<PAGE>


                                                                     Exhibit 4.5

================================================================================

                        MIRANT AMERICAS GENERATION, INC.

                                       TO

                             BANKERS TRUST COMPANY,
                                     TRUSTEE

                                   ----------

                          FOURTH SUPPLEMENTAL INDENTURE

                           DATED AS OF OCTOBER 9, 2001

                                  TO INDENTURE

                             DATED AS OF MAY 1, 2001

                                   ----------

                                  $300,000,000

                           7.20% SENIOR NOTES DUE 2008

================================================================================

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                              TABLE OF CONTENTS/1/

ARTICLE 1...................................................................1

SECTION 101. Establishment..................................................1
             -------------

SECTION 102. Definitions....................................................2
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SECTION 103. Payment of Principal and Interest..............................6
             ---------------------------------

SECTION 104. Denominations..................................................6
             -------------

SECTION 105. Form of 2008 Notes.............................................6
             ------------------

SECTION 106. Transfer and Exchange..........................................8
             ---------------------

SECTION 107. Legends.......................................................11
             -------

SECTION 108. Redemption....................................................11
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SECTION 109. Limitation on Liens...........................................12
             -------------------

SECTION 110. Limitation on Asset Sales.....................................14
             -------------------------

SECTION 111. Debt Incurrence Test..........................................15
             --------------------

ARTICLE 2..................................................................15

SECTION 201. Recitals by Company...........................................15
             -------------------

SECTION 202. Ratification and Incorporation of Original Indenture..........15
             ----------------------------------------------------

SECTION 203. Executed in Counterparts......................................16
             ------------------------

SECTION 204. GOVERNING LAW.................................................16
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/1/ This Table of Contents does not constitute part of the Indenture or have any
bearing upon the interpretation of any of its terms and provisions.

                                       i

<PAGE>


          THIS FOURTH SUPPLEMENTAL INDENTURE is made as of the 9th day of
October, 2001, between MIRANT AMERICAS GENERATION, INC., a Delaware corporation,
having its principal office at 1155 Perimeter Center West, Atlanta, Georgia
30338 (the "Company"), and BANKERS TRUST COMPANY, a New York banking
corporation, having its principal corporate trust office at Four Albany Street,
New York, New York 10006, as trustee (the "Trustee").

                              W I T N E S S E T H:

          WHEREAS, the Company has heretofore entered into an Indenture, dated
as of May 1, 2001 (the "Original Indenture"), with Bankers Trust Company, as
trustee;

          WHEREAS, the Original Indenture is incorporated herein by this
reference and the Original Indenture, as supplemented by this Fourth
Supplemental Indenture, is herein called the "Indenture";

          WHEREAS, under the Original Indenture, a new series of Senior Notes
may at any time be established by the Board of Directors of the Company in
accordance with the provisions of the Original Indenture and the terms of such
series may be described by a supplemental indenture executed by the Company and
the Trustee;

          WHEREAS, the Company proposes to create under the Indenture a new
series of Senior Notes which shall contain certain transfer restrictions as
described herein and a new series of Senior Notes which shall not contain such
transfer restrictions;

          WHEREAS, the Company may propose an exchange offer whereby the holders
of such restricted Senior Notes may exchange such securities for nonrestricted
Senior Notes in accordance with the procedures described herein; and

          WHEREAS, all conditions necessary to authorize the execution and
delivery of this Fourth Supplemental Indenture and to make it a valid and
binding obligation of the Company have been done or performed.

          NOW, THEREFORE, in consideration of the agreements and obligations set
forth herein and for other good and valuable consideration, the sufficiency of
which is hereby acknowledged, the parties hereto hereby agree as follows:

                                    ARTICLE 1

                           7.20% Senior Notes Due 2008

     SECTION 101. Establishment. There is hereby established a new series of
                  -------------
Senior Notes to be issued under the Indenture, to be designated as the Company's
7.20% Senior Notes due 2008 (the "Initial 2008 Notes"), and a new series of
Senior Notes to be issued under the Indenture upon exchange of the Initial 2008
Notes to be designated as the Company's 7.20% Exchange Senior

<PAGE>

Notes due 2008 (the "Exchange 2008 Notes", and, collectively, with the Initial
2008 Notes, the "2008 Notes").

     There are to be authenticated and delivered $300,000,000 principal amount
of Initial 2008 Notes and $300,000,000 principal amount of Exchange 2008 Notes,
and such principal amount of 2008 Notes may be increased from time to time
pursuant to Section 301 of the Original Indenture. All 2008 Notes need not be
issued at the same time and such series may be reopened at any time, without the
consent of any Holder, for issuances of additional 2008 Notes. Any such
additional 2008 Notes will have the same interest rate, maturity and other terms
as those initially issued. No 2008 Notes shall be authenticated and delivered in
excess of the principal amount as so increased, except as provided by Sections
203, 303, 304, 907 or 1107 of the Original Indenture. The 2008 Notes shall be
issued in definitive fully registered form.

     The form of the Trustee's Certificate of Authentication for the 2008 Notes
shall be in substantially the form set forth in Exhibit B hereto.

     Each 2008 Note shall be dated the date of authentication thereof and shall
bear interest from the date of original issuance thereof or from the most recent
Interest Payment Date to which interest has been paid or duly provided for.

     SECTION 102. Definitions. The following defined terms used herein shall,
                  -----------
unless the context otherwise requires, have the meanings specified below.
Capitalized terms used herein for which no definition is provided herein shall
have the meanings set forth in the Original Indenture.

     "Accredited Investor Note" shall have the meaning set forth in Section
105(c) hereof.

     "Asset Sale" means any sale, lease, sale-leaseback, transfer, conveyance or
other disposition of any assets, including by way of the issue by the Company or
any of the Company's Subsidiaries of equity interests in such Subsidiaries,
except (i) in the ordinary course of business to the extent that such property
is (A) worn out or is no longer useful or necessary in connection with the
operation of our business inventory or (B) being transferred to a wholly-owned
Subsidiary of the Company, and except (ii) for any new generating and any
expansions or repowerings of existing generating assets, (A) in each case the
construction of which is completed after the date of the issuance of the 2008
Notes and all assets and property that are related, ancillary or incidental to
such new, expanded or repowered generating assets, and (B) such assets are
disposed of within 24 months following successful completion of construction of
the new generating asset, expansion or repowering to which such assets relate.

     "Cash Flow Available for Senior Debt Service" for any period means, without
duplication, (i) EBITDA of the Company and the Company's consolidated
Subsidiaries for such period, minus (ii) EBITDA for such period of the
consolidated Subsidiaries, if any, of the Company that are financed with
Indebtedness that does not constitute Indebtedness of the Company, plus (iii)
distributions received by the Company from Subsidiaries described in the
foregoing clause (ii) during such period, minus (iv) distributions described in
the foregoing clause (iii) that are attributable to extraordinary gains included
in EBITDA, minus (v) any income reported by the

                                       2

<PAGE>

Company for such period for persons that are not consolidated Subsidiaries of
the Company that are financed with Indebtedness that does not constitute
Indebtedness of the Company, plus (vi) distributions received by the Company
from persons described in the foregoing clause (v) during such period, minus
(vii) distributions described in the foregoing clause (vi) that are attributable
to extraordinary gains included in EBITDA, minus (vii) reasonably projected
non-discretionary capital expenditures, net of any capital contributions and
proceeds of debt financing available for capital expenditures.

     "Clearstream" shall have the meaning set forth in Section 105(b) hereof.

     "Consolidated Net Assets" means, (at any date of determination) the total
of all assets (including acquisition premiums paid, but excluding reevaluations
thereof as a result of commercial appraisals, price level restatement or asset
write-ups/write-downs in conformance with GAAP or otherwise) appearing on the
Company's consolidated balance sheet, net of applicable reserves and deductions,
less the aggregate of the Company's consolidated current liabilities appearing
on such balance sheet.

     "Depositary" shall have the meaning set forth in Section 101 of the
Original Indenture.

     "Distribution Compliance Period" means the distribution compliance period
provided by Rule 903(b)(3)(ii)(A) as promulgated by the SEC under the Securities
Act.

     "Euroclear" shall have the meaning set forth in Section 105(b) hereof.

     "EBITDA" means, with respect to any person for any period, the (i) income
(or loss) before interest and taxes of such person, plus (ii) to the extent
deducted in determining such income (or loss), depreciation, amortization and
other similar non-cash charges and reserves, minus (iii) to the extent
recognized in determining such income (or loss), extraordinary gains (or
losses), minus (iv) to the extent recognized in determining such income (or
loss), unrealized gains (or losses) arising from the adoption of SFAS No. 133,
"Accounting for Derivative Instruments and Hedging Activities" or follow-up
revisions thereto, plus (v) to the extent deducted in determining such income
(or loss), payment in the nature of interest under lease obligations of the type
referred to in clause (iv) of the definition of Indebtedness.

     "Exchange Offer" means the offer that may be made pursuant to the
Registration Rights Agreement by the Company to exchange the Initial 2008 Notes
for the Exchange 2008 Notes.

