SC TO-T/A

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549


                                  SCHEDULE TO/A
                                 (Rule 14d-100)
        TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR SECTION 13(e)(1)
                     OF THE SECURITIES EXCHANGE ACT OF 1934
                                (Amendment No. 5)


                                   GENER S.A.
                       (Name of Subject Company (Issuer))


                               THE AES CORPORATION
                          MERCURY CAYMAN CO. III, LTD.
                       (Name of Filing Persons (Offerors))


             American Depositary Shares (each representing 68 shares
                         of Common Stock, no par value)
                         (Title of Class of Securities)


                                    368731105
                      (CUSIP Number of Class of Securities)


                                 BARRY J. SHARP
                SENIOR VICE PRESIDENT AND CHIEF FINANCIAL OFFICER
                               THE AES CORPORATION
                             1001 NORTH 19th STREET
                            ARLINGTON, VIRGINIA 22209

                  (Name, Address and Telephone Number of Person
  Authorized to Receive Notices and Communications on Behalf of Filing Persons)



                                    Copy to:
                             Michael E. Gizang, Esq.
                    Skadden, Arps, Slate, Meagher & Flom LLP
                                Four Times Square
                            New York, New York 10036
                            Telephone: (212) 735-3000



                            CALCULATION OF FILING FEE

              TRANSACTION VALUATION*         AMOUNT OF FILING FEE**
              $181,634,952.00                $36,327.00



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*Estimated for purposes of calculating the amount of the filing fee only in
accordance with Rules 0-11(d) and 0-11(a)(4) under the Securities Exchange Act
of 1934, based upon (a) $12.25, the average of the high and low price per Gener
American Depositary Share on November 2, 2000, as reported on the New York Stock
Exchange Composite Transaction Tape, multiplied by (b) 14,827,343, representing
the aggregate number of Gener American Depositary Shares outstanding on
September 30, 2000.

**One-fiftieth of 1% of the value of the transaction.

[x] Check the box if any part of the fee is offset as provided by Rule
0-11(a)(2) and identify the filing with which the offsetting fee was previously
paid. Identify the previous filing by registration statement number, or the Form
or Schedule and the date of its filing.

         Amount Previously Paid: $36,327.00
         Form or Registration No.:  Registration Statement on Form S-4
         Filing Party: The AES Corporation
         Date Filed: November 9, 2000

[ ] Check the box if the filing relates solely to preliminary communications
made before the commencement of a tender offer.

Check the appropriate boxes below to designate any transactions to which the
statement relates:

[x] third-party tender offer subject to Rule 14d-1.
[ ] issuer tender offer subject to Rule 13e-4.
[ ] going-private transaction subject to Rule 13e-3.
[ ] amendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting the results
of the tender offer: [ ]

     This Amendment No. 5 amends and supplements the Tender Offer Statement on
Schedule TO initially filed on November 9, 2000 (the "Schedule TO") by Mercury
Cayman Co. III, Ltd., a limited company organized under the laws of the Cayman
Islands (the "Purchaser") and a wholly owned subsidiary of The AES Corporation,
a Delaware corporation ("AES"), relating to the offer by the Purchaser to
exchange each issued and outstanding American Depositary Share (each, an "ADS"
and collectively, "ADSs") of Gener S.A. ("Gener"), each representing 68 shares
of Gener common stock, no par value (the "Shares"), for a fraction of a share of
common stock, par value $ 0.01 per share, of AES (the "AES Shares"), on the
terms and subject to the conditions described in the Prospectus (as defined
below), and the related ADS Letter of Transmittal (collectively referred to as
the "Offer").

     On December 7, 2000, AES filed Amendment No. 1 to its registration
statement on Form S-4 with the Securities and Exchange Commission relating to
the AES Shares to be issued to holders of Gener ADSs in the Offer (the
"Registration Statement"). The terms and conditions of the Offer are set forth
in the preliminary prospectus dated December 7, 2000, which is a part of the
Registration Statement (the "Prospectus"), and the related Letter of
Transmittal, which are annexed to the Schedule TO as Exhibits (a)(13) and
(a)(2), respectively.

     All of the information in the Prospectus and the related ADS Letter of
Transmittal, and any prospectus supplement or other supplement or amendment
thereto related to the Offer hereafter filed with the Securities and Exchange
Commission by AES, is hereby incorporated by reference in answer to Items 2
through 11 of this Schedule TO.

Item 11. Additional Information.

     Item 11 of the Schedule TO is hereby amended and supplemented as follows:

     On December 8, 2000, AES issued a press release announcing that it was
extending the expiration date of the offer until 12:00 midnight on Tuesday,
December 12, 2000. A copy of the press release is filed herewith as Exhibit
(a)(14) and the information set forth in the press release is incorporated
herein by reference.


Item 12. Exhibits.

     Item 12 is hereby amended and supplemented to add the following exhibit:

(a)(14)        Press release dated December 8, 2000.

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                                    SIGNATURE

     After due inquiry and to the best of my knowledge and belief, we certify
that the information set forth in this statement is true, complete and correct.


