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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 Transition Report Pursuant to Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 For the transition period from to Delaware ( State or other jurisdiction of incorporation or organization ) Large accelerated filer SIX FLAGS ENTERTAINMENT CORPORATION ( Exact name of registrant as specified in its charter ) 1000 Ballpark Way , Suite 400 Arlington , Texas ( Address of principal executive offices ) Title of each class Common stock , $ 0.025 par value per share Preferred Stock Purchase Rights Six Flags Commission File Number : 1-13703 Registrant's telephone number , including area code : ( 972 ) 595-5000 Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) SIX SIX Securities registered pursuant to Section 12 ( g ) of the Act : None ( I.R.S. Employer Identification No. ) 13-3995059 Accelerated filer Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act of 1993. Yes No Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Securities Exchange Act of 1934. 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 76011 ( Zip Code ) 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 No Non - accelerated filer Name of each exchange on which registered New York Stock Exchange New York Stock Exchange 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 definition of " large accelerated filer , " " accelerated filer , " " smaller reporting company " and " emerging growth company " in Rule 12b - 2 of the Exchange Act . 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 is a shell company ( as defined in Rule 12b - 2 of the Act ) . Yes No 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 by the registered public accounting firm that prepared or issued its audit report . On the last business day of the registrant's most recently completed second fiscal quarter , the aggregate market value of the common stock of the registrant held by non - affiliates was approximately $ 1,628.2 million based on the closing price $ 19.21 of the common stock on The New York Stock Exchange on such date . Shares of common stock beneficially held by each executive officer and director have been excluded from this computation because these persons may be deemed to be affiliates . This determination of affiliate status is not necessarily a conclusive determination for any other purposes . On February 19 , 2021 , there were 85,172,488 shares of common stock , par value $ 0.025 , of the registrant issued and outstanding . DOCUMENTS INCORPORATED BY REFERENCE Portions of the information required in Part III by Items 10 , 11 , 12 , 13 and 14 are incorporated by reference to the registrant's proxy statement for the 2021 annual meeting of stockholders , which will be filed by the registrant within 120 days after the close of its 2020 fiscal year .