     "GAAP" means U.S. generally accepted accounting principles.

     "Holder" means a registered holder of a 2008 Note.

     "Indebtedness" of any Person means (i) all indebtedness of such Person for
borrowed money, (ii) all obligations of such Person evidenced by bonds,
debentures, notes or other similar instruments, (iii) all indebtedness created
or arising under any conditional sale or other title retention agreement with
respect to property acquired by such Person, (iv) all capital lease obligations
of such Person (excluding leases of property in the ordinary course of
business), (v) any

                                       3

<PAGE>

other form of financing which is recognized in such Person's financial
statements as being a borrowing, and (vi) all Indebtedness of any other person
of the type referred to in clauses (i) through (v) guaranteed by such Person or
for which such Person shall otherwise become directly or indirectly liable, and
(vii) all Indebtedness of the type referred to in clauses (i) and (v) above
secured by (or for which the holder of such Indebtedness has an existing right,
contingent or otherwise, to be secured by) any lien or interest on property of
such Person but only to the extent of the lesser of the amount of such
Indebtedness and the value of such lien or interest on property.

     "Institutional Accredited Investor" has the meaning set forth in Section
105(c) hereof.

     "Interest Payment Dates" means April 1 and October 1 of each year.

     "Make-Whole Premium" has the meaning set forth in Section 108 hereof.

     "Non-U.S. Person" means a Person who fails to qualify as a U.S. Person, as
such term is defined in Rule 902 promulgated by the SEC under the Securities
Act.

     "Original Issue Date" means October 9, 2001.

     "Permitted Business" means a business that is the same or similar to the
Company's business as of May 1, 2001, or other business reasonably related,
ancillary or incidental thereto.

     "Permitted Indebtedness" means (i) Indebtedness existing on the date of the
2008 Notes, (ii) Indebtedness incurred for working capital purposes, (iii)
Indebtedness in respect of letters of credit, surety bonds or performance bonds
or guarantees issued in the ordinary course of business, (iv) Subordinated
Indebtedness, (v) Indebtedness incurred in exchange, or the net proceeds of
which are used to refund, refinance or replace, Indebtedness permitted to be
incurred pursuant to clause (i) above, provided that the principal amount of the
refinancing Indebtedness shall not exceed the principal amount of the
Indebtedness refinanced plus a reasonable premium in connection with the
refinancing.

     "Person" means any individual, corporation, partnership, limited liability
company, joint venture, association, joint-stock company, trust, unincorporated
organization or government or any agency or political subdivision thereof.

     "Pro Forma Basis" means , for the purpose of the Debt Incurrence Test
described in Section 110 of this Fourth Supplemental Indenture, that such
calculation shall give effect to the incurrence of such Indebtedness, any
associated increases in equity and the application of the proceeds thereof.

     "QIB" has the meaning set forth in Section 105(c) hereof.

     "Rating Agency" means Moody's Investors Service and Standard & Poor's
Ratings Service.

     "Ratings Reaffirmation" means a reaffirmation by a Rating Agency of its
original or then current credit ratings (as applicable) of any of the
Outstanding 2008 Notes, giving effect to the transaction giving rise to such
request for such reaffirmation.

                                       4

<PAGE>

     "Registration Rights Agreement" means the Registration Rights Agreement
dated as of October 9, 2001 among the Company and the Initial Purchasers named
therein.

     "Regular Record Date" means, with respect to each Interest Payment Date,
the close of business on the 15th calendar day preceding such Interest Payment
Date.

     "Regulation S" means Rules 901 through 905 as promulgated by the Securities
and Exchange Commission under the Securities Act of 1933, as amended.

     "Resale Restriction Termination Date" means the period of two years after
the later of the original issue date of an Accredited Investor Note and the last
date on which the Company or any affiliate of the Company was the owner of such
Accredited Investor Note (or any predecessor of such Accredited Investor).

     "Rule 144A" means Rule 144A as promulgated by the SEC under the Securities
Act.

     "SEC" means the Securities and Exchange Commission.

     "Securities Act" means the Securities Act of 1933, as amended.

     "Senior Debt Service" means, with respect to any Person for any period, the
sum, without duplication, of (i) the aggregate amount of interest expense with
respect to Indebtedness for borrowed money of such Person for such period
including (A) the net costs under interest rate hedge agreements, (B) all
capitalized interest, (C) the interest portion of any deferred payment
obligation and (D) payments in the nature of interest under capital lease
obligations of such person scheduled to be paid by such person during such
period (in each case, exclusive of Indebtedness which is by its terms
subordinated in right of payment to any other Indebtedness of such Person), and
(ii) the aggregate amount of all mandatory scheduled payments (whether
designated as payments or prepayments) and sinking fund payments with respect to
principal of any Indebtedness for borrowed money of such Person, including
payments in the nature of principal under lease obligations, but excluding
"bullet," "balloon" or other principal payments at final maturity, in each case
scheduled to be paid by such person during such period (in each case, exclusive
of Indebtedness which is by its terms subordinated in right of payment to any
other Indebtedness of such Person).

     "Senior Debt Service Coverage Ratio" means, for any period, the ratio of
(i) Cash Flow Available for Senior Debt Service for such period to (ii) Senior
Debt Service for such period.

     "Subsidiary" means any corporation or other entity of which sufficient
voting stock or other ownership or economic interests having ordinary voting
power to elect a majority of the board of directors (or equivalent body) are at
the time directly or indirectly held by the Company.

     "Subordinated Indebtedness" means, with respect to any person, Indebtedness
which is subordinated in right of payment to any other indebtedness of that
person.

                                       5

<PAGE>

     SECTION 103. Payment of Principal and Interest. The unpaid principal amount
                  ---------------------------------
of the 2008 Notes shall bear interest at the rate of 7.20% per annum until paid
or duly provided for. Interest shall be paid semi-annually in arrears on each
Interest Payment Date to the Person in whose name the 2008 Notes are registered
on the Regular Record Date for such Interest Payment Date, provided that
interest payable at the Stated Maturity of principal or on a Redemption Date as
provided herein will be paid to the Person to whom principal is payable. Any
such interest that is not so punctually paid or duly provided for will forthwith
cease to be payable to the Holders on such Regular Record Date and may either be
paid to the Person or Persons in whose name the 2008 Notes are registered at the
close of business on a Special Record Date for the payment of such defaulted
interest to be fixed by the Trustee ("Special Record Date"), notice whereof
shall be given to Holders of the 2008 Notes not less than ten days prior to such
Special Record Date, or be paid at any time in any other lawful manner not
inconsistent with the requirements of any securities exchange, if any, on which
the 2008 Notes shall be listed, and upon such notice as may be required by any
such exchange, all as more fully provided in the Original Indenture.

     Payments of interest on the 2008 Notes will include interest accrued to but
excluding the respective Interest Payment Dates. Interest payments for the 2008
Notes shall be computed and paid on the basis of a 360-day year of twelve 30-day
months. In the event that any date on which interest is payable on the 2008
Notes is not a Business Day, then a payment of the interest payable on such date
will be made on the next succeeding day that is a Business Day, except that, if
such Business Day is in the next succeeding calendar year, such payment shall be
made on the immediately preceding Business Day, in each case with the same force
and effect as if made on the date the payment was originally payable.

     Payment of the principal, premium, if any, and interest due at the Stated
Maturity or earlier redemption of the 2008 Notes shall be made upon surrender of
the 2008 Notes at the Corporate Trust Office of the Trustee, in such coin or
currency of the United States of America as at the time of payment is legal
tender for payment of public and private debts. Payments of interest (including
interest on any Interest Payment Date) will be made, subject to such surrender
where applicable, at the option of the Company, (i) by check mailed to the
address of the Person entitled thereto as such address shall appear in the
Security Register or (ii) by wire transfer at such place and to such account at
a banking institution in the United States as may be designated in writing to
the Trustee at least 16 days prior to the date for payment by the Person
entitled thereto.

     SECTION 104. Denominations. The 2008 Notes shall be issued in minimum
                  -------------
denominations of $100,000, or any integral multiple of $1,000 in excess thereof.

     SECTION 105. Form of 2008 Notes
                  ------------------

          (a) 2008 Notes offered and sold in reliance on Rule 144A shall be
represented initially in the form of one or more Global Notes in definitive,
fully registered form, without interest coupons, substantially in the form set
forth in Exhibit A (each such Note, a "Rule 144A Global Note"), deposited with
the Trustee, as custodian for the Depositary, and registered in the name of a
nominee of DTC. The aggregate principal amount of Rule 144A Global Notes may
from time to time be increased or decreased by adjustments made on the records
of the Trustee, as custodian for the Depositary or its nominee, as hereinafter
provided.

