MDU Resources Group, Inc.

Item 2.02. Results of Operations and Financial Condition. On August 6, 2026, MDU Resources Group, Inc. (the “Company”) issued a news release (the “News Release”) announcing its financial results for the second quarter of 2026. A copy of the News Release is furnished as Exhibit 99 to this Current Report on Form 8-K, which, in its entirety, is incorporated herein by reference. The Company is webcasting a conference call on August 6, 2026, to discuss its second quarter 2026 financial results, during which the Company will provide an update on the business. The information contained in Item 2.02 of this Current Report on Form 8-K, including Exhibit 99, shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, and shall not be deemed incorporated by reference into any filing under the Securities Act of 1933, as amended (the “Securities Act”), or the Exchange Act, except as expressly set forth by specific reference in such filing.

Item 7.01. Regulation FD Disclosure. In conjunction with the News Release, the Company also made available an investor presentation concerning its second quarter 2026 financial results, which is available under the “Investor Relations” section of the Company’s corporate website, located at investor.mdu.com. Information on the Company’s corporate website is not, and will not be deemed to be, a part of this Current Report on Form 8-K or incorporated into any other filings the Company may make with the U.S. Securities and Exchange Commission. The information contained in Item 7.01 of this Current Report on Form 8-K shall not be deemed “filed” for purposes of Section 18 of the Exchange Act, or otherwise subject to the liabilities of that section, and shall not be deemed incorporated by reference into any filing under the Securities Act, or the Exchange Act, except as expressly set forth by specific reference in such filing.