黑山 2025年度报告

Form 11-K ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2025 OR TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from __________ to __________ Commission File Number 001-31303 A.Full title of the plan and the address of the plan, if different from that of the issuer named below: BLACK HILLS CORPORATION 401(k) RETIREMENT SAVINGS PLAN B.Name of issuer of the securities held pursuant to the plan and the address of its principal executive office: Black Hills Corporation7001 Mount Rushmore RoadRapid City, South Dakota 57702 REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM Signature NOTE: All other schedules required by Section 2520.103-10 of the Department of Labor’s Rules and Regulationsfor Reporting and Disclosures under the Employee Retirement Income Security Act of 1974 have been omittedbecause they are not applicable. Table of Contents REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM To the Plan Participants and Plan Administrator ofBlack Hills Corporation 401(k) Retirement Savings Plan Opinion on the Financial Statements We have audited the accompanying statements of net assets available for benefits of Black Hills Corporation 401(k) RetirementSavings Plan (the “Plan”) as of December 31, 2025 and 2024, the related statement of changes in net assets available for benefitsfor the year ended December 31, 2025, and the related notes (collectively referred to as the “financial statements”). In our opinion,the financial statements present fairly, in all material respects, the net assets available for benefits of the Plan as of December 31, Basis for Opinion These financial statements are the responsibility of the Plan’s management. Our responsibility is to express an opinion on the Plan’sfinancial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting OversightBoard (United States) (PCAOB) and are required to be independent with respect to the Plan in accordance with the U.S. federal We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform theaudit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to erroror fraud. Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whetherdue to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, Report on Supplemental Schedule The supplemental schedule of assets (held at end of year) as of December 31, 2025 has been subjected to audit proceduresperformed in conjunction with the audit of the Plan’s financial statements. The supplemental schedule is the responsibility of thePlan’s management. Our audit procedures included determining whether the supplemental schedule reconciles to the financialstatements or the underlying accounting and other records, as applicable, and performing procedures to test the completeness and Minneapolis, MinnesotaJune 18, 2026 Table of Contents Table of Contents Table of Contents BLACK HILLS CORPORATION 401(k) RETIREMENT SAVINGS PLAN NOTES TO FINANCIAL STATEMENTSAs of December 31, 2025 and 2024 and for the Year Ended December 31, 2025 (1)DESCRIPTION OF THE PLAN The following description of the Black Hills Corporation 401(k) Retirement Savings Plan (the “Plan”) is provided for generalinformation purposes only. Participants should refer to the plan document for a more complete description of the Plan’s information. General— The Plan is a defined-contribution plan for eligible employees of Black Hills Corporation and subsidiary companies (the“Company” or “Plan Sponsor”). The Plan is subject to the provisions of the Employment Retirement Income Security Act of 1974, asamended (ERISA) and is designed to comply with the provisions of Section 401(k) of the Internal Revenue Code (IRC). Plan Administration—Charles Schwab Trust Bank (Charles Schwab) serves as custodian and trustee. The Plan is administeredby the Black Hills Corporation Benefits Committee (the “Committee”). Schwab Retirement Plan Services, Inc. is the recordkeeper ofthe Plan. Eligibility and Vesting— Employees meeting certain criteria, as defined in the Plan, are eligible to participate in the Plan onemonth following their date of employment. The Plan includes an automatic enrollment provision whereby all newly eligible employeesare automatically enrolled in the Plan unless they affirmatively elect not to participate in the Plan. Automatically enrolled participantshave their deferral rate set at 6% of eligible compensation and their contributions are invested in a target retirement fund appropriate Participants are vested immediately in their contributions, plus actual earnings thereon. Vesting in