<PAGE>

                                                                    Exhibit 4.01

          This Note is a Global Security within the meaning of the Indenture
hereinafter referred to and is registered in the name of the Depository named
below or a nominee of the Depository. This Note is not exchangeable for Notes
registered in the name of a Person other than the Depository or its nominee
except in the limited circumstances described herein and in the Indenture, and
no transfer of this Note (other than a transfer of this Note 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) may be registered except in
the limited circumstances described herein.

          Unless this certificate is presented by an authorized representative
of The Depository Trust Company, a New York corporation (the "Depository"), to
the Company or its agent for registration of transfer, exchange, or payment, and
any certificate issued is registered in the name of Cede & Co. or in such other
name as is requested by an authorized representative of the Depository (and any
payment is made to Cede & Co. or to such other entity as is requested by an
authorized representative of the Depository), 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.

                                 CITIGROUP INC.

REGISTERED                                                            REGISTERED

                                                              CUSIP: 172967 DD 0
                                                              ISIN: US172967DD00

No. R-0001-DTC-A                                                  Y_____________

          CITIGROUP INC., a Delaware corporation (the "Company", which term
includes any successor Person under the Indenture), for value received, hereby
promises to pay to Cede & Co., or registered assigns, the principal sum of
Y________ (or such other principal sum as has been most lately endorsed on the
Schedule of Exchanges of Interests hereto) on October 31, 2025 and to pay
interest thereon from and including October 31, 2005 or from the most recent
Interest Payment Date to which interest has been paid or duly provided for, in
equal amounts semi-annually on April 30 and October 31 of each year, commencing
May 1, 2006, at the rate of 2.40% per annum, in the amount of Yen 1,200 per each
Yen 100,000 principal amount of this Note, until the principal hereof is paid or
made available for payment. The interest so payable, and punctually paid or duly
provided for, on any Interest Payment Date will, as provided in the Indenture,
be paid to the Person in whose name this Note is registered at the close of
business on the Record Date for such interest, which shall be the April 15 or
October 15 (whether or not a Business Day) next preceding such Interest Payment
Date.

<PAGE>

          Any such interest not so punctually paid or duly provided for will
forthwith cease to be payable to the holder on such Record Date and may either
be paid to the Person in whose name this Note is registered at the close of
business on a subsequent Record Date, such subsequent Record Date to be not less
than five days prior to the date of payment of such defaulted interest, notice
whereof shall be given to holders of Notes of this series not less than 15 days
prior to such subsequent Record Date, or be paid at any time in any other lawful
manner not inconsistent with the requirements of any securities exchange on
which the Notes of this series may be listed, and upon such notice as may be
required by such exchange, all as more fully provided in the Indenture.

     In the case of any period of less than six months and any date other than
an Interest Payment Date, interest hereon will be calculated on the basis of the
actual number of days in the relevant period and a year of 365 days.

     If either a date for payment of principal or interest on the Notes or the
Maturity of the Notes falls on a day that is not a Business Day, the related
payment of principal or interest will be made on the next succeeding Business
Day as if made on the date the payment was due. No interest will accrue on any
amounts payable for the period from and after the date for payment of principal
or interest on the Notes or the Maturity of the Notes. For these purposes,
"Business Day" means any day which is a day on which commercial banks and
foreign exchange markets settle payments and are open for general business
(including dealings in foreign exchange and foreign currency deposits) in (a)
the relevant place of payment and (b) each of The City of New York, Tokyo and
London.

          Payment of the principal of and interest on this Note will be made at
the office or agency of the Company maintained for that purpose in London or The
City of New York in Japanese Yen, provided that holders of interests in this
Note through The Depository Trust Company will receive payment in United States
dollars unless they make an election to receive payment in Japanese Yen in
accordance with the procedures of The Depository Trust Company and the Fiscal
Agency Agreement dated as of October 31, 2005 (the "Fiscal Agency Agreement"),
in which case the exchange agent under the Fiscal Agency Agreement will convert
the Japanese Yen paid by the Company into U.S. dollars in accordance with the
Fiscal Agency Agreement.

