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Table of Contents ( Mark One ) ☑ ☐ 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 OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number : 0-32405 Delaware Seagen SEAGEN INC . ( Exact name of registrant as specified in its charter ) ( State or other Jurisdiction of incorporation or organization ) 91-1874389 ( I.R.S. Employer Identification No. ) Title of class Common Stock , par value $ 0.001 21823 30th Drive SE , Bothell , WA 98021 ( Address of principal executive offices , including zip code ) Registrant's telephone number , including area code : ( 425 ) 527-4000 Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) SGEN Securities registered pursuant to Section 12 ( g ) of the Act : None Name of each exchange on which registered The Nasdaq Stock Market LLC 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 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 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 ☑ ☐ Accelerated filer Smaller reporting company ㅁ Emerging growth company ☐ ㅁ 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 Exchange Act ) . Yes □ No ☑ The aggregate market value of the voting and non - voting common equity held by non - affiliates of the registrant was approximately $ 21.1 billion as of the last business day of the registrant's most recently completed second fiscal quarter , based upon the closing sale price on The Nasdaq Global Select Market reported for such date . Excludes an aggregate of 49,451,384 shares of the registrant's Common Stock held as of such date by officers , directors and stockholders that the registrant has concluded are or were affiliates of the registrant . Exclusion of such shares should not be construed to indicate that the holder of any such shares possesses the power , direct or indirect , to direct or cause the direction of the management or policies of the registrant or that such person is controlled by or under common control with the registrant . There were 181,164,446 shares of the registrant's Common Stock issued and outstanding as of February 9 , 2021 . DOCUMENTS INCORPORATED BY REFERENCE Part III incorporates information by reference from the registrant's definitive proxy statement to be filed with the Securities and Exchange Commission pursuant to Regulation 14A , not later than 120 days after the end of the fiscal year covered by this Annual Report on Form 10 - K , in connection with the registrant's 2021 Annual Meeting of Stockholders .