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( Mark One ) UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON , DC 20549 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 Delaware ( State or Other Jurisdiction of Incorporation or Organization ) 111 West Lemon Avenue , Monrovia , CA ( Address of Principal Executive Offices ) FORM 10 - K Title of each class Common Stock , par value $ 0.01 per share Commission file number : 001-36182 Xencor , Inc. ( Exact Name of Registrant as Specified in its Charter ) Securities registered pursuant to Section 12 ( b ) of the Act : ( 626 ) 305-5900 ( Registrant's Telephone Number , Including Area Code ) to Trading Symbol XNCR Accelerated filer 20-1622502 ( I.R.S. Employer Identification No. ) 91016 ( Zip Code ) 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 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 Name of each exchange on which registered The Nasdaq Global Market 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 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 . Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Securities Exchange Act of 1934 ) . Yes No The aggregate market value of the voting and non - voting common equity held by non - affiliates computed by reference to the price at which the common equity was last sold as of June 30 , 2020 was $ 1,843,897,240 . The number of outstanding shares of the registrant's common stock , par value $ 0.01 per share , as of February 16 , 2021 was 57,945,225 . DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant's proxy statement to be filed with the Securities and Exchange Commission pursuant to Regulation 14A in connection with the gistrant's 2021 Annual Meeting of Stockholders , which will be filed subsequent to the date hereof , are incorporated by reference into Part III of this Form 10 - K . 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 .