As filed with the Securities and Exchange Commission on September 13, 2000 SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 DATE OF REPORT - SEPTEMBER 4, 2000 Commission Registrant, State of Incorporation I.R.S. Employer File Number Address and Telephone Number Identification No. - ----------- ---------------------------------- ------------------ 0-25595 NIAGARA MOHAWK HOLDINGS, INC. 16-1549726 (a New York corporation) 300 Erie Boulevard West Syracuse, New York 13202 Telephone 315-474-1511 1-2987 NIAGARA MOHAWK POWER CORPORATION 15-0265555 (a New York corporation) 300 Erie Boulevard West Syracuse, New York 13202 Telephone 315-474-1511 ITEM 5. OTHER EVENTS - --------------------- (a) On September 5, 2000, Niagara Mohawk Holdings, Inc. ("Holdings") and National Grid Group plc ("National Grid") issued a joint press release announcing that they have signed a merger agreement dated September 4, 2000 under which National Grid will acquire Holdings through the formation of a new National Grid holding company and the exchange of Holdings' shares for a combination of cash and American Depositary Shares in the new holding company. (See attached Exhibit No. 99-1). (b) The terms and conditions of the merger are governed entirely by the Merger Agreement. Any description of the Merger Agreement contained herein or in the press release is qualified in its entirety by the Merger Agreement, which is filed as Exhibit 99-2 and is incorporated herein by reference. ITEM 7. FINANCIAL STATEMENTS AND EXHIBITS - ------------------------------------------ Exhibits - Following is the list of Exhibits furnished in accordance with the provisions of Item 601 of Regulation S-K, filed as part of this current report on Form 8-K. Exhibit 99-1 - Press Release issued on September 5, 2000 announcing that Holdings and National Grid signed a merger agreement. Exhibit 99-2 - Merger Agreement dated September 4, 2000 by and among Holdings, National Grid, New National Grid Limited, and Grid Delaware, Inc. -2- NIAGARA MOHAWK HOLDINGS, INC. AND SUBSIDIARY COMPANIES SIGNATURE Pursuant to the requirements of the Securities Exchange Act of 1934, each registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. NIAGARA MOHAWK HOLDINGS, INC. (Registrant) By: /s/ Steven W. Tasker ----------------------------------- Name: Steven W. Tasker Title: Vice President - Controller and Principal Accounting Officer, in his respective capacities as such Date: September 13, 2000 NIAGARA MOHAWK POWER CORPORATION (Registrant) By: /s/ Steven W. Tasker ----------------------------------- Name: Steven W. Tasker Title: Vice President - Controller and Principal Accounting Officer, in his respective capacities as such Date: September 13, 2000 -3- EXHIBIT INDEX Following is the index of Exhibits furnished in accordance with the provisions of Item 601 of Regulation S-K, filed as part of this current report on Form 8-K. Exhibit No. 99-1 - Joint press release issued on September 5, 2000 announcing that Holdings and National Grid signed a merger agreement dated September 4, 2000 Exhibit No. 99-2 - Merger Agreement dated September 4, 2000 by and among Holdings, National Grid, New National Grid Limited, and Grid Delaware, Inc. -4-