Page 1

Table of Contents 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 UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON , D.C. 20549 or □ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF For the transition period from to Delaware ( State or Other Jurisdiction of Incorporation or Organization ) Commission File Number : 001-37758 Moleculin Biotech , Inc. ( Exact name of registrant as specified in its charter ) Title of Each Class Common Stock , par value $ 0.001 per share 2834 ( Primary Standard Industrial Classification Code Number ) 5300 Memorial Drive , Suite 950 Houston , Texas 77007 ( 713 ) 300-5160 ( Address of Principal Executive Offices , Zip Code and Registrant's Telephone Number ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) MBRX 47-4671997 ( I.R.S. Employer Identification Number ) 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 X Non - accelerated filer Accelerated filer Name of Each exchange on which registered Nasdaq Stock Market LLC 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 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 periods as 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 if disclosure of delinquent filers pursuant to Item 405 of Regulation S - K is not contained herein , and will not be contained , to the best of registrant's knowledge , in definitive proxy or information statements incorporated by reference in Part III of this Form 10 - K or any amendment to this Form 10 - K . > Smaller reporting company Emerging growth company 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 the definitions of " large accelerated filer , " " accelerated filer , " " smaller reporting company " and " emerging growth company " in Rule 12b - 2 of the Exchange Act . ( check one ) Large accelerated filer 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 USC . 7262 ( b ) ) by the registered public accounting firm that prepared or issued its audit report .