                                       6

<PAGE>

          (b) 2008 Notes offered and sold in offshore transactions in reliance
on Regulation S shall be represented in the form of one or more Global Notes in
definitive, fully registered form, without interest coupons, substantially in
the form set forth in Exhibit A (each, a "Regulation S Global Note") deposited
with the Trustee, as custodian for the Depositary, and registered in the name of
a nominee of the Depositary for the respective accounts of the purchasers
thereof (or to such other accounts as they may direct) at Euroclear Bank
S.A./N.V., as operator of the Euroclear System ("Euroclear"), and Clearstream
Banking, societe anonyme ("Clearstream"). Prior to the expiration of the
applicable Distribution Compliance Period, beneficial interests in the
Regulation S Global Notes may be held only through Euroclear or Clearstream, and
any resale or other transfer of such interests to U.S. Persons shall not be
permitted during such period unless such resale or transfer is made pursuant to
Rule 144A, Regulation S or another available exemption from the Securities Act
and in accordance with the certification requirements provided by Section 106.

          (c) 2008 Notes offered and sold to Persons that are institutional
"accredited investors" meeting the requirements of Rule 501(a)(1), (2), (3) or
(7) promulgated by the SEC under the Securities Act (each, an "Institutional
Accredited Investor") that are not a Qualified Institutional Buyer (each, a
"QIB") as defined in Rule 144A, shall be issued in definitive, fully registered
form, without interest coupons, substantially in the form set forth in Exhibit A
(each, an "Accredited Investor Note"), registered in the name of the purchaser
thereof.

     Institutional Accredited Investors that are not QIBs may hold interests in
the Initial 2008 Notes only in definitive form. Any beneficial interest in an
Initial 2008 Note represented by a Global Note that is transferred to an
Institutional Accredited Investor which is not a QIB will be delivered in the
form of a definitive, certificated 2008 Note and will cease to be an interest in
such Global Note. Upon the transfer of a 2008 Note issued in definitive,
certificated form to an Institutional Accredited Investor which is not a QIB to
a QIB or in accordance with Regulation S, such 2008 Note shall be exchanged for
an interest in a Global Note. 2008 Notes issued in definitive, certificated form
to Institutional Accredited Investors who are not QIBs shall not be issued in
bearer form.

          (d) Except under the limited circumstances described below, beneficial
interests in Global Notes shall only be recorded by book-entry and owners of
beneficial interests in Global Notes shall not be entitled to receive physical
delivery of certificates representing the Notes. The Global Notes will not be
issuable in bearer form. Global Notes may not be transferred except by the
Depositary to a nominee of the Depositary or by a nominee of the Depositary to
the Depositary or another nominee of the Depositary or to a successor Depositary
or its nominee.

     Owners of beneficial interests in the Global Notes will not be considered
the Holders thereof for any purpose under the Indenture, and no Global Note
representing a 2008 Note shall be exchangeable, except for another Global Note
of like denomination and tenor to be registered in the name of the Depositary or
its nominee or to a successor Depositary or its nominee. The rights of Holders
of such Global Note shall be exercised only through the Depositary.

     Any beneficial interest in a Global Note that is transferred to a person
who takes delivery in the form of an interest in another Global Note will, upon
transfer, cease to be an interest in such

                                       7

<PAGE>

Global Note and become an interest in the other Global Note and, accordingly,
will thereafter be subject to all transfer restrictions, if any, and other
procedures applicable to beneficial interests in such other Global Note for so
long as it remains such an interest.

     A Global Note shall be exchangeable for 2008 Notes registered in the names
of persons other than the Depositary or its nominee only if (i) the Depositary
notifies the Company that it is unwilling or unable to continue as a Depositary
for such Global Note, or if at any time the Depositary ceases to be a clearing
agency registered under the Securities Exchange Act of 1934, as amended, at a
time when the Depositary is required to be so registered to act as such
Depositary and, in each case, no successor Depositary shall have been appointed
by the Company within 90 days of such notice, (ii) the Company in its sole
discretion determines that such Global Note shall be so exchangeable, or (iii)
there shall have occurred an Event of Default with respect to the 2008 Notes.
Any Global Note that is exchangeable pursuant to the preceding sentence shall be
exchangeable for 2008 Notes registered in such names as the Depositary shall
direct and 2008 Notes issued in exchange for Rule 144A Global Notes, Regulation
S Global Notes and Accredited Investor Notes pursuant to the preceding sentence
will bear, and be subject to, the legends relating to restrictions on transfer
required by Section 107 hereof.

     SECTION 106. Transfer and Exchange.
                  ---------------------

     (a) Transfer Restrictions. The Initial 2008 Notes, and those Exchange 2008
         ---------------------
Notes with respect to which any Person described in Section 107(b)(A), (B) or
(C) is the beneficial owner, may not be transferred except in compliance with
the applicable legends contained in Exhibit A unless otherwise determined by the
Company in accordance with applicable law.

     No service charge will be made for any transfer or exchange of 2008 Notes,
but the Trustee may require payment of a sum sufficient to cover any tax or
other governmental charge that may be imposed in connection therewith.

     The Company shall not be required (a) to issue, transfer or exchange any
2008 Notes during a period beginning at the opening of business 15 days before
the day of the mailing of a notice identifying the serial numbers of the 2008
Notes to be called for redemption, and ending at the close of business on the
day of the mailing, or (b) to transfer or exchange any 2008 Notes theretofore
selected for redemption in whole or in part, except the unredeemed portion of
any 2008 Note redeemed in part.

     (b) Transfer of Rule 144A Global Notes; Accredited Investor Notes. The
         -------------------------------------------------------------
following provisions shall apply with respect to any proposed transfer of a Rule
144A Global Note or a beneficial interest therein or an Accredited Investor Note
prior to the expiration of the Resale Restriction Termination Date:

               (i) a transfer of a Rule 144A Global Note or a beneficial
     interest therein or an Accredited Investor Note to a QIB shall be made upon
     the representation of the transferee that it is purchasing the 2008 Note
     for its own account or an account with respect to which it exercises sole
     investment discretion and that it and any such account is a QIB and is
     aware that the sale to it is being made in reliance on Rule 144A and

                                       8

<PAGE>

     acknowledges that it has received such information regarding the Company as
     the undersigned has requested pursuant to Rule 144A or has determined not
     to request such information and that it is aware that the transferor is
     relying upon its foregoing representations in order to claim the exemption
     from registration provided by Rule 144A;

               (ii) a transfer of a Rule 144A Global Note or a beneficial
     interest therein or an Accredited Investor Note to an Institutional
     Accredited Investor shall be made upon receipt by the Trustee or its agent
     of a certificate substantially in the form set forth in Exhibit C annexed
     hereto from the proposed transferee and, if requested by the Company or the
     Trustee, the delivery of an opinion of counsel, certifications and/or other
     information satisfactory to each of them; and

               (iii) a transfer of a Rule 144A Global Note or a beneficial
     interest therein or an Accredited Investor Note to a Non-U.S. Person shall
     be made upon receipt by the Trustee or its agent of a certificate
     substantially in the form set forth in Exhibit D annexed hereto from the
     proposed transferee and, if requested by the Company or the Trustee, the
     delivery of an opinion of counsel, certifications and/or other information
     satisfactory to each of them.

     (c) Transfer of Regulation S Global Notes. The following provisions shall
         -------------------------------------
apply with respect to any proposed transfer of a Regulation S Global Note prior
to the expiration of the Distribution Compliance Period:

               (i) a transfer of a Regulation S Global Note or a beneficial
     interest therein to a QIB shall be made upon receipt by the Trustee or its
     agent of a certificate substantially in the form set forth in Exhibit E
     annexed hereto from the transferor and, if requested by the Company or the
     Trustee, the delivery of an opinion of counsel, certifications and/or other
     information satisfactory to each of them;

               (ii) a transfer of a Regulation S Global Note or a beneficial
     interest therein to an Institutional Accredited Investor shall be made upon
     receipt by the Trustee or its agent of a certificate substantially in the
     form set forth in Exhibit C annexed hereto from the proposed transferee
     and, if requested by the Company or the Trustee, the delivery of an opinion
     of counsel, certifications and/or other information satisfactory to each of
     them; and

               (iii) a transfer of a Regulation S Global Note or a beneficial
     interest therein to a Non-U.S. Person shall be made upon receipt by the
     Trustee or its agent of a certificate substantially in the form set forth
     in Exhibit D annexed hereto from the proposed transferee and, if requested
     by the Company or the Trustee, the delivery of an opinion of counsel,
     certifications and/or other information satisfactory to each of them.

          Prior to or on the expiration of the Distribution Compliance Period,
beneficial interests in a Regulation S Global Note may only be held through
Euroclear or Clearstream or another agent member of Euroclear and Clearstream
acting for and on behalf of them, unless exchanged for interests in a Rule 144A
Global Note in accordance with the certification

                                       9

<PAGE>

requirements hereof. During the Distribution Compliance Period, interests in a
Regulation S Global Note, if any, may be exchanged for interests in the Rule
144A Global Note or for definitive 2008 Notes only in accordance with the
certification requirements described in this Section 106.

          After the expiration of the Distribution Compliance Period, interests
in the Regulation S Global Note may be transferred without requiring the
certification set forth in Exhibit D annexed hereto or any additional
certification.

          As used in the preceding two paragraphs of this Section 106(c), the
term "transfer" encompasses any sale, transfer or other disposition of any 2008
Notes referred to herein except for transfers from any Holder to an Affiliate of
such Holder; provided, that such transferring Holder shall deliver a letter to
the Trustee stating that the transferee is an Affiliate of such Holder. The
Trustee shall be entitled to rely on and be fully protected in its reliance on
such letter.

