Sec Form 3 Filing - Gallagher Kathleen P. @ Avidity Biosciences, Inc. - 2025-01-06

FORM 3 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Gallagher Kathleen P. 2. Issuer Name and Ticker or Trading Symbol Avidity Biosciences, Inc. [ RNA] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Program Officer (Last) (First) (Middle) C/O AVIDITY BIOSCIENCES, INC., 10578 SCIENCE CENTER DR., SUITE 125 3. Date of Earliest Transaction (MM/DD/YY) 01/06/2025 (Street) SAN DIEGO, CA92121 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 34,965 ( 1 ) D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Stock Option (Right to Buy) $ 25.12 ( 2 ) 04/25/2031 Common Stock 22,321 D Stock Option (Right to Buy) $ 22.56 ( 3 ) 10/27/2031 Common Stock 1,001 D Stock Option (Right to Buy) $ 14.7 ( 4 ) 01/19/2032 Common Stock 25,250 D Stock Option (Right to Buy) $ 16.65 ( 5 ) 07/17/2032 Common Stock 40,550 D Stock Option (Right to Buy) $ 22.47 ( 6 ) 01/19/2033 Common Stock 27,584 D Stock Option (Right to Buy) $ 8.82 ( 3 ) 08/06/2033 Common Stock 1,000 D Stock Option (Right to Buy) $ 8.24 ( 7 ) 08/19/2033 Common Stock 42,480 D Stock Option (Right to Buy) $ 10.16 ( 8 ) 01/19/2034 Common Stock 13,520 D Stock Option (Right to Buy) $ 44 ( 9 ) 08/29/2034 Common Stock 16,000 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Gallagher Kathleen P. C/O AVIDITY BIOSCIENCES, INC. 10578 SCIENCE CENTER DR., SUITE 125 SAN DIEGO, CA92121 Chief Program Officer Signatures /s/ John B. Moriarty, Jr., J.D., Attorney-in-Fact 01/08/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Includes restricted stock units (RSUs). Each RSU represents a contingent right to receive one share of the Issuer's common stock. The RSUs vest as follows: 1,991 RSUs on each of the first four anniversaries of January 20, 2023; 6,125 RSUs on each of the first four anniversaries of January 20, 2024; and 625 RSUs on each of the first four anniversaries of August 30, 2024, in each case subject to the Reporting Person's continuous service to the Issuer on each such vesting date. ( 2 )This option was granted on April 26, 2021 and vests in equal installments of 2,029 shares on each monthly anniversary of such grant date, until it is fully vested and exercisable on April 26, 2025. ( 3 )This option is fully vested and exercisable as of the date hereof. ( 4 )This option was granted on January 20, 2022 and vests in equal installments of 1,383 shares on each monthly anniversary of such grant date, until it is fully vested and exercisable on January 20, 2026. ( 5 )This option was granted on July 18, 2022 and vests in equal installments of 553 shares on each monthly anniversary of such grant date, until it is fully vested and exercisable on July 18, 2026. ( 6 )This option was granted on January 20, 2023 and vests in equal installments of 774 shares on each monthly anniversary of such grant date, until it is fully vested and exercisable on January 20, 2027. ( 7 )This option was granted on August 20, 2023 and vests in equal installments of 885 shares on each monthly anniversary of such grant date, until it is fully vested and exercisable on August 20, 2027. ( 8 )This option was granted on January 20, 2024 and vests in equal installments of 282 shares on each monthly anniversary of such grant date, until it is fully vested and exercisable on January 20, 2028. ( 9 )This option was granted on August 30, 2024 and vests in equal installments of 333 shares on each monthly anniversary of such grant date, until it is fully vested and exercisable on August 30, 2028.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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