Securities and Exchange Commission
                             Washington, D. C. 20549

                                  Schedule 13G
                    Under the Securities Exchange Act of 1934
                                (Amendment No. 4)

                                 AES Corporation
                                  Common Stock
                             CUSIP Number 00130H105

Date of Event Which Requires Filing of this Statement:     December 31, 2003

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

         [ X   ]  Rule 13d-1(b)
         [     ]  Rule 13d-1(c)
         [     ]  Rule 13d-1(d)
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

CUSIP No. 00130H105

         1)     Name of reporting person:
                  Legg Mason, Inc.
                Tax Identification No.:
                  52-1200960

         2)     Check the appropriate box if a member of a group:
                  a)     n/a
                  b)     n/a

         3)     SEC use only

         4)     Place of organization:
                  Maryland

Number of shares beneficially owned:  *

         *Beneficial ownership of the issuer's securities is no longer
attributed to Legg Mason, Inc. as parent company and is now reported directly by
its investment adviser subsidiaries.   See Item 4 for more details.

         5)     Sole voting power:          - 0 -
         6)     Shared voting power:        - 0 -
         7)     Sole dispositive power:     - 0 -
         8)     Shared dispositive power:   - 0 -

         9)     Aggregate amount beneficially owned by each reporting person:
                  - 0 -

         10)    Check if the aggregate amount in row (9) excludes certain shares
                  n/a

         11)    Percent of class represented by amount in row (9):
                  0%

         12)    Type of reporting person:
                  HC, CO

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
         Item 1a)     Name of issuer:
                           AES Corporation

         Item 1b)     Address of issuer's principal executive offices:
                           1001 N. 19th Street
                           Arlington, VA  22209

         Item 2a)    Name of person filing:
                           Legg Mason, Inc.

         Item 2b)    Address of  principal business office:
                           100 Light Street
                           Baltimore, MD  21202

         Item 2c)    Citizenship:
                           Maryland Corporation

         Item 2d)    Title of class of securities:
                           Common Stock

         Item 2e)    CUSIP number:     00130H105

         Item 3)  If this statement is filed pursuant to Rule 13d-1(b), or
                  13d-2(b), check whether the person filing is a:
         (a)[ ] Broker or dealer under Section 15 of the Act.
         (b)[ ] Bank as defined in Section 3(a) (6) of the Act.
         (c)[ ] Insurance Company as defined in Section 3(a) (6) of the Act.
         (d)[ ] Investment Company registered under Section 8 of the Investment
                       Company Act.
         (e)[ ] Investment Adviser registered under Section 203 of the
                       Investment Advisers Act of 1940.
         (f)[ ] Employee Benefit Plan, Pension Fund which is subject to ERISA
                           of 1974 or Endowment Fund; see 240.13d-1(b)(ii)(F).
         (g)[X] Parent holding company, in accordance with 240.13d-1(b)(ii)(G).
         (h)[ ] Group, in accordance with 240.13d-1(b)(1)(ii)(H).

         Item 4)    Ownership:

         (a)     Amount beneficially owned:              - 0 - *

                  *In accordance with Exchange Act Release No. 39538, the
                  investment adviser subsidiaries of Legg Mason, Inc. have
                  established informational barriers and therefore beneficial
                  ownership of the issuer's securities is no longer attributed
                  to Legg Mason, Inc. as parent company.

                  The investment adviser subsidiaries with beneficial ownership
                  of 5% or more of the issuer's securities have filed a
                  separate Schedule 13G that discloses their beneficial
                  ownership as of December 31, 2003.  See Schedule 13G filing
                  by Legg Mason Funds Management, Inc.

         (b)     Percent of Class:  0%

         (c)     Number of shares as to which such person has:
                  (i)    sole power to vote or to direct the vote:
                                    -  0 -
                  (ii)   shared power to vote or to direct the vote:
                                    - 0 -
                  (iii)  sole power to dispose or to direct the disposition of:
                                    - 0 -
                  (iv)   shared power to dispose or to direct the disposition of
                                    - 0 -

         Item 5)    Ownership of Five Percent or less of a class:
                           n/a

         Item 6)    Ownership of more than Five Percent on behalf of another
                    person:
                           n/a

         Item 7)    Identification and classification of the subsidiary which
                    acquired the security being reported on by the parent
                    holding company:
                           n/a

         Item 8)    Identification and classification of members of the group:
                           n/a

         Item 9)    Notice of dissolution of group:
                           n/a

         Item 10)   Certification:

                  By signing below I certify that, to the best of my knowledge
                  and belief, the securities referred to above were acquired and
                  held in the ordinary course of business and were not acquired
                  and 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 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.

         -------------------------------
         Date - February 13, 2004

         Legg Mason, Inc.


         By   ____________________________________________________
                   Peter L. Bain, Executive Vice President