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( Mark One ) 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 For the transition period from to UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10 - K SCHWEITZER - MAUDUIT INTERNATIONAL , INC . ( Exact name of registrant as specified in its charter ) Delaware ( State or other jurisdiction of incorporation or organization ) Suite 600 Georgia 100 North Point Center East , Alpharetta , ( Address of principal executive offices ) Securities Registered Pursuant to Section 12 ( g ) of the Act : None Non - accelerated filer 1-13948 ( Commission file number ) 1-800-514-0186 ( Registrant's telephone number , including area code ) X Securities registered pursuant to Section 12 ( b ) of the Act : Title of each class Common stock , $ 0.10 par value 0 Trading Symbol Name of each exchange on which registered SWM New York Stock Exchange Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . Yes x 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 x 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 x No o ( I.R.S. Employer Identification No. ) 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 x No ο Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S - K ( § 229.405 of this chapter ) is not contained herein , and will not be contained , to the best of registrant's knowledge , in definitive proxy or information statements incorporated by reference in Part III of this Form 10 - K or any amendment to this Form 10 K. 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 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 ) : Large accelerated filer 62-1612879 Accelerated filer O 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 Smaller reporting company Emerging growth company There were 31,415,733 shares of Common Stock issued and outstanding as of March 1 , 2021 . 30022 ( Zip Code ) | 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 x The aggregate market value of the outstanding common stock , par value $ 0.10 per share ( the " Common Stock " ) , of the registrant held by non - affiliates as of June 30 , 2020 ( the last business day of the registrant's most recently completed second fiscal quarter ) was $ 1.0 billion , based on the last sale price for the Common Stock of $ 33.41 per share as reported on the New York Stock Exchange on said date . For purposes of the foregoing sentence only , all directors and executive officers are assumed to be affiliates .