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П 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 OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 Commission File Number 001-03970 HARSCO CORPORATION ( Exact name of registrant as specified in its charter ) Delaware ( State or other jurisdiction of incorporation or organization ) 350 Poplar Church Road , Camp Hill , Pennsylvania ( Address of principal executive offices ) Registrant's telephone number , including area code 717-763-7064 Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) Title of each class Common stock , par value $ 1.25 per share HSC 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 ý No o Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Act . Yes o No ý 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 ý No o Name of each exchange on which registered 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 and post such files ) . Yes ý No o Indicate by check mark whether the registrant is a large accelerated filer , an accelerated filer , a non - accelerated filer , a smaller reporting company , or an emerging growth company . See 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 ý Non - accelerated filer 0 Class Common stock , par value $ 1.25 per share 23-1483991 ( I.R.S. employer identification number ) 17011 ( Zip Code ) 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 . o Selected portions of the 2021 Proxy Statement are incorporated by reference into Part III of this Report . 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 . Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Act ) . Yes No ý The aggregate market value of the Company's voting stock held by non - affiliates of the Company as of June 30 , 2020 was $ 1,065,987,000 Indicate the number of shares outstanding of each of the registrant's classes of common stock , as of the latest practicable date : DOCUMENTS INCORPORATED BY REFERENCE 0 Outstanding at January 31 , 2021 78,924,370 ロロ