<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.
                        3.500% NOTES DUE FEBRUARY 1, 2008
REGISTERED                                                            REGISTERED

                                                            CUSIP: 172967 BS 9
                                                          ISIN: US172967 BS 96
                                                        Common Code: 016211222

No. R-                                                                       $

                  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 $____________ on February 1, 2008 and to pay interest thereon from and
including January 31, 2003 or from the most recent Interest Payment Date to
which interest has been paid or duly provided for, semi-annually, on February 1
and August 1 of each year, commencing August 1, 2003, at the rate of 3.500% per
annum, 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 January 15 and July 15 (whether or not a
Business Day) immediately 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.

                  Interest hereon will be calculated on the basis of a 360-day
year comprised of twelve 30-day months.

                  If either an Interest Payment Date or the Maturity of the
Notes falls on a day that is not a Business Day, such Interest Payment Date or
Maturity will be the next succeeding Business Day. If a date for payment of
interest or principal on the Notes falls on a day that is not a business day in
the place of payment, such payment will be made on the next succeeding business
day in such place of payment 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
due date for payment of such principal or interest.

                  For these purposes, "Business Day" means any day which is a
day on which commercial banks settle payments and are open for general business
in The City of New York.

                  Payment of the principal of and interest on this Note will be
made at the office or agency of the Trustee maintained for that purpose in The
City of New York.

                  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 an authenticating agent on behalf of 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.

                                       2

<PAGE>

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

Dated: March 21, 2003

                          CITIGROUP INC.

                          By: _________________________________
                          Title: Treasurer

ATTEST:

By: ___________________________
Title: Assistant Secretary

                                       3

<PAGE>

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

Dated: March 21, 2003

                                    THE BANK OF NEW YORK,
                                    as Trustee

                                    By: _________________________________
                                        Name:
                                        Title:

                                    -or-

                                    CITIBANK, N.A.,
                                    as Authenticating Agent

                                    By: _________________________________
                                        Name:
                                        Title:

                                       4

<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 $2,000,000,000 and
increased to $3,000,000,000.

         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 the 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
supplemental indenture or the rights of the holders of Securities of such series
to be affected, provided that no such modification will (i) 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 (ii) 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 (iii) 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

                                       5

<PAGE>

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 $1,000 and integral multiples thereof only if (i) the
Depository notifies the Company that it is unwilling or unable to continue as
Depository for the Notes or (ii) the Depository ceases to be a clearing agency
registered under the Securities Exchange Act of 1934, as amended, or (iii) 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 in The City of New York for such
purpose, upon surrender of the definitive Note for registration of transfer at
the office or agency of the registrar, 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 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 (13) 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:

                                       6

<PAGE>

                  (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 any of the
                  following (as such terms are defined in the Internal Revenue
                  Code of 1986, as amended):

                  (a)      personal holding company;

                  (b)      foreign personal holding company;

                  (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 or by reason of the beneficial owner being a
                  bank that has invested in a Note as an extension of credit in
                  the ordinary course of its trade or business.

For purposes of items (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:

                                       7

<PAGE>

                  (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.

         (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;

                                       8

<PAGE>

                  (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 tax, assessment or other
                  governmental charge that is required to be made pursuant to
                  any European Union directive on the taxation of savings income
                  or any law implementing or complying with, or introduced to
                  conform to, any such directive.

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

         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, but excluding its territories
and its possessions.

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

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

                                        9

<PAGE>

                  (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 January
                           24, 2003 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 January 24, 2003, 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 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.

                                       10