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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 U UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10 - K TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM ΤΟ Canada ( State or other jurisdiction of incorporation or organization ) 200-3650 Gilmore Way Burnaby , British Columbia ( Address of principal executive offices ) XENON PHARMACEUTICALS INC . ( Exact Name of Registrant as Specified in its Charter ) Commission File Number 001-36687 Securities registered pursuant to Section 12 ( b ) of the Act : Title of each class Common Shares , without par value □ ☑ □ Registrant's telephone number , including area code : ( 604 ) 484-3300 Trading Symbol ( s ) XENE 98-0661854 ( I.R.S. Employer Identification No. ) V5G 4W8 ( Zip Code ) Name of each exchange on which registered The Nasdaq Stock Market LLC ( The Nasdaq Global Market ) 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 15 ( d ) of the Act . 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 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 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 Non - accelerated filer 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 . □ DOCUMENTS INCORPORATED BY REFERENCE Accelerated filer Smaller reporting company 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 Exchange Act ) . YES □ NO > The aggregate market value of the voting and non - voting common equity held by non - affiliates of the Registrant , based on the closing price of the common shares on The Nasdaq Global Market on June 30 , 2020 , was approximately $ 382.9 million . Common shares held by each executive officer and director and by each other person who may be deemed to be an affiliate of the Registrant , have been excluded from this computation . This determination of affiliate status is not necessarily a conclusive determination for other purposes . The number of common shares of the Registrant outstanding as of February 26 , 2021 was 35,809,247 . U Portions of the Registrant's Definitive Proxy Statement relating to the 2021 Annual Meeting of Shareholders , which will be filed with the Securities and Exchange Commission subsequent to the date hereof , are incorporated by reference into Part III of this Report . Such Proxy Statement will be filed with the Securities and Exchange Commission not later than 120 days following the end of the Registrant's fiscal year ended December 31 , 2020 .