<PAGE>

                                                                   EXHIBIT 4(aa)

                                 [Face of Note]


     The following legend applies if this Security is a Global Security: Unless
this certificate is presented by an authorized representative of The Depository
Trust Company, a New York corporation ("DTC"), to the Issuer 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 requested by an
authorized representative of DTC (and any payment is made to Cede & Co. or 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.

     This Security is not a deposit or other obligation of a depository
institution and is not insured by the Federal Deposit Insurance Corporation, the
Bank Insurance Fund or any other governmental agency.


CUSIP NO. ___________                           PRINCIPAL AMOUNT:  $___________
Clearstream Common Code ___________
ISIN ___________
REGISTERED NO. 1

                              WELLS FARGO & COMPANY

               _____% Junior Subordinated Notes due ______________


     WELLS FARGO & COMPANY, a corporation duly organized and existing under the
laws of the State of Delaware (hereinafter called the "Company", which term
includes any successor corporation under the Indenture hereinafter referred to),
for value received, hereby promises to pay to ___________, or registered
assigns, the principal sum of ____________________ ($________) on ___________
and to pay interest thereon from ___________ or from the most recent Interest
Payment Date to which interest has been paid or duly provided for semi-annually
(subject to deferral as set forth herein) on ___________ and ___________ of each
year commencing ___________ at the rate of ______% per annum, together with
Additional Sums, if any, as provided in Section 1007 of the Indenture, until the
principal hereof is paid or made available for payment; provided, however, that
any overdue installment of interest shall bear Additional Interest at the rate
of _____% per annum (to the extent that the payment of such interest shall be
legally enforceable), compounded semi-annually, from the date such installment
was due until it 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 Security (or
one or more Predecessor Securities) is registered at the close of business on
the Regular Record Date for such interest, which shall be ___________ or
___________ (whether or not a Business Day, as defined below), as the case may
be, next preceding such Interest Payment Date. If an Interest Payment Date is
not a Business Day, interest on this Security shall be payable on the next day
that is a Business Day, with the same force and effect as if made on such
Interest Payment
<PAGE>

Date, and without any interest or other payment with respect to the delay.
"Business Day" as used hereinabove is a day other than a Saturday, a Sunday or
any other day on which banking institutions in Minneapolis, Minnesota,
Wilmington, Delaware or New York, New York are authorized or required by law or
executive order to remain closed.

     Any interest not punctually paid or duly provided for will forthwith cease
to be payable to the Holder on such Regular Record Date and may either be paid
to the Person in whose name this Security (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 Trustee, notice
whereof shall be given to Holders of Securities of this series not less than 10
days prior to such Special Record Date, or be paid at any time in any other
lawful manner not inconsistent with the requirements of any securities exchange
on which the Securities 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.

     So long as no Event of Default has occurred and is continuing, the Company
shall have the right, at any time during the term of this Security, from time to
time to defer the payment of interest on this Security for up to ______
consecutive semi-annual interest payment periods with respect to each deferral
period (each an "Extension Period"), during which Extension Period the Company
shall have the right to make a partial payment of interest on any Interest
Payment Date, at the end of which the Company shall pay all interest then
accrued and unpaid including any Additional Interest, as provided below;
provided, however, that no Extension Period shall extend beyond the Stated
Maturity of the principal of this Security and no such Extension Period may end
on a date other than an Interest Payment Date. Prior to the termination of any
such Extension Period, the Company may further defer the payment of interest,
provided that no Extension Period shall exceed ______ consecutive semi-annual
interest payment periods, extend beyond the Stated Maturity of the principal of
this Security or end on a date other than an Interest Payment Date. Upon the
termination of any such Extension Period and upon the payment of all accrued and
unpaid interest and any Additional Interest then due on any Interest Payment
Date, the Company may elect to begin a new Extension Period, subject to the
above conditions. No interest or Additional Interest shall be due and payable
during an Extension Period, except at the end thereof, but each installment of
interest that would otherwise have been due and payable during such Extension
Period shall bear Additional Interest (to the extent that the payment of such
interest shall be legally enforceable) at the rate of ____% per annum,
compounded semi-annually, from the dates on which amounts would otherwise have
been due and payable until paid or made available for payment. The Company shall
give the Holder of this Security and the Trustee notice of its election to begin
any Extension Period at least one Business Day prior to the next succeeding
Interest Payment Date on which interest on this Security would be payable but
for such deferral or, so long as such Securities are held by Wells Fargo Capital
___, at least one Business Day prior to the earlier of (i) the next succeeding
date on which Distributions on the Capital Trust Securities of such Issuer Trust
would be payable but for such deferral, and (ii) the date on which the Property
Trustee of such Issuer Trust is required to give notice to holders of such
Capital Trust Securities of the record date or the date such Distributions are
payable.

