6-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OFFOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of February 2023

Commission File Number: 001-35931

Constellium SE

(Translation of registrant’s name into English)

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F:

Form 20-F  ☒    Form 40-F  ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule

101(b)(1): Yes  ☐    No  ☒

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule

101(b)(7): Yes  ☐    No  ☒

INFORMATION CONTAINED IN THIS FORM 6-K REPORT

Attached hereto as Exhibit 99.1 is a copy of a press release issued by Constellium SE (the “Company”) on February 16, 2023, regarding changes in the Company’s Chief Financial Officer position.

Exhibit Index

The information contained in Exhibit 99.1 of this Form 6-K, is incorporated byreference into any offering circular or registration statement (or into any prospectus that forms a part thereof) filed by Constellium SE with the Securities and Exchange Commission.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

EX-99.1

Exhibit 99.1

Constellium to appoint Jack Guo as Chief Financial Officer following Peter Matt’s decision to leave the Company

Paris, February 16, 2023 – **** Constellium SE (NYSE: CSTM) announced today that, following Peter Matt’s decision to leave the Company to pursue another career opportunity, Jack Guo will be appointed Chief Financial Officer, effective April 1st, 2023.

“I am delighted that Peter is offered such an exciting career opportunity. We are extremely grateful to him for his outstanding contributions to the transformation of Constellium as CFO,” stated Jean-Marc Germain, Constellium’s Chief Executive Officer. “He has been instrumental in our turnaround over the past 6 years through his focus on improving operating results, enhancing our financial flexibility, managing risks, building out our strategic agenda and developing a strong team, including his successor. We wish Peter all the very best in his new position.”

“With his financial expertise and extensive knowledge of Constellium’s business, Jack Guo is well-positioned to help drive our financial performance, further strengthen our financial position and navigate our growth trajectory,” Mr. Germain added.

Jack joined Constellium as a Vice President Finance in early 2017. He was promoted to Vice President Business Development and Strategy in September 2017 and has been a key contributor to our strategy development and the execution of a number of critical strategic projects. Prior to joining Constellium, he worked at Credit Suisse for twelve years, most recently as a Director in Investment Banking and Capital Markets primarily covering downstream aluminium activities. In addition, he spent five years in other senior finance roles in North America and Asia. Jack holds a BA of Economics from the University of Chicago and an MBA from Columbia University.

Constellium (NYSE: CSTM) is a global sector leader that develops innovative, value added aluminium products for a broad scope of markets and applications, including aerospace, automotive and packaging. Constellium generated €6.2 billion of revenue in 2021.