                                                 Mercury Cayman Co. III, Ltd.
                                                 By: /s/ Naveed Ismail
                                                 Name: Naveed Ismail
                                                 Title: President
                                                 Dated: December 8, 2000

                                                 The AES Corporation
                                                 By: /s/ Paul T. Hanrahan
                                                 Name: Paul T. Hanrahan
                                                 Title: Senior Vice President
                                                 Dated: December 8, 2000


                                  EXHIBIT INDEX

EXHIBIT                                                   EXHIBIT NAME
 NUMBER

(a)(1)    Prospectus relating to AES Shares to be issued in the U.S. Offer
          (incorporated by reference from The AES Corporation Registration
          Statement on Form S-4 filed on November 9, 2000).*

(a)(2)    Form of ADS Letter of Transmittal (incorporated by reference to
          Exhibit 99.1 to The AES Corporation Registration Statement on Form S-4
          filed on November 9, 2000).*

(a)(3)    Form of Notice of Guaranteed Delivery (incorporated by reference to
          Exhibit 99.2 to The AES Corporation Registration Statement on Form S-4
          filed on November 9, 2000).*

(a)(4)    Form of Letter to Brokers, Dealers, Commercial Banks, Trust Companies
          and Other Nominees (incorporated by reference to Exhibit 99.3 to The
          AES Corporation Registration Statement on Form S-4 filed on November
          9, 2000).*

(a)(5)    Form of Letter to Clients for use by Brokers, Dealers, Commercial
          Banks, Trust Companies and Other Nominees (incorporated by reference
          to Exhibit 99.4 to The AES Corporation Registration Statement on Form
          S-4 filed on November 9, 2000).*

(a)(6)    Guidelines for Certification of Taxpayer Identification Number on
          Substitute Form W-9 (incorporated by reference to Exhibit 99.5 to The
          AES Corporation Registration Statement on Form S-4 filed on November
          9, 2000).*

(a)(7)    Summary Advertisement scheduled for publication in The Wall Street
          Journal on November 13, 2000 (incorporated by reference to Exhibit
          99.6 to The AES Corporation Registration Statement on Form S-4 filed
          on November 9, 2000).*

(a)(8)    Press Release issued by AES on November 3, 2000 (incorporated by
          reference to Exhibit 99.7 to The AES Corporation Registration
          Statement on Form S-4 filed on November 9, 2000).*

(b)       None.

(d)       Letter Agreement between AES and Compania de Petroleos de Chile S.A.,
          dated November 3, 2000.*

(g)       None.

(h)       None.

(a)(9)    Press release dated November 22, 2000.*

(a)(10)   Press release dated November 28, 2000.*

(a)(11)   Agreement, dated as of November 28, 2000, between AES, TotalFinaElf,
          and Total Gas and Power Ventures.*

(a)(12)   Press release dated December 7, 2000.*

(a)(13)   Preliminary Prospectus, dated December 7, 2000, relating to AES Shares
          to be issued in Offer (incorporated by reference from Amendment No. 1
          to AES's Registration Statement on S-4 filed on December 7, 2000).*

(a)(14)   Press release dated December 8, 2000.

* Previously filed.


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EX-99.(A)(14)

                                [AES LETTERHEAD]

FOR IMMEDIATE RELEASE

                                                   Contact: Kenneth R. Woodcock
                                                            (703) 522-1315

                   AES EXTENDS GENER OFFER PENDING SHAREHOLDER
                                 MEETING RESULTS

ARLINGTON VA, DECEMBER 8, 2000 - The AES Corporation (NYSE: AES) announced today
that it had extended until 12:00 midnight on Tuesday, December 12, 2000, the
expiration date of its offer to exchange all Gener American Depositary Shares
pending the outcome of the vote of Gener shareholders. As previously announced,
Gener shareholders are scheduled to vote on December 12th on an amendment to
Gener's Bylaws to eliminate the provisions that limit the number of shares that
may be owned or voted by any shareholder or related person. The amendment of
Gener's Bylaws is a condition of AES's offers to exchange Gener's ADSs and to
purchase Gener's shares. As of the close of business on December 7, 2000,
732,937 ADSs had been tendered and not withdrawn pursuant to the exchange offer.
Except as modified by this extension, the terms and conditions of the exchange
offer and AES's concurrent Chilean offer remain in effect and unmodified.

AES is a leading global power company comprised of competitive generation,
distribution and retail supply businesses in Argentina, Australia, Bangladesh,
Brazil, Canada, China, Dominican Republic, El Salvador, Georgia, Hungary, India,
Kazakhstan, the Netherlands, Mexico, Pakistan, Panama, Sri Lanka, the United
Kingdom, the United States and Venezuela.

The company's generating assets include interests in one hundred thirty-nine
facilities totaling over 49 gigawatts of capacity. AES's electricity
distribution network has over 920,000 km of conductor and associated rights of
way and sells over 126,000 gigawatt hours per year to over 17 million
end-use consumers. In addition, through its various retail electricity supply
businesses, the company sells electricity to over 154,000 end-use customers.

AES is dedicated to providing electricity worldwide in a socially responsible
way.

                                    * * * * *



For more general information visit our web site at www.aesc.com or contact
investor relations at investing@aesc.com. The list aes-pr-announce is an
automated mailing list and can be found on the investing page of our web site.
Those who subscribe to this list will receive updates when AES issues a press
release.


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