Document:

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                                                                    Exhibit 4.20

                                  AMENDMENT TO

                               GUARANTEE AGREEMENT

                                       OF

                              PWG Capital Trust II

                         Dated as of December 22, 2000

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                  AMENDMENT dated as of December 22, 2000 ("Amendment") to the
GUARANTEE AGREEMENT of PWG Capital Trust II, between UBS Americas Inc. (as
successor by merger to Paine Webber Group Inc. ("PaineWebber")), as guarantor
(the "Guarantor"), and The Chase Manhattan Bank, a New York banking corporation,
as guarantee trustee (the "Guarantee Trustee"), dated as of March 14, 1997 (the
"Guarantee Agreement") for the benefit of the Holders from time to time of the
Preferred Securities of PWG Capital Trust II (the "Issuer").

                             RECITALS OF THE COMPANY

                  Pursuant to the Third Supplemental Indenture, dated as of
November 3, 2000, between PaineWebber and UBS Americas Inc. (the "Guarantor"),
the Guarantor succeeded to the obligations of PaineWebber under the Guarantee
Agreement.

                  The Guarantor has requested the Guarantee Trustee and the
Parent Guarantor to join with it in the execution and delivery of this amendment
(the "Amendment") in order to supplement and amend the Guarantee Agreement, by
amending and adding certain provisions thereof, to allow the Guarantor to accept
the Parent Guarantor's guarantee of the Guarantor's obligations under the
Guarantee Agreement.

                  The Guarantor is a wholly owned subsidiary of the Parent
Guarantor, and the Parent Guarantor wishes to guarantee, on a subordinated
basis, the Guarantor's obligations pursuant to the Guarantee Agreement.

                  The Parent Guarantor has authorized the execution and delivery
of this Amendment by a resolution of or under the authority of its board of
directors.

                  Section 9.02 of the Guarantee Agreement provides that the
Guarantee Agreement may be amended without the consent of any Holders of the
Preferred Securities of the Issuer, provided such action does not adversely
affect the interests of the Holders of the Preferred Securities of the Issuer.

                  The Guarantor has determined that the execution and delivery
of this Amendment by the Guarantor, the Parent Guarantor and the Guarantee
Trustee complies with said Section 9.02 and does not require the consent of any
Holder of the Preferred Securities of the Issuer.

                  At the request of the Guarantee Trustee, the Guarantor has
furnished the Guarantee Trustee with an Opinion of Counsel complying with the
requirements of Section 2.05 of the Guarantee Agreement, stating, among
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other things, that the execution of this Amendment is authorized or permitted by
the Guarantee Agreement.

                  All conditions and requirements necessary to make this
Amendment a valid agreement of the Guarantor, in accordance with the terms of
the Guarantee Agreement, and a valid amendment of and supplement to the
Guarantee Agreement have been done.

                  NOW THEREFORE, the Guarantor, the Parent Guarantor and the
Guarantee Trustee hereby agree as follows:

                  1. Section 1.01 of the Guarantee Agreement is hereby amended
by the insertion of the following definition:

                     "Parent Guarantor" means UBS AG, a Swiss banking
              corporation, until a successor Person shall have become such
              pursuant to the applicable provisions of this Guarantee Agreement
              and thereafter "Parent Guarantor" shall mean such Person.

                  2. The Guarantee Agreement is hereby amended by the insertion
of the following Article Five-A after the existing Article Five:

                                 ARTICLE FIVE-A

                              The Parent Guarantee

Section 5.01-A. Unconditional Guarantee; Subordination.

                  For value received, the Parent Guarantor hereby
unconditionally and irrevocably guarantees, as a primary obligor and not merely
as a surety, all of the obligations of the Guarantor under this Guarantee
Agreement, regardless of any defense, right of set-off or counterclaim that the
Issuer may have or assert.

                  The Parent Guarantor hereby agrees that this guarantee is an
absolute, present and continuing guarantee of payment and not of collectability
and that its obligations hereunder shall be unconditional, irrespective of the
validity, legality or enforceability of the Guarantee Agreement.

