OTHER INFORMATION
−Removed: During the three months ended September 30, 2025, none of our directors or executive officers adopted , modified or terminated any Rule 10b5-1 trading arrangement or any non-Rule 10b5-1 trading arrangement (as such terms are defined in Item 408 of Regulation S-K).
+Added: During the three months ended March 31, 2026, none of our directors or executive officers adopted , modified or terminated any Rule 10b5-1 trading arrangement or any non-Rule 10b5-1 trading arrangement (as such terms are defined in Item 408 of Regulation S-K).
+Added: 10.1* Transition Agreement and General Release with Jimmi Sue Smith.
+Added: 10.2 First Amendment to the Koppers Holdings Inc.
+Added: Amended and Restated Employee Stock Purchase Plan (Incorporated herein by reference to Exhibit 99.2 to our Registration Statement on Form S-8 filed on May 8, 2026 (File No.
+Added: 333-295681)).
+Added: 10.3* Form of Restricted Stock Unit Issuance Agreement Non-Employee Director - Time Vesting .
31.1* Certification of Chief Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.
8 unchanged sentences
(R EGISTRANT )
−Removed: November 7, 2025
−Removed: /s/ J IMMI S UE S MITH
−Removed: Jimmi Sue Smith
−Removed: Chief Financial Officer and Treasurer
+Added: /s/ B RADLEY A .
+Added: Interim Chief Financial Officer and
+Added: Treasurer and Chief Accounting Officer
(Principal Financial Officer and Duly Authorized Officer)
Compared sentence by sentence after normalising whitespace, quotation marks, case and digits, so re-formatting and restated figures do not read as changed language. Wording changes appear as one removal and one addition. The current filing and the prior one are authoritative.