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                               UNITED STATES
                    SECURITIES AND EXCHANGE COMMISSION
                           WASHINGTON, D.C. 20549


                                SCHEDULE 13G

                 UNDER THE SECURITIES EXCHANGE ACT OF 1934

                                 USEC Inc.
--------------------------------------------------------------------------------
                              (Name of Issuer)

                   Common Stock, par value $.10 per share
--------------------------------------------------------------------------------
                       (Title of Class of Securities)

                                 90333E108
                     ---------------------------------
                               (CUSIP Number)


                             February 17, 2005
                     ---------------------------------
          (Date of Event which Requires Filing of this Statement)



Check the appropriate box to designate the rule pursuant to which this
Schedule is filed:

                           |_| Rule 13d-1(b)

                           |X| Rule 13d-1(c)

                           |_| Rule 13d-1(d)



* The remainder of this cover page shall be filled out for a reporting
person's initial filing on this form with respect to the subject class of
securities, and for any subsequent amendment containing information which
would alter disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be
deemed to be "filed" for the purpose of Section 18 of the Securities
Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of
that section of the Act but shall be subject to all other provisions of the
Act (however, see the Notes).



----------------------------- ---------------------- CUSIP NO. 90333E108 13G PAGE 2 OF 9 PAGES ----------------------------- ---------------------- --------- --------------------------------------------------------------------- 1 NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Ziff Asset Management, L.P. --------- --------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (A) |_| (B) |_| --------- --------------------------------------------------------------------- 3 SEC USE ONLY --------- --------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware --------- --------------------------------------------------------------------- 5 SOLE VOTING POWER NUMBER OF 0 SHARES ------ ------------------------------------------------ 6 SHARED VOTING POWER BENEFICIALLY 4,956,100 OWNED BY ------ ------------------------------------------------ EACH 7 SOLE DISPOSITIVE POWER 0 REPORTING ------ ------------------------------------------------ PERSON 8 SHARED DISPOSITIVE POWER WITH 4,956,100 --------- --------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,956,100 --------- --------------------------------------------------------------------- 10 CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS) |_| --------- --------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.85% --------- --------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) PN --------- ---------------------------------------------------------------------

----------------------------- ---------------------- CUSIP NO. 90333E108 13G PAGE 3 OF 9 PAGES ----------------------------- ---------------------- --------- --------------------------------------------------------------------- 1 NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) PBK Holdings, Inc. --------- --------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (A) |_| (B) |_| --------- --------------------------------------------------------------------- 3 SEC USE ONLY --------- --------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware --------- --------------------------------------------------------------------- 5 SOLE VOTING POWER NUMBER OF 0 SHARES ------ ------------------------------------------------ 6 SHARED VOTING POWER BENEFICIALLY 4,956,100 OWNED BY ------ ------------------------------------------------ EACH 7 SOLE DISPOSITIVE POWER 0 REPORTING ------ ------------------------------------------------ PERSON 8 SHARED DISPOSITIVE POWER WITH 4,956,100 --------- --------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,956,100 --------- --------------------------------------------------------------------- 10 CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS) |_| --------- --------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.85% --------- --------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) CO --------- ---------------------------------------------------------------------

----------------------------- ---------------------- CUSIP NO. 90333E108 13G PAGE 4 OF 9 PAGES ----------------------------- ---------------------- --------- --------------------------------------------------------------------- 1 NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Philip B. Korsant --------- --------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (A) |_| (B) |_| --------- --------------------------------------------------------------------- 3 SEC USE ONLY --------- --------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION United States of America --------- --------------------------------------------------------------------- 5 SOLE VOTING POWER NUMBER OF 0 SHARES ------ ------------------------------------------------ 6 SHARED VOTING POWER BENEFICIALLY 4,956,100 OWNED BY ------ ------------------------------------------------ EACH 7 SOLE DISPOSITIVE POWER 0 REPORTING ------ ------------------------------------------------ PERSON 8 SHARED DISPOSITIVE POWER WITH 4,956,100 --------- --------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,956,100 --------- --------------------------------------------------------------------- 10 CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS) |_| --------- --------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.85% --------- --------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) IN --------- ---------------------------------------------------------------------

