<PAGE>

                                                                     EXHIBIT 4.5

                    FOURTH SUPPLEMENTAL INDENTURE (this "Fourth Supplemental
               Indenture") dated as of January 11, 2001, among TIME WARNER
               COMPANIES, INC., a Delaware corporation (the "Company"), AOL TIME
               WARNER INC., a Delaware Corporation ("AOL Time Warner"), AMERICA
               ONLINE, INC., a Delaware corporation ("America Online"), TIME
               WARNER INC., a Delaware corporation ("TWI"), TURNER BROADCASTING
               SYSTEM, INC., a Georgia corporation ("TBS"), and THE CHASE
               MANHATTAN BANK (formerly known as Chemical Bank), a New York
               banking corporation, as trustee (the "Trustee").

          WHEREAS the Company has executed and delivered to the Trustee an
Indenture (the "Original Indenture"), dated as of October 15, 1992, as amended
from time to time, by way of the First Supplemental Indenture, dated as of
December 15, 1992, between the Company and the Trustee (the "First Supplemental
Indenture"), the Second Supplemental Indenture, dated as of January 15, 1993,
among the Company and the Trustee (the "Second Supplemental Indenture") and the
Third Supplemental Indenture, dated as of October 10, 1996, among the Company,
TWI and the Trustee (the "Third Supplemental Indenture") (the Original
Indenture, as so amended, is herein called the "Indenture"), providing for the
issuance and sale by the Company from time to time of its senior debt securities
(the "Securities"), which term shall include any Securities issued under the
Indenture after the date hereof;

          WHEREAS TWI has, by way of the Third Supplemental Indenture,
unconditionally guaranteed the obligations of the Company under the Indenture
(the "TWI Guarantee") and has extended to the Holders of Securities certain
rights and privileges in connection with the TWI Guarantee;

          WHEREAS, pursuant to a Second Amended and Restated Agreement and Plan
of Merger, dated as of January 10, 2000, among AOL Time Warner, America Online,
TWI, America Online Merger Sub Inc. and Time Warner Merger Sub Inc., America
Online and TWI will become wholly owned subsidiaries of AOL Time Warner;

          WHEREAS Section 901(5) of the Indenture permits the Company, when
authorized by a resolution of the Board of Directors of the Company, and the
Trustee, at any time and from time to time, to enter into one or more indentures
supplemental to the Indenture, in form satisfactory to the Trustee, for the
purpose of adding to the rights of the Holders of the Securities;

          WHEREAS Section 901(7) of the Indenture permits the Company, when
authorized by a resolution of the Board of Directors of the Company, and the
Trustee, at any time and from time to time, to enter into one or more indentures
supplemental to the Indenture, in form satisfactory to the Trustee, for the
purpose of adding additional Events of Default in respect of the Securities;

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                                                                               2


          WHEREAS the Company proposes in and by this Fourth Supplemental
Indenture to supplement and amend the Indenture in certain respects as it
applies to Securities issued thereunder;

          WHEREAS TBS desires to unconditionally and irrevocably guarantee the
full and punctual payment of principal of and interest on the Securities when
due, whether at maturity, by acceleration, by redemption or otherwise, and all
other monetary obligations of the Company under the Indenture (including
obligations to the Trustee) and the Securities, and the full and punctual
performance within applicable grace periods of all other obligations of the
Company under the Indenture and the Securities (the "TBS Guarantee") and to
extend to the Holders of Securities certain rights and privileges in connection
with the TBS Guarantee;

          WHEREAS TWI desires to unconditionally and irrevocably guarantee all
the monetary obligations of TBS under the TBS Guarantee (including obligations
to the Trustee) and the full and punctual performance of all other obligations
of TBS under the TBS Guarantee (the "Additional TWI Guarantee", and together
with the TWI Guarantee, the "TWI Guarantees") and to extend to the Holders of
Securities certain rights and privileges in connection with the Additional TWI
Guarantee;

          WHEREAS America Online desires to unconditionally and irrevocably
guarantee all the monetary obligations of TWI under the TWI Guarantees
(including obligations to the Trustee) and the full and punctual performance of
all other obligations of TWI under the TWI Guarantees (the "America Online
Guarantee") and to extend to the Holders of Securities certain rights and
privileges in connection with the America Online Guarantee;

