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                                                                     EXHIBIT 4.5

                             SUPPLEMENTAL INDENTURE

         This Supplemental Indenture is made as of December 23, 1999 by and
between M&T Bank Corporation, a New York corporation, and Bankers Trust Company,
a New York banking corporation.

                                   WITNESSETH

         WHEREAS, M&T Bank Corporation, formerly known as First Empire State
Corporation, and Bankers Trust Company, as trustee, (in such capacity, the
"Indenture Trustee") previously entered into a Junior Subordinated Indenture
dated as of January 31, 1997 (the "Indenture") to provide for the issuance from
time to time of unsecured junior subordinated debt securities in series; and

         WHEREAS, First Empire State Corporation has changed its corporate name
to "M&T Bank Corporation;" and

         WHEREAS, the Administrators of the Issuer Trust have changed the name
of the First Empire Capital Trust I to "M&T Capital Trust I;" and

         WHEREAS, M&T Bank Corporation and the Indenture Trustee desire to amend
the Indenture to provide for the change of the name of First Empire State
Corporation to "M&T Bank Corporation."

         NOW THEREFORE, in consideration of the agreements and obligations set
forth herein and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, each party to this Amendment, for
the benefit of the other parties and for the benefit of the Holders, hereby
amends the Indenture, and agrees, intending to be legally bound, as follows:

SECTION 1.  DEFINITIONS.

         1.1. For all purposes of this Amendment, except as otherwise expressly
provided, terms used but not defined in this Amendment shall have the meanings
assigned to them in the Indenture.

         1.2. The words "First Empire State Corporation" are hereby amended to
read "M&T Bank Corporation" in each place they appear in the Indenture.

SECTION 2.  MISCELLANEOUS.

         2.1. CONTINUING AGREEMENT. The Indenture shall not be amended by this
Amendment except as specifically provided in this Amendment and, amended as so
specifically provided, the Indenture shall remain in full force and effect.
References in the Indenture to "this Indenture"

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shall be deemed to be references to the Indenture as amended by this Amendment.

         2.2. CONFLICTS. In the event of a conflict between the terms and
conditions of the Indenture and the terms and conditions of this Amendment, the
terms and conditions of this Amendment shall prevail.

         2.3. COUNTERPART ORIGINALS. The parties may sign any number of copies
of this Amendment. Each signed copy shall be an original, but all of them
together represent the same agreement.

         2.4. HEADINGS, ETC. The headings of the sections of this Amendment have
been inserted for convenience of reference only, are not to be considered a part
hereof, and shall in no way modify or restrict any of the terms or provisions
hereof.

         IN WITNESS WHEREOF the parties have caused this Amendment to be
executed as of the day and year first above written.

                                            M&T BANK CORPORATION

                                            By: /s/ Michael P. Pinto
                                                --------------------------------
                                            Michael P. Pinto
                                            Executive Vice President and Chief
                                            Financial Officer

                                            BANKERS TRUST COMPANY,
                                            as Trustee, and not in its
                                            individual capacity

                                            By: /s/ Christopher D. Lew
                                                --------------------------------
                                            Christopher D. Lew
                                            Assistant Treasurer<PAGE>

                                                                     EXHIBIT 4.7

                        AMENDMENT TO GUARANTEE AGREEMENT

         This Amendment to Guarantee Agreement (the "Amendment") is made as of
December 23, 1999 by and between M&T Bank Corporation, a New York corporation,
and Bankers Trust Company, a New York banking corporation.

                                   WITNESSETH

         WHEREAS, M&T Bank Corporation, formerly known as First Empire State
Corporation, (the "Guarantor"), and Bankers Trust Company, as trustee (in such
capacity, the "Guarantee Trustee") previously entered into a Guarantee Agreement
dated as of January 31, 1997 (the "Guarantee Agreement") by which the Guarantor
agreed to make certain payments to the Holders of Capital Securities issued
pursuant to an Amended and Restated Trust Agreement dated as of January 31, 1997
by and between Guarantor, in its capacity as Depositor, Bankers Trust Company,
as property trustee, and Bankers Trust (Delaware), a Delaware banking
corporation, as Delaware trustee; and

         WHEREAS, the Guarantor has changed its corporate name from "First
Empire State Corporation" to "M&T Bank Corporation;" and

         WHEREAS, the Administrators of the Issuer Trust have changed the name
of the Issuer Trust from "First Empire Capital Trust I" to "M&T Capital Trust
I;" and

         WHEREAS, the Guarantor and the Guarantee Trustee desire to amend the
Guarantee Agreement to provide for the change of the name of the Guarantor from
"First Empire State Corporation" to "M&T Bank Corporation," and the name of the
Issuer Trust from "First Empire Capital Trust I" to "M&T Capital Trust I."

         NOW THEREFORE, in consideration of the agreements and obligations set
forth herein and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, each party to this Amendment, for
the benefit of the other parties and for the benefit of the Holders, hereby
amends the Guarantee Agreement, and agrees, intending to be legally bound, as
follows:

SECTION 1.  DEFINITIONS.

         1.1. For all purposes of this Amendment, except as otherwise expressly
provided, terms used but not defined in this Amendment shall have the meanings
assigned to them in the Guarantee Agreement.

         1.2. The definition of "Guarantor" in the preamble of the Guarantee
Agreement is amended to mean M&T Bank Corporation.

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         1.3. The definition of "Issuer Trust" in the preamble of the Guarantee
Agreement is amended to mean "M&T Capital Trust I."

