Sec Form 3 Filing - Fitzgerald Kevin Joseph @ ALNYLAM PHARMACEUTICALS, INC. - 2024-03-20

FORM 3 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 Fitzgerald Kevin Joseph 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) CSO & EVP, Head of Research (Last) (First) (Middle) 675 WEST KENDALL STREET, HENRI A. TERMEER SQUARE 3. Date of Earliest Transaction (MM/DD/YY) 03/20/2024 (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 12,881 D Common Stock 537 I by Managed Account ( 1 )

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 Performance Stock Option 2017 (right to buy) $ 119.13 02/11/2021 03/01/2028 Common Stock 9,000 D Stock Option (right to buy) $ 85 ( 2 ) 02/28/2029 Common Stock 16,250 D Stock Option (right to buy) $ 97.72 ( 2 ) 12/07/2025 Common Stock 6,667 D Stock Option (right to buy) $ 118.05 ( 2 ) 02/26/2030 Common Stock 14,580 D Stock Option (right to buy) $ 119.13 ( 3 ) 03/01/2028 Common Stock 9,000 D Stock Option (right to buy) $ 147.47 ( 2 ) 02/23/2032 Common Stock 20,382 D Stock Option (right to buy) $ 151.59 ( 2 ) 02/24/2031 Common Stock 15,692 D Stock Option (right to buy) $ 152.61 ( 2 ) 03/01/2034 Common Stock 9,279 D Stock Option (right to buy) $ 190.01 ( 2 ) 02/27/2033 Common Stock 10,352 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Fitzgerald Kevin Joseph 675 WEST KENDALL STREET HENRI A. TERMEER SQUARE CAMBRIDGE, MA02142 CSO & EVP, Head of Research Signatures By: Brett Budzinski, Attorney-in-Fact For: Kevin Fitzgerald 03/28/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )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. ( 2 )The stock option vests as to 25% of the shares on the first anniversary of the grant date and the remaining shares vest 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. ( 3 )The stock option vests as to 25% of the shares on the first anniversary of the grant date and the remaining shares vest in equal installments at the end of each successive three-month period thereafter over the following thirty-three (33) months of the grant date, subject to the Reporting Persons continuous service with the Issuer as of each such vesting date.

Remarks: Exhibit List: Exhibit 24 - Power of Attorney

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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