Were Gina Mazzariello’s AMLX share sales under a Rule 10b5-1 plan?

The Form 4’s Rule 10b5-1 checkbox is not marked as affirmative, and the footnote explains the shares were sold automatically to satisfy tax withholding obligations in connection with vesting of performance stock units.

What price range applied to the main AMLX share block sold by Gina Mazzariello?

For the block of 9,525 AMLX shares, the filing reports a weighted average price of $32.4556, with individual sale prices ranging from $32.34 to $33.26 per share, executed in multiple transactions.

Amylyx legal chief sells 9,536 shares for taxes

Q: What insider transaction did AMLX disclose for Chief Legal Officer Gina Mazzariello?

Amylyx Pharmaceuticals disclosed that Chief Legal Officer Gina Mazzariello sold a total of 9,536 shares of AMLX common stock on September 10, 2026 in open-market transactions, as reported on a Form 4.

Q: Why did Gina Mazzariello’s AMLX shares get sold on September 10, 2026?

The filing states the 9,536 shares were sold to cover tax withholding obligations related to the vesting of performance stock units. The sales were described as automatic and not at the discretion of Gina Mazzariello.

Q: How many AMLX shares did Gina Mazzariello sell and at what prices?

Gina Mazzariello reported selling 9,525 shares at a weighted average price of $32.4556 and an additional 11 shares at $33.34 per share on September 10, 2026, for a total of 9,536 shares sold.

Amylyx’s Chief Legal Officer reported automatic sales of shares solely to satisfy tax withholding from vested performance stock units.

Available on EDGAR 09/14/2026 - 04:00 PM EDT Accepted by SEC EDGAR 09/14/2026 - 04:00 PM EDT

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Filing Sentiment

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Form Type

Rhea-AI Filing Summary

Amylyx Pharmaceuticals, Inc. (AMLX) reported that Chief Legal Officer Gina Mazzariello sold a total of 9,536 shares of common stock on September 10, 2026 in open-market transactions. Footnotes state these shares were automatically sold to cover tax withholding obligations upon vesting of performance stock units, and not at her discretion.

Insider Trade Summary

Net Seller: 9,536 shares

Net Sell 2 txns

Insider Mazzariello Gina

Role Chief Legal Officer

Sold 9,536 shs ($310K)

Share of Position Sold 4.8%

Type	Security	Shares	Price	Value
Sale	Common Stock ^{F1, F2}	9,525	$32.4556	$309K
Sale	Common Stock ^F1	11	$33.34	$366.74

Holdings After Transaction: Common Stock — 190,838 shares (Direct)

Holdings Before and After: Common Stock, 200,374 to 190,838 shares (Direct)

Other Insiders: 4 other insiders reported open-market sales of this stock in the 30 days up to this filing.

Footnotes (2)

F1. Represents shares required to be sold by the Reporting Person to cover tax withholding obligations in connection with the vesting of performance stock units. Such sales were automatic and not at the discretion of the Reporting Person.
F2. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $32.34 to $33.26. Full information regarding the number of shares sold at each separate price can be furnished to the SEC staff upon request.

Key Figures

Shares sold (main block): 9,525 shares Weighted average sale price: $32.4556 per share Sale price range: $32.34–$33.26 per share +3 more

6 metrics

Shares sold (main block) 9,525 shares Common stock sold on September 10, 2026 to cover tax withholding

Weighted average sale price $32.4556 per share For 9,525 AMLX shares sold in multiple transactions

Sale price range $32.34–$33.26 per share Price range for the 9,525-share sale block

Additional shares sold 11 shares Common stock sold at $33.34 per share on September 10, 2026

Additional sale price $33.34 per share Price for 11 AMLX shares sold on September 10, 2026

Total shares sold 9,536 shares Combined total of both reported sales on September 10, 2026

Key Terms

performance stock units, tax withholding obligations, weighted average price

3 terms

performance stock units financial

"in connection with the vesting of performance stock units"

Performance stock units are a type of company award that grants employees shares of stock only if certain performance goals are met. They motivate employees to work toward specific company achievements, aligning their interests with those of shareholders. For investors, they can influence a company's future stock supply and reflect management’s confidence in reaching key targets.

tax withholding obligations financial

"to cover tax withholding obligations in connection with the vesting"

weighted average price financial

"The price reported in Column 4 is a weighted average price."

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did AMLX disclose for Chief Legal Officer Gina Mazzariello?

Amylyx Pharmaceuticals disclosed that Chief Legal Officer Gina Mazzariello sold a total of 9,536 shares of AMLX common stock on September 10, 2026 in open-market transactions, as reported on a Form 4.

Why did Gina Mazzariello’s AMLX shares get sold on September 10, 2026?

The filing states the 9,536 shares were sold to cover tax withholding obligations related to the vesting of performance stock units. The sales were described as automatic and not at the discretion of Gina Mazzariello.

How many AMLX shares did Gina Mazzariello sell and at what prices?

Gina Mazzariello reported selling 9,525 shares at a weighted average price of $32.4556 and an additional 11 shares at $33.34 per share on September 10, 2026, for a total of 9,536 shares sold.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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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^*

Mazzariello Gina

(Last)

(First)

(Middle)

C/O AMYLYX PHARMACEUTICALS, INC.

55 CAMBRIDGE PARKWAY, SUITE 6W

(Street)

CAMBRIDGE

MASSACHUSETTS

02142

(City)

(State)

(Zip)

UNITED STATES

(Country)

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 Legal Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/10/2026

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

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

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

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	09/10/2026		S⁽¹⁾		9,525	D	$32.4556⁽²⁾	190,849	D
Common Stock	09/10/2026		S⁽¹⁾		11	D	$33.34	190,838	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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)

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 performance 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 $32.34 to $33.26. 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	09/14/2026
	** 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.
* Form 4: SEC 1474 (03-26)

Source: View Original Filing on SEC EDGAR