Sec Form 4 Filing - Garg Pushkal @ ALNYLAM PHARMACEUTICALS, INC. - 2024-03-01

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

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, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Garg Pushkal 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) CMO & EVP Dev & Med Affairs (Last) (First) (Middle) 675 WEST KENDALL STREET, HENRI A. TERMEER SQUARE 3. Date of Earliest Transaction (MM/DD/YY) 03/01/2024 (Street) CAMBRIDGE, MA02142 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 03/01/2024 A 4,751 ( 1 ) A $ 0 13,417 ( 2 ) D Common Stock 431 I by Managed Account ( 3 ) Common Stock 250 I by Trust ( 4 )

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 7. Title and Amount of Underlying Securities (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 of Derivative Security: 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) $ 152.61 03/01/2024 A 9,279 ( 5 ) 03/01/2034 Common Stock 9,279 $ 0 9,279 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Garg Pushkal 675 WEST KENDALL STREET HENRI A. TERMEER SQUARE CAMBRIDGE, MA02142 CMO & EVP Dev & Med Affairs Signatures By: Stephen Hall, Attorney-in-Fact For: Pushkal Garg 03/05/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )These shares are represented by restricted stock units (RSUs) granted under the Amended and Restated 2018 Stock Incentive Plan. Each RSU represents a contingent right to receive one share of common stock. The RSUs will vest over a three-year period, with one third vesting on each of the first, second and third anniversaries of the grant date, subject to the Reporting Persons continuous service with the Issuer as of each such vesting date. ( 2 )The Reporting Person has reported prior awards of RSUs in Table II of Form 4. The total reported in Column 5 includes the 4,751 newly awarded RSUs and 8,666 shares of common stock. The Reporting Person also holds 3,816 unvested RSUs that were previously reported in Table II. ( 3 )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. ( 4 )Represents shares held in trust, of which the Reporting Persons spouse is co-trustee. The Reporting Person disclaims beneficial ownership of these shares, and the filing of this report is not an admission that the Reporting Person is the beneficial owner of these securities for purposes of Section 16 or for any other purpose. ( 5 )The stock option vests as to 25% of the shares on the first anniversary of the grant date and the remaining shares vesting in equal installments at the end of each successive three-month period thereafter until the fourth anniversary of the grant date, subject to the Reporting Persons continuous service with the Issuer as of each such vesting 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).

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