Page 1

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON , D.C. 20549 FORM 10 - K ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31 , 2020 Commission file number 1-32737 KOPPERS HOLDINGS INC . ( Exact name of registrant as specified in its charter ) Pennsylvania ( State of incorporation ) 436 Seventh Avenue Pittsburgh , Pennsylvania 15219 ( Address of principal executive offices ) Title of each class Common Stock 20-1878963 ( IRS Employer Identification No. ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) KOP Securities registered pursuant to Section 12 ( g ) of the Act : None Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act : Yes No Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15 ( d ) of the Act . Yes ☐ No > Indicate by check mark whether the registrant ( 1 ) has filed all reports required to be filed by Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 during the preceding 12 months ( or for such shorter period that the registrant was required to file such reports ) and ( 2 ) has been subject to such filing requirements for the past 90 days . Yes No ( 412 ) 227-2001 ( Registrant's telephone number , including area code ) Name of each exchange on which registered The New York Stock Exchange Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S - T ( §232.405 of this chapter ) during the preceding 12 months ( or for such shorter period that the registrant was required to submit such files ) . Yes > No 3 Indicate by check mark whether the registrant is a large accelerated filer , an accelerated filer , a non - accelerated filer , a smaller reporting company , or emerging growth company . See the definitions of " large accelerated filer " , " accelerated filer " , " smaller reporting company " , and " emerging growth company " in Rule 12b - 2 of the Exchange Act .: Large accelerated filer Accelerated filer Non - accelerated filer Smaller reporting company Emerging Growth Company If an emerging growth company , indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13 ( a ) of the Exchange Act . Indicate by check mark whether the registrant has filed a report on and attestation to its management's assessment of the effectiveness of its internal control over financial reporting under Section 404 ( b ) of the Sarbanes - Oxley Act ( 15 U.S.C. 7262 ( b ) ) by the registered public accounting firm that prepared or issued its audit report . < No | Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . Yes The aggregate market value of shares of Common Stock held by non - affiliates of the registrant , based on the closing sales price of the Common Stock on the New York Stock Exchange on June 30 , 2020 was $ 386.9 million ( affiliates , for this purpose , have been deemed to be Directors and executive officers of Koppers Holdings Inc. ) . As of January 29 , 2021 , 21,098,544 shares of Common Stock of the registrant were issued and outstanding . DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant's definitive Proxy Statement for the 2021 Annual Meeting of Shareholders are incorporated by reference into Part III of this Annual Report on Form 10 - K .