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SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, DC 20549

FORM 8-K/A

CURRENT REPORT

AMENDMENT TO APPLICATION OR REPORT FILED
PURSUANT TO SECTION 13 OR 15(d) OF THE
SECURITIES EXCHANGE ACT OF 1934

Date of report (Date of earliest event reported) December 21, 2001

EDISON MISSION ENERGY
(Exact Name of Registrant as Specified in its Charter)

Delaware   000-24890   95-4031807
(State or Other Jurisdiction of Incorporation or Organization)   (Commission File Number)   (IRS Employer Identification No.)

18101 Von Karman Avenue, Irvine, California 92612
(Address of Principal Executive Offices) (Zip code)

Registrant's telephone number, including area code (949) 752-5588

NOT APPLICABLE
(Former Name or Former Address, if Changed Since Last Report)

The undersigned Registrant hereby amends the following items, financial statement, exhibits or other portions of its Current Report on Form 8-K filed January 7, 2002, as set forth in the pages attached hereto:

Item 7. Financial Statements and Exhibits

Items 1 through 6, and 8 through 9 are not included because they are not applicable.

Item 7.    Financial Statements, Pro Forma Financial Information and Exhibits

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UNAUDITED PRO FORMA CONSOLIDATED FINANCIAL STATEMENTS

        The following unaudited pro forma consolidated financial statements reflect the disposition of Ferrybridge and Fiddler's Ferry coal-fired electric generating plants in the United Kingdom to two wholly-owned subsidiaries of American Electric Power on December 21, 2001. In addition, the purchasers acquired other assets and assumed specific liabilities associated with the plants. The unaudited pro forma consolidated financial statements should be read in conjunction with the historical financial statements of Edison Mission Energy included in its Annual Report on Form 10-K for the year ended December 31, 2000 and Edison Mission Energy's Quarterly Report on Form 10-Q for the quarter ended September 30, 2001.

        The following unaudited pro forma consolidated financial statements have been prepared as if the disposition of the power plants had occurred on September 30, 2001, in the case of the pro forma consolidated balance sheet, and as of January 1, 2001 and 2000 for the consolidated pro forma income statements for the nine months ended September 30, 2001 and the year ended December 31, 2000, respectively. Edison Mission Energy will account for the disposition as discontinued operations in its Annual Report on Form 10-K for the year ended December 31, 2001 in accordance with Statement of Financial Accounting Standards No. 144, "Accounting for the Impairment or Disposal of Long-Lived Assets."

        These unaudited pro forma financial statements should be read in conjunction with the notes thereto. The unaudited pro forma financial statements have been prepared based upon assumptions deemed appropriate by management. The results have been prepared for informational purposes only and do not represent the historical results of operations in accordance with generally accepted accounting principles as reflected in Edison Mission Energy's Annual Report on Form 10-K for the year ended December 31, 2000 and Edison Mission Energy's Quarterly Report on Form 10-Q for the quarter ended September 30, 2001.

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EDISON MISSION ENERGY AND SUBSIDIARIES
UNAUDITED PRO FORMA CONSOLIDATED BALANCE SHEET
SEPTEMBER 30, 2001
(In thousands)

 
   Edison Mission
Energy
   Pro Forma
Adjustments
   Pro Forma
Consolidated
Assets                  
Current Assets   $ 1,804,205   $ (214,269 )(A) $ 1,589,936
Investments                  
  Energy projects     1,787,144     —     1,787,144
  Oil and gas     28,734     —     28,734
   
 
 
    Total investments     1,815,878     —     1,815,878
   
 
 
Net Property, Plant and Equipment     8,607,448     (834,210 )(B)   7,773,238
Other Assets     1,151,906     (27,977 )(C)   1,123,929
   
 
 
Total Assets   $ 13,379,437   $ (1,076,456 ) $ 12,302,981
   
 
 
Liabilities and Shareholder's Equity                  
Current Liabilities   $ 2,412,778   $ (1,021,488 )(D) $ 1,391,290
Long-Term Obligations Net of Current Maturities     6,829,591     —     6,829,591
Long-Term Deferred Liabilities     1,858,319     (31,803 )(E)   1,826,516
   
 
 
Total Liabilities     11,100,688     (1,053,291 )   10,047,397
   
 
 
Minority Interest     356,720     —     356,720
Preferred Securities of Subsidiaries     243,663     —     243,663
Total Shareholder's Equity (Deficit)     1,678,366     (23,165 )(F)   1,655,201
   