     (d) Exchange of Initial 2008 Notes for Exchange 2008 Notes. The Initial
         ------------------------------------------------------
2008 Notes may be exchanged for Exchange 2008 Notes pursuant to the terms of the
Exchange Offer. The Trustee shall make the exchange as follows:

     The Company shall present the Trustee with an Officers' Certificate
certifying the following:

          (A)  upon issuance of the Exchange 2008 Notes, the transactions
               contemplated by the Exchange Offer have been consummated; and

          (B)  the principal amount of Initial 2008 Notes properly tendered in
               the Exchange Offer that are represented by a Global Note or by
               Global Notes and the principal amount of Initial 2008 Notes
               properly tendered in the Exchange Offer that are represented by
               individual 2008 Notes, the name of each holder of such individual
               Initial 2008 Notes, the principal amount properly tendered in the
               Exchange Offer by each such holder and the name and address to
               which individual Exchange 2008 Notes shall be registered and sent
               for each such holder.

     The Trustee, upon receipt of (i) such Officers' Certificate, (ii) an
Opinion of Counsel to the Company addressed to the Trustee of the 2008 Notes (x)
to the effect that the Exchange 2008 Notes have been registered under Section 5
of the Securities Act of 1933, as amended, and the Indenture has been qualified
under the Trust Indenture Act and (y) with respect to the matters set forth in
Section 3(p) of the Registration Rights Agreement and (iii) a Company Order,
shall authenticate (A) a Global Note or Global Notes for Exchange 2008 Notes in
aggregate principal amount equal to the aggregate principal amount of Initial
2008 Notes represented by a Global Note or by Global Notes indicated in such
Officers' Certificate as having been properly tendered and (B) individual 2008
Notes representing Exchange 2008 Notes registered in the names of, and in the
principal amounts indicated in, such Officers' Certificate.

                                       10

<PAGE>

     If the principal amount of the Global Note or Global Notes for the Exchange
2008 Notes is less than the principal amount of the Global Note or Global Notes
for the Initial 2008 Notes, the Trustee shall make an endorsement on such Global
Note or Global Notes for Initial 2008 Notes indicating a reduction in the
principal amount represented thereby.

     The Trustee shall deliver such individual 2008 Notes for Exchange 2008
Notes to the holders thereof as indicated in such Officers' Certificate.

     SECTION 107. Legends.
                  -------

     (a) Except as permitted by subsection (b) of this Section 107 or as
otherwise determined by the Company in accordance with applicable law, each 2008
Note shall bear the applicable legends relating to restrictions on transfer
pursuant to the securities laws in substantially the form set forth on Exhibit A
hereto.

     (b) The Company shall issue, and the Trustee shall authenticate upon
Company Order, Exchange 2008 Notes in exchange for Initial 2008 Notes accepted
for exchange in the Exchange Offer, which Exchange 2008 Notes shall not bear the
legends required by subsection (a) above, in each case unless the holder of such
Initial 2008 Notes is either (A) a broker-dealer who purchased such Initial 2008
Notes directly from the Company for resale pursuant to Rule 144A or any other
available exemption under the Securities Act of 1933, as amended, (B) a Person
participating in the distribution of the Initial 2008 Notes or (C) a Person who
is an affiliate (as defined in Rule 144 under the Securities Act of 1933, as
amended) of the Company.

     SECTION 108. Redemption. At any time and at the Company's option, the
                  ----------
Company may redeem the 2008 Notes, in whole or in part (if in part, by lot or by
such other method as the Trustee shall deem fair or appropriate) at the
redemption price of 100% of principal amount of such 2008 Notes, plus accrued
interest on the principal amount of such 2008 Notes, if any, to the Redemption
Date, plus the Make-Whole Premium for such 2008 Notes.

          "Make-Whole Premium" means, with respect to the 2008 Notes, a
computation as of a date not more than five days prior to the Redemption Date of
the following:

          (i) the average life of the remaining scheduled payments of principal
in respect of Outstanding 2008 Notes (the "Remaining Average Life") as of the
Redemption Date;

          (ii) the yield to maturity for the United States treasury security
having an average life equal to the Remaining Average Life of the 2008 Notes and
trading in the secondary market at the price closest to the principal amount
thereof (the "Primary Issue") (subject to extrapolation if no United States
treasury security has an average life equal to the Remaining Average Life); and

          (iii) the discounted present value of the then-remaining scheduled
payments of principal and interest (but excluding that portion of any scheduled
payment of interest that is actually due and paid on the Redemption Date) in
respect of Outstanding 2008 Notes as of the

                                       11

<PAGE>

Redemption Date using a discount factor equal to the sum of (x) the yield to
maturity for the Primary Issue, plus (y) 25 basis points.

     The amount of Make-Whole Premium in respect of 2008 Notes to be redeemed or
repurchased shall be an amount equal to (x) the discounted present value of such
2008 Notes to be redeemed determined in accordance with clause (iii) above,
minus (y) the unpaid principal amount of such 2008 Notes; provided, however,
that the Make-Whole Premium shall not be less than zero.

     In the event of redemption of the 2008 Notes in part only, a new 2008 Note
or new 2008 Notes for the unredeemed portion will be issued in the name or names
of the Holder or Holders thereof upon the surrender thereof.

     The 2008 Notes will not have a sinking fund.

     Notice of redemption shall be given as provided in Section 1104 of the
Original Indenture.

     Any redemption of less than all of the 2008 Notes shall, with respect to
the principal thereof, be divisible by $1,000.

     SECTION 109. Limitation on Liens. The Company shall not issue, assume or
                  -------------------
guarantee any Indebtedness for borrowed money secured by any lien on any
non-cash assets of the Company, whether owned on the date that the 2008 Notes
are issued or thereafter acquired, without in any such case effectively securing
the outstanding 2008 Notes (together with, if the Company shall so determine,
any other Indebtedness of or guaranty by the Company ranking equally with the
2008 Notes equally and ratably with such Indebtedness (but only so long as such
Indebtedness is so secured); provided, however, that the foregoing restriction
shall not apply to the following liens:

     (a) any lien incurred or deposits made in the ordinary course of business;

     (b) liens imposed by law, such as carriers', warehousemen's and mechanics'
liens, arising in the ordinary course of business;

     (c) any lien on items of inventory or other goods and proceeds in respect
of bankers' acceptances;

     (d) liens in favor of the Company.

     (e) any lien created by the Company under or in connection with or arising
out of any pooling and settlement agreements or pooling and settlement
arrangements of the electricity industry or any transactions or arrangements
entered into in connection with hedging or management of risks relating to the
electricity industry;

     (f) any lien constituted by a right of set off or right over a margin call
account or any form of cash or cash collateral or any similar arrangement for
obligations incurred in respect of

                                       12

<PAGE>

the hedging or management of risks under transactions involving any currency or
interest rate swap, cap or collar arrangements, forward exchange transaction,
option, warrant, forward rate agreement, futures contract or other derivative
instrument of any kind;

     (g) any lien arising out of title retention or like provisions in
connection with the purchase of goods and equipment in the ordinary course of
business;

     (h) any lien securing reimbursement obligations under letters of credit,
guaranties and other forms of credit enhancement given in connection with the
purchase of goods and equipment in the ordinary course of business;

     (i) liens on any property or assets acquired from a corporation that is
merged with or into the Company, or any liens on the property or assets of any
corporation or other entity existing at the time such corporation or other
entity becomes a Subsidiary of the Company and, in either such case, is not
created in anticipation of any such transaction (unless such lien was created to
secure or provide for the payment of any part of the purchase price of such
corporation);

     (j) liens required by any contract or statute in order to permit the
Company to perform any contract or subcontract made by the Company with or at
the request of a governmental entity or any department, agency or
instrumentality thereof, or to secure partial, progress, advance or other
payments by the Company to such governmental unit pursuant to the provisions of
any contract or statute;

     (k) any lien securing industrial revenue, development or similar bonds
issued by or for the Company's benefit, provided that such industrial revenue,
development or similar bonds are nonrecourse to the Company;

     (l) any lien securing taxes or assessments or other applicable governmental
charges or levies;

     (m) any lien that arises pursuant to any order of attachment, distraint or
similar legal process arising in connection with court proceedings and any lien
that secures the reimbursement obligation for any bond obtained in connection
with an appeal taken in any court proceeding, so long as the execution or other
enforcement of such lien arising pursuant to such legal process is effectively
stayed and the claims secured thereby are being contested in good faith, and, if
appropriate, by appropriate legal proceedings, or any lien in favor of a
plaintiff or defendant in any action before a court or tribunal as security for
costs and/or expenses;

     (n) any lien arising by operation of law or by order of a court or tribunal
or any lien arising by an agreement of similar effect, including, without
limitation, judgement liens;

     (o) liens securing amounts not more than 90 days overdue or otherwise being
contested in good faith;

                                       13

<PAGE>

     (p) minor encumbrances, easements or reservations which do not in the
aggregate materially adverse affect the value of the properties or impair their
use;

     (q) liens on any property existing at the time of acquisition thereof
(which liens may also extend to subsequent repairs, alterations and improvements
to such property);

     (r) liens to secure purchase money Indebtedness not in excess of the cost
or value of the property acquired;

     (s) liens, if any, in existence on May 1, 2001;

     (t) any liens securing the Company's Indebtedness for borrowed money
incurred in connection with the financing of accounts receivable;

     (u) rights of financial institutions to offset credit balances and other
liens in the nature of bankers' liens;

     (v) other liens to secure Indebtedness so long as the amount of outstanding
Indebtedness secured by liens pursuant to this provision does not exceed 10% of
the Company's Consolidated Net Assets at the time of incurrence; and

     (w) liens granted in connection with extending, renewing, replacing or
refinancing (or successive extensions, renewals, replacements or refinancings)
any of the Indebtedness (so long as there is no increase in the principal amount
of the Indebtedness) described in clauses (a) through (v) above.

