Nicolas Brun - 09 Mar 2026 Form 4 Insider Report for CONSTELLIUM SE (CSTM)

Role: SVP PA, Comm & Sust
Signature: /s/ Kristine Carpenter, Attorney-in-Fact for Nicolas Brun
Issuer symbol: CSTM
Transactions as of: 09 Mar 2026
Net transactions value: -$436,684
Form type: 4
Filing time: 11 Mar 2026, 06:27:42 UTC
Previous filing: 11 Mar 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Brun Nicolas	SVP PA, Comm & Sust	300 EAST LOMBARD STREET, SUITE 1710, BALTIMORE	/s/ Kristine Carpenter, Attorney-in-Fact for Nicolas Brun	11 Mar 2026	0002093242

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	CSTM	Ordinary shares	Sale	$436,684	-17,701	-15%	$24.67	103,466	09 Mar 2026	Direct	F1
transaction	CSTM	Ordinary shares	Award		+23,710	+23%	$0.000000^*	127,176	09 Mar 2026	Direct	F2

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $24.63 to $24.72, inclusive. The reporting person undertakes to provide to Constellium SE, any security holder of Constellium SE, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth herein.
F2	Represents earned non-derivative performance stock units of the Issuer granted on March 9, 2023 that contained performance-vesting requirements, which vested on March 9, 2026.

Content

The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $24.63 to $24.72, inclusive. The reporting person undertakes to provide to Constellium SE, any security holder of Constellium SE, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth herein.

Represents earned non-derivative performance stock units of the Issuer granted on March 9, 2023 that contained performance-vesting requirements, which vested on March 9, 2026.