Were the Alnylam (ALNY) insider share sales made under a Rule 10b5-1 plan?

Yes. A footnote states the transaction was made pursuant to a Rule 10b5-1(c) trading plan adopted on December 16, 2025. Such plans schedule trades in advance, reducing the informational value of the specific timing of these insider sales for outside investors.

Alnylam (NASDAQ: ALNY) HR chief auto-sells shares to cover RSU taxes

Filing Impact

(Very High)

Filing Sentiment

(Negative)

Form Type

Rhea-AI Filing Summary

Alnylam Pharmaceuticals’ Chief Human Resources Officer Melissa McLaughlin reported routine share sales tied to equity compensation taxes.

The Form 4 shows a total sale of 3,910 shares of common stock on April 2 and 6, 2026, executed automatically under a mandatory sell-to-cover provision to satisfy minimum statutory tax withholding on vested restricted stock units. After these transactions, she holds 9,443 shares directly. The filing notes the sales were made under a pre-arranged Rule 10b5-1(c) trading plan adopted on December 16, 2025, indicating they were scheduled in advance rather than opportunistic trades.

Insider Trade Summary 10b5-1

Net Seller: 3,910 shares ($1,274,343)

Net Sell 14 txns

Insider McLaughlin Melissa

Role Chief Human Resources Officer

Sold 3,910 shs ($1.27M)

Type	Security	Shares	Price	Value
Sale	Common Stock	56	$320.14	$18K
Sale	Common Stock	909	$329.76	$300K
Sale	Common Stock	829	$330.46	$274K
Sale	Common Stock	293	$331.89	$97K
Sale	Common Stock	199	$333.94	$66K
Sale	Common Stock	265	$316.61	$84K
Sale	Common Stock	359	$317.44	$114K
Sale	Common Stock	209	$318.47	$67K
Sale	Common Stock	86	$319.69	$27K
Sale	Common Stock	147	$320.62	$47K
Sale	Common Stock	224	$321.64	$72K
Sale	Common Stock	245	$322.86	$79K
Sale	Common Stock	81	$323.64	$26K
Sale	Common Stock	8	$325.49	$3K

Holdings After Transaction: Common Stock — 11,673 shares (Direct)

Footnotes (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 required to cover minimum statutory tax withholding obligations that became due upon the vesting and settlement of restricted stock units. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $316.04 to $317.03. 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. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $317.07 to $318.05. 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. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $318.09 to $318.83. 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. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $319.19 to $320.10. 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. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $320.21 to $321.11. 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. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $321.26 to $322.20. 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. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $322.31 to $323.13. 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. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $323.39 to $324.01. 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. This transaction was made pursuant to a Rule 10b5-1(c) trading plan adopted by the Reporting Person on December 16, 2025. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $320.10 to $320.32. 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. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $329.22 to $330.18. 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. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $330.21 to $330.86. 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. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $331.77 to $332.14. 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. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $333.39 to $334.31. 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.

Key Figures

Total shares sold: 3,910 shares Shares held after transactions: 9,443 shares Sale price example (April 2, 2026): $316.61 per share +2 more

5 metrics

Total shares sold 3,910 shares Automatic sell-to-cover transactions on April 2 and 6, 2026

Shares held after transactions 9,443 shares Direct common stock ownership following final reported sale

Sale price example (April 2, 2026) $316.61 per share One tranche of common stock sold in open-market transactions

Sale price example (April 6, 2026) $333.94 per share One later tranche of common stock sold in open-market transactions

Rule 10b5-1 plan adoption date December 16, 2025 Trading plan governing the reported insider sales

Key Terms

mandatory sell-to-cover provision, restricted stock units, minimum statutory tax withholding obligations, Rule 10b5-1(c) trading plan, +1 more

5 terms

mandatory sell-to-cover provision financial

"Represents shares automatically sold by the Company on behalf of the reporting person pursuant to a mandatory sell-to-cover provision"

restricted stock units financial

"tax withholding obligations that became due upon the vesting and settlement of restricted stock units"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

minimum statutory tax withholding obligations financial

"required to cover minimum statutory tax withholding obligations that became due"

Rule 10b5-1(c) trading plan regulatory

"This transaction was made pursuant to a Rule 10b5-1(c) trading plan adopted by the Reporting Person"

A Rule 10b5-1(c) trading plan is a legally defined, pre-set schedule that lets company insiders automatically buy or sell stock at specified times or under set formulas when they are not in possession of undisclosed, sensitive information. Think of it like an automatic payment plan for trades: because the instructions are written in advance, trades under the plan help protect insiders from allegations of trading on secret information and give investors clearer expectations about when insiders will transact, which can affect liquidity and perceived transparency.

weighted average sales price financial

"The price reported represents the weighted average sales price of shares sold in multiple transactions"

Form 4 Insider Transactions: What Each Field Means →

04/07/2026 - 04:21 PM

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).

