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Table of Contents ANNUAL REPORT UNDER SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31 , 2020 OR TRANSITION REPORT UNDER SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , DC 20549 FORM 10 - K Title of each class Common Stock Delaware ( State or Other Jurisdiction of Incorporation or Organization ) One First Avenue , Parris Building 34 , Navy Yard Plaza Boston , Massachusetts ( Address of Principal Executive Offices ) Large Accelerated Filer Non- Accelerated Filer to Commission File Number 001-33038 ZIOPHARM Oncology , Inc. ( Exact Name of Registrant as Specified in Its Charter ) ■ ( 617 ) 259-1970 ( Registrant's Telephone Number , Including Area Code ) Securities registered pursuant to Section 12 ( b ) of the Act : 84-1475642 ( IRS Employer Identification No. ) 02129 ( Zip Code ) Trading Symbol ( s ) ZIOP 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 . Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15 ( d ) of the Act . Yes 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 past 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 Yes ✔ No No ✔ Name of each exchange on which registered The Nasdaq Stock Market LLC 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 or a smaller reporting company . See definition of “ large accelerated filer , " " accelerate filer ” and “ smaller reporting company " in Rule 12b - 2 of the Exchange Act . ( Check one ) : 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 . 000 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 Act ) . Yes No ✔ The aggregate market value of the registrant's common stock held by non - affiliates was $ 687,342,598 as of June 30 , 2020 ( the last business day of the registrant's most recently completed second fiscal quarter ) , based on a total of 209,555,670 shares of common stock held by non - affiliates and a closing price of $ 3.28 as reported on the Nasdaq Global Select on June 30 , 2020. For purposes of this computation , all officers , directors , and 10 % beneficial owners of the registrant are deemed to be affiliates . Such determination should not be deemed to be an admission that such officers , directors or 10 % beneficial owners are , in fact , affiliates of the registrant . As of February 24 , 2021 , there were 214,667,023 shares of the registrant's common stock , $ 0.001 par value per share , outstanding .