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Table of Contents 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 NO . 001-34223 CLEAN HARBORS , INC . ( Exact name of registrant as specified in its charter ) Massachusetts ( State or Other Jurisdiction of Incorporation or Organization ) 42 Longwater Drive Norwell ΜΑ ( Address of Principal Executive Offices ) 04-2997780 ( IRS Employer Identification No. ) 02061-9149 ( Zip Code ) Registrant's Telephone Number , Including area code : ( 781 ) 792-5000 Securities registered pursuant to Section 12 ( b ) of the Securities Exchange Act of 1934 : Name of each exchange on which registered New York Stock Exchange Title of each class Trading Symbol CLH Common Stock , $ 0.01 par value 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 Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Exchange Act . Yes 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 twelve 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 Large accelerated filer Non - accelerated filer 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 during the preceding 12 months ( or for such shorter period that the registrant was required to submit and post such files ) . Yes ý No Indicate by check mark whether the registrant is a large accelerated filer , an accelerated filer , a non - accelerated filer , smaller reporting company , or an 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 . ( Check one ) : 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 . X Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . Yes No ý On June 30 , 2020 ( the last business day of the registrant's most recently completed second fiscal quarter ) , the aggregate market value of the voting and non - voting common stock of the registrant held by non - affiliates of the registrant was approximately $ 3.1 billion , based on the closing price of such common stock as of that date on the New York Stock Exchange . Reference is made Part III of this report for the assumptions on which this calculation is based . On February 17 , 2021 , there were outstanding 54,796,559 shares of Common Stock , $ 0.01 par value . DOCUMENTS INCORPORATED BY REFERENCE Certain portions of the registrant's definitive proxy statement for its 2021 annual meeting of stockholders ( which will be filed with the Commission not later than April 23 , 2021 ) are incorporated by reference into Part III of this report .