                  This guarantee shall bind the Parent Guarantor and its
successors and assigns. This guarantee constitutes a direct, unconditional and
unsecured obligation of the Parent
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Guarantor. The obligations of the Parent Guarantor hereunder will be
subordinated in right of payment to the prior payment in full of the deposit
liabilities of the Parent Guarantor and all other liabilities of the Parent
Guarantor (including all deposit liabilities and other liabilities of the head
office and all offices of the Parent Guarantor wherever located), except (i) any
liabilities which by their terms rank pari passu with or are subordinated to the
obligations of the Parent Guarantor under this guarantee; (ii) any Existing Pari
Passu Obligations (as defined in the Indenture); (iii) any liabilities which by
their terms rank pari passu with or are subordinated to liabilities which by
their terms rank pari passu with or are subordinated to the obligations of the
Parent Guarantor under this guarantee or any Existing Pari Passu Obligations;
and (iv) any Existing Junior Subordinated Obligations (as defined under the
Indenture). For the avoidance of doubt, (A) the obligations of the Parent
Guarantor hereunder will rank pari passu with any Existing Pari Passu
Obligations and any liabilities which by their terms rank pari passu with this
guarantee or any Existing Pari Passu Obligations; and (B) the obligations of the
Parent Guarantor hereunder will be senior to any Existing Junior Subordinated
Obligations and any liabilities which by their terms are subordinated to the
obligations of the Parent Guarantor under this guarantee or under any Existing
Pari Passu Obligations.

                  3. Section 9.03 is hereby amended by the insertion of the
following subsection (d):

                     (d) if given to the Parent Guarantor, to the address set
              forth below or such other address as the Parent Guarantor may give
              notice of to the Holders:

                       UBS AG
                       Bahnhofstrasse 45, Zurich
                       Switzerland
                       Facsimile No.:
                       Attention: General Counsel

                  4. The Guarantee Agreement is hereby amended by the insertion
of the following paragraphs at the end of Article IX:

Section 9.09.  Successors and Assigns of the Parent Guarantor.

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                  All guarantees and agreements contained in the Guarantee
Agreement shall bind the successors, assignees, receivers, trustees and
representatives of the Parent Guarantor and shall inure to the benefit of the
Holders of the Preferred Securities then outstanding. Except in connection with
a consolidation, merger or conveyance, transfer or lease of assets involving the
Parent Guarantor under Article Ten of the Indenture, the Parent Guarantor shall
not assign its obligations hereunder.

                  5. Ratification and Confirmation. As amended and modified by
this Amendment, the Guarantee Agreement is in all respects ratified and
confirmed and the Guarantee Agreement and this Amendment shall be read, taken
and construed as one and the same instrument.

                  6. Counterparts. This Amendment may be executed in any number
of counterparts and all said counterparts executed and delivered each as an
original shall constitute but one and the same instrument.

                  7. Trustee's Duties, Responsibilities and Liabilities. The
Trustee assumes no duties, responsibilities or liabilities by reason of this
Amendment other than as set forth in the Amendment, and this Amendment is
executed and accepted by the Trustee subject to all the terms and conditions of
their acceptance of the trust under the Guarantee Agreement, as fully as if said
terms and conditions were herein set forth at length.

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                  This Amendment is executed as of the day and year first above
written.

                                        UBS AMERICAS INC. (as
                                        successor by merger to
                                        Paine Webber Group Inc.)

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

                                        UBS AG

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

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

                                        THE CHASE MANHATTAN BANK, as
                                        Guarantee Trustee

                                        By:
                                            --------------------------
                                            Name:
                                            Title:<PAGE>   1
                                                                    Exhibit 4.27

REGISTERED                            REGISTERED

NUMBER
R                  Paine Webber Group Inc.
                   9-1/4% NOTE DUE 2001

                                CUSIP 695629 AJ4

                       SEE REVERSE FOR CERTAIN DEFINITIONS

Paine Webber Group Inc., a Delaware corporation (the "Company"), promises to pay
to

9-1/4%                           9-1/4%
DUE                              DUE
2001                             2001

, or registered assigns,
the principal sum of             One Hundred Fifty Dollars on December 15, 2001.