          WHEREAS AOL Time Warner desires to unconditionally and irrevocably
guarantee (i) all the monetary obligations of (a) America Online under the
America Online Guarantee and (b) TWI under the TWI Guarantees (including in each
case obligations to the Trustee) and the full and punctual performance of all
other obligations of America Online under the America Online Guarantee and TWI
under the TWI Guarantees (the "AOL Time Warner Guarantee") and to extend to the
Holders of Securities certain rights and privileges in connection with the AOL
Time Warner Guarantee; and

          WHEREAS the Company, AOL Time Warner, America Online, TWI and TBS have
requested that the Trustee execute and deliver this Fourth Supplemental
Indenture and all requirements necessary to make this Fourth Supplemental
Indenture a valid instrument in accordance with its terms and to make the TBS
Guarantee a valid obligation of TBS, the Additional TWI Guarantee a valid
obligation of TWI, the America Online Guarantee a valid obligation of America
Online and the AOL Time Warner Guarantee a valid obligation of AOL Time Warner
and the execution and delivery of this Fourth Supplemental Indenture has been
duly authorized in all respects.

          NOW, THEREFORE, the Company, AOL Time Warner, America Online, TWI, TBS
and the Trustee hereby agree that the following Sections of this Fourth

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                                                                               3


Supplemental Indenture supplement the Indenture with respect to Securities
issued thereunder:

          SECTION 1. Definitions. Capitalized terms used herein and not defined
herein have the meanings ascribed to such terms in the Indenture.

          SECTION 2. The TBS Guarantee. (a) TBS irrevocably and unconditionally
guarantees, to each Holder of Securities (including each Holder of Securities
issued under the Indenture after the date of this Fourth Supplemental Indenture)
and to the Trustee and its successors and assigns, (i) the full and punctual
payment of principal of and interest on the Securities when due, whether at
maturity, by acceleration, by redemption or otherwise, and all other monetary
obligations of the Company under the Indenture (including obligations to the
Trustee) and the Securities and (ii) the full and punctual performance within
applicable grace periods of all other obligations of the Company under the
Indenture and the Securities. TBS further agrees that its obligations hereunder
shall be unconditional irrespective of the absence or existence of any action to
enforce the same, the recovery of any judgment against the Company, AOL Time
Warner, America Online, TWI or TBS (except to the extent such judgment is paid)
or any waiver or amendment of the provisions of the Indenture or the Securities
to the extent that any such action or any similar action would otherwise
constitute a legal or equitable discharge or defense of a guarantor (except that
such waiver or amendment shall be effective in accordance with its terms).

          (b) TBS further agrees that the TBS Guarantee constitutes a guarantee
of payment, performance and compliance and not merely of collection.

          (c) TBS further agrees to waive presentment to, demand of payment from
and protest to the Company of any of the AOL Time Warner Guarantee, the America
Online Guarantee, the TWI Guarantees or the TBS Guarantee, and also waives
diligence, notice of acceptance of the TBS Guarantee, presentment, demand for
payment, notice of protest for nonpayment, the filing of claims with a court in
the event of merger or bankruptcy of the Company and any right to require a
proceeding first against the Company or any other Person. The obligations of TBS
shall not be affected by any failure or policy on the part of the Trustee to
exercise any right or remedy under the Indenture or the Securities of any
series.

          (d) The obligation of TBS to make any payment hereunder may be
satisfied by causing the Company, AOL Time Warner, America Online or TWI to make
such payment. If any Holder of any Security or the Trustee is required by any
court or otherwise to return to the Company, AOL Time Warner, America Online,
TWI or TBS, or any custodian, trustee, liquidator or other similar official
acting in relation to any of the Company, AOL Time Warner, America Online, TWI
or TBS, any amount paid by any of them to the Trustee or such Holder, the TBS
Guarantee, to the extent theretofore discharged, shall be reinstated in full
force and effect.

<PAGE>

                                                                               4


          (e) TBS also agrees to pay any and all costs and expenses (including
reasonable attorneys' fees) incurred by the Trustee or any Holder of Securities
in enforcing any of their respective rights under the TBS Guarantee.

          (f) Any term or provision of this Fourth Supplemental Indenture to the
contrary notwithstanding, the maximum aggregate amount of the TBS Guarantee
shall not exceed the maximum amount that can be hereby guaranteed without
rendering this Fourth Supplemental Indenture, as it relates to TBS, voidable
under applicable law relating to fraudulent conveyance or fraudulent transfer or
similar laws affecting the rights of creditors generally.