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^*

McLaughlin Melissa

(Last)

(First)

(Middle)

675 WEST KENDALL STREET

(Street)

CAMBRIDGE

MASSACHUSETTS

02142

(City)

(State)

(Zip)

UNITED STATES

(Country)

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

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
04/02/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	04/02/2026		S⁽¹⁾		265	D	$316.61⁽²⁾	13,088	D
Common Stock	04/02/2026		S⁽¹⁾		359	D	$317.44⁽³⁾	12,729	D
Common Stock	04/02/2026		S⁽¹⁾		209	D	$318.47⁽⁴⁾	12,520	D
Common Stock	04/02/2026		S⁽¹⁾		86	D	$319.69⁽⁵⁾	12,434	D
Common Stock	04/02/2026		S⁽¹⁾		147	D	$320.62⁽⁶⁾	12,287	D
Common Stock	04/02/2026		S⁽¹⁾		224	D	$321.64⁽⁷⁾	12,063	D
Common Stock	04/02/2026		S⁽¹⁾		245	D	$322.86⁽⁸⁾	11,818	D
Common Stock	04/02/2026		S⁽¹⁾		81	D	$323.64⁽⁹⁾	11,737	D
Common Stock	04/02/2026		S⁽¹⁾		8	D	$325.49	11,729	D
Common Stock	04/06/2026		S⁽¹⁰⁾		56	D	$320.14⁽¹¹⁾	11,673	D
Common Stock	04/06/2026		S⁽¹⁰⁾		909	D	$329.76⁽¹²⁾	10,764	D
Common Stock	04/06/2026		S⁽¹⁰⁾		829	D	$330.46⁽¹³⁾	9,935	D
Common Stock	04/06/2026		S⁽¹⁰⁾		293	D	$331.89⁽¹⁴⁾	9,642	D
Common Stock	04/06/2026		S⁽¹⁰⁾		199	D	$333.94⁽¹⁵⁾	9,443	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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)

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 required to cover minimum statutory tax withholding obligations that became due upon the vesting and settlement of restricted stock units.

2. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $316.04 to $317.03. 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 $317.07 to $318.05. 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 $318.09 to $318.83. 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.

5. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $319.19 to $320.10. 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.

6. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $320.21 to $321.11. 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.

7. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $321.26 to $322.20. 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 $322.31 to $323.13. 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 $323.39 to $324.01. 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. This transaction was made pursuant to a Rule 10b5-1(c) trading plan adopted by the Reporting Person on December 16, 2025.

11. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $320.10 to $320.32. 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 $329.22 to $330.18. 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 price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $330.21 to $330.86. 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.

14. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $331.77 to $332.14. 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.

15. The price reported represents the weighted average sales price of shares sold in multiple transactions at prices ranging from $333.39 to $334.31. 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.

	/s/ Brett Budzinski, Attorney-in-Fact For Melissa McLaughlin	04/07/2026
	** 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).
** 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.
* Form 4: SEC 1474 (03-26)

Source: View Original Filing on SEC EDGAR

FAQ

What did Alnylam (ALNY) executive Melissa McLaughlin report in this Form 4?

Melissa McLaughlin reported automatic sales of 3,910 Alnylam common shares. These transactions were tied to equity compensation taxes and executed under a pre-arranged Rule 10b5-1 trading plan, rather than being discretionary open-market sales initiated for portfolio or valuation reasons.

Why were Alnylam (ALNY) shares sold by the HR chief in this filing?

The shares were sold to cover minimum statutory tax withholding on vested restricted stock units. A mandatory sell-to-cover provision in the award agreement triggered the sales, meaning the company automatically sold shares on her behalf to satisfy tax obligations owed at settlement.

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

After the reported transactions, Melissa McLaughlin directly holds 9,443 shares of Alnylam common stock. This figure comes from the last line of the Form 4 table and reflects her remaining direct ownership position following the automatic sell-to-cover sales disclosed.

Are the Alnylam (ALNY) insider sales in this Form 4 open-market disposals?

While coded as open-market sales in the Form 4, a key footnote explains they were mandatory sell-to-cover transactions. The company sold shares automatically to meet tax withholding obligations on vested restricted stock units, rather than reflecting a discretionary decision to reduce holdings.