[Form 4] Alnylam Pharmaceuticals, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Dennis A. Ausiello, a director of Alnylam Pharmaceuticals, executed multiple equity transactions on 08/14/2025 under a Rule 10b5-1(c) trading plan adopted May 15, 2025. The Form 4 reports exercises of stock options (codes M(1)) for option blocks of 9,000; 5,153; 4,581; 5,228; 4,032; and 3,454 shares at exercise prices ranging from $72.01 to $189.87 per share, each creating corresponding shares of common stock. The filing also shows open-market sales (codes S(1)) of multiple share blocks at weighted-average prices reported in ranges between $430.39 and $443.10 per share. After the reported transactions, the reporting person’s beneficial ownership counts are shown on individual lines (for example, 9,911; 15,064; 19,645; 24,873; 28,905; 32,359; then decreasing after sales to 911). Additionally, 3,500 shares are reported as indirectly owned by a trust for which the reporting person's spouse is trustee. The Form 4 was signed by an attorney-in-fact on behalf of Mr. Ausiello on 08/15/2025.

Positive

• Transactions were executed under a Rule 10b5-1(c) trading plan, providing pre-established timing and an affirmative defense for the trades
• Full disclosure of option vesting dates, exercise prices, and weighted-average sale price ranges enhances transparency
• Indirect holdings are disclosed (3,500 shares held in a trust with spouse as trustee), meeting governance disclosure norms

Negative

• Significant insider sales across multiple blocks at prices roughly between $430 and $443 per share, which reduce reported direct holdings
• Large option exercises followed by sales could be interpreted as insiders realizing gains rather than long-term accumulation

Insights

Securities Analyst

TL;DR: Routine option exercises and systematic sales under a 10b5-1 plan; primarily liquidity events, not an unexpected disclosure.

The filing documents contemporaneous exercises of multiple vested stock options followed by systematic sales executed under a Rule 10b5-1(c) plan adopted May 15, 2025. Exercises span option grants with strike prices from $72.01 to $189.87 and result in newly issued common shares; subsequent sales occurred across several price bands between ~$430 and ~$443, using weighted-average pricing disclosures. For investors, this represents insider liquidity managed via a pre-established plan rather than ad-hoc market timing. The presence of an attorney-in-fact signature is procedural. No new material corporate developments, financings, or governance changes are disclosed.

Corporate Governance Expert

TL;DR: Disclosure aligns with standard governance practices; 10b5-1 adoption provides affirmative defense for trading timing.

The report clearly states the transactions were made pursuant to a Rule 10b5-1(c) plan adopted May 15, 2025, which is an accepted governance mechanism to mitigate insider trading concerns. The Form 4 identifies direct and indirect holdings and notes a trust holding 3,500 shares with the spouse as trustee, satisfying disclosure of potential indirect ownership. From a compliance standpoint, the filing appears complete: transaction codes, exercise details, weighted-average sales prices ranges and vesting dates for options are provided. No governance irregularities or unexplained transfers are apparent in this filing.

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^*

Ausiello Dennis A

(Last) (First) (Middle)

675 WEST KENDALL STREET

HENRI A. TERMEER SQUARE

(Street)

CAMBRIDGE MA 02142

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
ALNYLAM PHARMACEUTICALS, INC. [ ALNY ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

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

3. Date of Earliest Transaction (Month/Day/Year)
08/14/2025

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	08/14/2025		M(1)		9,000	A	$72.01	9,911	D
Common Stock	08/14/2025		M(1)		5,153	A	$128.31	15,064	D
Common Stock	08/14/2025		M(1)		4,581	A	$148.77	19,645	D
Common Stock	08/14/2025		M(1)		5,228	A	$151.22	24,873	D
Common Stock	08/14/2025		M(1)		4,032	A	$171.95	28,905	D
Common Stock	08/14/2025		M(1)		3,454	A	$189.87	32,359	D
Common Stock	08/14/2025		S(1)		1,985	D	$430.81(2)	30,374	D
Common Stock	08/14/2025		S(1)		1,938	D	$432.94(3)	28,436	D
Common Stock	08/14/2025		S(1)		2,098	D	$434.5(4)	26,338	D
Common Stock	08/14/2025		S(1)		7,675	D	$435.4(5)	18,663	D
Common Stock	08/14/2025		S(1)		5,358	D	$436(6)	13,305	D
Common Stock	08/14/2025		S(1)		1,922	D	$437.56(7)	11,383	D
Common Stock	08/14/2025		S(1)		2,086	D	$438.34(8)	9,297	D
Common Stock	08/14/2025		S(1)		5,302	D	$439.27(9)	3,995	D
Common Stock	08/14/2025		S(1)		1,238	D	$440.54(10)	2,757	D
Common Stock	08/14/2025		S(1)		1,205	D	$441.88(11)	1,552	D
Common Stock	08/14/2025		S(1)		641	D	$442.66(12)	911	D
Common Stock								3,500	I	by Trust(13)

