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  4. [Form 4] Avidity Biosciences, Inc. Insider Trading Activity

RNA Officer Exercises Options at $9.05 and Sells 6,562 Shares

Filing Impact
(Moderate)
Filing Sentiment
(Negative)
Form Type
4

Rhea-AI Filing Summary

Avidity Biosciences insider activity: The Chief Commercial Officer executed simultaneous option exercises and share sales on 10/03/2025. The reporting person exercised a stock option with a $9.05 exercise price to acquire 6,562 shares and immediately sold 6,562 shares under a Rule 10b5-1 trading plan adopted on 09/11/2024. The sales produced a weighted-average price of $45.3781 (sales ranged $44.80–$47.21), and the reporting person’s beneficial ownership after the transactions is 55,000 shares (with 177,188 shares underlying outstanding options).

Positive

  • None.

Negative

  • None.

Insights

TL;DR: Officer exercised options at $9.05 and sold the same number of shares under a 10b5-1 plan on 10/03/2025.

The transaction shows a common liquidity pattern: exercising options that were vested or vesting and using a pre-established 10b5-1 plan to sell the acquired shares. The exercise price was $9.05 for 6,562 shares and the reported weighted-average sale price was $45.3781

Key dependencies and near-term items to watch include any future scheduled option vesting (the option vests monthly so full vesting completes by the fourth anniversary of the 01/01/2024 vesting commencement) and whether additional plan-based sales are reported; these affect insider liquidity and incremental share supply.

Insider Mosbrooker Eric
Role Chief Commercial Officer
Sold 6,562 shs ($298K)
Type Security Shares Price Value
Exercise Stock Option (Right to Buy) 6,562 $0.00 --
Exercise Common Stock 6,562 $9.05 $59K
Sale Common Stock 6,562 $45.3781 $298K
Holdings After Transaction: Stock Option (Right to Buy) — 177,188 shares (Direct); Common Stock — 61,562 shares (Direct)
Footnotes (1)
  1. The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan previously adopted by the Reporting Person on September 11, 2024. This represents a weighted-average price. These shares were sold in multiple transactions at prices ranging from $44.80 to $47.21. The Reporting Person undertakes to provide the Issuer, any securityholder of the Issuer, or the Staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. 1/48th of the total number of shares subject to the option shall vest on each monthly anniversary of January 1, 2024 (the "Vesting Commencement Date"), subject to the Reporting Person's continuous service to the Issuer on each such vesting date, so that the options shall be fully vested on the fourth anniversary of the Vesting Commencement Date.
Form 4 Insider Transactions: What Each Field Means →
SEC Form 4
FORM 4 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
or Section 30(h) of the Investment Company Act of 1940
OMB APPROVAL
OMB Number: 3235-0287
Estimated average burden
hours per response: 0.5
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
X
 Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.
1. Name and Address of Reporting Person*
Mosbrooker Eric
(Last) (First) (Middle)
C/O AVIDITY BIOSCIENCES, INC.
3020 CALLAN RD.
(Street)
SAN DIEGO CA 92121
(City) (State) (Zip)
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 Commercial Officer
3. Date of Earliest Transaction (Month/Day/Year)
10/03/2025
4. If Amendment, Date of Original Filed (Month/Day/Year)
 6. Individual or Joint/Group Filing (Check Applicable Line)
X Form filed by One Reporting Person
Form filed by More than One Reporting Person
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 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 10/03/2025 M(1) 6,562 A $9.05 61,562 D
Common Stock 10/03/2025 S(1) 6,562 D $45.3781(2) 55,000 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 (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 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 (Month/Day/Year) 7. Title and Amount of Securities Underlying Derivative Security (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: 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) $9.05 10/03/2025 M(1) 6,562 (3) 12/31/2033 Common Stock 6,562 $0 177,188 D
Explanation of Responses:
1. The sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan previously adopted by the Reporting Person on September 11, 2024.
2. This represents a weighted-average price. These shares were sold in multiple transactions at prices ranging from $44.80 to $47.21. The Reporting Person undertakes to provide the Issuer, any securityholder of the Issuer, or the Staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
3. 1/48th of the total number of shares subject to the option shall vest on each monthly anniversary of January 1, 2024 (the "Vesting Commencement Date"), subject to the Reporting Person's continuous service to the Issuer on each such vesting date, so that the options shall be fully vested on the fourth anniversary of the Vesting Commencement Date.
Remarks:
/s/ John B. Moriarty, Jr., J.D., Attorney-in-Fact 10/07/2025
** Signature of Reporting Person Date
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).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

Source: View Original Filing on SEC EDGAR