     Payment of interest, including Additional Interest, on this Security will
be made in immediately available funds at the office or agency of the Company
maintained for that purpose in the City of Minneapolis, Minnesota, 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,

                                       2
<PAGE>

at the option of the Company, payment of interest may be paid by check mailed to
the Person entitled thereto at such Person's last address as it appears in the
Security Register or by wire transfer to such account as may have been
designated by such Person. Payment of principal of and interest, including
Additional Interest, on this Security at Maturity will be made against
presentation of this Security at the office or agency of the Company maintained
for that purpose in the City of Minneapolis, Minnesota.

     Reference is hereby made to the further provisions of this Security 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 referred to on the reverse hereof by manual signature or its duly
authorized agent under the Indenture referred to on the reverse hereof by manual
signature, this Security shall not be entitled to any benefit under the
Indenture or be valid or obligatory for any purpose.

                                       3
<PAGE>

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


DATED:  ________________

                                   WELLS FARGO & COMPANY


                                   By:
                                      ----------------------------------------
                                        Name:
                                               -------------------------------
                                        Title:
                                               -------------------------------
[SEAL]
                                   Attest:
                                          ------------------------------------
                                          Secretary or Assistant Secretary


TRUSTEE'S CERTIFICATE OF
AUTHENTICATION
This is one of the Securities of the
series designated therein referred to
in the within-mentioned Indenture.

--------------------------------- ,
         as Trustee

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


OR

Wells Fargo Bank Minnesota, N.A., as
Authenticating Agent for the Trustee



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

                                       4
<PAGE>

                                [Reverse of Note]


                              WELLS FARGO & COMPANY

               _____% Junior Subordinated Notes due ______________

     This Security is one of a duly authorized issue of junior subordinated
securities of the Company (herein called the "Securities"), issued and to be
issued in one or more series under an indenture dated as of ______________, as
amended or supplemented from time to time (herein called the "Indenture"),
between the Company and _____________________, 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
Securities, and of the terms upon which the Securities are, and are to be,
authenticated and delivered. This Security is one of the series designated on
the face hereof, limited in aggregate principal amount to $______________;
provided, however, that the Company may, so long as no Event of Default has
occurred and is continuing, without the consent of the Holders of the Securities
of this series, issue additional Securities with the same terms as the
Securities of this series, and such additional Securities shall be considered
part of the same series under the Indenture as the Securities of this series.

     The Company may at any time, at its option, on or after _________, ____,
and subject to the terms and conditions of Article Eleven of the Indenture,
redeem the Securities of this series in whole at any time or in part from time
to time, at a Redemption Price equal to 100% of the principal amount thereof,
together, in the case of any such redemption, with accrued interest, including
any Additional Interest, to but excluding the Redemption Date.

     In addition, upon the occurrence and during the continuation of a Tax
Event, an Investment Company Event or a Capital Treatment Event in respect of
the Issuer Trust, the Company may, at its option, at any time within 90 days of
the occurrence and during the continuation of such Tax Event, Investment Company
Event or Capital Treatment Event, as the case may be, redeem the Securities of
this series, in whole but not in part, subject to the terms and conditions of
Article Eleven of the Indenture, at a Redemption Price equal to 100% of the
principal amount thereof, together, in the case of any such redemption, with
accrued interest, including any Additional Interest, to but excluding the
Redemption Date.

     The Securities of this series are not subject to repayment at the option of
the Holder hereof prior to ________________. The Securities of this series will
not be entitled to any sinking fund.

     The indebtedness evidenced by the Securities of this series is, to the
extent and in the manner set forth in the Indenture, subordinate and subject in
right of payment to the prior payment in full of the principal of and premium,
if any, and interest on all Senior Debt of the Company, and

                                       5
<PAGE>

each Holder of the Securities of this series, by accepting the same, agrees to
and shall be bound by the provisions of the Indenture with respect hereto. The
Securities of this series shall rank on a parity with all Trust Related
Securities and shall, not in limitation of the preceding sentence, rank junior
to _________________________.

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

     The Indenture permits, with certain exceptions as therein provided, the
amendment thereof and the modification of the rights and obligations of the
Company and the rights of the Holders of the Securities of each series to be
affected under the Indenture at any time by the Company and the Trustee with the
consent of the Holders of a majority in principal amount of the Securities at
the time Outstanding of all series to be affected, acting together. The
Indenture also contains provisions permitting the Holders of a majority in
principal amount of the Securities of all series at the time Outstanding
affected by certain provisions of the Indenture, acting together, on behalf of
the Holders of all Securities of such series, to waive compliance by the Company
with those provisions of the Indenture. Certain past defaults under the
Indenture and their consequences may be waived under the Indenture by the
Holders of a majority in principal amount of the Securities of each series at
the time Outstanding, on behalf of the Holders of all Securities of such series.
All of the rights of the Holders set forth in this paragraph are subject to the
rights of the holders of Capital Trust Securities as set forth in the Indenture.
Any such consent or waiver by the Holder of this Security shall be conclusive
and binding upon such Holder and upon all future Holders of this Security and of
any Security 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 Security.