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)	$72.01	08/14/2025		M(1)			9,000	07/01/2020(14)	06/30/2029	Common Stock	9,000	$0.0	0	D
Stock Option (right to buy)	$128.31	08/14/2025		M(1)			5,153	05/18/2023(15)	05/17/2032	Common Stock	5,153	$0.0	0	D
Stock Option (right to buy)	$148.77	08/14/2025		M(1)			4,581	07/01/2021(16)	07/01/2030	Common Stock	4,581	$0.0	0	D
Stock Option (right to buy)	$151.22	08/14/2025		M(1)			5,228	05/16/2025(17)	05/16/2034	Common Stock	5,228	$0.0	0	D
Stock Option (right to buy)	$171.95	08/14/2025		M(1)			4,032	07/15/2022(18)	07/14/2031	Common Stock	4,032	$0.0	0	D
Stock Option (right to buy)	$189.87	08/14/2025		M(1)			3,454	05/18/2024(19)	05/18/2033	Common Stock	3,454	$0.0	0	D

Explanation of Responses:

1. All transactions reported on this Form 4 were made pursuant to a Rule 10b5-1(c) trading plan adopted by the reporting person on May 15, 2025.

2. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $430.39 to $431.24. The reporting person will provide to the issuer, any security holder of the issuer or the SEC staff, upon request, information regarding the number of shares sold at each price within the range.

3. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $432.10 to $433.06. The reporting person will provide to the issuer, any security holder of the issuer or the SEC staff, upon request, information regarding the number of shares sold at each price within the range.

4. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $433.59 to $434.56. The reporting person will provide to the issuer, any security holder of the issuer or the SEC staff, upon request, information regarding the number of shares sold at each price within the range.

5. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $434.69 to $435.66. The reporting person will provide to the issuer, any security holder of the issuer or the SEC staff, upon request, information regarding the number of shares sold at each price within the range.

6. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $435.79 to $436.35 The reporting person will provide to the issuer, any security holder of the issuer or the SEC staff, upon request, information regarding the number of shares sold at each price within the range.

7. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $436.84 to $437.83 The reporting person will provide to the issuer, any security holder of the issuer or the SEC staff, upon request, information regarding the number of shares sold at each price within the range.

8. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $437.85 to $438.71 The reporting person will provide to the issuer, any security holder of the issuer or the SEC staff, upon request, information regarding the number of shares sold at each price within the range.

9. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $438.91 to $439.89 The reporting person will provide to the issuer, any security holder of the issuer or the SEC staff, upon request, information regarding the number of shares sold at each price within the range.

10. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $440.24 to $440.93 The reporting person will provide to the issuer, any security holder of the issuer or the SEC staff, upon request, information regarding the number of shares sold at each price within the range.

11. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $441.41 to $442.11 The reporting person will provide to the issuer, any security holder of the issuer or the SEC staff, upon request, information regarding the number of shares sold at each price within the range.

12. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $442.44 to $443.10 The reporting person will provide to the issuer, any security holder of the issuer or the SEC staff, upon request, information regarding the number of shares sold at each price within the range.

13. The shares of ALNY common stock are held in a trust, of which the reporting person's spouse is the trustee.

14. The stock option was fully vested as of July 1, 2020.

15. The stock option was fully vested as of May 18, 2023.

16. The stock option was fully vested as of July 1, 2021.

17. The stock option was fully vested as of May 16, 2025.

18. The stock option was fully vested as of July 15, 2022.

19. The stock option was fully vested as of May 18, 2024.

	By: Brett Budzinski, Attorney-in-Fact For: Dennis A. Ausiello	08/15/2025
	** 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 ALNY director Dennis Ausiello do on 08/14/2025?

He exercised multiple stock options and executed multiple share sales on 08/14/2025 under a Rule 10b5-1(c) trading plan.

Were these transactions part of a 10b5-1 plan for ALNY (ticker: ALNY)?

Yes. The Form 4 states all transactions were made pursuant to a Rule 10b5-1(c) trading plan adopted May 15, 2025.

What option exercise sizes and strike prices are reported on the Form 4?

Option exercises reported: 9,000 ($72.01), 5,153 ($128.31), 4,581 ($148.77), 5,228 ($151.22), 4,032 ($171.95), and 3,454 ($189.87).

At what prices were the ALNY shares sold?

Sales were reported as weighted-average prices in ranges from approximately $430.39 to $443.10 per share, with specific blocks reported at different weighted-average ranges.

Does the Form 4 disclose any indirect ownership for Dennis Ausiello?

Yes. The filing reports 3,500 shares as indirectly owned by a trust for which the reporting person's spouse is the trustee.