Highlights Knife River’s Failure to Deliver Promised Margin Improvement as It Falls Further Behind Peers

Outlines Clear Path to 22% Adjusted EBITDA Margins by FY2029 Through Improved Aggregates Pricing and Meaningful Cost Reductions

Believes Knife River Should Evaluate Strategic Alternatives Given the Scarcity and Strategic Value of Its Assets

Starboard Value LP (together with its affiliates, "Starboard"), a stockholder of Knife River Corporation ("Knife River" or the "Company") (NYSE:KNF), today announced that it has delivered a letter to Brian Gray, the Company’s President and Chief Executive Officer, with a copy to the Company’s Board of Directors.

The full text of Starboard's letter to the Company can be viewed here.

About Starboard Value LP

Starboard Value LP is an investment adviser with a focused and differentiated fundamental approach to investing in publicly traded companies. Starboard invests in deeply undervalued companies and actively engages with management teams and boards of directors to identify and execute on opportunities to unlock value for the benefit of all shareholders.

View source version on businesswire.com: https://www.businesswire.com/news/home/20260924538020/en/

Investor:

Peter Feld, (212) 201-4878

Gavin Molinelli, (212) 201-4828

www.starboardvalue.com

Media:

Longacre Square Partners

Greg Marose / Joe Germani, (646) 386-0091

starboard@longacresquare.com