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Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 冈 ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the Fiscal Year Ended December 31 , 2020 Form 10 - K 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 ) or Commission File No. 001-32260 Westlake Chemical Corporation ( Exact name of registrant as specified in its charter ) 2801 Post Oak Boulevard , Suite 600 Houston , Texas 77056 Securities registered pursuant to Section 12 ( b ) of the Act : Title of each class Common Stock , $ 0.01 par value 1.625 % Senior Notes due 2029 ( Address of principal executive offices , including zip code ) ( 713 ) 960-9111 ( Registrant's telephone number , including area code ) Large accelerated filer Non - accelerated filer Trading Symbol ( s ) WLK WLK29 76-0346924 ( I.R.S. Employer Identification No. ) Name of each exchange on which registered The New York Stock Exchange The New York Stock Exchange 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 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 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 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 during the preceding 12 months ( or for such shorter period that the registrant was required to submit such files ) . Yes No 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 : Accelerated filer Smaller reporting company Emerging growth company 0 0