     In the event that the Company shall propose to pledge, mortgage or
hypothecate any property, other than as permitted by clauses (a) through (w)
above, the Company shall (prior thereto) give written notice thereof to the
Trustee, who shall give notice to the Holders, and the Company shall, prior to
or simultaneously with such pledge, mortgage or hypothecation, effectively
secure all the 2008 Notes equally and ratably with such Indebtedness.

     This Section 109 shall be defeasable pursuant to Section 401(2) of the
Original Indenture.

     SECTION 110. Limitation on Asset Sales. Except for the sale, conveyance,
                  -------------------------
transfer or lease of the Company's properties and assets substantially as an
entirety as permitted pursuant to Article 8 of the Original Indenture, and other
than assets required to be sold to conform with governmental regulations, the
Company shall not, and shall not permit any of its Subsidiaries to, consummate
any Asset Sale, if the aggregate net book value of all such Asset Sales during
the most recent 12-month period would exceed 10% of the Company's Consolidated
Net Assets computed as of the end of the Company's most recently ended full
fiscal quarter preceding such Asset Sale; provided, however, that any such Asset
Sale will be disregarded for purposes of the 10% limitation specified above if
the proceeds thereof (i) are, within 18 months of such Asset Sale, invested or
reinvested by the Company or any Subsidiary in a Permitted Business, (ii) are
used by the Company or a Subsidiary to repay Indebtedness of the Company or such
Subsidiary or are used by the Company or a Subsidiary to purchase and retire

                                       14

<PAGE>

some or all of the 2008 Notes, or (iii) are retained by the Company or its
Subsidiaries. Additionally, if after giving effect to any Asset Sale that
otherwise would cause the 10% limitation to be exceeded, each Rating Agency then
rating the 2008 Notes confirms the then current rating of the 2008 Notes, the
portion of such Asset Sale in excess of the 10% limitation will also be
disregarded for purposes of the foregoing limitations.

     This Section 110 shall be defeasable pursuant to Section 401(2) of the
Original Indenture.

     SECTION 111. Debt Incurrence Test.
                  --------------------

     (a) The Company shall not incur any Indebtedness for borrowed money other
than Permitted Indebtedness unless on a Pro Forma Basis for the debt incurrence
and any related transaction either (i) based on projections prepared by the
Company on a reasonable basis, the projected Senior Debt Service Coverage Ratio
for each of the succeeding two twelve-month periods (commencing with the month
in which such Indebtedness is to be incurred) or, with respect to any date
within the 24-month period prior to the final maturity date for the 2008 Notes,
the number of complete twelve-month periods, if any, until such final maturity
date for the 2008 Notes, in each case measured as individual twelve-month
periods, is projected to be greater than or equal to 2.5 to 1, or (ii) each
Rating Agency then rating the 2008 Notes provides a Ratings Reaffirmation of the
then existing rating of such 2008 Notes after giving effect to such additional
Indebtedness.

     (b) At any time following the date on which financial statements for five
full years of the Company's operations are available (commencing with the year
ended December 31, 1999), the Company may cease to comply with the covenant
provided in paragraph (a) of this Section 110 if each Rating Agency then rating
the Outstanding Senior Notes provides a Ratings Reaffirmation of at least the
original rating of such Senior Notes after giving effect to such fact, in which
case from and after the date of such reaffirmation such covenant shall be deemed
to be of no further force and effect.

     (c) This Section 111 shall be defeasable pursuant to Section 401(2) of the
Original Indenture.

                                    ARTICLE 2

                            Miscellaneous Provisions

     SECTION 201. Recitals by Company. The recitals in this Fourth Supplemental
                  -------------------
Indenture are made by the Company only and not by the Trustee, and all of the
provisions contained in the Original Indenture in respect of the rights,
privileges, immunities, powers and duties of the Trustee shall be applicable in
respect of 2008 Notes and of this Fourth Supplemental Indenture as fully and
with like effect as if set forth herein in full.

     SECTION 202. Ratification and Incorporation of Original Indenture. As
                  ----------------------------------------------------
supplemented hereby, the Original Indenture is in all respects ratified and
confirmed, and the

                                       15

<PAGE>

Original Indenture and this Fourth Supplemental Indenture shall be read, taken
and construed as one and the same instrument.

     SECTION 203. Executed in Counterparts. This Fourth Supplemental Indenture
                  ------------------------
may be simultaneously executed in several counterparts, each of which shall be
deemed to be an original, and such counterparts shall together constitute but
one and the same instrument.

     SECTION 204. GOVERNING LAW. THIS FOURTH SUPPLEMENTAL INDENTURE AND EACH
                  -------------
2008 NOTE ISSUED HEREUNDER SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE
WITH, THE LAWS OF THE STATE OF NEW YORK.

                                       16

<PAGE>

          IN WITNESS WHEREOF, each party hereto has caused this instrument to be
signed in its name and behalf by its duly authorized officers, all as of the day
and year first above written.

                                          MIRANT AMERICAS GENERATION, INC.


                                          By: /s/ DONALD B. DYSERT
                                             -----------------------------------
                                             Name: Donald B. Dysert
                                             Title: Vice President and Treasurer


                                          BANKERS TRUST COMPANY, as Trustee


                                          By: /s/ RICHARD L. BUCKWALTER
                                             -----------------------------------
                                             Name: Richard L. Buckwalter
                                             Title: Vice President

<PAGE>

                                    EXHIBIT A

                                FORM OF 2008 NOTE

<PAGE>

          [INCLUDE IF NOTE IS A GLOBAL NOTE -- UNLESS THIS NOTE IS PRESENTED BY
AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY, A NEW YORK
CORPORATION ("DTC"), TO MIRANT AMERICAS GENERATION, INC. (THE "COMPANY") OR ITS
AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY NOTE ISSUED IS
REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS IS REQUESTED BY AN
AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE TO CEDE & CO. OR TO
SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY
TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON
IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST
HEREIN.

          TRANSFERS OF THIS GLOBAL NOTE IN WHOLE SHALL BE LIMITED TO TRANSFERS
TO A NOMINEE OF DTC OR BY A NOMINEE OF DTC TO DTC OR ANOTHER NOMINEE OF DTC OR
BY DTC OR ANY SUCH NOMINEE TO A SUCCESSOR DEPOSITARY OR A NOMINEE OF SUCH
SUCCESSOR DEPOSITARY AND TRANSFERS OF THIS GLOBAL NOTE IN PART SHALL BE LIMITED
TO TRANSFERS MADE IN ACCORDANCE WITH THE RESTRICTIONS SET FORTH IN THE INDENTURE
REFERRED TO ON THE REVERSE HEREOF.

     THIS GLOBAL NOTE SHALL BE EXCHANGEABLE FOR NOTES REGISTERED IN THE NAMES OF
PERSONS OTHER THAN DTC OR ITS NOMINEE ONLY IF (I) DTC NOTIFIES THE COMPANY THAT
IT IS UNWILLING OR UNABLE TO CONTINUE AS A DEPOSITARY FOR SUCH GLOBAL NOTE, OR
IF AT ANY TIME DTC CEASES TO BE A CLEARING AGENCY REGISTERED UNDER THE
SECURITIES EXCHANGE ACT OF 1934, AS AMENDED, AT A TIME WHEN DTC IS REQUIRED TO
BE SO REGISTERED TO ACT AS SUCH DEPOSITARY AND, IN EACH CASE, NO SUCCESSOR
DEPOSITARY SHALL HAVE BEEN APPOINTED BY THE COMPANY WITHIN 90 DAYS OF SUCH
NOTICE, (II) THE COMPANY IN ITS SOLE DISCRETION DETERMINES THAT SUCH GLOBAL NOTE
SHALL BE SO EXCHANGEABLE, OR (III) THERE SHALL HAVE OCCURRED AN EVENT OF DEFAULT
WITH RESPECT TO THE NOTES. ANY GLOBAL NOTE THAT IS EXCHANGEABLE PURSUANT TO THE
PRECEDING SENTENCE SHALL BE EXCHANGEABLE FOR NOTES REGISTERED IN SUCH NAMES AS
THE DEPOSITARY SHALL DIRECT AND NOTES ISSUED IN EXCHANGE FOR RULE 144A GLOBAL
NOTES, REGULATION S GLOBAL NOTES AND ACCREDITED INVESTOR NOTES PURSUANT TO THE
PRECEDING SENTENCE, SHALL BEAR, AND BE SUBJECT TO, THE LEGENDS RELATING TO
RESTRICTIONS ON TRANSFER REQUIRED BY THE INDENTURE RELATING HERETO.]

