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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 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 Delaware ( State or other jurisdiction of incorporation or organization ) Title of each class Common Stock , par value $ 0.0001 PUMA BIOTECHNOLOGY , INC . ( Exact name of registrant as specified in its charter ) per to Commission File Number : 001-35703 10880 Wilshire Boulevard , Suite 2150 Los Angeles , CA 90024 ( 424 ) 248-6500 ( Address , including zip code , and telephone number , including area code , of registrant's principal executive offices ) 77-0683487 ( I.R.S. Employer Identification No. ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading symbol PBYI share Name of each exchange on which registered The NASDAQ Stock Market LLC ( NASDAQ Global Select 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 X 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 ( § 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 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 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 . X 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 . X Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Act ) . Yes No X The aggregate market value of voting stock held by non - affiliates of the registrant was approximately $ 413.3 million as of June 30 , 2020 , based upon the closing price of $ 10.43 per share of the registrant's common stock on the NASDAQ Global Select Market on Friday , June 30 , 2020 , the last business day of the registrant's most recently completed second fiscal quarter . Shares of common stock held by each executive officer , director and holder of 10 % or more of the outstanding common stock have been excluded in that such persons may be deemed to be affiliates . This determination of affiliate status is not necessarily a conclusive determination for other purposes . As of February 18 , 2021 , there were 40,258,460 shares of the registrant's common stock outstanding . Documents Incorporated by Reference : Portions of the Proxy Statement for the registrant's 2021 Annual Meeting of Stockholders , or the 2021 Proxy Statement , are incorporated by reference into Part III of the Form 10 - K to the extent stated herein .