United States
                              Securities and Exchange Commission
                                    Washington, D.C. 20549


                                        SCHEDULE 13D

                          Under the Securities Exchange Act of 1934
                                      (Amendment No. 9)

                         John Hancock Patriot Preferred Dividend Fund
                                      (Name of Issuer)


                                         Common Stock
                               (Title of Class of Securities)


                                         41013J-10-7
                                       (CUSIP Number)



                                  The Commerce Group, Inc.
                                       211 Main Street
                                      Webster, MA 01570
                                       (508) 943-9000
                        (Name, Address and Telephone Number of Person
                      Authorized to Receive Notices and Communications)



                                        May 26, 2006
                  (Date of Event which Requires Filing of this Statement)


If the filing person has previously filed a statement on Schedule 13G to
report the acquisition that is the subject of this Schedule 13D, and is filing
this schedule because of Section 240. Rule 13d-1(e), 240.13d-1(f) or 240.13d-
1(g), check the following box:    [  ]

The information required on the remainder of this cover page shall not be
deemed to be "filed" for the purpose of Section 18 of the Securities Exchange
Act of 1934 ("Act") or otherwise subject to the liabilities of that section of
the Act but shall be subject to all other provisions of the Act.





















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CUSIP No.: 41013J-10-7                      THE COMMERCE GROUP, INC.
                                            SCHEDULE 13D
                                            AMENDMENT No. 9
                                            JUNE 2, 2006




1.       NAME OF REPORTING PERSON
         I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

            The Commerce Group Inc.
            ID# 04-2599931

 2.       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                                                          (a) [  ]
                                                          (b) [  ]

3.       SEC USE ONLY

4.       SOURCE OF FUNDS                                      [WC]

5        CHECK BOX IF DISCLOSURE OF LEGAL                     [  ]
         PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)

6.       CITIZENSHIP OR PLACE OF ORGANIZATION

         Massachusetts

         NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

7.       SOLE VOTING POWER                             1,478,700
8.       SHARED VOTING POWER                                   0
9.       SOLE DISPOSITIVE POWER                        1,478,700
10.      SHARED DISPOSITIVE POWER                              0

11.      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            1,478,700

12.      CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
         CERTAIN SHARES    [    ]

13.      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
            20.4%

14.      TYPE OF REPORTING PERSON
           [HC]


















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CUSIP No.: 41013J-10-7                      THE COMMERCE GROUP, INC.
                                            SCHEDULE 13D
                                            AMENDMENT No. 9
                                            June 2, 2006


ITEM 1.  SECURITY AND ISSUER

     This Schedule 13D relates to the shares of beneficial interest (the
"Shares") of John Hancock Patriot Preferred Dividend Fund (the "Fund"), a
Massachusetts business trust registered as an investment company under the
Investment Company Act of 1940, as amended (the "Investment Company Act").
The principal executive offices of the Fund are located at 601 Congress
Street, Boston, MA  02210.


ITEM 2.  IDENTITY AND BACKGROUND

     This Schedule 13D is being filed by The Commerce Group Inc. (the
"Reporting Person"), a corporation formed under the laws of Massachusetts.
The Reporting Person is a corporation whose principal offices are located at
211 Main Street, Webster, MA 01570.


ITEM 3.  SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION

     The source of the funds used by the Reporting Person to purchase shares
listed in Item 5(a) was working capital.  This amount of the funds used to
purchase such shares reported in Annex A aggregated approximately $1,448,998.


ITEM 4.  PURPOSE OF TRANSACTION

     No material change has taken place since the previous filing.


ITEM 5.  INTEREST IN SECURITIES OF THE ISSUER

     (a) The Fund's reports with the Securities and Exchange Commission report
that 7,257,200 Shares are outstanding.  Based upon such number, the Reporting
Person beneficially owns 20.4% of the Fund's outstanding Shares.

