X0508 4 2025-12-16 0 0001315257 Koppers Holdings Inc. KOP 0001806249 Apostolou Stephanie L 436 SEVENTH AVENUE PITTSBURGH PA 15219 0 1 0 0 Chief Legal&Sus Officer & Sec. 0 Dividend Equivalent Rights 2025-12-16 4 A 0 245 0 A Common Stock 245 349 D The dividend equivalent rights ("DERs") accrued with respect to additional time-based and performance-based restricted stock units ("RSUs" and "PSUs", respectively) credited to the reporting person. Of this total, 208 DERs accrued with respect to RSUs granted on January 4, 2022, January 4, 2023, January 4, 2024, and January 3, 2025, and 37 DERs accrued with respect to PSUs granted on January 4, 2023. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock. Stephanie L. Apostolou 2025-12-17