RNA Form 4: Sarah Boyce Executes Options and Sells Shares Under 10b5-1 Plan

Rhea-AI Filing Summary

Avidity Biosciences director and CEO Sarah Boyce exercised 50,000 vested stock options at an exercise price of $1.24 and concurrently sold 50,000 common shares on 09/05/2025. The sales produced a weighted-average sale price of $49.9487 per share, with sale prices in the range $49.76 to $50.12. After these transactions, Ms. Boyce directly beneficially owns 305,871 shares and holds derivative rights to 50,000 shares exercisable through 12/17/2029, for a total direct beneficial ownership reported as 1,022,015 derivative-linked shares and 355,871 pre-transaction common shares as shown on the Form 4. The option exercise and sales were executed under a Rule 10b5-1 trading plan adopted August 15, 2024.

Positive

• Transaction executed under a Rule 10b5-1 plan, providing procedural compliance and clarity on timing
• Option award was fully vested at time of exercise, removing vesting uncertainty

Negative

• Insider sold 50,000 shares, reducing direct beneficial ownership to 305,871 shares
• Sale realized substantial proceeds at a weighted-average price of $49.9487, which may be interpreted as an insider liquidity event

Insights

Corporate Governance Expert

TL;DR: Insider exercised fully vested options and sold shares under a pre-established 10b5-1 plan, a routine governance-compliant liquidity action.

The filing shows the Reporting Person exercised 50,000 options at $1.24 and sold 50,000 shares at a weighted-average of $49.9487 on 09/05/2025 under a Rule 10b5-1 plan adopted 08/15/2024. The disclosure of the plan and the execution under that plan aligns with governance best practices for avoiding allegations of trading on material nonpublic information. The option award was fully vested as of the transaction date, reducing ambiguity about intent. For governance review, the material points are the explicit 10b5-1 adoption date, the option vesting status, and the post-transaction beneficial ownership levels disclosed on the Form 4.

Securities Analyst

TL;DR: The transaction is a notable insider liquidity event but appears mechanically driven by option exercise and an approved trading plan.

The report quantifies a 50,000-share option exercise at $1.24 and immediate sale at an average of $49.9487, indicating realization of substantial intrinsic value per share. The seller retained 305,871 shares directly after the sale and shows derivative holdings tied to 50,000 option shares exercisable through 12/17/2029. While the sale size is modest relative to many public float sizes, it is material to disclose and useful for modeling insider ownership trends. No additional company operational or financial metrics are provided in this Form 4.

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
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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^*

Boyce Sarah

(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)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	President and CEO

3. Date of Earliest Transaction (Month/Day/Year)
09/05/2025

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	09/05/2025		M(1)		50,000	A	$1.24	355,871	D
Common Stock	09/05/2025		S(1)		50,000	D	$49.9487(2)	305,871	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)	$1.24	09/05/2025		M(1)			50,000	(3)	12/17/2029	Common Stock	50,000	$0	1,022,015	D

Explanation of Responses:

1. The option exercise and sales reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan previously adopted on August 15, 2024 by the Reporting Person.

2. This represents a weighted-average price. These shares were sold in multiple transactions at prices ranging from $49.76 to $50.12. 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. This option award is fully vested and exercisable as of the date hereof.

Remarks:

	/s/ John B. Moriarty, Jr., J.D., Attorney-in-Fact	09/05/2025
	** 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.

FAQ

What did Sarah Boyce report on the Form 4 for RNA on 09/05/2025?

The Form 4 reports that Sarah Boyce exercised 50,000 options at $1.24 and sold 50,000 common shares on 09/05/2025 under a Rule 10b5-1 plan.

At what price were the shares sold according to the Form 4?

The shares were sold at a weighted-average price of $49.9487, with individual sale prices ranging from $49.76 to $50.12.

How many shares does Sarah Boyce beneficially own after the transactions?

After the reported transactions, the Form 4 shows 305,871 shares beneficially owned directly and derivative rights tied to 50,000 shares exercisable through 12/17/2029.

Was the option award exercisable when exercised?

Yes. The Form 4 states the option award was fully vested and exercisable as of the transaction date.

When was the Rule 10b5-1 plan adopted for these transactions?

The Form 4 discloses the Rule 10b5-1 trading plan was adopted on August 15, 2024.