Knife River Corp 8-KCurrent Reports (8-K / ad hoc)

Changes / Accountants

Item 9.01. Financial Statements and Exhibits. (d) Exhibits. Exhibit Number Description 99.1 Investor Presentation dated September 2026 . 104 Cover Page Interactive Data File (embedded within the Inline XBRL document). 2 SIGNATURE Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. Knife River Corporation Date September 23, 2026 By /s/ Nathan W. Ring Nathan W. Ring Vice President and Chief Financial Officer 3