<PAGE>
OFFER TO EXCHANGE EACH OUTSTANDING AMERICAN DEPOSITARY SHARE
(EACH AMERICAN DEPOSITARY SHARE REPRESENTS 68 SHARES OF COMMON STOCK)
OF
GENER S.A.
FOR SHARES OF COMMON STOCK OF THE AES CORPORATION
HAVING A VALUE OF $16
BY
MERCURY CAYMAN CO. III, LTD.
A WHOLLY OWNED SUBSIDIARY OF
THE AES CORPORATION
THE U.S. OFFER AND THE WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT, NEW
YORK CITY TIME, ON MONDAY, DECEMBER 11, 2000, UNLESS EXTENDED. GENER AMERICAN
DEPOSITARY SHARES TENDERED PURSUANT TO THE U.S. OFFER MAY BE WITHDRAWN AT ANY
TIME PRIOR TO THE EXPIRATION OF THE U.S. OFFER.
November 9, 2000
To Our Clients:
Enclosed for your consideration are the preliminary Prospectus, dated
November 9, 2000 (the "Prospectus"), and the related ADS Letter of Transmittal
(which together with any amendments or supplements thereto constitute the "U.S.
Offer") relating to the offer by Mercury Cayman Co. III, Ltd. (the
"Purchaser"), a limited company organized under the laws of the Cayman Islands
and a wholly owned subsidiary of The AES Corporation ("AES"), to exchange a
fraction of a share of AES common stock having a value of $16 for each American
Depositary Share (each, an "ADS") of Gener S.A., a corporation organized under
the laws of the Republic of Chile ("Gener"), upon the terms and subject to the
conditions set forth in the Prospectus dated November 9, 2000. Holders of ADSs
whose ADSs are not immediately available or who cannot deliver their American
Depositary Receipts ("ADRs") and all other required documents to ChaseMellon
Shareholder Services, L.L.C., as exchange agent (the "Exchange Agent"), or
complete the procedures for book-entry transfer prior to the expiration date
(as defined in the Prospectus), must tender their ADSs according to the
Guaranteed Delivery Procedures set forth under the section "OUR
OFFER--Procedure for Accepting Our Offer" of the Prospectus.
THIS MATERIAL IS BEING FORWARDED TO YOU AS THE BENEFICIAL OWNER OF ADSs
HELD BY US FOR YOUR ACCOUNT BUT NOT REGISTERED IN YOUR NAME. WE ARE (DIRECTLY
OR INDIRECTLY) THE HOLDER OF RECORD OF ADSs HELD BY US FOR YOUR ACCOUNT. A
TENDER OF SUCH ADSs CAN BE MADE ONLY BY US AS THE HOLDER OF RECORD AND PURSUANT
TO YOUR INSTRUCTIONS. THE ADS LETTER OF TRANSMITTAL IS FURNISHED TO YOU FOR
YOUR INFORMATION ONLY AND CANNOT BE USED BY YOU TO TENDER YOUR ADSs HELD BY US
FOR YOUR ACCOUNT.
Accordingly, we request instruction as to whether you wish to have us
tender on your behalf any or all ADSs held by us for your account pursuant to
the terms and conditions set forth in the U.S. Offer.
SHARES OF COMMON STOCK, NO PAR VALUE, OF GENER ("SHARES"), EXCEPT INSOFAR
AS THEY ARE REPRESENTED BY ADSs, CANNOT BE TENDERED BY MEANS OF THE ADS LETTER
OF TRANSMITTAL. SHARES CANNOT BE TENDERED PURSUANT TO THE U.S. OFFER AND CAN
ONLY BE TENDERED PURSUANT TO AES'S CONCURRENT CHILEAN OFFER. ADDITIONAL
INFORMATION ON THE CHILEAN OFFER MAY BE OBTAINED FROM DEUTSCHE SECURITIES
CORREDORES DE BOLSA LIMITADA, THE DEALER MANAGER FOR THE CHILEAN OFFER. PLEASE
NOTE, HOWEVER, THAT DOCUMENTATION ON THE CHILEAN OFFER WILL NOT BE AVAILABLE IN
ENGLISH.
<PAGE>
PLEASE NOTE THE FOLLOWING:
1. The consideration per ADS is a fraction of an AES share having a
value of $16. THE U.S. OFFER IS OPEN TO ALL HOLDERS OF ADSs OF GENER.
2. The U.S. Offer is being made for any and all outstanding ADSs of
Gener. The fraction of an AES share into which each ADS of Gener will
be exchanged in the U.S. Offer will be determined by dividing $16 by
the average of the high and low selling prices per share of AES
common stock on the New York Stock Exchange, as reported on the New
York Stock Exchange Composite Transaction Tape, for each of the ten
New York Stock Exchange trading days ending on the second New York
Stock Exchange trading day immediately prior to the date on which the
U.S. Offer expires.
3. Tendering holders will not be obligated to pay transfer taxes, except
as set forth in Instruction 6 of the ADS Letter of Transmittal, on
the transfer of ADSs pursuant to the U.S. Offer. However, U.S.
federal income tax backup withholding at a rate of 31% may be
required, unless the required taxpayer identification information is
provided. See Instruction 11 of the ADS Letter of Transmittal.