          SECTION 3. The Additional TWI Guarantee. (a) TWI irrevocably and
unconditionally guarantees, to each Holder of Securities (including each Holder
of Securities issued under the Indenture after the date of this Fourth
Supplemental Indenture) and to the Trustee and its successors and assigns, (i)
the full and punctual payment of all monetary obligations of TBS under the TBS
Guarantee (including obligations to the Trustee) and (ii) the full and punctual
performance within applicable grace periods of all other obligations of TBS
under the TBS Guarantee. TWI further agrees that its obligations hereunder shall
be unconditional irrespective of the absence or existence of any action to
enforce the same, the recovery of any judgment against the Company, AOL Time
Warner, America Online, TWI or TBS (except to the extent such judgment is paid)
or any waiver or amendment of the provisions of the Indenture or the Securities
to the extent that any such action or any similar action would otherwise
constitute a legal or equitable discharge or defense of a guarantor (except that
such waiver or amendment shall be effective in accordance with its terms).

          (b) TWI further agrees that the Additional TWI Guarantee constitutes a
guarantee of payment, performance and compliance and not merely of collection.

          (c) TWI further agrees to waive presentment to, demand of payment from
and protest to the Company of any of the AOL Time Warner Guarantee, the America
Online Guarantee, the TWI Guarantees or the TBS Guarantee, and also waives
diligence, notice of acceptance of the Additional TWI Guarantee, presentment,
demand for payment, notice of protest for nonpayment, the filing of claims with
a court in the event of merger or bankruptcy of the Company and any right to
require a proceeding first against the Company or any other Person. The
obligations of TWI shall not be affected by any failure or policy on the part of
the Trustee to exercise any right or remedy under the Indenture or the
Securities of any series.

          (d) The obligation of TWI to make any payment hereunder may be
satisfied by causing the Company, AOL Time Warner, America Online or TBS to make
such payment. If any Holder of any Security or the Trustee is required by any
court or otherwise to return to the Company, AOL Time Warner, America Online,
TWI or TBS, or any custodian, trustee, liquidator or other similar official
acting in relation to any of the Company, AOL Time Warner, America Online, TWI
or TBS, any amount paid by any of them to the Trustee or such Holder, the
Additional TWI Guarantee, to the extent theretofore discharged, shall be
reinstated in full force and effect.

<PAGE>

                                                                               5


          (e) TWI also agrees to pay any and all costs and expenses (including
reasonable attorneys' fees) incurred by the Trustee or any Holder of Securities
in enforcing any of their respective rights under the Additional TWI Guarantee.

          (f) Any term or provision of this Fourth Supplemental Indenture to the
contrary notwithstanding, the maximum aggregate amount of the Additional TWI
Guarantee shall not exceed the maximum amount that can be hereby guaranteed
without rendering this Fourth Supplemental Indenture, as it relates to TWI,
voidable under applicable law relating to fraudulent conveyance or fraudulent
transfer or similar laws affecting the rights of creditors generally.

          SECTION 4. The America Online Guarantee. (a) America Online
irrevocably and unconditionally guarantees, to each Holder of Securities
(including each Holder of Securities issued under the Indenture after the date
of this Fourth Supplemental Indenture) and to the Trustee and its successors and
assigns, (i) the full and punctual payment of all monetary obligations of TWI
under the TWI Guarantees (including obligations to the Trustee) and (ii) the
full and punctual performance within applicable grace periods of all other
obligations of TWI under the TWI Guarantees. America Online further agrees that
its obligations hereunder shall be unconditional irrespective of the absence or
existence of any action to enforce the same, the recovery of any judgment
against the Company, AOL Time Warner, America Online, TWI or TBS (except to the
extent such judgment is paid) or any waiver or amendment of the provisions of
the Indenture or the Securities to the extent that any such action or any
similar action would otherwise constitute a legal or equitable discharge or
defense of a guarantor (except that such waiver or amendment shall be effective
in accordance with its terms).

          (b) America Online further agrees that the America Online Guarantee
constitutes a guarantee of payment, performance and compliance and not merely of
collection.

