X0609 4 2026-05-07 0 0001315257 Koppers Holdings Inc. KOP 0001533627 JENSEN TRACI L false 436 SEVENTH AVENUE PITTSBURGH PA 15219 1 0 0 0 0 Common Stock 2026-05-07 4 M 0 50 0 A 32059.104 D Common Stock 2026-05-07 4 A 0 3280 0 A 35339.104 D Dividend Equivalent Rights 2026-05-07 4 M 0 50 0 D Common Stock 50 0 D Represents shares acquired upon release of dividend equivalent rights ("DERs"), as reported in Table II, on a one-for-one basis. The reporting person was awarded time-based restricted stock units ("RSUs"). These DERs were released in connection with the vesting of RSUs granted on May 8, 2025. Each DER is the economic equivalent of one share of Koppers Holdings Inc. common stock. /s/ Stephanie L. Apostolou, Attorney in Fact 2026-05-11