     [INCLUDE IF THIS NOTE IS A RULE 144A GLOBAL NOTE OR AN ACCREDITED INVESTOR
NOTE; DO NOT INCLUDE IF THIS SECURITY IS A REGULATION S GLOBAL NOTE -- THIS NOTE
(OR ITS PREDECESSOR) WAS ORIGINALLY ISSUED IN A TRANSACTION EXEMPT FROM
REGISTRATION UNDER THE UNITED STATES SECURITIES ACT OF 1933, AS AMENDED (THE
"SECURITIES ACT"), AND MAY NOT BE OFFERED, SOLD, PLEDGED OR OTHERWISE
TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR AN APPLICABLE

                                      A-1

<PAGE>

EXEMPTION THEREFROM AND IN ANY EVENT MAY BE SOLD OR OTHERWISE TRANSFERRED ONLY
IN ACCORDANCE WITH THE INDENTURE, COPIES OF WHICH ARE AVAILABLE FOR INSPECTION
AT THE CORPORATE TRUST OFFICE OF THE TRUSTEE IN NEW YORK.

[INCLUDE IF THIS NOTE IS A REGULATION S GLOBAL NOTE - THE NOTES COVERED HEREBY
HAVE NOT BEEN REGISTERED UNDER THE U.S. SECURITIES ACT OF 1933 (THE "SECURITIES
ACT") AND MAY NOT BE OFFERED AND SOLD WITHIN THE UNITED STATES OR TO, OR FOR THE
ACCOUNT OR BENEFIT OF, U.S. PERSONS (i) AS PART OF THEIR DISTRIBUTION AT ANY
TIME OR (ii) OTHERWISE UNTIL 40 DAYS AFTER THE LATER OF THE OFFERING AND THE
CLOSING DATE, EXCEPT IN EITHER CASE IN ACCORDANCE WITH REGULATION S (OR RULE
144A IF AVAILABLE) UNDER THE SECURITIES ACT. TERMS USED ABOVE HAVE THE MEANING
GIVEN TO THEM BY REGULATION S.]

     EACH PURCHASER OF THIS NOTE IS HEREBY NOTIFIED THAT THE SELLER MAY BE
RELYING ON THE EXEMPTION FROM THE PROVISIONS OF SECTION 5 OF THE SECURITIES ACT
PROVIDED BY RULE 144A THEREUNDER. EACH HOLDER OF THIS NOTE REPRESENTS TO MIRANT
AMERICAS GENERATION, INC. THAT (a) SUCH HOLDER WILL NOT SELL, PLEDGE OR
OTHERWISE TRANSFER THIS NOTE (WITHOUT THE CONSENT OF MIRANT AMERICAS GENERATION,
INC.) OTHER THAN (i) TO A QUALIFIED INSTITUTIONAL BUYER IN A TRANSACTION
COMPLYING WITH RULE 144A UNDER THE SECURITIES ACT, (ii) IN ACCORDANCE WITH RULE
144 UNDER THE SECURITIES ACT, (iii) OUTSIDE THE UNITED STATES IN A TRANSACTION
MEETING THE REQUIREMENTS OF REGULATION S UNDER THE SECURITIES ACT, (iv) PURSUANT
TO ANOTHER AVAILABLE EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT,
SUBJECT, IN THE CASE OF CLAUSES (ii), (iii) OR (iv), TO THE RECEIPT BY MIRANT
AMERICAS GENERATION, INC. OF AN OPINION OF COUNSEL OR SUCH OTHER EVIDENCE
ACCEPTABLE TO MIRANT AMERICAS GENERATION, INC. THAT SUCH RESALE, PLEDGE OR
TRANSFER IS EXEMPT FROM THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT OR
(v) PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT AND THAT (b) THE HOLDER
WILL, AND EACH SUBSEQUENT HOLDER IS REQUIRED TO, NOTIFY ANY PURCHASER OF THIS
NOTE OF THE RESALE RESTRICTIONS REFERRED TO HEREIN AND DELIVER TO THE TRANSFEREE
(OTHER THAN A QUALIFIED INSTITUTIONAL BUYER) PRIOR TO THE SALE A COPY OF THE
TRANSFER RESTRICTIONS APPLICABLE HERETO (COPIES OF WHICH MAY BE OBTAINED FROM
THE TRUSTEE).

BECAUSE OF THE FOREGOING RESTRICTIONS, PURCHASERS ARE ADVISED TO CONSULT LEGAL
COUNSEL PRIOR TO MAKING ANY RESALE, PLEDGE OR TRANSFER OF ANY OF THE NOTES.
INVESTORS SHOULD BE AWARE THAT THEY MAY BE REQUIRED TO BEAR THE FINANCIAL RISKS
OF THIS INVESTMENT FOR AN INDEFINITE PERIOD OF TIME.]

                                      A-2

<PAGE>

NO. [ ]                                                                CUSIP NO.

                        MIRANT AMERICAS GENERATION, INC.
                                7.20% SENIOR NOTE
                               DUE October 1, 2008

<TABLE>
<S>                             <C>
     Principal Amount:          $
                                 ---------

     Regular Record Date:       15th calendar day prior to Interest Payment Date

     Original Issue Date:       October 9, 2001

     Stated Maturity:           October 1, 2008

     Interest Payment Dates:    April 1 and October 1

     Interest Rate:             7.20% per annum

     Authorized Denomination:   $100,000, or any integral multiple of $1,000 in excess thereof
</TABLE>

     Mirant Americas Generation, Inc., a Delaware corporation (the "Company",
which term includes any successor corporation under the Indenture referred to on
the reverse hereof), for value received, hereby promises to pay to
                                     , or registered assigns, the principal sum
-------------------------------------
of           DOLLARS ($__________) on the Stated Maturity shown above (or upon
   ---------
earlier redemption), and to pay interest thereon from the Original Issue Date
shown above, or from the most recent Interest Payment Date to which interest has
been paid or duly provided for, semi-annually in arrears on each Interest
Payment Date as specified above, commencing on the Interest Payment Date next
succeeding the Original Issue Date shown above and on the Stated Maturity (or
upon earlier redemption) at the rate per annum shown above until the principal
hereof is paid or made available for payment and on any overdue principal and on
any overdue installment of interest. The interest so payable, and punctually
paid or duly provided for, on any Interest Payment Date (other than an Interest
Payment Date that is the Stated Maturity or on a Redemption Date) will, as
provided in such Indenture, be paid to the Person in whose name this Note (the
"Note") is registered at the close of business on the Regular Record Date as
specified above next preceding such Interest Payment Date, provided that any
interest payable at Stated Maturity or on any Redemption Date will be paid to
the Person to whom principal is payable. Except as otherwise provided in the
Indenture, any such interest not so punctually paid or duly provided for will
forthwith cease to be payable to the Holder on such Regular Record Date and may
either be paid to the Person in whose name this Note is registered at the close
of business on a Special Record Date for the payment of such defaulted interest
to be fixed by the Trustee, notice whereof shall be given to Holders of Notes of
this series not less than 10 days prior to such Special Record Date, or be paid
at any time in any other lawful manner not inconsistent with the requirements of
any securities exchange, if any, on which the Notes of this series shall be
listed, and

                                      A-3

<PAGE>

upon such notice as may be required by any such exchange, all as more fully
provided in the Indenture.

     Payments of interest on this Note will include interest accrued to but
excluding the respective Interest Payment Dates. Interest payments for this Note
shall be computed and paid on the basis of a 360-day year of twelve 30-day
months. In the event that any date on which interest is payable on this Note is
not a Business Day, then payment of the interest payable on such date will be
made on the next succeeding day that is a Business Day, except that, if such
Business Day is in the next succeeding calendar year, payment shall be made on
the immediately preceding Business Day, in each case with the same force and
effect as if made on the date the payment was originally payable. A "Business
Day" shall mean any day other than a Saturday or a Sunday or a day on which
banks New York, New York are authorized or obligated by law or executive order
to remain closed or a day on which the Trustee's Corporate Trust Office is
closed for business.

     Payment of the principal, premium, if any, and interest due at the Stated
Maturity or earlier redemption of this Note shall be made upon surrender of this
Note at the Corporate Trust Office of the Trustee, in such coin or currency of
the United States of America as at the time of payment is legal tender for
payment of public and private debts. Payments of interest (including interest on
any Interest Payment Date) will be made, subject to such surrender where
applicable, at the option of the Company, (i) by check mailed to the address of
the Person entitled thereto as such address shall appear in the Security
Register or (ii) by wire transfer at such place and to such account at a banking
institution in the United States as may be designated in writing to the Trustee
at least 16 days prior to the date for payment by the Person entitled thereto.