          (c) America Online further agrees to waive presentment to, demand of
payment from and protest to the Company of any of the AOL Time Warner Guarantee,
the America Online Guarantee, the TWI Guarantees or the TBS Guarantee, and also
waives diligence, notice of acceptance of the America Online Guarantee,
presentment, demand for payment, notice of protest for nonpayment, the filing of
claims with a court in the event of merger or bankruptcy of the Company and any
right to require a proceeding first against the Company or any other Person. The
obligations of America Online shall not be affected by any failure or policy on
the part of the Trustee to exercise any right or remedy under the Indenture or
the Securities of any series.

          (d) The obligation of America Online to make any payment hereunder may
be satisfied by causing the Company, AOL Time Warner, TWI or TBS to make such
payment. If any Holder of any Security or the Trustee is required by any court
or otherwise to return to the Company, AOL Time Warner, America Online, TWI or
TBS, or any custodian, trustee, liquidator or other similar official acting in
relation to any of the Company, AOL Time Warner, America Online, TWI or TBS, any
amount paid by

<PAGE>

                                                                               6


any of them to the Trustee or such Holder, the America Online Guarantee, to the
extent theretofore discharged, shall be reinstated in full force and effect.

          (e) America Online also agrees to pay any and all costs and expenses
(including reasonable attorneys' fees) incurred by the Trustee or any Holder of
Securities in enforcing any of their respective rights under the America Online
Guarantee.

          (f) Any term or provision of this Fourth Supplemental Indenture to the
contrary notwithstanding, the maximum aggregate amount of the America Online
Guarantee shall not exceed the maximum amount that can be hereby guaranteed
without rendering this Fourth Supplemental Indenture, as it relates to America
Online, voidable under applicable law relating to fraudulent conveyance or
fraudulent transfer or similar laws affecting the rights of creditors generally.

          SECTION 5. The AOL Time Warner Guarantee. (a) AOL Time Warner
irrevocably and unconditionally guarantees, to each Holder of Securities
(including each Holder of Securities issued under the Indenture after the date
of this Fourth Supplemental Indenture) and to the Trustee and its successors and
assigns, (i) the full and punctual payment of all monetary obligations of
America Online under the America Online Guarantee and TWI under the TWI
Guarantees (including in each case obligations to the Trustee) and (ii) the full
and punctual performance within applicable grace periods of all other
obligations of America Online under the America Online Guarantee and TWI under
the TWI Guarantees. AOL Time Warner further agrees that its obligations
hereunder shall be unconditional irrespective of the absence or existence of any
action to enforce the same, the recovery of any judgment against the Company,
AOL Time Warner, America Online, TWI or TBS (except to the extent such judgment
is paid) or any waiver or amendment of the provisions of the Indenture or the
Securities to the extent that any such action or any similar action would
otherwise constitute a legal or equitable discharge or defense of a guarantor
(except that such waiver or amendment shall be effective in accordance with its
terms).

          (b) AOL Time Warner further agrees that the AOL Time Warner Guarantee
constitutes a guarantee of payment, performance and compliance and not merely of
collection.

          (c) AOL Time Warner further agrees to waive presentment to, demand of
payment from and protest to the Company of any of the AOL Time Warner Guarantee,
the America Online Guarantee, the TWI Guarantees or the TBS Guarantee, and also
waives diligence, notice of acceptance of the Guarantee, presentment, demand for
payment, notice of protest for nonpayment, the filing of claims with a court in
the event of merger or bankruptcy of the Company and any right to require a
proceeding first against the Company or any other Person. The obligations of AOL
Time Warner shall not be affected by any failure or policy on the part of the
Trustee to exercise any right or remedy under the Indenture or the Securities of
any series.

          (d) The obligation of AOL Time Warner to make any payment hereunder
may be satisfied by causing the Company, America Online, TWI or TBS to make such

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                                                                               7


payment. If any Holder of any Security or the Trustee is required by any court
or otherwise to return to the Company, AOL Time Warner, America Online, TWI or
TBS, or any custodian, trustee, liquidator or other similar official acting in
relation to any of the Company, AOL Time Warner, America Online, TWI or TBS, any
amount paid by any of them to the Trustee or such Holder, the AOL Time Warner
Guarantee, to the extent theretofore discharged, shall be reinstated in full
force and effect.

