Alnylam (NASDAQ: ALNY) CEO sell-to-cover 2,933 shares for tax withholding

Rhea-AI Filing Summary

Alnylam Pharmaceuticals Chief Executive Officer Yvonne Greenstreet reported automatic tax-related stock sales. On March 4, 2026, she sold a total of 2,933 shares of Alnylam common stock in a series of open-market transactions, at weighted average prices ranging from about $318 to $326 per share.

According to the disclosure, these sales were executed by the company under a mandatory sell-to-cover provision to satisfy minimum statutory tax withholding tied to vesting restricted stock units. After these sales, Greenstreet directly owned 95,695 shares, and also held 407 shares indirectly through a managed account related to the company’s 401(k) matching program.

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

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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).

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^*

Greenstreet Yvonne

(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
X	Officer (give title below)		Other (specify below)
	Chief Executive Officer

3. Date of Earliest Transaction (Month/Day/Year)
03/04/2026

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	03/04/2026		S(1)		135	D	$319.03(2)	98,493	D
Common Stock	03/04/2026		S(1)		129	D	$320.01(3)	98,364	D
Common Stock	03/04/2026		S(1)		274	D	$320.81(4)	98,090	D
Common Stock	03/04/2026		S(1)		368	D	$321.82(5)	97,722	D
Common Stock	03/04/2026		S(1)		444	D	$323.01(6)	97,278	D
Common Stock	03/04/2026		S(1)		973	D	$323.84(7)	96,305	D
Common Stock	03/04/2026		S(1)		345	D	$324.88(8)	95,960	D
Common Stock	03/04/2026		S(1)		265	D	$325.67(9)	95,695	D
Common Stock								407	I	by Managed Account(10)

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

Explanation of Responses:

1. Represents shares automatically sold by the Company on behalf of the reporting person pursuant to a mandatory sell-to-cover provision in the award agreement to cover minimum statutory tax withholding obligations upon the vesting of restricted stock units.

2. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $318.27 to $319.27. 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 $319.28 to $320.28. 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 $320.33 to $321.33. 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 $321.34 to $322.31. 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 $322.36 to $323.36. 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 $323.38 to $324.35. 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.

8. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $324.39 to $325.38. 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 $325.40 to $326.21. 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. Reflects shares of ALNY common stock acquired by the Reporting Person under the issuer 401(k) plan as a result of the issuer 401(k) matching contribution program.

	By: Brett Budzinski, Attorney-in-Fact For: Yvonne Greenstreet	03/06/2026
	** 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).
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FAQ

What did Alnylam (ALNY) CEO Yvonne Greenstreet report in this Form 4 filing?

Yvonne Greenstreet reported automatic tax-related stock sales. A total of 2,933 Alnylam common shares were sold in multiple open-market transactions on March 4, 2026, executed under a mandatory sell-to-cover provision linked to vesting restricted stock units.

How many Alnylam (ALNY) shares did the CEO sell and at what prices?

The CEO reported selling 2,933 shares of Alnylam common stock. The weighted average sales prices for the transactions ranged from approximately $318 to $326 per share, with more detailed price breakdowns available on request from the issuer or SEC staff.

Why were Yvonne Greenstreet’s Alnylam (ALNY) shares sold according to the Form 4?

The shares were sold to cover tax withholding obligations. The filing states the company automatically sold the shares under a mandatory sell-to-cover provision in the award agreement to satisfy minimum statutory tax withholding upon vesting of restricted stock units.

How many Alnylam (ALNY) shares does the CEO hold after these transactions?

Following the reported sales, Yvonne Greenstreet directly held 95,695 Alnylam common shares. The filing also notes an additional 407 shares held indirectly through a managed account, reflecting stock acquired via the company’s 401(k) matching contribution program.

Are any of the Alnylam (ALNY) CEO’s holdings indirect or plan-related?

Yes. In addition to directly owned shares, the Form 4 shows 407 Alnylam shares held indirectly in a managed account. A footnote explains these shares were acquired under the issuer’s 401(k) plan through the company’s matching contribution program.