X0508 4 2026-03-02 0 0001315257 Koppers Holdings Inc. KOP 0001229771 BALL M LEROY 436 SEVENTH AVENUE PITTSBURGH PA 15219 1 1 0 0 CEO 0 Common Stock 2026-03-02 4 S 0 2184 36.53 D 454364.4007 D Common Stock 2026-03-02 4 S 0 328 37.45 D 454036.4007 D Common Stock 2026-03-02 4 S 0 3763 37.02 D 450273.4007 D Common Stock 2026-03-02 4 G 0 325 0 D 449948.4007 D The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $36.22 to $37.16, inclusive. The reporting person undertakes to provide to the Securities and Exchange Commission, the issuer or any security holder of the issuer, upon request, full information regarding the number of shares sold at each separate price. The price reported in column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $37.42 to $37.51, inclusive. The reporting person undertakes to provide to the Securities and Exchange Commission, the issuer or any security holder of the issuer, upon request, full information regarding the number of shares sold at each separate price. /s/ Stephanie L. Apostolou, Attorney in Fact 2026-03-04