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Table of Contents ☑ 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 : 000-26422 WINDTREE THERAPEUTICS , INC . Delaware ( Exact name of registrant as specified in its charter ) ( State or other jurisdiction of incorporation or organization ) 2600 Kelly Road , Suite 100 Warrington , Pennsylvania ( Address of principal executive offices ) Title of each class 94-3171943 ( I.R.S. Employer Identification No. ) 18976-3622 ( Zip Code ) Registrant's telephone number , including area code : ( 215 ) 488-9300 Securities registered pursuant to Section 12 ( b ) of the Act : Common Stock , $ 0.001 par value Trading symbol ( s ) WINT Name of exchange on which registered The Nasdaq Capital 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 × Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Exchange 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 , 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 ☑