     The Indenture contains provisions for defeasance at any time of (a) the
entire indebtedness on this Security and (b) certain restrictive covenants and
certain Events of Default, upon compliance by the Company with certain
conditions set forth therein, which provisions apply to this Security.

     Upon due presentment for registration of transfer of this Security at the
office or agency of the Company in the City of Minneapolis, Minnesota, a new
Security or Securities of this series in authorized denominations for an equal
aggregate principal amount will be issued to the transferee in exchange herefor,
as provided in the Indenture and subject to the limitations provided therein and
to the limitations described below, without charge except for any tax or other
governmental charge imposed in connection therewith.

     If this Security is a Global Security, this Security is exchangeable for
definitive Securities in registered form only if (x) the Depositary notifies the
Company that it is unwilling or unable to continue as Depositary for this
Security or if at any time the Depositary ceases to be a clearing agency
registered under the Securities Exchange Act of 1934, as amended, and a
successor depositary is not appointed within 90 days (y) the Company in its sole
discretion determines that this Security shall be exchangeable for definitive
Securities in registered form and notifies the Trustee thereof or (z) an Event
of Default with respect to the Securities represented hereby has occurred and is
continuing. If this Security is exchangeable pursuant to the preceding sentence,
it shall be exchangeable for definitive Securities in registered form, bearing
interest, including

                                       6
<PAGE>

Additional Interest, at the same rate, having the same date of issuance,
redemption provisions, Stated Maturity and other terms and of authorized
denominations aggregating a like amount.

     If this Security is a Global Security, this Security may not be transferred
except as a whole by the Depositary to a nominee of the Depositary or by a
nominee of the Depositary to the Depositary or another nominee of the Depositary
or by the Depositary or any such nominee to a successor of the Depositary or a
nominee of such successor. Except as provided above, owners of beneficial
interests in this global Security will not be entitled to receive physical
delivery of Securities in definitive form and will not be considered the Holders
hereof for any purpose under the Indenture.

     Subject to the rights of holders of Senior Debt of the Company set forth in
this Security and the Indenture referred to above, no reference herein to the
Indenture and no provision of this Security 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, including any Additional Interest, on this
Security at the times, place and rate, and in the coin or currency, herein
prescribed, except as otherwise provided in this Security and except that in the
event the Company deposits money or Eligible Instruments as provided in Articles
4 and 17 of the Indenture, such payments will be made only from proceeds of such
money or Eligible Instruments.

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

     No recourse shall be had for the payment of the principal of or the
interest, including Additional Interest, on this Security, or for any claim
based hereon, or otherwise in respect hereof, or based on or in respect of the
Indenture or any indenture supplemental thereto, against any incorporator,
stockholder, officer or director, as such, past, present or future, of the
Company or any successor corporation, whether by virtue of any constitution,
statute or rule of law, or by the enforcement of any assessment or penalty or
otherwise, all such liability being, by the acceptance hereof and as part of the
consideration for the issuance hereof, expressly waived and released.

     The Company and, by its acceptance of this Security or a beneficial
interest herein, the Holder of, and any Person that acquires a beneficial
interest in, this Security, agree that for United States Federal, state and
local tax purposes it is intended that this Security constitute indebtedness.

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

                                       7
<PAGE>

                                  ABBREVIATIONS

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

TEN COM  --  as tenants in common

TEN ENT  --  as tenants by the entireties

JT TEN   --  as joint tenants with right
             of survivorship and not
             as tenants in common

UNIF GIFT MIN ACT  --  _____________________ Custodian _________________________
                             (Cust)                            (Minor)

Under Uniform Gifts to Minors Act

___________________________________________
                  (State)

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


     FOR VALUE RECEIVED, the undersigned hereby sell(s) and transfer(s) unto

Please Insert Social Security or
Other Identifying Number of Assignee

______________________________________

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________
(PLEASE PRINT OR TYPE NAME AND ADDRESS INCLUDING POSTAL ZIP CODE OF ASSIGNEE)

                                       8
<PAGE>

the within Security of WELLS FARGO & COMPANY and does hereby irrevocably
constitute and appoint __________________ attorney to transfer the said Security
on the books of the Company, with full power of substitution in the premises.

Dated:  _________________________


                                          ______________________________________

                                          ______________________________________



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

                                       9