 
 
Total Liabilities and Shareholder's Equity   $ 13,379,437   $ (1,076,456 ) $ 12,302,981
   
 
 

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EDISON MISSION ENERGY AND SUBSIDIARIES
UNAUDITED PRO FORMA CONSOLIDATED STATEMENT OF INCOME (LOSS)
FOR THE NINE MONTHS ENDED SEPTEMBER 30, 2001
(In thousands)

 
   Edison Mission
Energy
   Pro Forma
Adjustments
   Pro Forma
Consolidated
  
Operating Revenues                    
  Electric revenues   $ 2,359,071   $ 382,266 (G) $ 1,976,805  
  Equity in income from energy projects     288,846     —     288,846  
  Equity in income from oil and gas investments     42,878     —     42,878  
  Net gains (losses) from energy trading and price risk management     29,311     (10,033 )(G)   39,344  
  Operation and maintenance services     38,225     3,120 (G)   35,105  
   
 
 
 
    Total operating revenues     2,758,331     375,353     2,382,978  
   
 
 
 
Operating Expenses                    
  Fuel     905,525     203,726 (H)   701,799  
  Plant operations     700,168     140,232 (H)   559,936  
  Operation and maintenance services     20,627     —     20,627  
  Depreciation and amortization     276,063     72,783 (I)   203,280  
  Long-term incentive compensation     2,718     —     2,718  
  Asset impairment charges     1,923,574     1,899,089 (J)   24,485  
  Administrative and general     119,024     —     119,024  
   
 
 
 
    Total operating expenses     3,947,699     2,315,830     1,631,869  
   
 
 
 
  Operating income (loss)     (1,189,368 )   (1,940,477 )   751,109  
   
 
 
 
Other Income (Expense)                    
  Interest and other income (expense)     82,755     4,726 (K)   78,029  
  Interest expense     (488,016 )   (67,595) (L)   (420,421 )
  Dividends on preferred securities     (17,421 )   —     (17,421 )
   
 
 
 
    Total other income (expense)     (422,682 )   (62,869 )   (359,813 )
   
 
 
 
  Income (loss) before income taxes     (1,612,050 )   (2,003,346 )   391,296  
  Provision (benefit) for income taxes     (592,272 )   (769,455) (M)   177,183  
  Minority interest     (18,662 )   —     (18,662 )
   
 
 
 
Income (Loss) Before Accounting Change     (1,038,440 )   (1,233,891 )   195,451  
Cumulative effect of change in accounting for derivatives, net of tax     20,897     5,751 (N)   15,146  
   
 
 
 
Income (Loss) From Continuing Operations   $ (1,017,543 ) $ (1,228,140 ) $ 210,597  
   
 
 
 

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EDISON MISSION ENERGY AND SUBSIDIARIES
UNAUDITED PRO FORMA CONSOLIDATED STATEMENT OF INCOME
FOR THE YEAR ENDED DECEMBER 31, 2000
(In thousands)

 
   Edison Mission
Energy
   Pro Forma
Adjustments
   Pro Forma
Consolidated
  
Operating Revenues                    
  Electric revenues   $ 2,951,038   $ 689,730 (G) $ 2,261,308  
  Equity in income from energy projects     221,819     —     221,819  
  Equity in income from oil and gas investments     45,057     —     45,057  
  Net losses from energy trading and price risk management     (17,339 )   —     (17,339 )
  Operation and maintenance services     40,459     2,981 (G)   37,478  
   
 
 
 
    Total operating revenues     3,241,034     692,711     2,548,323  
   
 
 
 
Operating Expenses                    
  Fuel     1,081,817     272,798 (H)   809,019  
  Plant operations     813,198     186,675 (H)   626,523  
  Operation and maintenance services     28,135     —     28,135  
  Depreciation and amortization     382,130     100,156 (I)   281,974  
  Long-term incentive compensation     (55,952 )   —     (55,952 )
  Administrative and general     160,879     —     160,879  
   
 
 
 
    Total operating expenses     2,410,207     559,629     1,850,578  
   
 
 
 
  Operating income     830,827     133,082     697,745  
   
 
 
 
Other Income (Expense)                    
  Interest and other income (expense)     73,926     17,530 (K)   56,396  
  Interest expense     (689,397 )   (131,034 )(L)   (558,363 )
  Dividends on preferred securities     (32,075 )   —     (32,075 )
   
 
 
