Page 1

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON , DC 20549 FORM 10 - K ( 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 TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM Commission file number : 001-39321 ΤΟ AVIDITY BIOSCIENCES , INC . Delaware ( Exact name of registrant as specified in its charter ) ( State or Other Jurisdiction of Incorporation or Organization ) 10975 N. Torrey Pines Road , Suite 150 La Jolla , CA ( Address of Principal Executive Offices ) Title of each class ( 858 ) 401-7900 ( Registrant's Telephone Number , Including Area Code ) Securities registered pursuant to Section 12 ( b ) of the Act : Common Stock , par value $ 0.0001 per share Trading Symbol ( s ) RNA 46-1336960 ( I.R.S. Employer Identification No. ) 92037 ( Zip Code ) Name of each exchange on which registered The Nasdaq Global 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 Securities Exchange Act of 1934. 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 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 ☑ Emerging growth company ☑ Accelerated filer ☐ Smaller reporting 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 Act ) . Yes ☐ No ☑ As of June 30 , 2020 , the aggregate market value of the registrant's common stock held by non - affiliates of the registrant was approximately $ 887.4 million , based on the closing price of the registrant's common stock on the Nasdaq Global Market of $ 28.26 per share . As of February 26 , 2021 , the registrant had 37,584,600 shares of common stock outstanding . DOCUMENTS INCORPORATED BY REFERENCE Certain sections of the registrant's definitive proxy statement for the 2021 annual meeting of stockholders to be filed with the Securities and Exchange Commission pursuant to Regulation 14A not later than 120 days after the end of the fiscal year covered by this Form 10 - K are incorporated by reference into Part III of this Form 10 - K .