<Page> SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-A/A (Amendment No. 2) FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 THE MONTANA POWER COMPANY (Exact name of registrant as specified in its charter) MONTANA 1-4566 81-017530 (State of incorporation (Commission (IRS Employers or organization) File Number Identification No.) 40 EAST BROADWAY, BUTTE, MONTANA 59701 (Address of principal executive offices) (Zip Code) If this Form relates to the registration of a class of securities pursuant to Section 12(b) of the Exchange Act and is effective upon filing pursuant to General Instruction A.(c) please check the following box. /X/ If this Form relates to the registration of a class of securities pursuant to Section 12(g) of the Exchange Act and is effective pursuant to General Instruction A.(d) please check the following box. / / Securities to be registered pursuant to Section 12(b) of the Act: NONE Title of Each Class Name of Each Exchange on Which to be so Registered: Each Class is to be Registered NONE NONE Securities to be registered pursuant to Section 12(g) of the Act: PREFERRED SHARE PURCHASE RIGHTS (Title of Class) <Page> The undersigned registrant hereby amends Item 1 of its Registration on Form 8-A, filed on June 6, 1989 as amended on March 12, 1999 (as so amended, the "Form 8-A"), by adding the information set forth below. The registrant also amends Item 2 of the Form 8-A by adding the Second Amendment to the Rights Agreement as Exhibit 5. ITEM 1. DESCRIPTION OF REGISTRANT'S SECURITIES TO BE REGISTERED. SECOND AMENDMENT TO THE RIGHTS AGREEMENT On September 29, 2000, NorthWestern Corporation, a Delaware corporation ("NorthWestern"), The Montana Power Company, a Montana corporation (the "Company") and Touch America Holdings, Inc. ("Touch America") entered into a Unit Purchase Agreement (the "Purchase Agreement") providing, among other things, for the sale of The Montana Power L.L.C., a Montana limited liability company and a wholly-owned subsidiary of Touch America ("Sub") to NorthWestern. Such sale will constitute the sale of the utility business of the Company. On December 15, 2000, the Company, Sub and Touch America entered into an Agreement and Plan of Merger, (the "Merger Agreement") providing, among other things, for the merger of Sub with and into the Company, whereupon Sub will become the surviving entity and shareholders of the Company will become shareholders of Touch America. On January 24, 2001, the Company and First Chicago Trust Company of New York, as Rights Agent (the "Rights Agent") entered into the Second Amendment (the "Second Amendment") to the Rights Agreement between the Company and the Rights Agent (the "Rights Agreement") dated as of June 6, 1989 and amended as of March 12, 1999. The Second Amendment provides, among other things, that (a) neither the Merger Agreement nor the Purchase Agreement, nor the consummation of the transactions contemplated thereby, will cause (i) Sub, Touch America, NorthWestern or any of their affiliates or associates to have beneficial ownership of any Common Shares solely as a result of any such event, (ii) Sub, Touch America, NorthWestern or any of their affiliates or associates to be deemed an "Acquiring Person" under the Rights Agreement or (iii) the "Shares Acquisition Date" or the "Distribution Date" under the Rights Agreement to occur upon any such event, and (b) the "Rights" (each of the above as defined in the Rights Agreement) will expire immediately prior to (i) conversion of Shares pursuant to the Merger Agreement, (ii) the closing of the purchase of the Units (as defined in the Purchase Agreement) or (iii) the Effective Time (as defined in the Merger Agreement) of the Merger. The Second Amendment to the Rights Agreement shall be effective as of September 29, 2000. A copy of the Second Amendment is available free of charge from the Company. This summary description of the Second Amendment does not purport to be complete and is qualified in its entirety by reference to the Second Amendment which is attached hereto as Exhibit 6 and is incorporated herein by reference. <Page> 3 ITEM 2. EXHIBITS The undersigned registrant hereby amends Item 2 to the Form by restating Item 2, to read as follows: Exhibit No. Description (1) Rights Agreement dated as of June 6, 1989 between the Company and First Chicago Trust of New York, as Rights Agent (the "Rights Agreement") (previously filed as Exhibit 4(d) to the Company's Registration Statement on Form 8-A/A dated September 20, 1991 which exhibit is hereby incorporated by reference). (2) Form of Statement of Creation of Preferred Stock (attached as Exhibit A to the Rights Agreement). (3) Form of Rights Certificate (attached as Exhibit B to the Rights Agreement). (4) First Amendment to the Rights Agreement dated as of March 12, 1999 between the Company and First Chicago Trust of New York, as Rights Agent (previously filed as Exhibit 4(a) to the Company's Registration Statement on Form 8-A/A dated March 12, 1999, which exhibit is hereby incorporated by reference). (5) Second Amendment to the Rights Agreement dated as of January 24, 2001 between the Company and First Chicago Trust of New York), as Rights Agent (filed herewith). <Page> 4 SIGNATURES Pursuant to the requirements of Section 12 of the Securities Exchange Act of 1934, the registrant has duly caused this amendment to the registration statement to be signed on its behalf by the undersigned hereunto duly authorized. THE MONTANA POWER COMPANY Date: January 28, 2002 By: /s/ Robert P. Gannon --------------------- Name: Robert P. Gannon Title: Chairman of the Board <Page> 5 EXHIBIT INDEX Exhibit Page No. 1. Rights Agreement dated as of June 6, 1989 between the Company and First Chicago Trust of New York, as Rights Agent (the "Rights Agreement") (previously filed as Exhibit 4(d) to the Company's Registration Statement on Form 8-A/A dated September 20, 1991, which exhibit is hereby incorporated by reference). 2. Form of Statement of Creation of Preferred Stock (attached as Exhibit A to the Rights Agreement). 3. Form of Rights Certificate (attached as Exhibit B to the Rights Agreement). 4. First Amendment to the Rights Agreement dated as of March 2, 1999 between the Company and First Chicago Trust of New York, as Rights Agent (previously filed as Exhibit 4a to the Company's Registration Statement on Form 8-A/A dated March 12, 1999, which exhibit is hereby incorporated by reference). 5. Second Amendment to the Rights Agreement dated as of December 15, 2000 between the Company and First Chicago Trust of New York, as Rights Agent (filed herewith).