                 INTEREST PAYMENT DATES: June 15 and December 15
                       RECORD DATES: June 1 and December 1

        Additional provisions of this Note and certain definitions are set forth
on the reverse hereof.

        This Note shall not be valid or become obligatory for any purpose until
the certificate of authentication hereon shall have been signed by the Trustee
under the Indenture referred to on the reverse hereof.

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

Dated:

TRUSTEE'S CERTIFICATE OF AUTHENTICATION
This in one of the Securities of the series designated therein referred
to in the within-mentioned Indenture.
CHEMICAL BANK,
as Trustee
By

Authorized Officer

                            [PAINE WEBBER GROUP INC.

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                                    CORPORATE
                                     S E A L
                                     1 9 7 3
                                    DELAWARE]

                            Paine Webber Group Inc.,

Attest                                    By
     /s/  ______________                      /s/ David Buchanan
              Secretary                        Chairman of the Board

                             PAINE WEBBER GROUP INC.
                              9 1/4% NOTE DUE 2001

        1. INDENTURE

This Note is one of a series of unsecured debentures, notes or other evidences
of indebtedness (collectively, the "Securities") of Paine Webber Group Inc., a
Delaware corporation (the "Company"), issued and to be issued under an Indenture
dated as of March 15, 1988 between the Company and the Trustee, as amended by a
supplemental Indenture dated as of September 22, 1989 and by a supplemental
Indenture dated as of March 22, 1991 (as so amended, the "Indenture"). The
Indenture permits the issuance of an unlimited number of series of Securities in
an unlimited aggregate principal amount. This Note is one of a series designated
the 9 1/4% Notes Due 2001 (the "Notes"), which series is limited in aggregate
principal amount to $150,000,000. The Notes are subject to the terms stated in
the Indenture, and those made part of the Indenture by reference to the Trust
Indenture Act of 1939, as amended (the "Act"), and holders of Notes are referred
to the Indenture and the Act for a statement of those terms.

        2. INTEREST

        The Company promises to pay interest on the principal amount of this
Note at the rate per annum shown above. The Company will pay interest
semiannually on June 15 and December 15 of each year. Interest on the Notes will
accrue from the most recent date to which interest has been paid or if no
interest has been paid from December 15, 2001. Interest will be computed on the
basis of a 360-day year of twelve 30-day months.

        3. METHOD OF PAYMENT

        The Company will pay interest on the Notes (except defaulted interest)
to the persons who are registered Holders of Notes at the close of business on
June 1 or December 1 next preceding the interest payment date. Holders must
surrender Notes to a Paying Agent to collect principal payments. The Company
will pay principal and interest in money of the United States that at the time
of payment is legal tender for payment of public and private debts. However, the
Company may pay interest by its check payable in such money. It may mail an
interest check to a holder's registered address.

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        4. PAYING AGENT AND REGISTRAR

        Initially, Chemical Bank (the "Trustee") will act as Paying Agent and
Registrar. The Company may change the Paying Agent or Registrar without notice.

        5. DENOMINATIONS; TRANSFER; EXCHANGE

        The Notes are in registered form without coupons in denominations of
$1,000 and any multiple of $1,000. A holder may transfer or exchange Notes in
accordance with the Indenture. The Registrar may require a holder, among other
things, to furnish appropriate endorsements and transfer documents and to pay
any taxes and fees required by law or permitted by the Indenture.

        6. PERSONS DEEMED OWNERS

        The registered holder of this Note may be treated as the owner of it for
all purposes.

        7. UNCLAIMED MONEY

        If money for the payment of principal of or interest on the Notes
remains unclaimed for two years after such principal or interest has become due
and payable, it shall be repaid by the Trustee or Paying Agent to the Company at
its request. Thereafter, holders entitled to the money must look only to the
Company and not to the Trustee or Paying Agent for payment.

