Filed pursuant to Rule No. 424(b)(3)
                                                  Registration Number 333-115148


                           PROSPECTUS SUPPLEMENT NO. 4

                                   DYNEGY INC.

                                  $225,000,000

               4.75% CONVERTIBLE SUBORDINATED DEBENTURES DUE 2023
                   AND SHARES OF CLASS A COMMON STOCK ISSUABLE
                        UPON CONVERSION OF THE DEBENTURES

                              DYNEGY HOLDINGS INC.

         GUARANTEE OF 4.75% CONVERTIBLE SUBORDINATED DEBENTURES DUE 2023

         This prospectus supplement supplements the prospectus, dated August 2,
2004, of Dynegy Inc., relating to the sale by certain of our securityholders
(including their pledgees, donees, assignees, transferees, successors and others
who later hold any of the securityholders' interests) of, among other things, up
to $225,000,000 aggregate principal amount of our 4.75% Convertible Subordinated
Debentures due 2023 and the shares of Class A common stock issuable upon
conversion of the debentures. You should read this prospectus supplement in
conjunction with the prospectus, and this prospectus supplement is qualified by
reference to the prospectus, except to the extent that the information in this
prospectus supplement supersedes the information contained in the prospectus.

         The table of selling securityholders contained in the prospectus is
hereby modified to add the following:



                                                   PRINCIPAL
                                                   AMOUNT OF
                                                  CONVERTIBLE
                                                  DEBENTURES                                                   PERCENTAGE
                                                 BENEFICIALLY       CLASS A       CLASS A                      OF CLASS A
                                                 OWNED BEFORE        COMMON       COMMON         CLASS A         COMMON
                                                 THE OFFERING     STOCK OWNED      STOCK      COMMON STOCK    STOCK OWNED
                                                 AND THAT MAY      BEFORE THE    THAT MAY      OWNED AFTER     AFTER THE
NAME OF SELLING SECURITY HOLDER                     BE SOLD         OFFERING      BE SOLD     THE OFFERING      OFFERING
--------------------------------------------     ------------     ------------   ---------    -------------   ------------
                                                                                               
Aviator Master Fund.........................      $6,169,000           --        1,496,966         --              --
Aviator Overseas II Fund....................      $  831,000           --          201,650         --              --
UBS AG London Branch........................      $5,000,000           --        1,213,297         --              --


         INVESTING IN THE DEBENTURES OR SHARES OF CLASS A COMMON STOCK INVOLVES
RISKS THAT ARE DESCRIBED IN THE "RISK FACTORS" SECTION BEGINNING ON PAGE 9 OF
THE PROSPECTUS.

         NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES
COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR PASSED UPON THE
ADEQUACY OR ACCURACY OF THIS PROSPECTUS SUPPLEMENT. ANY REPRESENTATION TO THE
CONTRARY IS A CRIMINAL OFFENSE.

          The date of this prospectus supplement is February 28, 2005.