RNA Form 4: Sarah Boyce Exercises Options, Sells 25,000 Shares Under 10b5-1

Rhea-AI Filing Summary

Sarah Boyce, President and CEO and a director of Avidity Biosciences, Inc. (RNA), exercised options and sold shares on 08/28/2025 under a previously adopted Rule 10b5-1 trading plan. The reporting person exercised a stock option to acquire 25,000 shares at an exercise price of $1.24 and contemporaneously sold 25,000 shares at a weighted-average sales price of $49.388 per share (sales ranged $49.23–$49.52). The filings show direct beneficial ownership of common stock decreased from 330,871 shares before the sale to 305,871 shares after the sale. The option award exercised was fully vested and exercisable as of the transaction date, and Table II reports 25,000 underlying shares from the exercised option and a total of 1,072,015 derivative securities beneficially owned following the transaction as reported on the form. The trades were effected pursuant to a 10b5-1 plan adopted August 15, 2024.

Positive

• Trade executed under a Rule 10b5-1 plan, indicating pre-established trading intentions
• Option award fully vested and exercisable at time of exercise
• Filing discloses weighted-average sale price and price range, improving transparency

Negative

• Insider sold 25,000 shares, reducing direct beneficial ownership from 330,871 to 305,871 shares
• Material monetization by the CEO could be viewed negatively by some investors despite plan use

Insights

Corporate Governance Expert

TL;DR: Routine insider exercise and sale under a documented 10b5-1 plan; no governance red flags apparent from the filing.

The Form 4 shows a standard option exercise and immediate sale of the same number of shares by the CEO/director under a Rule 10b5-1 plan adopted in 2024, which provides an affirmative defense against insider trading allegations when properly implemented. The option was fully vested and exercisable at $1.24, and the sale occurred at a weighted-average price of $49.388, reducing direct holdings by 25,000 shares. From a governance perspective, the filing discloses the plan and dates required; there is no indication of ad hoc, undisclosed trades. Documentation of the plan adoption date and the attorney-in-fact signature further supports procedural compliance.

Securities Analyst

TL;DR: Insider monetized a portion of equity via exercise and sale; transaction size is modest relative to total reported ownership.

The reporting shows an exercise at $1.24 and sale at a ~49.39 price, realizing substantial per-share spread on 25,000 shares. Direct common shares declined from 330,871 to 305,871 after the sale. The form also reports 1,072,015 derivative securities beneficially owned following the transaction, which may reflect outstanding option/award positions; the filing states the exercised option is fully vested. This is a standard liquidity event by an executive rather than a signal of undisclosed material change in company fundamentals, as it was executed via a pre-established 10b5-1 plan.

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^*

Boyce Sarah

(Last) (First) (Middle)

C/O AVIDITY BIOSCIENCES, INC.

10578 SCIENCE CENTER DRIVE, SUITE 125

(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)
08/28/2025

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	08/28/2025		M(1)		25,000	A	$1.24	330,871	D
Common Stock	08/28/2025		S(1)		25,000	D	$49.388(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	08/28/2025		M(1)			25,000	(3)	12/17/2029	Common Stock	25,000	$0	1,072,015	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 $49.23 to $49.52. 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	08/29/2025
	** 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 (RNA) do on 08/28/2025?

She exercised 25,000 options at $1.24 per share and sold 25,000 common shares under a Rule 10b5-1 plan on 08/28/2025.

At what price were the shares sold and what was the exercise price?

Exercise price: $1.24 per share. Weighted-average sale price: $49.388 per share (sales ranged $49.23–$49.52).

How did the transactions affect Sarah Boyce's ownership in RNA?

Direct common stock holdings decreased from 330,871 shares to 305,871 shares following the transactions.

Was the option exercised fully vested?

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

Was the sale part of a pre-established trading plan?

Yes. The trades were effected pursuant to a Rule 10b5-1 trading plan adopted August 15, 2024.