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UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 20 - F ☐ REGISTRATION STATEMENT PURSUANT TO SECTION 12 ( b ) OR ( g ) OF THE SECURITIES EXCHANGE ACT OF 1934 OR ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 ☐ ☐ For the fiscal year ended December 31 , 2020 OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 OR SHELL COMPANY REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 Commission File Number 001-35931 Constellium SE ( Exact Name of Registrant as Specified in its Charter ) Constellium SE ( Translation of Registrant's name into English ) France ( Jurisdiction of incorporation or organization ) Washington Plaza , 40-44 rue Washington 75008 Paris France ( Head Office ) 300 East Lombard Street Suite 1710 Baltimore , MD , 21202 United States ( Address of principal executive offices ) Rina E. Teran Chief Securities Counsel 300 East Lombard Street , Suite 1710 , Baltimore , MD , 21202 United States Tel : ( 443 ) 420-7861 E - mail : rina.teran@constellium.com ( Name , telephone , e - mail and / or facsimile number and address of company contact person ) Securities registered or to be registered pursuant to Section 12 ( b ) of the Act . Title of each class Ordinary Shares Trading Symbol CSTM Name of each exchange on which registered New York Stock Exchange Securities registered or to be registered pursuant to Section 12 ( g ) of the Act : None Securities for which there is a reporting obligation pursuant to Section 15 ( d ) of the Act : None Indicate the number of outstanding shares of each of the issuer's classes of capital or common stock as of the close of the period covered by the annual report : 139,962,672 Ordinary Shares , Nominal Value € 0.02 per share Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . x Yes □ No If this report is an annual or transition report , indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15 ( d ) of the Securities Exchange Act of 1934. □ Yes × No Note Checking the box above will not relieve any registrant required to file reports pursuant to Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 from their obligations under those Sections . Indicate by check mark whether the registrant ( 1 ) has filed all reports required to be filed by Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 during the preceding 12 months ( or for such shorter period that the registrant was required to file such reports ) , and ( 2 ) has been subject to such filing requirements for the past 90 days . x Yes □ No Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S - T ( § 232.405 of this chapter ) during the preceding 12 months ( or for such shorter period that the registrant was required to submit such files ) . × Yes □ No Indicate by check mark whether the registrant is a large accelerated filer , an accelerated filer , a non - accelerated filer , or an emerging growth company . See definition of “ large accelerated filer " , " accelerated filer " , and " emerging growth company " in Rule 12b - 2 of the Exchange Act .