Koppers Holdings Inc.

Q: Jun 30 2026

Q: Mar 31 2026

FY: Dec 31 2025

Q: Sep 30 2025

Q: Jun 30 2025

Q: Mar 31 2025

FY: Dec 31 2024

Q: Sep 30 2024

Q: Jun 30 2024

Q: Mar 31 2024

FY: Dec 31 2023

Q: Sep 30 2023

Q: Jun 30 2023

Q: Mar 31 2023

FY: Dec 31 2022

Q: Sep 30 2022

Q: Jun 30 2022

Q: Mar 31 2022

FY: Dec 31 2021

Q: Sep 30 2021

Results of Operations and Financial Condition

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers: Compensatory Arrangements of Certain Officers

Results of Operations and Financial Condition

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers: Compensatory Arrangements of Certain Officers

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers: Compensatory Arrangements of Certain Officers

Results of Operations and Financial Condition

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers: Compensatory Arrangements of Certain Officers

Cost Associated with Exit or Disposal Activities

Results of Operations and Financial Condition

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers: Compensatory Arrangements of Certain Officers

Results of Operations and Financial Condition

Entry into a Material Definitive Agreement

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers: Compensatory Arrangements of Certain Officers

Results of Operations and Financial Condition

Results of Operations and Financial Condition

Entry into a Material Definitive Agreement

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers: Compensatory Arrangements of Certain Officers

Cost Associated with Exit or Disposal Activities

Results of Operations and Financial Condition

2.02,9.01

Registration statement under Securities Act of 1933 to be offered to employees pursuant to certain plans

Registration statement under Securities Act of 1933 to be offered to employees pursuant to certain plans

Registration statement under Securities Act of 1933 to be offered to employees pursuant to certain plans

Registration statement under Securities Act of 1933 to be offered to employees pursuant to certain plans

Registration statement under Securities Act of 1933 to be offered to employees pursuant to certain plans

Registration statement under Securities Act of 1933 to be offered to employees pursuant to certain plans

Automatic Shelf Registration

Prospectus Supplement for Primary Offering

Registration statement under Securities Act of 1933 to be offered to employees pursuant to certain plans

Registration statement under Securities Act of 1933 to be offered to employees pursuant to certain plans

Automatic Shelf Registration

Registration statement under Securities Act of 1933 to be offered to employees pursuant to certain plans

Registration statement under Securities Act of 1933 to be offered to employees pursuant to certain plans

Notice of Effectiveness

Post-effective amendment to a registration statement

Automatic Shelf Registration

Prospectus Supplement for Primary Offering

Notice of Effectiveness

Registration statement under Securities Act of 1933 (amendment)

Registration statement under Securities Act of 1933 (amendment)

Definitive Proxy Statement

Additional Information for Proxy Statement/ Votes

Definitive Proxy Statement

Definitive Proxy Statement

Preliminary Proxy Statement

Definitive Proxy Statement

Definitive Proxy Statement

Additional Information for Proxy Statement/ Votes

Additional Information for Proxy Statement/ Votes

Definitive Proxy Statement

Additional Information for Proxy Statement/ Votes

Definitive Proxy Statement

Definitive Proxy Statement

Definitive Proxy Statement

Definitive Proxy Statement

Definitive Proxy Statement

Definitive Proxy Statement

Preliminary Proxy Statement

Definitive Proxy Statement

Preliminary Proxy Statement

MOTLEY DAVID L

Sandifer Andrew D

Feng Xudong

WILKERSON SONJA MICHELLE

BALL M LEROY

BALL M LEROY

Lucas Stephen G

Sullivan James A.

Lucas Stephen G

Sullivan James A.

Pearce Bradley A

Sullivan James A.

Pearce Bradley A

Sullivan James A.

VANGUARD CAPITAL MANAGEMENT LLC

BALL M LEROY

MOTLEY DAVID L

WILKERSON SONJA MICHELLE

Sandifer Andrew D

Feng Xudong

Annual Report Scanned (Paper)

Annual Report Scanned (Paper)

Annual Report Scanned (Paper)

Letter from the SEC

Correspondence with the SEC

Letter from the SEC

Annual Report Scanned (Paper)

Annual Report Scanned (Paper)

Post-effective amendment to an automatic shelf registration statement

Letter from the SEC

Annual Report Scanned (Paper)

Letter from the SEC

Correspondence with the SEC

Letter from the SEC

Annual Report Scanned (Paper)

Annual Report Scanned (Paper)

Correspondence with the SEC

Annual Report Scanned (Paper)

Letter from the SEC

Letter from the SEC