Koppers Holdings(KOP) - 2025 Q4 - Annual Report

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 Commission file number 1-32737 KOPPERS HOLDINGS INC. (Exact name of registrant as specified in its charter) Pennsylvania 20-1878963 FORM 10-K (Mark One) x ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2025 OR o TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from ________to (State of incorporat ...