Sec Form 4/A Filing - FRATES JAMES M @ Amylyx Pharmaceuticals, Inc. - 2023-03-16

FORM 4/A 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) 03/16/2023 (Street) CAMBRIDGE, MA02141 4. If Amendment, Date Original Filed (MM/DD/YY) 03/20/2023 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 03/16/2023 M( 1 )( 2 ) 32,500 A $ 6.88 66,509 ( 1 ) D Common Stock 03/16/2023 S( 2 ) 30,796 D $ 31.8593 ( 3 ) 35,713 ( 1 ) D Common Stock 03/16/2023 S( 2 ) 1,704 D $ 32.4649 ( 4 ) 34,009 ( 1 ) D Common Stock 03/16/2023 A 21,667 ( 5 ) A $ 0 55,676 ( 1 ) 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 (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) $ 32.08 03/16/2023 A 97,500 ( 6 ) 03/16/2033 Common Stock 97,500 $ 0 97,500 D Stock Option (right to buy) $ 6.88 03/16/2023 M( 1 )( 2 ) 32,500 ( 7 ) 01/25/2031 Common Stock 32,500 $ 0 414,500 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 03/24/2023 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On March 16, 2023, the Reporting Person filed a Form 4 (the "Original Form 4") which inadvertently omitted the exercise of 32,500 options by the Reporting Person. The Original Form 4 reported the sale of shares of Common Stock of the Issuer ("Common Stock") underlying those options, pursuant to a Rule 10b5-1 trading plan. This Form 4 amendment is being filed for the purpose of amending and restating the Original Form 4 solely to report the exercise of the stock options and the resulting increase in beneficial ownership of Common Stock. The Reporting Person has not sold any additional shares of Common Stock beyond those sales reported in the Original Form 4. ( 2 )These transactions were effected by the Reporting Person pursuant to a Rule 10b5-1 trading plan adopted on November 15, 2022. ( 3 )The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $31.33 to $32.30. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request. ( 4 )The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $32.33 to $32.93. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request. ( 5 )The reported transaction involves the Reporting Person's receipt of a restricted stock unit award (a "RSU"). The RSU shall vest in 4 equal annual installments, with the first installment vesting on the first day of the month of the one year anniversary of the date of grant, subject to the Reporting Person's continued service to the Issuer through such vesting date. ( 6 )1/4 of the shares subject to the option shall vest and become exercisable on the first day of the month of the one year anniversary of the date of grant, and the remaining shares shall vest monthly over the remaining 36 months, subject to the Reporting Person's continuous service to the Issuer through such vesting date. ( 7 )113,024 shares underlying this option vested on January 25, 2022, with the remaining shares vesting in monthly installments of 9,416 shares thereafter.

Remarks: Exhibit List: Exhibit 24. This signed and dated Power of Attorney is being filed to replace the Power of Attorney exhibit submitted with the Form 3 filed on January 6, 2022.

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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