X0508 4 2025-12-16 0 0001315257 Koppers Holdings Inc. KOP 0001776180 Pearce Bradley A 436 SEVENTH AVENUE PITTSBURGH PA 15219 0 1 0 0 Chief Accounting Officer 0 Dividend Equivalent Rights 2025-12-16 4 A 0 113 0 A Common Stock 113 168 D The dividend equivalent rights ("DERs") accrued with respect to additional time-based restricted stock units ("RSUs") credited to the reporting person with respect to RSUs granted on January 4, 2022, January 4, 2023, January 4, 2024, and January 3, 2025. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock. /s/ Stephanie L. Apostolou, Attorney in Fact 2025-12-17