Sec Form 4 Filing - FRATES JAMES M @ Amylyx Pharmaceuticals, Inc. - 2024-04-16

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 FRATES JAMES M 2. Issuer Name and Ticker or Trading Symbol Amylyx Pharmaceuticals, Inc. [ AMLX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Financial Officer (Last) (First) (Middle) C/O AMYLYX PHARMACEUTICALS, INC., 43 THORNDIKE STREET 3. Date of Earliest Transaction (MM/DD/YY) 04/16/2024 (Street) CAMBRIDGE, MA02141 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 04/16/2024 A 91,180 ( 1 ) A $ 0 225,964 D Common Stock 15,459 I By Trust ( 2 ) Common Stock 11,072 I By Trust ( 3 )

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) $ 2.01 04/16/2024 A 120,000 ( 4 ) 04/15/2034 Common Stock 120,000 $ 0 120,000 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other FRATES JAMES M C/O AMYLYX PHARMACEUTICALS, INC. 43 THORNDIKE STREET CAMBRIDGE, MA02141 Chief Financial Officer Signatures /s/ Joshua B. Cohen, as Attorney in Fact 04/18/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The reported transaction involves the Reporting Person's receipt of a restricted stock unit ("RSU") award. The RSUs shall vest as follows: 33% on September 30, 2024, 33% on March 31, 2025 and 34% on September 30, 2025, subject to the Reporting Person's continued service to the Issuer through each such vesting date. ( 2 )Shares held by the James M. Frates 2024 Grantor Retained Annuity Trust No. 1, for which the Reporting Person serves as trustee and is the sole annuitant. The Reporting Person disclaims beneficial ownership of such shares for purposes of Section 16 except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that such shares are beneficially owned by him for Section 16 or any other purpose. ( 3 )Shares held by the FRATES FAMILY 2013 IRREV TRUST, for which the Reporting Person serves as trustee. The Reporting Person disclaims beneficial ownership of such shares for purposes of Section 16 except to the extent of his pecuniary interest therein, if any, and this report shall not be deemed an admission that such shares are beneficially owned by him for Section 16 or any other purpose. ( 4 )25% of the shares subject to the option shall vest and become exercisable on April 16, 2025, and the remaining shares shall vest monthly over the remaining 36 months, subject to the Reporting Person's continuous service to the Issuer through 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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