Sec Form 4 Filing - Gary Jesse E @ CENTURY ALUMINUM CO - 2021-07-01

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

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, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Gary Jesse E 2. Issuer Name and Ticker or Trading Symbol CENTURY ALUMINUM CO [ CENX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) President & CEO (Last) (First) (Middle) C/O CENTURY ALUMINUM COMPANY, ONE SOUTH WACKER DRIVE, SUITE 1000 3. Date of Earliest Transaction (MM/DD/YY) 07/01/2021 (Street) CHICAGO, IL60606 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 Common Stock 07/01/2021 A 171,276 ( 1 ) A $ 0 332,732 ( 2 ) D Common Stock 64,400 ( 3 ) I By Trust

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 7. Title and Amount of Underlying Securities (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 of Derivative Security: 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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Gary Jesse E C/O CENTURY ALUMINUM COMPANY ONE SOUTH WACKER DRIVE, SUITE 1000 CHICAGO, IL60606 X President & CEO Signatures /s/ John DeZee, Attorney-in-Fact for Jesse E. Gary 07/02/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents awards granted to the Reporting Person consisting of (i) 13,740 time vesting share units under the Issuer's 2021-2023 Long-Term Incentive Plan under Rule 16b-3(d), all of which will vest in the ordinary course on the last day of the Plan Period, December 31, 2023 and (ii) 157,536 time vesting share units, 78,768 of which vest in the ordinary course on July 1, 2022, 47,261 of which vest in the ordinary course on July 1, 2023 and 31,507 of which vest in the ordinary course on July 1, 2024. ( 2 )Includes unvested time vesting share units granted to the Reporting Person (i) pursuant to Issuer's 2019-2021, 2020-2022 and 2021-2023 Long-Term Incentive Plans under Rule 16b-3(d) and (ii) 157,536 time vesting share units, 78,768 of which vest in the ordinary course on July 1, 2022, 47,261 of which vest in the ordinary course on July 1, 2023 and 31,507 of which vest in the ordinary course on July 1, 2024. ( 3 )Represents shares transferred by the Reporting Person to a self-settled, revocable trust for estate planning purposes. The Reporting Person serves as the trustee of the trust.

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).

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