4. The U.S. Offer and withdrawal rights will expire at 12:00 midnight,
New York City time, on Monday, December 11, 2000, unless the U.S.
Offer is extended.
5. As of the date hereof, the Board of Directors of Gener has not
reviewed or taken a position with respect to the U.S. Offer.
6. Notwithstanding any other provision of the U.S. Offer, exchange of a
fraction of an AES share having a value of $16 for each ADS pursuant
to the U.S. Offer will, in all cases, be made only after timely
receipt by the Exchange Agent of (a) ADRs, as appropriate pursuant to
the procedures set forth under the section "OUR OFFER--Procedure for
Accepting Our Offer" of the Prospectus, or a timely book-entry
confirmation with respect to such ADSs, (b) the ADS Letter of
Transmittal (or facsimile thereof), properly completed and duly
executed, with any required signature guarantees or an Agent's
Message (as defined in the Prospectus) in connection with a
book-entry transfer, and (c) any other documents required by the ADS
Letter of Transmittal.
7. The Purchaser's obligation to exchange ADSs for AES shares is subject
to a number of conditions, including (i) Gener shareholder approval
at a Gener shareholders' meeting of the amendments to Gener's Bylaws
and the effectiveness under Chilean law of such amendments, (ii) AES
being satisfied, in its sole discretion, that the proposed Gener
transaction with TotalFinaElf has been terminated and will not
proceed, (iii) AES having purchased Gener shares in the Chilean
Offer, (iv) that the per share selling price of AES common stock on
the New York Stock Exchange on any New York Stock Exchange trading
day between the date of the U.S. Offer and the expiration of the U.S.
Offer, including any extensions thereof, not having been less than
$50, and (v) other customary terms and conditions described under the
section "OUR OFFER--Conditions of Our Offer."
The U.S. Offer is made solely by the Prospectus, and the related ADS
Letter of Transmittal and the ADS Notice of Guaranteed Delivery. The Purchaser
is not aware of any jurisdiction where the making of the U.S. Offer is
prohibited by administrative or judicial action pursuant to any valid state
statute. If the Purchaser becomes aware of any valid state statute prohibiting
the making of the U.S. Offer or the acceptance of ADSs pursuant thereto, the
Purchaser will make a good faith effort to comply with such state statute. If,
after such good faith effort, the Purchaser cannot comply with such state
statute, the U.S. Offer will not be made to, nor will tenders be accepted from
or on behalf of, the holders of ADSs in such state. In any jurisdiction where
the securities, blue sky or other laws require the U.S. Offer to be made by a
licensed broker or dealer, the U.S. Offer shall be deemed to be made on behalf
of the Purchaser by Deutsche Bank Securities Inc., the Dealer Manager, or one
or more registered brokers or dealers licensed under the laws of such
jurisdiction.
If you wish to have us tender any or all of the ADSs held by us for your
account, please so instruct us by completing, executing, detaching and
returning to us the instruction form set forth herein. If you authorize the
tender of your ADSs, all such ADSs will be tendered unless otherwise specified
below. An envelope to return your instructions to us is enclosed. YOUR
INSTRUCTIONS SHOULD BE FORWARDED TO US IN AMPLE TIME TO PERMIT US TO SUBMIT A
TENDER ON YOUR BEHALF PRIOR TO THE EXPIRATION DATE.
2
<PAGE>
INSTRUCTIONS WITH RESPECT TO THE
OFFER TO EXCHANGE EACH OUTSTANDING AMERICAN DEPOSITARY SHARE
(EACH AMERICAN DEPOSITARY SHARE REPRESENTS 68 SHARES OF COMMON STOCK)
OF
GENER S.A.
FOR SHARES OF THE AES CORPORATION COMMON STOCK
HAVING A VALUE OF $16
BY
MERCURY CAYMAN CO. III, LTD.
A WHOLLY OWNED SUBSIDIARY OF
THE AES CORPORATION
The undersigned acknowledge(s) receipt of your letter and the Prospectus
dated November 9, 2000, and the related ADS Letter of Transmittal, and Notice
of Guaranteed Delivery in connection with the U.S. Offer by Purchaser to
exchange a fraction of an AES share having a value of $16 for each outstanding
ADSs of Gener pursuant to the terms and subject to the conditions set forth in
the Prospectus.
This will instruct you to tender the number of Gener ADSs indicated below
(or if no number is indicated below, all Gener ADSs) held by you for the
account of the undersigned, upon the terms and subject to the conditions set
forth in the Prospectus and the related ADS Letter of Transmittal.
Dated: November 9, 2000
Acct #: ----------------------- SIGN HERE
Number of Gener ADSs to be Tendered*:
---------------------- ----------------------
Signature(s)
----------------------
Please Print
----------------------
Address
Dated:
---------------------- -----------------------------
Area Code and Telephone #
--------------------------------
Tax ID or Social Security #
* Unless otherwise indicated, it will be assumed that all your
Gener ADSs are to be tendered
PLEASE RETURN THIS FORM TO THE
BROKERAGE FIRM MAINTAINING YOUR ACCOUNT
3