          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 or by the authenticating agent on behalf of the Trustee referred to
on the reverse hereof by manual signature, this Note shall not be entitled to
any benefit under the Indenture or be valid or obligatory for any purpose.

<PAGE>

          IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed under its corporate seal.

Dated: October 31, 2005

                                        CITIGROUP INC.


                                        By:
                                            ------------------------------------
                                        Title: Treasurer


ATTEST:


By:
    ---------------------------------
Assistant Secretary

<PAGE>

          This is one of the Notes of the series issued under the
within-mentioned Indenture.

Dated: October 31, 2005

                                        THE BANK OF NEW YORK,
                                        as Trustee


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

                                        -or-


                                        CITIBANK, N.A., LONDON OFFICE,
                                        as Authenticating Agent


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

<PAGE>

          This Note is one of a duly authorized issue of Securities of the
Company (the "Notes"), issued and to be issued in one or more series under the
Indenture, dated as of March 15, 1987 (as amended and supplemented to date, the
"Indenture"), between the Company and The Bank of New York, as Trustee (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 Notes
and of the terms upon which the Notes are, and are to be, authenticated and
delivered. This Note is one of the series designated on the face hereof,
initially issued in the aggregate principal amount of Y50,000,000,000.

          So long as the Notes of this series are in the form of Global
Securities only, all Notes of this series will collectively be evidenced (a) by
this Global Note (the "DTC Global Note") and (b) by the Global Security of this
series registered in the name of Citivic Nominees Limited (the "International
Global Note"). The DTC Global Note and the International Global Note will at all
times collectively represent the aggregate principal amount of this series
outstanding from time to time. If at any time a portion of the International
Global Note is exchanged for an interest in the DTC Global Note, the principal
amount of the DTC Global Note shall be increased by the amount of such portion,
and the DTC Global Note shall be endorsed on the Schedule of Exchanges of
Interests thereto to reflect such principal increase, subject to the limitation
that in no event may the principal amount of the DTC Global Note be greater than
the equivalent in U.S. dollars of $500,000,000. If at any time a portion of the
DTC Global Note is exchanged for an interest in the International Global Note,
the principal amount of the DTC Global Note shall be decreased by the amount of
such portion, and the DTC Global Note shall be endorsed on the Schedule of
Exchanges of Interests thereto to reflect such principal decrease. To ascertain
the U.S. dollar equivalent of the principal amount endorsed on the Schedule of
Exchanges of Interests attached to the DTC Global Note, inquiry shall be made of
the exchange agent under the Fiscal Agency Agreement, and the U.S. dollar
equivalent quoted by such exchange agent (and the date of such quote) shall be
noted on such Schedule of Exchanges of Interests next to the corresponding Yen
amount.

          If an event of default (as defined in the Indenture) with respect to
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 and with the effect
provided in the Indenture.

          The Indenture contains provisions for defeasance at any time of the
entire indebtedness of this Note upon compliance by the Company with certain
conditions set forth in Sections 11.03 and 11.04 thereof, which provisions apply
to this Note.

          The Indenture contains provisions permitting the Company and the
Trustee, without the consent of the holders of Securities, to establish, among
other things, the form and terms of any series of Securities issuable thereunder
by one or more supplemental indentures, and, with the consent of the holders of
not less than 66 2/3% in aggregate principal amount of Securities at the time
Outstanding which are affected thereby, to modify the Indenture or any

<PAGE>

supplemental indenture or the rights of the holders of Securities of such series
to be affected, provided that no such modification will (x) extend the fixed
maturity of any Securities, reduce the rate or extend the time of payment of
interest thereon, reduce the principal amount thereof or the premium, if any,
thereon, reduce the amount of the principal of Original Issue Discount
Securities payable on any date, change the currency in which Securities are
payable, or impair the right to institute suit for the enforcement of any such
payment on or after the maturity thereof, without the consent of the holder of
each Security so affected, or (y) reduce the aforesaid percentage of Securities
of any series the consent of the holders of which is required for any such
modification without the consent of the holders of all Securities of such series
then Outstanding, or (z) modify, without the written consent of the Trustee, the
rights, duties or immunities of the Trustee.