          (e) AOL Time Warner also agrees to pay any and all costs and expenses
(including reasonable attorneys' fees) incurred by the Trustee or any Holder of
Securities in enforcing any of their respective rights under the AOL Time Warner
Guarantee.

          (f) Any term or provision of this Fourth Supplemental Indenture to the
contrary notwithstanding, the maximum aggregate amount of the AOL Time Warner
Guarantee shall not exceed the maximum amount that can be hereby guaranteed
without rendering this Fourth Supplemental Indenture, as it relates to AOL Time
Warner, voidable under applicable law relating to fraudulent conveyance or
fraudulent transfer or similar laws affecting the rights of creditors generally.

          SECTION 6. Amendment to Defeasance upon Deposit of Funds or Government
Obligations. Section 403 of Article Four of the Indenture is hereby supplemented
and amended by adding the following sentence following clause (5) and before the
definition of "Discharged":

          "If the Company, at its option, with respect to a series of
     Securities, satisfies the applicable conditions pursuant to either clause
     (a) or (b) above, then (x), in the event the Company satisfies the
     conditions to clause (a) and elects clause (a) to be applicable, each of
     AOL Time Warner, America Online, TWI and TBS shall be deemed to have paid
     and discharged the entire indebtedness represented by, and obligations
     under, the AOL Time Warner Guarantee, the America Online Guarantee, the TWI
     Guarantees and the TBS Guarantee of the Securities of such series and to
     have satisfied all the obligations under this Indenture relating to the
     Securities of such series and (y) in an any case, each of AOL Time Warner,
     America Online, TWI and TBS shall cease to be under any obligation to
     comply with any term, provision or condition set forth in Article Eight
     (and any other covenants applicable to such Securities that are determined
     pursuant to Section 301 to be subject to this provision), and clause
     (5)(ii) of Section 501 (and any other Events of Default applicable to such
     series of Securities that are determined pursuant to Section 301 to be
     subject to this provision) shall be deemed not to be an Event of Default
     with respect to such series of Securities at any time thereafter."

          SECTION 7. Amendments to the Events of Default and Remedies. (a)
Clause (5) of Section 501 of Article Five of the Indenture is hereby amended by
redesignating clause (5) as clause (5)(i) and by adding thereto at the end
thereof the following:

<PAGE>

                                                                               8


          "; or (ii) default in the performance, or breach, of any covenant or
     warranty of AOL Time Warner, America Online, TWI or TBS in this Indenture
     (as it may be supplemented from time to time) in respect of the Securities
     of such series (other than a covenant or warranty in respect of the
     Securities of such series a default in the performance of which or the
     breach of which is elsewhere in this Section specifically dealt with), all
     of such covenants and warranties in the Indenture (as so supplemented)
     which are not expressly stated to be for the benefit of a particular series
     of Securities being deemed in respect of the Securities of all series for
     this purpose, and continuance of such default or breach for a period of 90
     days after there has been given, by registered or certified mail, to AOL
     Time Warner, America Online, TWI or TBS, as the case may be, by the Trustee
     or to AOL Time Warner, America Online, TWI or TBS, as the case may be, and
     the Trustee by the Holders or at least 25% in principal amount of the
     Outstanding Securities of such series, a written notice specifying such
     default or breach and requiring it to be remedied and stating that such
     notice is a 'Notice of Default' hereunder; or".

          (b) Clause (6) of Section 501 of Article Five of the Indenture is
hereby amended by redesignating clause (6) as clause (6)(i) and by adding
thereto at the end thereof the following:

          "; or (ii) the entry of an order for relief against AOL Time Warner or
     any Material U.S. Subsidiary thereof under the Federal Bankruptcy Act by a
     court having jurisdiction in the premises or a decree or order by a court
     having jurisdiction in the premises adjudging AOL Time Warner or any
     Material U.S. Subsidiary thereof bankrupt or insolvent under any other
     applicable Federal or State law, or the entry of a decree or order
     approving as properly filed a petition seeking reorganization, arrangement,
     adjustment or composition of or in respect of AOL Time Warner or any
     Material U.S. Subsidiary thereof under the Federal Bankruptcy Act or any
     other applicable Federal or State law, or appointing a receiver,
     liquidator, assignee, trustee, sequestrator (or other similar official) of
     AOL Time Warner or any Material U.S. Subsidiary thereof or of any
     substantial part of its property, or ordering the winding up or liquidation
     of its affairs, and the continuance of any such decree or order unstayed
     and in effect for a period of 90 consecutive days; or".

