X0508 4 2026-02-26 0 0001315257 Koppers Holdings Inc. KOP 0001229771 BALL M LEROY 436 SEVENTH AVENUE PITTSBURGH PA 15219 1 1 0 0 CEO 0 Common Stock 2026-02-26 4 A 0 50025 0 A 477569.4007 D Common Stock 2026-02-26 4 M 0 1215 0 A 478784.4007 D Common Stock 2026-02-26 4 F 0 22236 37.24 D 456548.4007 D Dividend Equivalent Rights 2026-02-26 4 A 0 1215 0 A Common Stock 1215 1669 D Dividend Equivalent Rights 2026-02-26 4 M 0 1215 0 D Common Stock 1215 454 D On January 4, 2023, the reporting person was granted performance share units ("PSUs") for which the performance criteria for the measurement period from January 1, 2023 through December 31, 2025 have been satisfied. Represents shares acquired upon release of dividend equivalent rights ("DERs"), as reported in Table II, on a one-for-one basis. Shares surrendered to the issuer by the reporting person as payment for the tax withholding related to the vesting of PSUs. The DERs accrued with respect to additional PSUs credited to the reporting person with respect to PSUs granted on January 4, 2023. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock. These DERs were released in connection with the vesting of PSUs granted on January 4, 2023. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock. /s/ Stephanie L. Apostolou, Attorney in Fact 2026-03-02