          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.

          This Note is a Global Security registered in the name of a nominee of
the Depository. This Note is exchangeable for Notes registered in the name of a
person other than the Depository or its nominee only in the limited
circumstances hereinafter described. Unless and until it is exchanged in whole
or in part for definitive Notes in certificated form, this Note 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.

          The Notes represented by this Global Security are exchangeable for
definitive Notes in certificated form of like tenor as such Notes in
denominations of Y1,000,000 and integral multiples thereof only if (i) the
Depository notifies the Company that it is unwilling or unable to continue as
Depository for the DTC Global Note or (ii) the Depository ceases to be a
clearing agency registered under the Securities Exchange Act of 1934, as
amended, or (iii) both the Euroclear System and Clearstream Banking, societe
anonyme, notify the Company that they are unwilling or unable to continue as a
clearing system for the International Global Note or (iv) the Company in its
sole discretion decides to allow the Notes to be exchanged for definitive Notes
in registered form. Any Notes that are exchangeable pursuant to the preceding
sentence are exchangeable for certificated Notes issuable in authorized
denominations and registered in such names as the Depository shall direct. As
provided in the Indenture and subject to certain limitations therein set forth,
the transfer of definitive Notes in certificated form is registrable in the
register maintained by the Company for such purpose, upon surrender of the
definitive Note for registration of transfer at the office or agency of the
Company in any place where the principal of and interest on the definitive Note
are payable, duly endorsed by, or accompanied by a written instrument of
transfer in form satisfactory to the Company and the registrar duly executed by,
the holder thereof or his attorney duly authorized in writing, and thereupon one
or more new Notes of this series and of like tenor, of authorized denominations
and for the same aggregate principal amount, will be issued to the designated
transferee or transferees. Subject to the foregoing, this Note is not
exchangeable, except for a Global Security or Global Securities of

<PAGE>

this issue of the same principal amount to be registered in the name of the
Depository or its nominee.

          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.

          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 Company will pay additional amounts ("Additional Amounts") to the
beneficial owner of any Note that is a non-United States person in order to
ensure that every net payment on such Note will not be less, due to payment of
U.S. withholding tax, than the amount then due and payable. For this purpose, a
"net payment" on a Note means a payment by the Company or a paying agent,
including payment of principal and interest, after deduction for any present or
future tax, assessment or other governmental charge of the United States. These
Additional Amounts will constitute additional interest on the Note.

          The Company will not be required to pay Additional Amounts, however,
in any of the circumstances described in items (1) through (12) below.

          (1)  Additional Amounts will not be payable if a payment on a Note is
               reduced as a result of any tax, assessment or other governmental
               charge that is imposed or withheld solely by reason of the
               beneficial owner:

               (a)  having a relationship with the United States as a citizen,
                    resident or otherwise;

               (b)  having had such a relationship in the past or

               (c)  being considered as having had such a relationship.

          (2)  Additional Amounts will not be payable if a payment on a Note is
               reduced as a result of any tax, assessment or other governmental
               charge that is imposed or withheld solely by reason of the
               beneficial owner:

               (a)  being treated as present in or engaged in a trade or
                    business in the United States;

               (b)  being treated as having been present in or engaged in a
                    trade or business in the United States in the past or

               (c)  having or having had a permanent establishment in the United
                    States.

