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                                                                     EXHIBIT 4.4


                            FORM OF GLOBAL DEBENTURE

THIS SECURITY IS A GLOBAL DEBENTURE UNDER THE INDENTURE HEREINAFTER REFERRED TO
AND IS REGISTERED IN THE NAME OF A DEPOSITORY (AS DEFINED IN THE INDENTURE) OR A
NOMINEE THEREOF. UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE OR IN PART FOR
SECURITIES IN DEFINITIVE FORM, THIS GLOBAL DEBENTURE MAY NOT BE TRANSFERRED
EXCEPT AS A WHOLE BY THE DEPOSITORY TO A NOMINEE OF THE DEPOSITORY, OR BY A
NOMINEE OF THE DEPOSITORY TO THE DEPOSITORY OR ANOTHER NOMINEE OF THE
DEPOSITORY, OR BY THE DEPOSITORY OR ANY SUCH NOMINEE TO A SUCCESSOR DEPOSITORY
OR A NOMINEE OF SUCH SUCCESSOR DEPOSITORY.

UNLESS THIS SECURITY IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO THE COMPANY OR ITS
AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE, OR PAYMENT, AND ANY SECURITY
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.

No.                                                               $400,000,000
CUSIP No. 530715AN1

                            LIBERTY MEDIA CORPORATION

                   3-1/2% Senior Exchangeable Debentures due 2031

                                Global Debenture

      Liberty Media Corporation, a Delaware corporation (hereinafter called the
"Company", which term includes any successor corporation under the Indenture
referred to below), for value received, hereby promises to pay to Cede & Co., or
registered assigns, the amount provided in Section 204 of the Fifth Supplemental
Indenture referred to herein (such amount being referred to herein as the
Maturity Repayment Amount) on January 15, 2031, and to pay interest on the
Original Principal Amount of this Debenture from January 11, 2001, or from the
most recent date to which interest has been paid or provided for, semiannually
on January 15 and July 15 in each year (each, an "Interest Payment Date"),
commencing July 15, 2001, at the rate of 3-1/2% per annum, until the Maturity
Repayment Amount is paid or made available for payment. Interest on this
Debenture shall be calculated on the basis of a 360-day year consisting of
twelve 30-day months. The interest so payable and paid or provided for on any
Interest Payment Date will, as provided in such Indenture, be paid to the Person
in whose name this Debenture (or one or more Predecessor Securities) is
registered at the close of business on the Regular Record Date for such
interest, which shall be the January 1 or July 1 (whether or not a Business
Day), as the case may be, immediately preceding such Interest Payment Date. Any
such interest which is payable, but is not paid or provided for, on any Interest
Payment Date shall forthwith cease to be payable to the registered Holder hereof
on the relevant Regular Record Date by virtue of having
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been such Holder, and may be paid to the Person in whose name this Debenture (or
one or more Predecessor Securities) is registered at the close of business on a
Special Record Date for the payment of such Defaulted Interest to be fixed by
the Company, notice whereof shall be given to the Holders of Debentures not less
than 10 days prior to such Special Record Date, or may be paid at any time in
any other lawful manner not inconsistent with the requirements of any securities
exchange on which the Debentures may be listed, and upon such notice as may be
required by such exchange, all as more fully provided in such Indenture.

      Payment of the Maturity Repayment Amount and the interest on this
Debenture will be made at the office or agency of the Company maintained for
that purpose in The Borough of Manhattan, The City of New York, 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; provided, however, that, at the
option of the Company, interest may be paid by check mailed to the address of
the Person entitled thereto as such address shall appear in the Security
Register; provided, further, that payment to DTC or any successor Depository may
be made by wire transfer to the account designated by DTC or such successor
Depository in writing.

      This Security is a global Debenture issued on the date hereof which
represents $400,000,000 of the Original Principal Amount of the Company's 3-1/2%
Senior Exchangeable Debentures due 2031. This Debenture is one of a duly
authorized issue of securities of the Company (herein called the "Debentures")
issued and to be issued in one or more series under an Indenture dated as of
July 7, 1999 (herein called, together with the Fifth Supplemental Indenture
referred to below and all other indentures supplemental thereto, the
"Indenture") between the Company and The Bank of New York, as Trustee (herein
called the "Trustee", which term includes any successor trustee under the
Indenture), to which Indenture and all indentures supplemental thereto reference
is hereby made for a statement of the respective rights, limitations of rights,
duties and immunities thereunder of the Company, the Trustee and the Holders of
the Debentures, and of the terms upon which the Debentures are, and are to be,
authenticated and delivered. This Debenture is one of the series designated on
the face hereof, initially limited (subject to exceptions provided in the
Indenture) to the aggregate Original Principal Amount specified in the Fifth
Supplemental Indenture between the Company and the Trustee, dated as of January
11, 2001, establishing the terms of the Debentures pursuant to the Indenture
(the "Fifth Supplemental Indenture").

