Sec Form 4 Filing - Ryfold Ltd @ CENTURY ALUMINUM CO - 2017-09-14

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 Ryfold Ltd 2. Issuer Name and Ticker or Trading Symbol CENTURY ALUMINUM CO [ CENX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O ESTERA TRUST (JERSEY) LIMITED,, 13-14 ESPLANADE 3. Date of Earliest Transaction (MM/DD/YY) 09/14/2017 (Street) ST HELIER, Y9JE1 1EE 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ 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

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 Call Option (obligation to sell) $ 100 ( 1 ) 09/14/2017 J( 1 ) 1 09/14/2017( 1 ) 09/14/2027( 1 ) Common Stock 27,500,000 ( 1 ) $ 100 ( 1 ) 1 D ( 2 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Ryfold Ltd C/O ESTERA TRUST (JERSEY) LIMITED, 13-14 ESPLANADE ST HELIER, Y9JE1 1EE X Estera Trust (Jersey) Ltd C/O ESTERA TRUST (JERSEY) LIMITED, 13-14 ESPLANADE ST HELIER, Y9JE1 1EE X Ryfold Trust C/O ESTERA TRUST (JERSEY) LIMITED, 13-14 ESPLANADE ST HELIER, Y9JE1 1EE X Signatures RYFOLD LIMITED By: /s/ Brendan Dowling, Director 09/14/2017 Signature of Reporting Person Date ESTERA TRUST (JERSEY) LIMITED By: /s/ Brendan Dowling, Director 09/14/2017 Signature of Reporting Person Date ESTERA TRUST (JERSEY) LIMITED, in its capacity as trustee of THE RYFOLD TRUST By: /s/ Brendan Dowling, Director 09/14/2017 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On the September 14, 2017, Glencore AG and Ryfold Limited ("Ryfold") entered into a Call Option Agreement (the "Givolon Call Option Agreement") pursuant to which Glencore AG acquired an American-style call option that gives Glencore AG the right to purchase from Ryfold, at any time prior to the expiration thereof, 100% of the equity interests in Givolon Limited, a wholly-owned subsidiary of Ryfold ("Givolon"), for an aggregate exercise price of $100 (the "Givolon Call Option"). The Givolon Call Option will expire on September 14, 2027. Glencore AG paid Ryfold an aggregate premium of $100 for the Givolon Call Option. ( 2 )Ryfold's interest in the Call Option is held indirectly by each of Ryfold's parent, The Ryfold Trust, and Estera Trust (Jersey) Limited ("Estera") solely in its capacity as trustee of The Ryfold Trust. Givolon holds directly a number of shares of Common Stock equal to the number of shares reported on Table II, which shares are indirectly owned by each of Ryfold, Ryfold's parent, The Ryfold Trust, and Estera solely in its capacity as trustee of The Ryfold Trust. Estera does not have and disclaims any pecuniary interest in such Common Stock and in the Call Option reported on Table II.

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