          (c) Clause (7) of Section 501 of Article Five of the Indenture is
hereby amended by redesignating clause (7) as clause (7)(i) and by adding
thereto at the end thereof the following:

          "; or (ii) the consent by AOL Time Warner or any Material U.S.
     Subsidiary thereof to the institution of bankruptcy or insolvency
     proceedings against it, or the filing by it of a petition or answer or
     consent seeking reorganization or relief under the Federal Bankruptcy Act
     or any other applicable Federal or State law, or the consent by it to the
     filing of any such petition or to the appointment of a receiver,
     liquidator, assignee, trustee, sequestrator (or other similar official) of
     AOL Time Warner or any Material U.S. Subsidiary thereof or

<PAGE>

                                                                               9


     of any substantial part of its property, or the making by it of an
     assignment for the benefit of creditors, or the admission by it in writing
     of its inability to pay its debts generally as they become due, or the
     taking of corporate action by AOL Time Warner or any Material U.S.
     Subsidiary thereof in furtherance of any such action; or".

          SECTION 8. Amendments to Article Eight. (a) The introductory clause
and clause (1) of Section 801 of Article Eight of the Indenture is hereby
supplemented and amended to read in its entirety as follows:

          "Section 801. Company May Consolidate, etc., only on Certain Terms.
     None of the Company, AOL Time Warner, America Online, TWI or TBS shall
     consolidate with or merge into any other corporation or convey or transfer
     its properties and assets substantially as an entirety to any Person,
     unless:

          "(1)(a) In the case of the Company, the corporation formed by such
     consolidation or into which the Company is merged or the Person which
     acquires by conveyance or transfer the properties and assets of the Company
     substantially as an entirety shall be organized and existing under the laws
     of the United States of America or any State or the District of Columbia,
     and shall expressly assume, by an indenture supplemental hereto, executed
     and delivered to the Trustee, in form satisfactory to the Trustee, the due
     and punctual payment of the principal of (and premium, if any) and interest
     on all the Securities and the performance of every covenant of this
     Indenture (as supplemented from time to time) on the part of the Company to
     be performed or observed; (b) in the case of AOL Time Warner, America
     Online, TWI or TBS, the corporation formed by such consolidation or into
     which AOL Time Warner, America Online, TWI or TBS is merged or the Person
     which acquires by conveyance or transfer the properties and assets of AOL
     Time Warner, America Online, TWI or TBS substantially as an entirety shall
     be either (i) the Company or (ii) a Person organized and existing under the
     laws of the United States of America or any State or the District of
     Columbia, and in the case of clauses (ii), shall expressly assume, by an
     indenture supplemental hereto, executed and delivered to the Trustee, in
     form satisfactory to the Trustee, the performance of every covenant of this
     Indenture (as supplemented from time to time) on the part of AOL Time
     Warner, America Online, TWI or TBS to be performed or observed;".

          (b) Section 802 of Article Eight of the Indenture is supplemented and
amended to read in its entirety as follows:

          "Section 802. Successor Person Substituted. Upon any consolidation or
     merger, or any conveyance or transfer of the properties and assets of the
     Company, AOL Time Warner, America Online, TWI or TBS substantially as an
     entirety in accordance with Section 801, the successor Person formed by
     such consolidation or into which the Company, AOL Time Warner, America
     Online, TWI or TBS is merged or to which such conveyance or transfer is
     made shall succeed to, and be substituted for, and may exercise every right
     and power of, the

<PAGE>

                                                                              10


     Company, AOL Time Warner, America Online, TWI or TBS, as the case may be,
     under this Indenture with the same effect as if such successor had been
     named as the Company, AOL Time Warner, America Online, TWI or TBS herein,
     as the case may be. In the event of any such conveyance or transfer, the
     Company, AOL Time Warner, America Online, TWI or TBS, as the case may be,
     as the predecessor shall be discharged from all obligations and covenants
     under this Indenture and the Securities and may be dissolved, wound up or
     liquidated at any time thereafter."