     The unpaid principal amount of this Note shall bear interest at the rate
per annum set forth above.

     The Company has entered into a Registration Rights Agreement dated October
9, 2001 with the Initial Purchasers described therein. Pursuant to the
Registration Rights Agreement, the Company has agreed to file with the SEC a
registration statement under the Securities Act ("Registration Statement") for
an offer to exchange the Initial 2008 Notes for a like aggregate principal
amount of Exchange 2008 Notes issued pursuant to the Indenture that are in all
material respects identical to the Initial 2008 Notes except that such Exchange
2008 Notes shall be issued pursuant to an effective Registration Statement.

     From and after the date on which an Additional Interest Event (as defined
in the Registration Rights Agreement) occurs, the interest rate payable on this
Note shall increase (in addition to the interest rate set forth above) and
additional interest reflecting such increase shall accrue with respect to this
Note, as described in the Registration Rights Agreement, until but not including
the date on which all such Additional Interest Events shall be cured and cease
to exist (and provided no other Additional Interest Event with respect to this
Note shall then be continuing), at the rate of one-half of one percent (0.50%)
per annum, which additional interest shall be payable hereon at the times, in
the manner and subject to the same terms and conditions set forth herein and in
the Indenture, as though the interest rate set forth above had been increased by
one-half of one percent (0.50%) per annum.

                                      A-4

<PAGE>

     REFERENCE IS HEREBY MADE TO THE FURTHER PROVISIONS OF THIS NOTE SET FORTH
ON THE REVERSE HEREOF, WHICH FURTHER PROVISIONS SHALL FOR ALL PURPOSES HAVE THE
SAME EFFECT AS IF SET FORTH AT THIS PLACE.

     Unless the certificate of authentication hereon has been executed by the
Trustee by manual signature, this Note shall not be entitled to any benefit
under the Indenture or be valid or obligatory for any purpose.

                                      A-5

<PAGE>

     IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed by its duly authorized officer.

Dated: October 9, 2001.

                                        MIRANT AMERICAS GENERATION, INC.


                                        By:
                                               ---------------------------------
                                        Name:
                                               ---------------------------------
                                        Title:
                                               ---------------------------------

                                      A-6

<PAGE>

                          CERTIFICATE OF AUTHENTICATION

     This is one of the Senior Notes of the series designated therein referred
to in the within-mentioned Indenture.


                                        BANKERS TRUST COMPANY,
                                        as Trustee


                                        By:
                                           -------------------------------------
                                                    Authorized Officer

                                      A-7

<PAGE>

                             (Reverse Side of Note)

     This Note is one of a duly authorized issue of Senior Notes of the Company,
issued and issuable in one or more series under an Indenture, dated as of May 1,
2001, as supplemented by the Fourth Supplemental Indenture dated as of October
9, 2001 (collectively, the "Indenture"), between the Company and Bankers Trust
Company, to which Indenture reference is hereby made for a statement of the
respective rights, limitation of rights, duties and immunities thereunder of the
Company, the Trustee and the Holders of the Senior Notes issued thereunder and
of the terms upon which said Senior Notes are, and are to be, authenticated and
delivered. This Note is one of the series designated on the face hereof as 7.20%
Senior Notes due October 1, 2008 (the "2008 Notes") in aggregate principal
amount of up to $300,000,000, subject to increase as provided for in the
Indenture. Capitalized terms used herein for which no definition is provided
herein shall have the meanings set forth in the Indenture.

     At any time and at the Company's option, the Company may redeem this Note,
in whole or in part (if in part, by lot or by such other method as the Trustee
shall deem fair or appropriate) at the redemption price of 100% of principal
amount of such Note, plus accrued interest on the principal amount of this Note,
if any, to the Redemption Date, plus the Make-Whole Premium for such Note.

          "Make-Whole Premium" means a computation as of a date not more than
five days prior to the Redemption Date of the following:

          (i) the average life of the remaining scheduled payments of principal
in respect of outstanding 2008 Notes (the "Remaining Average Life") as of the
Redemption Date;

          (ii) the yield to maturity for the United States treasury security
having an average life equal to the Remaining Average Life of the 2008 Notes and
trading in the secondary market at the price closest to the principal amount
thereof (the "Primary Issue") (subject to extrapolation if no United States
treasury security has an average life equal to the Remaining Average Life); and

          (iii) the discounted present value of the then-remaining scheduled
payments of principal and interest (but excluding that portion of any scheduled
payment of interest that is actually due and paid on the Redemption Date) in
respect of Outstanding 2008 Notes as of the Redemption Date using a discount
factor equal to the sum of (x) the yield to maturity for the Primary Issue, plus
(y) 25 basis points.

     The amount of Make-Whole Premium in respect of 2008 Notes to be redeemed or
repurchased shall be an amount equal to (x) the discounted present value of such
2008 Notes to be redeemed determined in accordance with clause (iii) above,
minus (y) the unpaid principal amount of such 2008 Notes; provided, however,
that the Make-Whole Premium shall not be less than zero.

                                      A-8

<PAGE>

     In the event of redemption of this Note in part only, a new Note or Notes
of this series for the unredeemed portion hereof will be issued in the name or
names of the Holder or Holders hereof upon the surrender hereof. The Notes will
not have a sinking fund.

     If an Event of Default with respect to the Notes of this series shall occur
and be continuing, the principal of the Notes of this series may be declared due
and payable in the manner, with the effect and subject to the conditions
provided in the Indenture.

     The Indenture permits, with certain exceptions as therein provided, the
amendment thereof and the modification of the rights and obligations of the
Company and the rights of the Holders of the Notes of each series to be affected
under the Indenture at any time by the Company and the Trustee with the consent
of the Holders of not less than a majority in principal amount of the
Outstanding Notes of each series to be affected. The Indenture also contains
provisions permitting the Holders of specified percentages in principal amount
of the Notes of each 2008 Note at the time Outstanding, on behalf of the Holders
of all Notes of such series, to waive compliance by the Company with certain
provisions of the Indenture and certain past defaults under the Indenture and
their consequences. Any such consent or waiver by the Holder of this Note shall
be conclusive and binding upon such Holder and upon all future Holders of this
Note and of any Note issued upon the registration of transfer hereof or in
exchange hereof or in lieu hereof, whether or not notation of such consent or
waiver is made upon this Note. Without notice to or the consent of any Holder,
the Company and the Trustee may amend the Indenture or the Notes for the purpose
of curing any ambiguity, or of curing, correcting, or supplementing any
defective provision thereof or hereof, or in any manner that the Company and the
Trustee may determine that is not inconsistent with the Indenture and the Notes
and will not adversely affect the interests of any Holder.

     The Indenture contains certain covenants, including without limitation,
covenants with respect to the following matters: (i) debt incurrence; (ii)
Liens, (iii) Asset Sales; and (iv) mergers, consolidations and certain transfers
of assets. Until such time as the Company is registered as a reporting company
under the Exchange Act, the Company must furnish to the Trustee annual
statements as to the Company's compliance with such limitations in accordance
with the terms of the Indenture.

     The Indenture contains provisions for, upon compliance by the Company with
certain conditions set forth in the Indenture, the defeasance of certain
restrictive covenants and agreements.

     No reference herein to the Indenture and no provision of this Note or of
the Indenture shall alter or impair the obligation of the Company, which is
absolute and unconditional, to pay the principal of and interest on this Note at
the times, place and rate, and in the coin or currency, herein prescribed.

     As provided in the Indenture and subject to certain limitations therein set
forth, the transfer of this Note is registrable in the Security Register, upon
surrender of this Note for registration of transfer at the office or agency of
the Company for such purpose, duly endorsed by, or accompanied by a written
instrument of transfer in form satisfactory to the Company and the Security
Registrar and duly executed by, the Holder hereof or his attorney duly
authorized in writing, and thereupon

                                      A-9

<PAGE>

one or more new Notes of this series, of authorized denominations and of like
tenor and for the same aggregate principal amount, will be issued to the
designated transferee or transferees. No service charge shall be made for any
such registration of transfer or exchange, but the Company or the Trustee may
require payment of a sum sufficient to cover any tax or other governmental
charge payable in connection therewith.

     Prior to due presentment of this Note for registration of transfer, the
Company, the Trustee and any agent of the Company or the Trustee may treat the
Person in whose name this Note is registered as the owner hereof for all
purposes, whether or not this Note be overdue, and neither the Company, the
Trustee nor any such agent shall be affected by notice to the contrary.

     The Notes are issuable only in registered form without coupons in minimum
denominations of $100,000 and integral multiples of $1,000 in excess thereof. As
provided in the Indenture and subject to certain limitations therein set forth,
Notes are exchangeable for a like aggregate principal amount of Notes of this
series of a different authorized denomination, as requested by the Holder
surrendering the same upon surrender of the Note or Notes to be exchanged at the
office or agency of the Company.

     This Note shall be governed by, and construed in accordance with, the laws
of the State of New York.

     The Trustee will furnish to any Holder upon written request and without
charge a copy of the Indenture. Requests may be made to Bankers Trust Company,
Four Albany Street, New York, New York 10006, Attention: Corporate Trust Office.

