UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                  SCHEDULE 13G
                                  (Rule 13d-2)

             INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT
              TO RULES 13d-l(b), (c) AND (d) AND AMENDMENTS THERETO
                             FILED PURSUANT TO 13d-2
                               (Amendment No. 8)*

                                   SONIC CORP.
                                (Name of Issuer)

                          COMMON STOCK, $0.01 PAR VALUE
                         (Title of Class of Securities)

                                    835451105
                                 (CUSIP Number)

                                DECEMBER 31, 2002
             (Date of Event Which Requires Filing of this Statement)

Check the  appropriate box to designate the rule pursuant to which this Schedule
is filed:

                                /X/ Rule 13d-l(b)

                                / / Rule 13d-l(c)

                                / / Rule 13d-l(d)



* The remainder of this cover page shall be filled out for a reporting  person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter
disclosures provided in a prior cover page.

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(however,see the  Notes).








                                  SCHEDULE 13G

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CUSIP No. 835451105                                        Page 2 of 4 Pages
--------------------------------                     ---------------------------


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           NAME OF REPORTING PERSON
1          SS. OR I.R.S IDENTIFICATION NO. OF ABOVE PERSON
           Massachusetts Financial Services Company ("MFS")
           I.R.S. Identification No.:  04-2747644
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2          CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*              (a)/ /
                                                                          (b)/ /
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3          SEC USE ONLY

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4          CITIZENSHIP OR PLACE OF ORGANIZATION

           Delaware

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                       5        SOLE VOTING POWER
      NUMBER OF
       SHARES                   678,058
                       ---------------------------------------------------------

    BENEFICIALLY
      OWNED BY         6        SHARED VOTING POWER
        EACH
      REPORTING                 0

                       ---------------------------------------------------------

       PERSON
        WITH           7        SOLE DISPOSITIVE POWER

                                702,190

                       ---------------------------------------------------------

                       8        SHARED DISPOSITIVE POWER

                                0
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9          AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
           702,190 shares of common stock of which shares are also beneficially
           owned by certain other non-reporting entities as well as MFS.

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10         CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN
           SHARES                                                            / /

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11         PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           1.75 %

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12         TYPE OF REPORTING PERSON*

           IA
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SCHEDULE 13G

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CUSIP No. 835451105                                      Page 3 of 4 Pages
--------------------------------                     ---------------------------


ITEM 1(a). NAME OF ISSUER:

         See Cover Page.

ITEM 1(b). ADDRESS OF ISSUER'S PRINCIPAL EXECUTIVE OFFICES:

         101 Park Avenue, Oklahoma City, OK  73102

ITEM 2(a). NAME OF PERSON FILING:

         See Item 1 on Page 1.

ITEM 2(b). ADDRESS OF PRINCIPAL OFFICES OR, IF NONE, RESIDENCE:

         500 Boylston Street, Boston, MA 02116

ITEM 2(c). CITIZENSHIP:

         See Item 4 on Page 2

ITEM 2(d). TITLE OF CLASS OF SECURITIES:

         See Cover Page

ITEM 2(e). CUSIP NUMBER:

         See Cover Page

ITEM 3.

         See Item 12 on Page 2.

ITEM 4. OWNERSHIP:

     The  information  in Items 5-11 on the cover page (page 2) of this Schedule
13G is incorporated by reference.






                                  SCHEDULE 13G

--------------------------------                     ---------------------------

CUSIP No. 835451105                                         Page 4 of 4 Pages
--------------------------------                     ---------------------------


ITEM 5. OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS.

         If this statement is being filed to report the fact that as of the date
hereof the reporting person had ceased to be the beneficial owner of more than
five percent of the class of securities, check the following /X/

ITEM 6. OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON.

         Not applicable.

ITEM 7. IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE
         SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY.

         Not Applicable.

ITEM 8. IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP.

         Not Applicable.

ITEM 9. NOTICE OF DISSOLUTION OF GROUP.

         Not Applicable.

ITEM 10. CERTIFICATION.

     By signing  below I certify  that,  to the best of my knowledge and belief,
the  securities  referred  to above were not  acquired  and are not held for the
purpose of or with the effect of  changing  or  influencing  the  control of the
issuer of the  securities  and were not acquired and are not held in  connection
with or as a participant in any transaction having that purpose or effect.

     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.

Dated: February 11, 2003

Massachusetts Financial Services Company

By:/s/ STEPHEN E. CAVAN
   ------------------------------------------
     Stephen E. Cavan
     Senior Vice President, Secretary and General Counsel



     The original  statement  shall be signed by each person on whose behalf the
statement is filed or his authorized representative.  If the statement is signed
on behalf of a person by his authorized  representative  other than an executive
officer  or   general   partner  of  the   filing   person,   evidence   of  the
representative's  authority to sign on behalf of such person shall be filed with
the  statement,  provided,  however,  that a power of attorney  for this purpose
which is already on file with the Commission may be  incorporated  by reference.
The name and any title of each person who signs the statement  shall be typed or
printed beneath his signature.

ATTENTION.  INTENTIONAL  MISSTATEMENTS  OR OMISSIONS OF  FACT CONSTITUTE FEDERAL
CRIMINAL VIOLATIONS (SEE 18 U.S.C. 1001).