          SECTION 9. Supplemental Indentures. Clauses (1) and (2) of Section 901
of Article Nine of the Indenture are supplemented and amended to read in their
entirety as follows:

          "(1) to evidence the succession of another corporation or Person to
     the Company, AOL Time Warner, America Online, TWI or TBS, and the
     assumption by any such successor of the respective covenants of the
     Company, AOL Time Warner, America Online, TWI or TBS herein and in the
     Securities contained; or

          "(2) to add to the covenants of the Company, AOL Time Warner, America
     Online, TWI or TBS or to surrender any right or power herein conferred upon
     the Company, AOL Time Warner, America Online, TWI or TBS, for the benefit
     of the Holders of the Securities of any or all series (and if such
     covenants or the surrender of such right or power are to be for the benefit
     of less than all series of Securities, stating that such covenants are
     expressly being included or such surrenders are expressly being made solely
     for the benefit of one or more specified series); or".

          SECTION 10. Reports. AOL Time Warner shall file with the Trustee, and
transmit to Holders, such information, documents and other reports, and such
summaries thereof, as may be required pursuant to the Trust Indenture Act at the
times and in the manner provided pursuant to such Act; provided that any such
information, documents or reports required to be filed with the Commission
pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 shall be
filed with the Trustee within 15 days after the same is so required to be filed
with the Commission.

          SECTION 11. This Fourth Supplemental Indenture. This Fourth
Supplemental Indenture shall be construed as supplemental to the Indenture and
shall form a part of it, and the Indenture is hereby incorporated by reference
herein and each is hereby ratified, approved and confirmed.

          SECTION 12. GOVERNING LAW. THIS FOURTH SUPPLEMENTAL INDENTURE SHALL BE
GOVERNED AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

          SECTION 13. Counterparts. This Fourth Supplemental Indenture may be
executed in two or more counterparts, each of which shall constitute an
original, but all of which when taken together shall constitute but one
instrument.

<PAGE>

                                                                              11


          SECTION 14. Headings. The headings of this Fourth Supplemental
Indenture are for reference only and shall not limit or otherwise affect the
meaning hereof.

          SECTION 15. Trustee Not Responsible for Recitals. The recitals herein
contained are made by the Company, AOL Time Warner, America Online, TWI and TBS
and not by the Trustee, and the Trustee assumes no responsibility for the
correctness thereof. The Trustee shall not be responsible in any manner
whatsoever for or in respect of the validity or sufficiency of this Fourth
Supplemental Indenture.

          SECTION 16. Separability. In case any one or more of the provisions
contained in this Fourth Supplemental Indenture or in the Securities shall for
any reason be held to be invalid, illegal or unenforceable in any respect, such
invalidity, illegality or unenforceability shall not affect any other provisions
of this Fourth Supplemental Indenture or of the Securities, but this Fourth
Supplemental Indenture and the Securities shall be construed as if such invalid
or illegal or unenforceable provision had never been contained herein or
therein.

<PAGE>

                                                                              12


          IN WITNESS WHEREOF, the parties hereto have caused this Fourth
Supplemental Indenture to be duly executed by their respective authorized
officers as of the date first written above.

                                        TIME WARNER COMPANIES, INC.,


                                        by /s/ Thomas W. McEnerney
                                           -------------------------------------
                                        Name: Thomas W. McEnerney
                                        Title: Vice President


                                        AOL TIME WARNER INC.,


                                        by /s/ J. Michael Kelly
                                           -------------------------------------
                                        Name: J. Michael Kelly
                                        Title: Executive Vice President
                                        and Chief Financial Officer


                                        AMERICA ONLINE, INC.,


                                        by /s/ Paul T. Cappuccio
                                           -------------------------------------
                                        Name: Paul T. Cappuccio
                                        Title: Senior Vice President


                                        TIME WARNER INC.,


                                        by /s/ Thomas W. McEnerney
                                           -------------------------------------
                                        Name: Thomas W. McEnerney
                                        Title: Vice President


                                        TURNER BROADCASTING SYSTEM, INC.,


                                        by /s/ Thomas W. McEnerney
                                           -------------------------------------
                                        Name: Thomas W. McEnerney
                                        Title: Vice President

<PAGE>

                                                                              13


                                        THE CHASE MANHATTAN BANK, as Trustee,


                                        by /s/ R. Lorenzen
                                           -------------------------------------
                                        Name: R. Lorenzen
                                        Title: Assistant Vice President