MDU Resources Group, Inc.

Item 5.02. Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. At the annual stockholders’ meeting of MDU Resources Group, Inc. (the “Company”) held on May 11, 2026 (the “Annual Meeting”), the Company’s stockholders approved the MDU Resources Group, Inc. Long-Term Performance-Based Incentive Plan, as amended and restated (the “LTIP”). The material changes to the LTIP were as follows: (1) increased the number of shares of the Company’s common stock available for issuance under the LTIP by 6,564,000 shares, for a total of 15,806,806 shares available for issuance; and (2) expanded eligibility for a director emeritus to participate in the LTIP. The LTIP became effective immediately upon stockholder approval at the Annual Meeting. Each of Nicole A. Kivisto, President and Chief Executive Officer; Jason L. Vollmer, Chief Financial Officer; Garret Senger, Chief Utilities Officer; Anthony D. Foti, Chief Legal Officer and Corporate Secretary; and Rob L. Johnson, President, WBI Energy, Inc., collectively referred to as the Company’s named executive officers (the “NEOs”), as well as other officers of the Company, participate in the LTIP. A summary of the material terms of the LTIP is set forth in the Company’s definitive proxy statement for the Annual Meeting filed with the U.S. Securities and Exchange Commission on April 1, 2026 (the “Proxy Statement”). The summaries of the LTIP set forth above, and in the Proxy Statement, are qualified in their entirety by reference to the full text of the LTIP, a copy of which is filed as Exhibit 10.1 to this Current Report on Form 8-K, and incorporated herein by reference.

Item 5.05. Amendments to the Registrant’s Code of Ethics, or Waiver of a Provision of the Code of Ethics. On May 13, 2026, the Company’s Board of Directors (the “Board”) adopted an updated and revised code of business conduct, referred to as the “Leading With Integrity Policy” (the “Policy”), as part of the Company’s periodic review process. This Policy applies to all non-employee directors, director emeriti, officers, and employees of the Company and its subsidiaries. The updates and revisions to the Policy, among other things: (i) clarify and revise provisions relating to artificial intelligence, confidential information, conflicts of interest, physical security, and regulatory compliance, and (ii) make other non-substantive administrative and stylistic changes. The summary description of these updates and revisions to the Policy set forth above is qualified in its entirety by reference to the full text of the Policy, as amended, which can be found on the Company’s corporate website at investor.mdu.com/governance/governance-documents/. The contents on the Company’s corporate website are not incorporated by reference in this report.

Item 5.07. Submission of Matters to a Vote of Security Holders. On May 11, 2026, the Company held the Annual Meeting in a virtual-only format and stockholders voted on the four proposals set forth below. The final voting results are listed below. Proposal 1: Election of Directors. Stockholders elected the eight nominees to the Board for one-year terms expiring at the annual stockholders’ meeting to be held in 2027, based upon the votes set forth in the table below: Name Votes For Votes Against Abstentions Broker Non-Votes ───────────────────────────────────────────────────────────────────────────────────────────────── Darrel T. Anderson 156,497,374 1,772,995 207,111 25,924,878 Vernon A. Dosch 157,748,991 508,798 219,691 25,924,878 Marian M. Durkin 156,077,464 1,507,033 892,983 25,924,878 Douglas W. Jaeger 157,108,513 1,149,629 219,338 25,924,878 Charles M. Kelley 157,868,483 382,487 226,510 25,924,878 Nicole A. Kivisto 157,782,494 498,930 196,056 25,924,878 Tammy J. Miller 157,313,621 952,917 210,942 25,924,878 Priti R. Patel 157,647,380 608,760 221,340 25,924,878 Proposal 2: Advisory Vote to Approve Executive Compensation. Stockholders approved, on an advisory basis, the compensation of the NEOs, based upon the votes set forth in the table below: Votes For Votes Against Abstentions Broker Non-Votes ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────── 155,483,583 2,448,238 545,659 25,924,878 Proposal 3: Approval of LTIP. Stockholders approved the LTIP, based upon the votes set forth in the table below: Votes For Votes Against Abstentions Broker Non-Votes ─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────── 154,587,051 2,817,302 1,073,127 25,924,878 Proposal 4: Ratification of Appointment of Independent Registered Public Accounting Firm. Stockholders ratified the appointment of Deloitte & Touche LLP as the Company’s independent registered public accounting firm for fiscal year 2026, based upon the votes set forth in the table below: Votes For Votes Against Abstentions ──────────────────────────────────────────────────────────────────────────────── 173,965,507 10,089,093 347,758