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United States Securities and Exchange Commission Washington , D.C. 20549 FORM 10 - K ( 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 Commission File Number 001-31921 Delaware ( State or other jurisdiction of incorporation or organization ) 9900 West 109th Street , Suite 100 Overland Park , Kansas ( Address of principal executive offices ) Compass to Compass Minerals International , Inc. ( Exact name of registrant as specified in its charter ) Minerals Registrant's telephone number , including area code : ( 913 ) 344-9200 Trading Symbol CMP ( I.R.S. Employer Identification No. ) Securities registered pursuant to Section 12 ( b ) of the Act : Title of each class Common stock , $ 0.01 par value 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 . Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Act . 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 р No 36-3972986 ☐ Non - accelerated filer 66210 ( Zip Code ) Name of each exchange on which registered The New York Stock Exchange Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . Yes Yes 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 ) . р No DOCUMENTS INCORPORATED BY REFERENCE Yes 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 . Large accelerated filer р Accelerated filer р ☐ No No 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 . Yes ☐ No р As of June 30 , 2020 , the aggregate market value of the registrant's common stock held by non - affiliates of the registrant was $ 1,653,658,110 , based on the closing sale price of $ 48.75 per share , as reported on the New York Stock Exchange . The number of shares outstanding of the registrant's $ 0.01 par value common stock at February 23 , 2021 was 33,974,215 shares .