        8. AMENDMENT; SUPPLEMENT; WAIVER

        The Company and the Trustee may, without the consent of any holders of
Securities, agree to amend or supplement the Indenture or the Securities to,
among other things, add to the covenants of the Company for the benefit of
holders of all or any series of Securities, add to the Events of Default with
respect to all or any series of the Securities and, provided that such action
shall not adversely affect the interests of the holders of any series of
Securities in any material respect, cure ambiguities, defects or inconsistencies
in the Indenture or make other provisions. Subject to certain exceptions, the
holders of not less than a majority in principal amount of the outstanding
Securities of any series may waive any past default by the Company, with respect
to such series, on behalf of all holders of Securities of such series. Subject
to certain exceptions, the Company and the Trustee may agree to amend or
supplement the Indenture or the Securities of any series in any manner with the
consent of holders of not less than 66-2/3% in principal amount of the
outstanding Securities of each series to be affected.

        9. OBLIGATIONS OF THE COMPANY

        The Notes are direct, unsecured obligations of the Company. The
Indenture does not limit the amount of the Company's other unsecured debt.

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        10. SUCCESSOR CORPORATION

        Any successor corporation resulting from a consolidation or merger
involving the Company, or from a conveyance, transfer or lease of the assets of
the Company substantially as an entirety, shall succeed to all rights and
obligations of the Company under the Notes and the Indenture, and thereafter,
except in the case of a lease, the predecessor corporation will be relieved of
all such obligations.

        11. DEFAULTS AND REMEDIES

An Event of Default is default for 30 days in payment of any interest on the
Notes; default in payment of any principal on the Notes, default in the
performance or breach by the Company of any covenant or warranty under the
Indenture for the benefit of the Notes and the continuance of the default or
breach for a period of 60 days following receipt of notice of such default or
breach; and certain events of bankruptcy or insolvency affecting the Company. If
an Event of Default occurs and is continuing, the Trustee or the holders of at
least 25% in principal amount of the Notes may declare the principal amount of
the Notes to be due and payable immediately. Holders of Notes may not enforce
the Indenture or the Notes except as provided in the Indenture. The Trustee may
refuse to enforce the Indenture or the Notes unless it receives indemnity
satisfactory to it. Subject to the above and other limitations, holders of a
majority in principal amount of the Notes may direct the Trustee in its exercise
of any trust or power with respect to the Notes. The Trustee may withhold from
holders of Notes notice of a default by the Company (except a default in payment
of principal or interest) if it is determined that withholding notice is in the
interest of such holders.

        12. TRUSTEE DEALINGS WITH THE COMPANY

        Chemical Bank, the Trustee under the Indenture, in its individual or
other capacity may make loans to, accept deposits from and perform services for
the Company or its affiliates, and may otherwise deal with the Company or its
affiliates, as if it were not Trustee.

        13. NO RECOURSE AGAINST OTHERS

        A director, officer, employee or stockholder of the Company, as such,
shall not have any liability for any obligations of the Company under the Notes
or the Indenture or for any claim based on, in respect of or by reason of such
obligations or their creation. Each holder of a Note by accepting such Note
waives all such claims and releases such directors, officers, employees and
stockholders from all such liability. Such waiver and release are part of the
consideration for the issue of the Notes.

        14. COPIES OF INDENTURE

        The Company will furnish to any holder of Notes upon written request and
without charge a copy of the Indenture. Requests may be made to:
Secretary,

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Paine Webber Group Inc., 1285 Avenue of the Americas, New York, New York
10019.

        15. GOVERNING LAW

        The Notes shall be governed by and construed in accordance with the laws
of the State of New York.
                             ______________________

                                  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),
                         assign(s) and transfer(s) unto

PLEASE INSERT SOCIAL SECURITY OR OTHER
    IDENTIFYING NUMBER OF ASSIGNEE
______________________
____________________________________________
____________________________________________

                   Please print or typewrite name and address
                     including postal zip code of assignee

the within Note and all rights thereunder, hereby irrevocably constituting and
appointing

_______________________________________________________________________attorney
to transfer said Note on the books of the Company, with full power of
substitution in the premises.

Dated: ________________________

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