and 2012, and for each of the three years in the period ended December 31, 2013, appearing as Exhibit 99.1 in Dynegy Inc.'s Current Report on Form 8-K dated October 6, 2014, which is incorporated by reference in this Prospectus, have been audited by Deloitte & Touche LLP, independent auditors, as stated in their report (which report expresses an unqualified opinion and includes an emphasis-of-matter paragraph relating to certain income and expense allocations), which is incorporated herein by reference. Such combined financial statements have been so incorporated in reliance upon the report of such firm given upon their authority as experts in accounting and auditing.

        The combined financial statements of EquiPower Resources Corp. and Subsidiaries and Brayton Point Holdings, LLC and Subsidiary as of and for the years ended December 31, 2013, 2012, and 2011 appearing as Exhibit 99.3 in Dynegy Inc.'s Current Report on Form 8-K dated October 6, 2014, have been audited by Deloitte & Touche LLP, independent auditors, as stated in their report (which report expresses an unqualified opinion and includes an emphasis-of-matter paragraph relating to the sale of EquiPower Resources Corp. and Subsidiaries and Brayton Point Holdings, LLC and Subsidiary) which is incorporated by reference herein. Such financial statements have been so incorporated in reliance upon the report of such firm given upon their authority as experts in accounting and auditing.

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