Results of Operations and Financial Condition On July 29, 2026 , NorthWestern Energy Group, Inc. d/b/a NorthWestern Energy (Nasdaq: NWE) (the “ Company ”), issued a press release (the “ Press Release ”) discussing financial results for the quarter ended June 30, 2026, and affirming earnings guidance for 2026 in the range of $3.68 to $3.83 per diluted share. The Press Release is furnished as Exhibit 99.1 hereto and is incorporated herein by reference. The information in this Current Report on…

Entry into Material Definitive Agreement On June 15, 2026, NorthWestern Energy Public Service Corporation (" NWE Public Service "), a wholly owned subsidiary of NorthWestern Energy Group, Inc., d/b/a NorthWestern Energy (Nasdaq: NWE) (“ NWE Group ”), issued and sold $150 million principal amount of NWE Public Service's South Dakota First Mortgage Bonds (the " SD Bonds "). The SD Bonds were issued in a transaction exempt from the registration requirements of the Securities Act of 1933, have no…

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. The information set forth in

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. The information set forth in

Entry Into a Material Definitive Agreement. On May 27, 2026, NorthWestern Corporation (" NW Corp "), a wholly owned subsidiary of NorthWestern Energy Group, Inc., d/b/a NorthWestern Energy (Nasdaq: NWE) (“ NWE Group ”), entered into a $225 million secured term loan credit agreement (the “ Term Loan ”) with Bank of America, N.A., as administrative agent (the " Administrative Agent "), and BOFA Securities, Inc., BMO Bank N.A., Keybank National Association, and U.S. Bank National Association, as…

Results of Operations and Financial Condition On April 29, 2026 , NorthWestern Energy Group, Inc. d/b/a NorthWestern Energy (Nasdaq: NWE) (the “ Company ”), issued a press release (the “ Press Release ”) discussing financial results for the quarter ended March 31, 2026, and affirming earnings guidance for 2026 in the range of $3.68 to $3.83 per diluted share. The Press Release is furnished as Exhibit 99.1 hereto and is incorporated herein by reference. The information in this Current Report o…

The filing describes the establishment of a new short-term incentive plan for officers and employees, which is not a management change.

Results of Operations and Financial Condition On February 11, 2026, NorthWestern Energy Group, Inc. d/b/a NorthWestern Energy (Nasdaq: NWE) (the “ Company ”), issued a press release (the “ Press Release ”) discussing financial results for the year ended December 31, 2025, and announcing earnings guidance for 2026 in the range of $3.68 to $3.83 per diluted share. The Press Release is furnished as Exhibit 99.1 hereto and is incorporated herein by reference. The information in this Current Repor…

Entry into Material Definitive Agreement On November 7, 2025, NorthWestern Corporation (" NW Corp "), a wholly owned subsidiary of NorthWestern Energy Group, Inc., d/b/a NorthWestern Energy (Nasdaq: NWE) (“ NWE Group ”), reopened its March 2025 issuance of NW Corp's Montana First Mortgage Bonds (“ 2030 Notes ”) and issued and sold an additional $100 million principal amount of such bonds (the " Additional MT Bonds "). The Additional MT Bonds form a single series with and have substantially th…

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. The information set forth in

Vice President — John Hines: The filing announces a planned retirement of a Vice President after 20 years of service, which is an orderly succession rather than a sudden loss of a C-suite executive.

Results of Operations and Financial Condition. O n October 29, 2025 , NorthWestern Energy Group, Inc. d/b/a NorthWestern Energy (Nasdaq: NWE) (the “ Company ”) issued a press release (the “ Press Release ”) discussing financial results for the quarter ended September 30, 2025, and affirming earnings guidance for 2025 in the range of $3.53 to $3.65 per diluted share. The Press Release is furnished as Exhibit 99.1 hereto and is incorporated herein by reference. The information in this Current R…

Entry Into a Material Definitive Agreement.

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. As previously disclosed, on April 12, 2024, NorthWestern Energy Group, Inc. d/b/a NorthWestern Energy (Nasdaq: NWE) (the “ Company ”) entered into a $100 million Term Loan Credit Agreement (as subsequently amended, the “ Term Loan ”) with U.S. Bank National Association ("U.S. Bank"), as lender. On September 29, 2025, the Company entered into Amendment No. 3 to Term Loan Credit Ag…

Entry into a Material Definitive Agreement. On August 18, 2025, NorthWestern Energy Group, Inc., a Delaware corporation (“ NorthWestern ” or the “ Company ”) entered into an Agreement and Plan of Merger (the “ Merger Agreement ”) with Black Hills Corporation, a South Dakota corporation (“ Black Hills ” or the “ Company ”) and River Merger Sub Inc., a Delaware corporation and direct wholly owned subsidiary of Black Hills (“ Merger Sub ”). The Merger Agreement, which has been unanimously approv…

CEO — Linden R. Evans: The current CEO is retiring in an orderly succession to a named successor (Brian B. Bird) as part of a merger, which constitutes a planned transition rather than a sudden loss of leadership.

Results of Operations and Financial Condition. O n July 30, 2025 , NorthWestern Energy Group, Inc. d/b/a NorthWestern Energy (Nasdaq: NWE) (the “ Company ”) issued a press release (the “ Press Release ”) discussing financial results for the quarter ended June 30, 2025, and announcing earnings guidance for 2025 in the range of $3.53 to $3.65 per diluted share. The Press Release is furnished as Exhibit 99.1 hereto and is incorporated herein by reference. The information in this Current Report o…

Entry into Material Definitive Agreement On May 1, 2025, NorthWestern Energy Public Service Corporation (" NWE Public Service "), a wholly owned subsidiary of NorthWestern Energy Group, Inc., d/b/a NorthWestern Energy (Nasdaq: NWE) (“ NWE Group ”), issued and sold $100 million principal amount of NWE Public Service's South Dakota First Mortgage Bonds (the " SD Bonds "). The SD Bonds were issued in a transaction exempt from the registration requirements of the Securities Act of 1933, have not…

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. The information set forth in

Results of Operations and Financial Condition. On April 29, 2025, NorthWestern Energy Group, Inc. d/b/a NorthWestern Energy (Nasdaq: NWE) (the “ Company ”) issued a press release (the “ Press Release ”) discussing financial results for the quarter ended March 31, 2025. The Press Release is furnished as Exhibit 99.1 hereto and is incorporated herein by reference. The information in this Current Report on Form 8-K provided under

Entry into Material Definitive Agreement On March 21, 2025, NorthWestern Corporation (" NW Corp "), a wholly owned subsidiary of NorthWestern Energy Group, Inc., d/b/a NorthWestern Energy (Nasdaq: NWE) (“ NWE Group ”), issued and sold $400 million principal amount of NW Corp's Montana First Mortgage Bonds (the " MT Bonds "). The MT Bonds were issued and sold to certain initial purchasers without being registered under the Securities Act of 1933, as amended (the " Securities Act " ), in relian…

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. The information set forth in

Results of Operations and Financial Condition On February 12, 2025, NorthWestern Energy Group, Inc. d/b/a NorthWestern Energy (Nasdaq: NWE) (the “ Company ”), issued a press release (the “ Press Release ”) discussing financial results for the year ended December 31, 2024. The Press Release is furnished as Exhibit 99.1 hereto and is incorporated herein by reference. The information in this Current Report on Form 8-K provided under

The filing describes the establishment of a short-term incentive compensation plan, which is a routine administrative matter and not a change in management personnel.

Director — David L. Goodin: The filing announces the appointment of a new director to the board, which is a routine governance event and not a departure of a sitting executive.