Amylyx (AMLX) Co-CEO sells shares to cover RSU tax withholding

Rhea-AI Filing Summary

Amylyx Pharmaceuticals Co-Chief Executive Officer Justin B. Klee reported an open-market sale of common stock tied to tax withholding. On March 2, he sold 29,282 shares at a weighted average price of $14.4717 per share to cover withholding obligations from vesting restricted stock units. The filing notes these sales were automatic and not at his discretion, and he continued to hold 3,334,616 shares of Amylyx common stock directly after the transaction.

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^*

Klee Justin B.

(Last) (First) (Middle)

C/O AMYLYX PHARMACEUTICALS, INC.

55 CAMBRIDGE PARKWAY, SUITE 6W

(Street)

CAMBRIDGE MA 02142

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Amylyx Pharmaceuticals, Inc. [ AMLX ]

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

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Co-Chief Executive Officer

3. Date of Earliest Transaction (Month/Day/Year)
03/02/2026

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

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

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

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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	03/02/2026		S(1)		29,282(1)	D	$14.4717(2)	3,334,616	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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Represents shares required to be sold by the Reporting Person to cover tax withholding obligations in connection with the vesting of restricted stock units. Such sales were automatic and not at the discretion of the Reporting Person.

2. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $14.450 to $15.360. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

	/s/ Joshua B. Cohen, as Attorney in Fact	03/04/2026
	** 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.

FAQ

What insider transaction did Amylyx (AMLX) report for Justin B. Klee?

Amylyx reported that Co-Chief Executive Officer Justin B. Klee sold 29,282 shares of common stock. The sale occurred on March 2 and was tied to tax withholding obligations arising from the vesting of restricted stock units, rather than a discretionary share sale.

At what price did Justin B. Klee’s Amylyx (AMLX) shares sell in this Form 4?

The reported weighted average sale price was $14.4717 per share. Footnotes explain the shares were sold in multiple transactions at prices ranging from $14.450 to $15.360, with detailed trade breakdowns available to the SEC staff upon request.

Why did Amylyx Co-CEO Justin B. Klee sell shares according to this Form 4?

The shares were sold to cover tax withholding obligations triggered by the vesting of restricted stock units. The filing specifies that these sales were automatic and not at Justin B. Klee’s discretion, indicating they were for tax purposes rather than optional profit-taking.

How many Amylyx (AMLX) shares does Justin B. Klee hold after this reported sale?

Following the tax-related sale, Justin B. Klee directly held 3,334,616 shares of Amylyx common stock. This figure reflects his ownership after selling 29,282 shares on March 2 to satisfy withholding obligations related to the vesting of restricted stock units.

What type of transaction is reported in Justin B. Klee’s Amylyx Form 4?

The Form 4 reports an open-market sale of non-derivative common stock. The transaction code is “S,” and the filing clarifies that the sale was executed automatically to satisfy tax withholding requirements associated with vesting restricted stock units held by Justin B. Klee.