 
    Total other income (expense)     (647,546 )   (113,504 )   (534,042 )
   
 
 
 
  Income before income taxes     183,281     19,578     163,703  
  Provision (benefit) for income taxes     72,536     (8,748 )(M)   81,284  
  Minority interest     (3,183 )   —     (3,183 )
   
 
 
 
Income Before Accounting Change     107,562     28,326     79,236  
Cumulative effect on prior years of change in accounting for major maintenance costs, net of tax     17,690     (4,115 )(N)   21,805  
   
 
 
 
Income From Continuing Operations   $ 125,252   $ 24,211   $ 101,041  
   
 
 
 

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EDISON MISSION ENERGY
NOTES TO UNAUDITED PRO FORMA
CONSOLIDATED FINANCIAL STATEMENTS

        The above unaudited pro forma consolidated financial statements reflect Edison Mission Energy's results of operations for the year ended December 31, 2000 as included in its Annual Report on Form 10-K, as well as its results of operations for the nine months ended September 30, 2001 and its financial position as of September 30, 2001 as included in its Quarterly Report on Form 10-Q.

(A)
To primarily reflect the cash consideration received in connection with the disposition of the Ferrybridge and Fiddler's Ferry power plants, offset by the cash paid for related transaction costs and cash paid in connection with the repayment of the borrowings outstanding under the existing debt facility related to the acquisition of the power plants. In addition, reflects the sale of inventories to purchasers.

(B)
To reflect the disposition of the Ferrybridge and Fiddler's Ferry power plants.

(C)
To reflect the write-off of unamortized debt issue costs related to the early repayment of the existing debt facility.

(D)
To primarily reflect the repayment of the borrowings outstanding under the existing debt facility related to the acquisition of the power plants with the net proceeds received from the sale of the power plants. In addition, reflects the assumption of specified accounts payable by the purchasers.

(E)
To reflect the assumption of specified other long-term deferred liabilities by the purchasers.

(F)
To primarily reflect the extraordinary loss attributable to the write-off of unamortized debt issue costs partially offset by a gain on disposal of the Ferrybridge and Fiddler's Ferry power plants for the period between October 1, 2001 and December 21, 2001. During the third quarter of 2001, Edison Mission Energy recorded an asset impairment charge of $1.154 billion after-tax in connection with the announced sale of the power plants.

(G)
To reflect the elimination of electric revenues, net losses from price risk management and other services revenues generated from the power plants sold.

(H)
To reflect the elimination of fuel and plant operations costs incurred at the power plants sold.

(I)
Reflects pro forma decrease in depreciation and amortization resulting from the sale of the power plants.

(J)
Reflects asset impairment charge recorded in the third quarter of 2001 to reduce the carrying amount of the power plants to reflect the estimated fair value less the cost to sell and related currency adjustments.

(K)
Reflects pro forma decrease in interest income associated with the decrease in cash.

(L)
Reflects pro forma decrease in interest expense associated with the repayment of long-term debt related to the acquisition of the power plants.

(M)
Reflects the adjustment necessary to eliminate current and deferred income taxes associated with the power plants sold.

(N)
Reflects the cumulative effect of change in accounting directly related to the operations of the power plants sold.

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SIGNATURE

        Pursuant to the requirements of the Securities and Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

Date: March 6, 2002   EDISON MISSION ENERGY
 (Registrant)

 
 
By:
 
/s/  RAYMOND W. VICKERS      
Raymond W. Vickers
 Senior Vice President and
General Counsel

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QuickLinks

FORM 8-K/A
UNAUDITED PRO FORMA CONSOLIDATED FINANCIAL STATEMENTS
EDISON MISSION ENERGY AND SUBSIDIARIES UNAUDITED PRO FORMA CONSOLIDATED BALANCE SHEET SEPTEMBER 30, 2001 (In thousands)
EDISON MISSION ENERGY AND SUBSIDIARIES UNAUDITED PRO FORMA CONSOLIDATED STATEMENT OF INCOME (LOSS) FOR THE NINE MONTHS ENDED SEPTEMBER 30, 2001 (In thousands)
EDISON MISSION ENERGY AND SUBSIDIARIES UNAUDITED PRO FORMA CONSOLIDATED STATEMENT OF INCOME FOR THE YEAR ENDED DECEMBER 31, 2000 (In thousands)
EDISON MISSION ENERGY NOTES TO UNAUDITED PRO FORMA CONSOLIDATED FINANCIAL STATEMENTS
SIGNATURE