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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 Commission File Number 001-39231 Delaware ( State or other jurisdiction of incorporation or organization ) Two Commerce Square 2001 Market Street , 28th Floor ( Address of principal executive offices ) Large accelerated filer Non - accelerated filer PASSAGE BIO , INC . ( Exact Name of Registrant as Specified in Its Charter ) Title of each class Common stock to ( 267 ) 866-0311 ( Registrant's telephone number , including area code ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol PASG 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 Act . Yes ☐ No 冈 Indicate by check mark whether the issuer ( 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 0 82-2729751 ( I.R.S. Employer Identification No. ) 19103 ( Zip Code ) 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 Name of each exchange on which registered The Nasdaq Stock Market LLC ( Nasdaq Global Market ) 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 . DOCUMENTS INCORPORATED BY REFERENCE 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 . 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 common equity held by non - affiliates of the Registrant on June 30 , 2020 ( the last business day of the Registrant's second fiscal quarter ) , based upon the closing price of $ 27.33 of the Registrant's common stock as reported on The Nasdaq Global Market , was approximately $ 771.5 million . The number of shares of the registrant's common stock outstanding as of March 1 , 2021 , was 53,831,466 . П X Portions of the Registrant's Definitive Proxy Statement ( " Proxy Statement " ) relating to the 2021 Annual Meeting of Stockholders will be filed with the Commission within 120 days after the end of the Registrant's 2020 fiscal year and is incorporated by reference into Part III of this Report .