          (3)  Additional Amounts will not be payable if a payment on a Note is
               reduced as a result of any tax, assessment or other governmental
               charge that is imposed or withheld solely by reason of the
               beneficial owner being or having been a:

               (a)  personal holding company;

               (b)  foreign personal holding company;

<PAGE>

               (c)  foreign private foundation or other foreign tax-exempt
                    organization;

               (d)  passive foreign investment company;

               (e)  controlled foreign corporation or

               (f)  corporation which has accumulated earnings to avoid United
                    States federal income tax.

          (4)  Additional Amounts will not be payable if a payment on a Note is
               reduced as a result of any tax, assessment or other governmental
               charge that is imposed or withheld solely by reason of the
               beneficial owner owning or having owned, actually or
               constructively, 10 percent or more of the total combined voting
               power of all classes of stock of the Company entitled to vote.

For purposes of item (1) through (4) above, "beneficial owner" means a
fiduciary, settlor, beneficiary, member or shareholder of the holder if the
holder is an estate, trust, partnership, limited liability company, corporation
or other entity, or a person holding a power over an estate or trust
administered by a fiduciary holder.

          (5)  Additional Amounts will not be payable to any beneficial owner of
               a Note that is a:

               (a)  fiduciary;

               (b)  partnership;

               (c)  limited liability company or

               (d)  other fiscally transparent entity

               or that is not the sole beneficial owner of the Note, or any
               portion of the Note. However, this exception to the obligation to
               pay Additional Amounts will only apply to the extent that a
               beneficiary or settlor in relation to the fiduciary, or a
               beneficial owner or member of the partnership, limited liability
               company or other fiscally transparent entity, would not have been
               entitled to the payment of an Additional Amount had the
               beneficiary, settlor, beneficial owner or member received
               directly its beneficial or distributive share of the payment.

          (6)  Additional Amounts will not be payable if a payment on a Note is
               reduced as a result of any tax, assessment or other governmental
               charge that is imposed or withheld solely by reason of the
               failure of the beneficial owner or any other person to comply
               with applicable certification, identification, documentation or
               other information reporting requirements. This exception to the
               obligation to pay Additional Amounts will only apply if
               compliance with such reporting requirements is required by
               statute or regulation of the United States or by an applicable
               income tax treaty to which the United States is a party as a
               precondition to exemption from such tax, assessment or other
               governmental charge.

          (7)  Additional Amounts will not be payable if a payment on a Note is
               reduced as a result of any tax, assessment or other governmental
               charge that is collected or imposed by any method other than by
               withholding from a payment on a Note by the Company or a paying
               agent.

<PAGE>

          (8)  Additional Amounts will not be payable if a payment on a Note is
               reduced as a result of any tax, assessment or other governmental
               charge that is imposed or withheld by reason of a change in law,
               regulation, or administrative or judicial interpretation that
               becomes effective more than 15 days after the payment becomes due
               or is duly provided for, whichever occurs later.

          (9)  Additional Amounts will not be payable if a payment on a Note is
               reduced as a result of any tax, assessment or other governmental
               charge that is imposed or withheld by reason of the presentation
               by the beneficial owner of a Note for payment more than 30 days
               after the date on which such payment becomes due or is duly
               provided for, whichever occurs later.

          (10) Additional Amounts will not be payable if a payment on a Note is
               reduced as a result of any:

               (a)  estate tax;

               (b)  inheritance tax;

               (c)  gift tax;

               (d)  sales tax;

               (e)  excise tax;

               (f)  transfer tax;

               (g)  wealth tax;

               (h)  personal property tax or

               (i)  any similar tax, assessment or other governmental charge.

          (11) Additional Amounts will not be payable if a payment on a Note is
               reduced as a result of any tax, assessment, or other governmental
               charge required to be withheld by any paying agent from a payment
               of principal or interest on a Note if such payment can be made
               without such withholding by any other paying agent.

          (12) Additional Amounts will not be payable if a payment on a Note is
               reduced as a result of any combination of items (1) through (11)
               above.

          Except as specifically provided herein, the Company will not be
required to make any payment of any tax, assessment or other governmental charge
imposed by any government or a political subdivision or taxing authority of such
government.

