Ownership Submission
FORM 3
 UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
  Foresite Capital Management I, LLC
 2. Date of Event Requiring Statement (Month/Day/Year)
05/16/2013		 3. Issuer Name and Ticker or Trading Symbol
AMBIT BIOSCIENCES CORP [AMBI]
(Last)
(First)
(Middle)
3052 PACIFIC AVENUE		 4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director __X__ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

SAN FRANCISCO, CA 94115		 6. Individual or Joint/Group Filing(Check Applicable Line)
___ Form filed by One Reporting Person
_X_ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Beneficially Owned
1.Title of Security
(Instr. 4)		 2. Amount of Securities Beneficially Owned
(Instr. 4)		 3. Ownership Form: Direct (D) or Indirect (I)
(Instr. 5)		 4. Nature of Indirect Beneficial Ownership
(Instr. 5)
Common Stock 2,000,000
I
See footnote (1)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 4)		 2. Date Exercisable and Expiration Date
(Month/Day/Year)		 3. Title and Amount of Securities Underlying Derivative Security
(Instr. 4)		 4. Conversion or Exercise Price of Derivative Security 5. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 5)		 6. Nature of Indirect Beneficial Ownership
(Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
Foresite Capital Management I, LLC
3052 PACIFIC AVENUE
SAN FRANCISCO, CA 94115		     X    
Foresite Capital Fund I, L.P.
3052 PACIFIC AVENUE
SAN FRANCISCO, CA 94115		     X    
Tananbaum James B.
3052 PACIFIC AVENUE
SAN FRANCISCO, CA 94115		     X    

Signatures

/s/ James B. Tananbaum, as managing member of Foresite Capital Management I, LLC 10/16/2013
**Signature of Reporting Person Date
/s/ James B. Tananbaum, as managing member of the GP of Foresite Capital Fund I, L.P. 10/16/2013
**Signature of Reporting Person Date
/s/ James B. Tananbaum 10/16/2013
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 5(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) Shares are owned directly by Foresite Capital Fund I, L.P. ("FCF I"). Foresite Capital Management I, LLC ("FCM I"), the Designated Filer and general partner of FCF I, may be deemed to have the sole voting and dispositive power over 2,000,000 shares of the Issuer's Common Stock. James Tananbaum ("Tananbaum"), in his capacity as managing member of FCM I, may be deemed to have the sole voting and dispositive power over 2,000,000 shares of the Issuer's Common Stock.
 
Remarks:
Each Reporting Person disclaims the existence of a "group". Each of FCM I and its partners and Tananbaum disclaims beneficial ownership of any of these shares except to the extent of any pecuniary interest therein, and the filing of this report is not an admission that FCM I and its partners or Tananbaum is the beneficial owner of these shares for purposes of Section 16 or any other purpose.

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, See Instruction 6 for procedure.

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