      The Debentures are redeemable at the option of the Company, in whole or in
part at any time or from time to time on or after January 15, 2006, on the terms
set forth in Section 208(a) of the Fifth Supplemental Indenture.

      The Debentures are exchangeable at the option of the Holders thereof, on
the terms set forth in Section 209 of the Fifth Supplemental Indenture.

      If an Event of Default (as defined in the Indenture, including the
amendments thereto in the Fifth Supplemental Indenture) with respect to the
Debentures shall occur and be continuing, the principal of the Debentures may be
declared due and payable in the manner and with the effect provided in the
Indenture.

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      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 Securities of each series issued
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 aggregate principal amount of the
Securities at the time Outstanding of each series affected thereby. The
Indenture also contains provisions permitting the Holders of specified
percentages in aggregate principal amount of the Securities of any series at the
time Outstanding, on behalf of the Holders of all Securities 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 Debenture shall be conclusive and
binding upon such Holder and upon all future Holders of this Debenture and of
any Debentures issued upon the registration of transfer hereof or in exchange
herefor or in lieu hereof, whether or not notation of such consent or waiver is
made upon this Debenture or such Debentures.

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

      As provided in the Indenture and subject to certain limitations set forth
therein and in this Debenture, the transfer of this Debenture may be registered
on the Security Register upon surrender of this Debenture for registration of
transfer at the office or agency of the Company maintained for the purpose in
any place where the Maturity Repayment Amount and interest on this Debenture are
payable, duly endorsed by, or accompanied by a written instrument of transfer in
form satisfactory to the Company and the Security Registrar duly executed by,
the Holder hereof or by his attorney duly authorized in writing, and thereupon
one or more new Debentures of this series and of like tenor, of authorized
denominations and for the same aggregate Original Principal Amount, will be
issued to the designated transferee or transferees.

      The Debentures are issuable only in registered form without coupons in the
denominations specified in the Fifth Supplemental Indenture establishing the
terms of the Debentures, all as more fully provided in the Indenture. As
provided in the Indenture, and subject to certain limitations set forth in the
Indenture and in this Debenture, the Debentures are exchangeable for a like
aggregate Original Principal Amount of Debentures of this series in different
authorized denominations, as requested by the Holders surrendering the same.

      No service charge shall be made for any such registration of transfer or
exchange, but the Company may require payment of a sum sufficient to cover any
tax or other governmental charge payable in connection therewith, other than in
certain cases provided in the Indenture.

      Prior to due presentment of this Debenture 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 Debenture is registered as the owner hereof for
all purposes, whether or not this Debenture be overdue, and neither the Company,
the Trustee nor any such agent shall be affected by notice to the contrary.

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

      All terms used in this Debenture which are defined in the Indenture shall
have the meanings assigned to them in the Indenture.

      Unless the certificate of authentication hereon has been executed by or on
behalf of the Trustee under the Indenture by the manual signature of one of its
authorized signatories, this Debenture shall not be entitled to any benefits
under the Indenture or be valid or obligatory for any purpose.



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      IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed.




                                          LIBERTY MEDIA CORPORATION



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



                     TRUSTEE'S CERTIFICATE OF AUTHENTICATION

      This is one of the Debentures of the series designated herein referred to
in the within-mentioned Indenture.

Dated:                     , 2001         THE BANK OF NEW YORK,
                                          as Trustee


                                       By:
                                          --------------------------------
                                                 Authorized Signatory

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                             CERTIFICATE OF TRANSFER


     To transfer or assign this Debenture, fill in the form below:

I or we transfer and assign this Debenture to


--------------------------------------------------------------------------------
                        (Insert assignee's tax I.D. number)


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

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

--------------------------------------------------------------------------------
               (Print or Type assignee's name, address and zip code)

and irrevocably appoint ________________ agent to transfer this Debenture on the
books of the Company. The agent may substitute another to act for him.


Date:                               Your signature:
     -------------------------                     ---------------------------





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                                   SCHEDULE A

                              SCHEDULE OF EXCHANGES

The following exchanges of Debentures represented by this global Debenture have
been made:


<TABLE>
<CAPTION>
Original Principal               Change in         Original
Amount of this                   Original          Principal Amount
global Debenture                 Principal Amount  of this global
as of               Date         of this global    Debenture
                    exchange     Debenture due to  following such
, 2001              made         exchange          exchange          Notation made by
--------------------------------------------------------------------------------------
<S>                 <C>          <C>               <C>               <C>
   $400,000,000


</TABLE>