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

                                  FORM 12B-25

                          NOTIFICATION OF LATE FILING


                                                Commission File Number 001-16107


(Check One): [ ] Form 10-K  [ ] Form 20-F  [ ] Form 11-K   [x] Form 10-Q
[ ] Form N-SAR  [ ] Form N-CSR

               For Period Ended:  September 30, 2003


                                                                                
                      [ ] Transition Report on Form 10-K
                      [ ] Transition Report on Form 20-F
                      [ ] Transition Report on Form 11-K
                      [ ] Transition Report on Form 10-Q
                      [ ] Transition Report on Form N-SAR


               For the Transition Period Ended:

  Read Instruction (on back page) Before Preparing Form. Please Print or Type.

    NOTHING IN THIS FORM SHALL BE CONSTRUED TO IMPLY THAT THE COMMISSION HAS
                   VERIFIED ANY INFORMATION CONTAINED HEREIN.

If the notification relates to a portion of the filing checked above, identify
the Item(s) to which the notification relates:

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

PART I -- REGISTRANT INFORMATION

Mirant Corporation
--------------------------------------------------------------------------------
Full Name of Registrant

Southern Energy Inc.
--------------------------------------------------------------------------------
Former Name if Applicable

1155 Perimeter Center West, Suite 100
--------------------------------------------------------------------------------
Address of Principal Executive Office (Street and Number)

Atlanta, Georgia 30338
--------------------------------------------------------------------------------
City, State and Zip Code

PART II -- RULE 12B-25(B) AND (C)

If the subject report could not be filed without unreasonable effort or expense
and the registrant seeks relief pursuant to Rule 12b-25(b), the following should
be completed. (Check box if appropriate.)


     
[x]   (a)  The reason described in reasonable detail in Part III of
           this form could not be eliminated without unreasonable
           effort or expense

[ ]   (b)  The subject annual report, semi-annual report, transition
           report on Form 10-K, Form 20-F, Form 11-K, Form N-SAR or
           Form N-CSR, or portion thereof, will be filed on or before
           the fifteenth calendar day following the prescribed due
           date; or the subject quarterly report or transition report
           on Form 10-Q, or portion thereof, will be filed on or before
           the fifth calendar day following the prescribed due date;
           and

[ ]   (c)  The accountant's statement or other exhibit required by Rule
           12b-25(c) has been attached if applicable.




PART III -- NARRATIVE

State below in reasonable detail why Forms 10-K, 20-F, 11-K, 10-Q, N-SAR, N-CSR,
or the transition report or portion thereof, could not be filed within the
prescribed time period.
(Attach Extra Sheets if Needed)

         The audit of the Company's 2002 financial statements and the reaudits
of the Company's 2000 and 2001 financial statements were completed on April 29,
2003, which ultimately delayed the Company's ability to focus on its financial
reporting process for the quarters ended March 31, 2003, June 30, 2003 and
September 30, 2003. The Form 10-Q for the quarter ended June 30, 2003 was filed
on October 28, 2003. The delay of this filing caused the Company to require
additional time to complete its financial reporting process for the quarter
ended September 30, 2003.

         The Company intends to file its quarterly report on Form 10-Q for the
quarter ended September 30, 2003 as soon as practicably possible after
completion of its financial reporting process for that quarter.

PART IV -- OTHER INFORMATION

(1) Name and telephone number of person to contact in regard to this
    notification

    Dan Streek                         (678)                  579-5000
    ------------------------        -----------      --------------------------
            (Name)                  (Area Code)         (Telephone Number)

(2) Have all other periodic reports required under Section 13 or 15(d) of the
    Securities Exchange Act of 1934 or Section 30 of the Investment Company Act
    of 1940 during the preceding 12 months or for such shorter period that the
    registrant was required to file such report(s) been filed ? If answer is no,
    identify report(s).  Yes [ ]   No [x]

     1. Form 10-K for the year ended December 31, 2002 (the Form 10-K did not
        include the interim financial information required by Item 302 of
        Regulation S-K).
    ----------------------------------------------------------------------------

(3) Is it anticipated that any significant change in results of operations from
    the corresponding period for the last fiscal year will be reflected by the
    earnings statements to be included in the subject report or portion
    thereof?  Yes [x]   No [ ]

    Note: On July 14, 2003, the Company and substantially all of its
    wholly-owned subsidiaries in the United States filed voluntary petitions for
    relief under Chapter 11 of the Bankruptcy Code in the U.S. Bankruptcy Court
    for the Northern District of Texas, Fort Worth Division. As such, the
    Company anticipates that significant changes could be reflected in the form
    of lower profitability and decreased cash flow. As of the date of this Form
    12b-25, the Company has not completed its financial reporting process for
    the third quarter of 2003. Therefore, the Company is not in a position to
    quantify any potential differences between the comparable periods.


    If so, attach an explanation of the anticipated change, both narratively and
    quantitatively, and, if appropriate, state the reasons why a reasonable
    estimate of the results cannot be made.
--------------------------------------------------------------------------------

                               Mirant Corporation
              ------------------------------------------------------
                  (Name of Registrant as Specified in Charter)

has caused this notification to be signed on its behalf by the undersigned
hereunto duly authorized.

Date November 20, 2003                  By /s/ Dan Streek
                                           ------------------------------
                                           Dan Streek
                                           Vice President and Controller
                                           (Principal Accounting Officer)