          As used in this Note, "United States person" means:

          (a)  any individual who is a citizen or resident of the United States;

          (b)  any corporation, partnership or other entity created or organized
               in or under the laws of the United States;

          (c)  any estate if the income of such estate falls within the federal
               income tax jurisdiction of the United States regardless of the
               source of such income and

          (d)  any trust if a United States court is able to exercise primary
               supervision over its administration and one or more United States
               persons have the authority to control all of the substantial
               decisions of the trust.

<PAGE>

          Additionally, "non-United States person" means a person who is not a
United States person, and "United States" means the United States of America,
including the States and the District of Columbia, its territories, its
possessions and other areas within its jurisdiction.

          Except as provided below, the Notes may not be redeemed prior to
maturity.

          (1) The Company may, at its option, redeem the Notes if:

               (a)  the Company becomes or will become obligated to pay
                    Additional Amounts as described above;

               (b)  the obligation to pay Additional Amounts arises as a result
                    of any change in the laws, regulations or rulings of the
                    United States, or an official position regarding the
                    application or interpretation of such laws, regulations or
                    rulings, which change is announced or becomes effective on
                    or after October 21, 2005 and

               (c)  the Company determines, in its business judgment, that the
                    obligation to pay such Additional Amounts cannot be avoided
                    by the use of reasonable measures available to it, other
                    than substituting the obligor under the Notes or taking any
                    action that would entail a material cost to the Company.

          (2)  The Company may also redeem the Notes, at its option, if:

               (a)  any act is taken by a taxing authority of the United States
                    on or after October 21, 2005, whether or not such act is
                    taken in relation to the Company or any affiliate, that
                    results in a substantial probability that the Company will
                    or may be required to pay Additional Amounts as described
                    under above;

               (b)  the Company determines, in its business judgment, that the
                    obligation to pay such Additional Amounts cannot be avoided
                    by the use of reasonable measures available to it, other
                    than substituting the obligor under the Notes or taking any
                    action that would entail a material cost to the Company and

               (c)  the Company receives an opinion of independent counsel to
                    the effect that an act taken by a taxing authority of the
                    United States results in a substantial probability that the
                    Company will or may be required to pay the Additional
                    Amounts described under above, and delivers to the Trustee a
                    certificate, signed by a duly authorized officer, stating
                    that based on such opinion the Company is entitled to redeem
                    the Notes pursuant to their terms.

Any redemption of the Notes as set forth in clauses (1) or (2) above shall be in
whole, and not in part, and will be made at a redemption price equal to 100% of
the principal amount of the Notes Outstanding plus accrued interest thereon to
the date of redemption. Holders shall be given not less than 30 days nor more
than 60 days prior notice by the Trustee of the date fixed for such redemption.

          All terms used in this Note which are defined in the Indenture shall
have the meanings assigned to them in the Indenture. The Notes are governed by
the laws of the State of New York.

<PAGE>

                       SCHEDULE OF EXCHANGES OF INTERESTS

          The following exchanges of a part of this Note for an interest in
another Global Security or for a certificated Note, or exchanges of a part of
another Global Security or certificated Note for an interest in this Note, have
been made:

<TABLE>
<CAPTION>
                                                                                               Signature of
             Amount of decrease in      Amount of increase in    Principal Amount of this   Authorized Officer
 Date of   Principal Amount of this   Principal Amount of this      Note following such        of Trustee or
Exchange             Note                       Note              decrease (or increase)       Fiscal Agent
--------   ------------------------   ------------------------   ------------------------   ------------------
<S>        <C>                        <C>                        <C>                        <C>

October 31, 2005 (original issuance)                                                              Y___________

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</TABLE>

*    This Schedule may be used by the Trustee, Paying Agent, Fiscal Agent or
     other agent of the Company in respect of this Note, and, if so used, shall
     be deemed a part thereof for all purposes.