                                      A-10

<PAGE>

                                  ABBREVIATIONS

The following abbreviations, when used in the inscription on the face of this
instrument, shall be construed as though they were written out in full according
to applicable laws or regulations:

TEN COM- as tenants in      UNIF GIFT MIN ACT-        Custodian
         common                                ------           --------
TEN ENT- as tenants by                                    (Cust)         (Minor)
         the entireties
JT TEN-  as joint tenants                             under Uniform Gifts to
         with right of                                Minors Act
         survivorship and
         not as tenants                               ------------------------
         in common                                        (State)

                    Additional abbreviations may also be used
                          though not on the above list.

                                   ----------

     FOR VALUE RECEIVED, the undersigned hereby sell(s) and transfer(s) unto
                           (please insert Social Security or other identifying
---------------------------
number of assignee)

--------------------------------------------------------------------------------
PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING POSTAL ZIP CODE
OF ASSIGNEE

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
the within Note and all rights thereunder, hereby irrevocably constituting and
appointing

--------------------------------------------------------------------------------
agent to transfer said Note on the books of the Company, with full power of
substitution in the premises.

Dated:
       -----------------------    ----------------------------------------------

                                  ----------------------------------------------

                                  NOTICE: The signature to this assignment must
                                  correspond with the name as written upon the
                                  face of the within instrument in every
                                  particular without alteration or enlargement,
                                  or any change whatever.

<PAGE>

                                    EXHIBIT B

                          CERTIFICATE OF AUTHENTICATION

     This is one of the Senior Notes of the series designated therein referred
to in the within-mentioned Indenture.

                                        BANKERS TRUST COMPANY,
                                        as Trustee


                                        By:
                                           -------------------------------------
                                                 Authorized Officer

<PAGE>

                                    EXHIBIT C
                    FORM OF INSTITUTIONAL ACCREDITED INVESTOR
                          TRANSFEREE COMPLIANCE LETTER

Bankers Trust Company
Four Albany Street
New York, New York  10006

Re:  Mirant Americas Generation, Inc.
     7.20% Notes due 2008

Ladies and Gentlemen:

     In connection with our proposed purchase of $           aggregate principal
                                                  ----------
amount of 7.20% Senior Notes due 2008 (the "Notes") of Mirant Americas
Generation, Inc., a Delaware corporation (the "Company"), we confirm that:

1.   We understand that the Notes have not been registered under the Securities
     Act of 1933, as amended (the "Securities Act") and may not be sold except
     as permitted in the following sentence. We agree, on our own behalf and on
     behalf of any accounts for which we are acting as hereinafter stated, to
     offer, sell, pledge or otherwise transfer such Notes prior to the date
     which is two years after the later of the original issue date of the Notes
     and the last date on which the Company or any affiliate of the Company was
     the owner of the Notes (or any predecessor of such Note), only (i) to the
     Company, (ii) so long as such Notes are eligible for resale pursuant to
     Rule 144A under the Securities Act ("Rule 144A"), to a person whom we
     reasonably believe is a "qualified institutional buyer" (as defined in Rule
     144A) (a "QIB") that purchases for its own account or for the account of a
     QIB to whom notice is given that the resale, pledge or transfer is being
     made in reliance on Rule 144A, (iii) to an institution that is an
     "accredited investor" as defined in Rule 501(a)(1), (2), (3) or (7) under
     the Securities Act that is acquiring the Notes in a minimum amount of
     $100,000 for investment purposes and not for distribution and an
     Institutional Accredited Investor Transferee Compliance Letter in the form
     hereof is delivered to the Company and to the Trustee under the Indenture
     relating to the Notes by such accredited investor, (iv) pursuant to any
     other available exemption from registration under the Securities Act, or
     (v) pursuant to an effective registration statement under the Securities
     Act, in each case in accordance with any applicable securities laws of any
     state of the United States, and we will notify any purchaser of the Notes
     from us of the above resale restrictions, if then applicable. We further
     understand that in connection with any transfer of the Notes by us that the
     Company and the Trustee may request, and if so requested we will furnish,
     such opinions of counsel, certificates and/or other information as they may
     reasonably require to confirm that any such transfer complies with the
     foregoing restrictions.

2.   We are an institutional investor and are an "accredited investor" (as
     defined in Rule 501(a)(1), (2), (3) or (7) under the Securities Act) and we
     have such knowledge and experience in financial and business matters as to
     be capable of evaluating the merits and

<PAGE>

     risks of our investment in the Notes, and we and any accounts for which we
     are acting are each able to bear the economic risk of our or its
     investment.

3.   We understand that the Notes will be issued solely in physical certificated
     form (and not in the form of interests in securities deposited with The
     Depository Trust Company) and the minimum principal amount of Notes that
     may be purchased by an institutional accredited investor is $100,000.

4.   We are acquiring the Notes purchased by us for our own account or for one
     or more accounts as to each of which we exercise sole investment
     discretion.

5.   You are entitled to rely upon this letter and you are irrevocably
     authorized to produce this letter or a copy hereof to any interested party
     in any administrative or legal proceeding or official inquiry with respect
     to the matters covered hereby.

                                                  Very truly yours,

                                                  [Name of Purchaser]


                                                  By:
                                                       -------------------------
                                                       Authorized Signature

Dated:          ,
        --------  ----

cc:  Mirant Americas Generation, Inc.

<PAGE>

                                    EXHIBIT D
                    FORM OF REGULATION S TRANSFER CERTIFICATE

Bankers Trust Company
Four Albany Street
New York, New York  10006

Re:  Mirant Americas Generation, Inc.
     7.20% Senior Notes due 2008

Ladies and Gentlemen:

     In connection with our proposed purchase of $           aggregate principal
                                                  ----------
amount of 7.20% Senior Notes due 2008 (the "Notes") of Mirant Americas
Generation, Inc., a Delaware corporation (the "Company"), we confirm that:

     1.   The offer of the Notes was not made to a person in the United States;

     2.   Either (i) at the time the buy order was originated, the transferee
          was outside the United States or we and any person acting on our
          behalf reasonably believed that the transferee was outside the United
          States or (ii) the transaction was executed in, on or through the
          facilities of a designated off-shore securities market and neither we
          nor any person acting on our behalf knows that the transaction has
          been pre-arranged with a buyer in the United States;

     3.   No directed selling efforts have been made in the United States in
          contravention of the requirements of Rule 903(a) or Rule 904(a) of
          Regulation S, as applicable; and

     4.   The transaction is not part of a plan or scheme to evade the
          registration requirements of the Securities Act.

     In addition, if the sale is made during a Distribution Compliance Period
and the provisions of Rule 903(b)(3) or Rule 904(b) of Regulation S are
applicable thereto, we confirm that such sale has been made in accordance with
the applicable provisions of Rule 903(b)(3) or Rule 904(b), as the case may be.

     The Company and the Trustee are entitled to rely upon this letter and are
irrevocably authorized to produce this letter or a copy hereof to any interested
party in any administrative or legal proceedings or official inquiry with
respect to the matters covered hereby. Terms used in this certificate have the
meanings set forth in Regulation S.

Very truly yours,

[Name of Transferor]

<PAGE>


By:                                         By:
        -----------------------------             ------------------------------
        Authorized Signature                      Signature Medallion Guaranteed

Dated:          ,                           Dated:          ,
        --------  ----                              --------  ----

cc:  Mirant Americas Generation, Inc.

<PAGE>

                                    EXHIBIT E
                  FORM OF TRANSFER CERTIFICATE FOR TRANSFER OR
                        EXCHANGE FROM REGULATION S GLOBAL
                          NOTE TO RULE 144A GLOBAL NOTE

Bankers Trust Company
Four Albany Street
New York, New York  10006

Re:  Mirant Americas Generation, Inc.
     7.20% Senior Notes due 2008

Ladies and Gentlemen:

     In connection with our proposed purchase of $           aggregate principal
                                                  ----------
amount of 7.20% Senior Notes due 2008 (the "Notes") of Mirant Americas
Generation, Inc., a Delaware corporation (the "Company"), we confirm that such
purchase is being effected pursuant to and in accordance with Rule 144A under
the Securities Act of 1933, as amended ("Rule 144A"), and, accordingly, we do
hereby further certify that the Notes are being transferred to a person that we
reasonably believe is purchasing the Notes for its own account, or for one or
more accounts with respect to which such person exercises sole investment
discretion, and such person and each such account is a "qualified institutional
buyer" within the meaning of Rule 144A, in each case in a transaction meeting
the requirements of Rule 144A and in accordance with any applicable securities
laws of any state of the United State.

     The Company and Bankers Trust Company, a New York banking corporation, are
entitled to rely upon this letter and are irrevocably authorized to produce this
letter or a copy hereof to any interested party in any administrative or legal
proceedings or official inquiry with respect to the matters covered hereby.

Very truly yours,

[Name of Transferor]


By:
        -----------------------------
        Authorized Signature

Dated:          ,
        --------  ----

cc:  Mirant Americas Generation, Inc.