SECTION 2.  MISCELLANEOUS.

         2.1. CONTINUING AGREEMENT. The Guarantee Agreement shall not be amended
by this Amendment except as specifically provided in this Amendment and, amended
as so specifically provided, the Guarantee Agreement shall remain in full force
and effect. References in the Guarantee Agreement to "this Guarantee Agreement"
shall be deemed to be references to the Guarantee Agreement as amended by this
Amendment.

         2.2. CONFLICTS. In the event of a conflict between the terms and
conditions of the Guarantee Agreement and the terms and conditions of this
Amendment, the terms and conditions of this Amendment shall prevail.

         2.3. COUNTERPART ORIGINALS. The parties may sign any number of copies
of this Amendment. Each signed copy shall be an original, but all of them
together represent the same agreement.

         2.4. HEADINGS, ETC. The headings of the sections of this Amendment have
been inserted for convenience of reference only, are not to be considered a part
hereof, and shall in no way modify or restrict any of the terms or provisions
hereof.

         IN WITNESS WHEREOF the parties have caused this Amendment to be
executed as of the day and year first above written.

                                            M&T BANK CORPORATION,
                                            as Guarantor

                                            By: /s/ Michael P. Pinto
                                                --------------------------------
                                                Michael P. Pinto
                                                Executive Vice President and
                                                Chief Financial Officer

                                            BANKERS TRUST COMPANY,
                                            as Guarantee Trustee,
                                            and not in its individual capacity

                                            By: /s/ Christopher D. Lew
                                                --------------------------------
                                                Christopher D. Lew
                                                Assistant Treasurer<PAGE>

                                                                     EXHIBIT 4.9

                AMENDMENT TO AMENDED AND RESTATED TRUST AGREEMENT

         This Amendment to Amended and Restated Trust Agreement (the
"Amendment") is made as of December 23, 1999 by and between M&T Bank
Corporation, a New York corporation, and Bankers Trust Company, a New York
banking corporation.

                                   WITNESSETH

         WHEREAS, M&T Bank Corporation, formerly known as First Empire State
Corporation, (the "Depositor"), Bankers Trust Company, as property trustee, (in
such capacity, the "Property Trustee" and, in its separate corporate capacity
and not in its capacity as Property Trustee, the "Bank"), and Bankers Trust
(Delaware), a Delaware banking corporation, as Delaware trustee (the "Delaware
Trustee") previously entered into an Amended and Restated Trust Agreement dated
as of June 6, 1997 (the "Trust Agreement"); and

         WHEREAS, the Depositor has changed its corporate name from "First
Empire State Corporation" to "M&T Bank Corporation;" and

         WHEREAS, the Administrators of the Issuer Trust have changed the name
of the Issuer Trust from "First Empire Capital Trust II" to "M&T Capital Trust
II;" and

         WHEREAS, the Depositor, as Holder of a Majority in Liquidation Amount
of the Common Securities, and the Property Trustee desire to further amend the
Trust Agreement to provide for the change of the name of the Depositor from
"First Empire State Corporation" to "M&T Bank Corporation," and the name of the
Issuer Trust from "First Empire Capital Trust II" to "M&T Capital Trust II."

         NOW THEREFORE, in consideration of the agreements and obligations set
forth herein and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, each party to this Amendment, for
the benefit of the other parties and for the benefit of the Holders, hereby
amends the Trust Agreement, and agrees, intending to be legally bound, as
follows:

SECTION 1.  DEFINITIONS.

         1.1. For all purposes of this Amendment, except as otherwise expressly
provided, terms used but not defined in this Amendment shall have the meanings
assigned to them in the Trust Agreement.

         1.2. The definition of "Depositor" in the preamble of the Trust
Agreement is amended to mean M&T Bank Corporation.

         1.3. The definition of "Issuer Trust" in Section of 1.1 of the Trust
Agreement is amended to mean "M&T Capital Trust II."

<PAGE>

SECTION 2. MISCELLANEOUS.

         2.1. CONTINUING AGREEMENT. The Trust Agreement shall not be amended by
this Amendment except as specifically provided in this Amendment and, amended as
so specifically provided, the Trust Agreement shall remain in full force and
effect. References in the Trust Agreement to "this Trust Agreement" shall be
deemed to be references to the Trust Agreement as amended by this Amendment.

         2.2. CONFLICTS. In the event of a conflict between the terms and
conditions of the Trust Agreement and the terms and conditions of this
Amendment, the terms and conditions of this Amendment shall prevail.

         2.3. COUNTERPART ORIGINALS. The parties may sign any number of copies
of this Amendment. Each signed copy shall be an original, but all of them
together represent the same agreement.

         2.4. HEADINGS, ETC. The headings of the sections of this Amendment have
been inserted for convenience of reference only, are not to be considered a part
hereof, and shall in no way modify or restrict any of the terms or provisions
hereof.

         IN WITNESS WHEREOF the parties have caused this Amendment to be
executed as of the day and year first above written.

                                        M&T BANK CORPORATION,
                                        as Holder of a Majority in Liquidation
                                        Amount of the Common Securities

                                        By:  /s/ Michael P. Pinto
                                             ----------------------------------
                                             Michael P. Pinto
                                             Executive Vice President and Chief
                                             Financial Officer

                                        BANKERS TRUST COMPANY,
                                        as Property Trustee,
                                        and not in its individual capacity

                                        By: /s/ Christopher D. Lew
                                            ------------------------------------
                                            Christopher D. Lew
                                            Assistant Treasurer

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