ITEM 1. (A) NAME OF ISSUER USEC Inc. ITEM 1. (B) ADDRESS OF ISSUER'S PRINCIPAL EXECUTIVE OFFICES 2 Democracy Center 6903 Rockledge Drive Bethesda, MD 20817 ITEM 2. (A) NAME OF PERSON FILING This Schedule 13G is being filed on behalf of the following persons (the "Reporting Persons")*: (i) Ziff Asset Management, L.P. ("ZAM"); (ii) PBK Holdings, Inc. ("PBK"); and (iii) Philip B. Korsant * Attached as Exhibit A is a copy of an agreement among the Reporting Persons that this Schedule 13G is being filed on behalf of each of them. ITEM 2. (B) ADDRESS OF PRINCIPAL BUSINESS OFFICE OR, IF NONE, RESIDENCE Ziff Asset Management, L.P. 283 Greenwich Avenue Greenwich, CT 06830 PBK Holdings, Inc. 283 Greenwich Avenue Greenwich, CT 06830 Philip B. Korsant 283 Greenwich Avenue Greenwich, CT 06830 ITEM 2. (C) CITIZENSHIP See Item 4 of the attached cover pages. ITEM 2. (D) TITLE OF CLASS OF SECURITIES Common Stock, par value $.10 per share ITEM 2. (E) CUSIP NUMBER 90333E108 ITEM 3. Not applicable as this Schedule 13G is filed pursuant to Rule 13d-1(c). ITEM 4. OWNERSHIP (a) Amount beneficially owned: See Item 9 of the attached cover pages. (b) Percent of class: See Item 11 of the attached cover pages. (c) Number of shares as to which such person has: (i) Sole power to vote or to direct the vote: See Item 5 of the attached cover pages. (ii) Shared power to vote or to direct the vote: See Item 6 of the attached cover pages. (iii) Sole power to dispose or to direct the disposition: See Item 7 of the attached cover pages. (iv) Shared power to dispose or to direct the disposition: See Item 8 of the attached cover pages. ITEM 5. OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS Not Applicable. ITEM 6. OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON Philip B. Korsant shares voting and dispositive power over the shares of Common Stock that he beneficially owns with ZAM, the owner of record of the shares of Common Stock. PBK also shares voting and dispositive power over the shares of Common Stock that it beneficially owns with ZAM. ITEM 7. IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY Not Applicable. ITEM 8. IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP Not Applicable. ITEM 9. NOTICE OF DISSOLUTION OF GROUP Not Applicable. ITEM 10. CERTIFICATION By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

SIGNATURE After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct. Dated: February 25, 2005 ZIFF ASSET MANAGEMENT, L.P. By: PBK Holdings, Inc., its general partner By: /s/ DAVID GRAY ------------------------------------ Name: David Gray Title: Vice President PBK HOLDINGS, INC. By: /s/ DAVID GRAY ------------------------------------ Name: David Gray Title: Vice President /s/ PHILIP B. KORSANT --------------------------------------- Philip B. Korsant

EXHIBIT A The undersigned, Ziff Asset Management, L.P., a Delaware limited partnership, PBK Holdings, Inc., a Delaware corporation, and Philip B. Korsant, hereby agree and acknowledge that the information required by this Schedule 13G, to which this Agreement is attached as an exhibit, is filed on behalf of each of them. The undersigned further agree that any further amendments or supplements thereto shall also be filed on behalf of each of them. Dated: February 25, 2005 ZIFF ASSET MANAGEMENT, L.P. By: PBK Holdings, Inc., its general partner By: /s/ DAVID GRAY ------------------------------------ Name: David Gray Title: Vice President PBK HOLDINGS, INC. By: /s/ DAVID GRAY ------------------------------------ Name: David Gray Title: Vice President /s/ PHILIP B. KORSANT --------------------------------------- Philip B. Korsant