<Page>


                                                                    Exhibit 10.4


                         AMENDMENT TO EXCHANGE AGREEMENT


         This AMENDMENT TO EXCHANGE AGREEMENT (this "Amendment") dated as of
November 19, 2001 is by and between Enron Corp., an Oregon corporation
("Enron"), and Dynegy Inc., an Illinois corporation ("Dynegy").

                                    RECITALS

         A.       On November 9, 2001, Enron and Dynegy entered into an Exchange
Agreement (the "Exchange Agreement").

         B.       The parties to the Exchange Agreement now desire to amend the
Exchange Agreement as specified below.

         NOW THEREFORE, in consideration of the mutual agreements herein
contained and other good and valuable consideration, the sufficiency of which is
hereby acknowledged, the parties hereby agree as follows:

         1.       Section 5.3. of the Exchange Agreement is hereby amended in
its entirety to provide as follows:

                  5.3.     LISTING APPLICATION.

                           (a) Enron shall promptly prepare and submit to the
         New York Stock Exchange ("NYSE") a listing application covering the
         shares of Enron Common Stock issuable pursuant to the exercise of the
         Enron Exchange Option and the Dynegy Exchange Option and shall use
         commercially reasonable best efforts to obtain, prior to the exercise
         of the Enron Exchange Option or the Dynegy Exchange Option, approval
         for the listing of such shares of Enron Common Stock on the NYSE,
         subject to official notice of issuance.

                           (b) If required pursuant to the rules of the New York
         Stock Exchange, Enron shall take all action necessary, in accordance
         with applicable law and its articles of incorporation and bylaws, to
         convene a meeting of its shareholders as promptly as practicable to
         consider and vote upon the issuance of the shares of Enron Common Stock
         pursuant to the exercise of the Enron Exchange Option and the Dynegy
         Exchange Option. Enron shall recommend approval of such matters and use
         its commercially reasonable best efforts to solicit from its
         shareholders proxies in favor of such matters.

         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
signed by their respective officers thereunto duly authorized, all as of the day
and year first written above.

<Page>



                                     ENRON CORP.,
                                     an Oregon corporation

                                     By:       /s/ Raymond M. Bowen, Jr.
                                               ---------------------------------
                                               Name: Raymond M. Bowen, Jr.
                                               Title:  Authorized Agent



                                     DYNEGY INC.,
                                     an Illinois corporation

                                     By:       /s/ Hugh A. Tarpley
                                               ---------------------------------
                                               Name: Hugh A Tarpley
                                               Title:  Authorized Agent

















                                       2