Constellium (CSTM) CFO reports vested stock awards and tax-driven share sale

Rhea-AI Filing Summary

CONSTELLIUM SE EVP & CFO Jack Q. Guo reported a mix of stock award vesting and related share sales. On March 9, 2026, he acquired 75,874 ordinary shares through vested stock awards at $0.00 per share. On March 10, 2026, he sold 41,717 ordinary shares at $25.87 per share, and a footnote explains this sale was made solely to satisfy tax withholding obligations upon vesting of prior restricted and performance stock unit awards. After these transactions, he directly owns 190,879 ordinary shares of Constellium.

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

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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^*

Guo Jack Q.

(Last) (First) (Middle)

300 EAST LOMBARD STREET

SUITE 1710

(Street)

BALTIMORE MD 21202

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
CONSTELLIUM SE [ CSTM ]

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

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	EVP & CFO

3. Date of Earliest Transaction (Month/Day/Year)
03/09/2026

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
Ordinary shares	03/09/2026		A		75,874(1)	A	$0	232,596	D
Ordinary shares	03/10/2026		S(2)		41,717	D	$25.87	190,879	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 earned non-derivative performance stock units of Constellium SE (the "Issuer") granted on March 9, 2023 that contained performance-vesting requirements, which vested on March 9, 2026.

2. The Reporting Person sold 41,717 ordinary shares of the Issuer upon the vesting of restricted stock unit and performance stock unit awards previously granted on March 9, 2023, solely to satisfy tax withholding obligations incurred upon vesting.

Remarks:

	/s/ Kristine Carpenter, Attorney-in-Fact for Jack Guo	03/11/2026
	** 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 transactions did Constelium (CSTM) CFO Jack Q. Guo report?

Jack Q. Guo reported vested stock awards and a related share sale. He received 75,874 ordinary shares at no cost, then sold 41,717 shares at $25.87 each to cover tax withholding tied to those vesting awards.

How many Constellium (CSTM) shares did the CFO acquire in this Form 4?

The CFO acquired 75,874 ordinary shares through vested stock awards. These were granted as performance and restricted stock units that vested on March 9, 2026, and were reported at a transaction price of $0.00 per share in the filing.

How many Constellium (CSTM) shares did the CFO sell, and at what price?

He sold 41,717 ordinary shares of Constellium. The reported sale price was $25.87 per share on March 10, 2026, according to the Form 4, with the transaction coded as a non-derivative open-market or private transaction.

Why did Constellium (CSTM) CFO Jack Q. Guo sell 41,717 shares?

The filing states the 41,717 shares were sold solely to satisfy tax withholding obligations. These obligations arose when previously granted restricted stock unit and performance stock unit awards vested, prompting a sale to cover associated tax liabilities.

How many Constellium (CSTM) shares does the CFO hold after these transactions?

After the reported grant vesting and related sale, the CFO directly owns 190,879 ordinary shares. This post-transaction holding figure is listed in the Form 4 as his total direct ownership following the March 10, 2026 sale.

Were the Constellium (CSTM) CFO’s recent share sales discretionary or tax-related?

The share sale was tax-related rather than purely discretionary. A footnote explains that the 41,717 ordinary shares were sold upon vesting of prior awards solely to satisfy tax withholding obligations incurred at that vesting event.