     (b) The Reporting Person is the beneficial owner (through its insurance
subsidiary as listed below) of 1,478,700 shares, over which it has sole power
of disposition and voting.  Such number of Shares represents approximately
20.4% of the outstanding Shares.


                                              Shares                Cost

   The Commerce Insurance Company            1,478,700          $15,858,849


     (c) During the period from March 26, 2006 through May 26, 2006, the
Reporting Person has effected the following purchases of common stock, all of
which were made on the New York Stock Exchange (see attached Annex A).

     (d) No person other than the Reporting Person has the right to receive or
the power to direct the receipt of dividends from, or the proceeds from the
sale of, the shares of Common Stock owned by the Reporting Person.

     (e) It is inapplicable to state the date on which the Reporting Person
ceased to be the beneficial owner of more than five percent of the Common
Stock.


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CUSIP No.: 41013J-10-7                      THE COMMERCE GROUP, INC.
                                            SCHEDULE 13D
                                            AMENDMENT No. 9
                                            JUNE 2, 2006




ITEM 6.  CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS
         WITH RESPECT TO SECURITIES OF THE ISSUER

     The Reporting Person does not have any contract, arrangement,
understanding or relationship (legal or otherwise) with any person with
respect to any securities of the Fund, including, but not limited to, the
transfer or voting of any such securities, finders' fees, joint ventures, loan
or option arrangements, puts or calls, guarantees of profits, division of
profits or loss, or the giving or withholding of proxies.



ITEM 7.  MATERIAL TO BE FILED AS EXHIBITS

   Annex A   Item 5(c) Information





                                            SIGNATURE



After reasonable inquiry and to the best of my knowledge and belief, I certify
that the information set forth in this statement is true, complete and
correct.



JUNE 2, 2006                               THE COMMERCE GROUP INC.









                                          /s/ John M. Meciak
                                          John M. Meciak
                                          Assistant Treasurer














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                                                  ANNEX  A
                                         Item 5 (c) - Information
PPF   41013J-10-7    JOHN HANCOCK PATRIOT PREF DIV FUND


COMMERCE INSURANCE COMPANY
    PURCHASES

From 3/26/06 - 5/26/06

  TRADE           SETTLEMENT         SHARES             PRICE         ACQUISITION
  DATE               DATE           PURCHASED        PER SHARE            COST
                                                                
  03/28/06        03/31/06           5,900             $12.93        $   76,502.35
  04/03/06        04/06/06           4,400              12.78            56,372.80
  04/04/06        04/07/06           2,500              12.86            32,235.50
  04/05/06        04/10/06           1,100              12.89            14,218.49
  04/06/06        04/11/06           3,300              13.00            43,014.51
  04/07/06        04/17/06          27,100              13.04           354,253.91
  04/10/06        04/13/06           6,000              13.00            78,225.00
  04/11/06        04/17/06           5,500              12.98            71,593.50
  04/12/06        04/18/06           1,100              13.00            14,338.50
  04/17/06        04/20/06           3,700              12.46            46,231.50
  04/18/06        04/21/06           2,100              12.27            25,843.44
  04/19/06        04/24/06           2,900              12.44            36,171.41
  04/26/06        05/01/06          10,000              12.15           121,800.00
  05/01/06        05/04/06           3,200              12.30            39,472.00
  05/09/06        05/12/06           2,200              12.24            27,005.00
  05/15/06        05/18/06           1,700              11.99            20,442.50
  05/17/06        05/22/06             600              11.94             7,185.00
  05/18/06        05/23/06           2,000              11.91            23,890.00
  05/22/06        05/25/06           1,500              11.93            17,947.50
  05/23/06        05/26/06           4,700              11.96            56,360.52
  05/24/06        05/30/06           9,100              11.91           108,656.73
  05/25/06        05/31/06           6,900              11.93            82,553.67
  05/26/06        06/01/06           7,900              11.95        $   94,683.87

      TOTALS                       115,400                           $1,448,997.70






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