M&T BANK CORP
424B3, 2000-08-04
STATE COMMERCIAL BANKS
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<PAGE>   1
                                                FILED PURSUANT TO RULE 424(b)(3)
                                                REGISTRATION STATEMENT 333-40640

          First mailed to Keystone Shareholders on or about August 3, 2000

                            KEYSTONE FINANCIAL, INC.

Dear Keystone Shareholder:

     M&T Bank Corporation and Keystone Financial, Inc. have agreed to a
transaction in which M&T will merge with Keystone and Keystone Financial Bank,
N.A. will merge with M&T's subsidiary bank, Manufacturers and Traders Trust
Company.

     As a result of the merger, you will receive either $21.50 in cash or 0.05
of a share of M&T common stock for each share of Keystone common stock that you
own. You will be able to elect whether you want cash or stock for your shares of
Keystone common stock. Elections will be limited by the requirement that 65% of
the shares of outstanding Keystone common stock, determined as provided in the
merger agreement, be exchanged for M&T common stock. Therefore, the actual
allocation of cash and shares of M&T common stock that you receive will depend
on the elections of other Keystone shareholders and may be different from what
you elect. The federal income tax consequences of the merger to you will depend
on whether you receive cash, stock or a combination of cash and stock in
exchange for your shares of Keystone common stock.

     M&T is a bank holding company headquartered in Buffalo, New York, with
total assets of approximately $21.7 billion as of June 30, 2000. M&T's common
stock is listed on the New York Stock Exchange under the symbol MTB. The last
reported sale price of M&T common stock on the New York Stock Exchange on July
27, 2000 was $467.00 per share.

     Completion of the merger requires that we obtain the necessary government
approvals and approval of the shareholders of Keystone, as well as the
shareholders of M&T. We have scheduled a special meeting for our shareholders to
vote on the merger agreement. The meeting will be held at the Harrisburg Hilton
Hotel, Market Square, Harrisburg, Pennsylvania on Tuesday, September 5, 2000 at
10:00 a.m., local time.

     It is very important that your shares be voted at the meeting, regardless
of whether you plan to attend in person. To assure that your shares are
represented on this very important matter, please sign, date and return the
enclosed proxy card in the enclosed postage-prepaid envelope whether or not you
plan to attend the meeting. You may also vote by internet using the proxy link
found at www.keyfin.com. This link will take you directly to the web page listed
on your proxy card. If you hold shares in your own name and do attend, you may
revoke your proxy and vote your shares in person at the meeting.

     This document contains a more complete description of the meeting, the
terms of the merger and the procedures for electing stock or cash. We urge you
to review this entire document carefully. You may also obtain information about
M&T and Keystone from documents filed with the Securities and Exchange
Commission.

     I enthusiastically support the merger and join our board of directors in
unanimously recommending that you vote in favor of the merger.

                                            Sincerely,

                                            Carl Campbell Signature
                                            Carl L. Campbell
                                            Chairman, President and
                                            Chief Executive Officer

     Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities or determined if this
Joint Proxy Statement-Prospectus is truthful or complete. Any representation to
the contrary is a criminal offense. The shares of M&T common stock offered
through the merger are not insured by the Federal Deposit Insurance Corporation
and are not deposits or other obligations of, or guaranteed by, any bank
subsidiary of M&T.

         The date of this Joint Proxy Statement-Prospectus is July 28, 2000.
<PAGE>   2

                            KEYSTONE FINANCIAL, INC.
                               ONE KEYSTONE PLAZA
                            FRONT AND MARKET STREETS
                         HARRISBURG, PENNSYLVANIA 17105

                   NOTICE OF SPECIAL MEETING OF SHAREHOLDERS

     NOTICE IS HEREBY GIVEN that a special meeting of shareholders of Keystone
Financial, Inc. will be held at the Harrisburg Hilton Hotel, Market Square,
Harrisburg, Pennsylvania on Tuesday, September 5, 2000 at 10:00 a.m., local
time, for the following purposes:

     1. Consider and vote upon a proposal to approve an Agreement and Plan of
        Reorganization among Keystone Financial, Inc., M&T and its wholly owned
        subsidiary, Olympia Financial Corp., and a related Agreement and Plan of
        Merger (collectively, the "merger agreement"), a copy of which is
        included in Appendix A to the accompanying Joint Proxy
        Statement-Prospectus, pursuant to which (i) Keystone will be merged with
        and into Olympia; (ii) subject to the allocation and election procedures
        set forth in the merger agreement, each outstanding share of common
        stock of Keystone will be converted, at the election of the holder, into
        the right to receive either $21.50 in cash without interest or 0.05 of a
        share of common stock of M&T with cash in lieu of any fractional shares;
        (iii) up to 1,725,000 shares of M&T common stock will be issued in
        connection with the proposed merger; and

     2. To consider and act upon such other matters as may properly come before
        the meeting or any adjournments thereof.

     Only shareholders of record at the close of business on July 27, 2000 will
be entitled to notice of, and to vote at, the meeting or any adjournments
thereof. The affirmative vote of a majority of the votes cast by holders of
Keystone Financial, Inc. common stock entitled to vote at the meeting is
required for approval of the merger.

     Information regarding voting rights and the business to be transacted at
the meeting is given in the accompanying Joint Proxy Statement-Prospectus.

                                         By Order of the Board of Directors

                                         Ben Rooke Signature
                                         Ben G. Rooke
                                         Vice Chairman,
                                         General Counsel and Secretary
Harrisburg, Pennsylvania
July 28, 2000

                                   IMPORTANT

     Your vote is important regardless of the number of shares you own. Whether
or not you expect to attend the meeting, please sign, date and promptly return
the accompanying proxy card using the enclosed postage-prepaid envelope, or vote
by internet using the proxy voting link found at www.keyfin.com. If you are a
record shareholder and for any reason you should desire to revoke your proxy,
you may do so at any time before it is voted at the meeting.
<PAGE>   3

                      WHERE YOU CAN FIND MORE INFORMATION

     This document incorporates important business and financial information
about M&T and Keystone that is not included in or delivered with this document.
You may read and copy any materials M&T and Keystone have filed with the
Securities and Exchange Commission at the Commission's Public Reference Room
located at 450 Fifth Street, N.W., Washington, D.C. 20549. You may obtain
information on the operation of the Public Reference Room by calling the
Commission at 1-800-SEC-0330. You may also visit the Commission's web site at
www.sec.gov to obtain reports, proxy and information statements, and other
information that M&T or Keystone has filed electronically.

     Copies of any of these documents without their exhibits are also available
without charge to any person to whom we deliver this document. You must make a
written or oral request to, in the case of information concerning M&T, M&T Bank
Corporation, One M&T Plaza, Buffalo, New York 14203, attention: Clifford P.
Johnson, Vice President, Corporate Reporting (telephone: (716) 842-5973); or, in
the case of information concerning Keystone, Keystone Financial Inc., One
Keystone Plaza, Front and Market Streets, Harrisburg, Pennsylvania 17105,
attention: Ben G. Rooke, Vice Chairman, General Counsel and Secretary
(telephone: (717) 233-1555). IN ORDER TO ENSURE TIMELY DELIVERY OF THE
DOCUMENTS, ANY REQUEST SHOULD BE MADE, IN THE CASE OF KEYSTONE SHAREHOLDERS, BY
AUGUST 29, 2000 AND, IN THE CASE OF M&T SHAREHOLDERS, BY SEPTEMBER 12, 2000. You
may also obtain information about the companies from our respective web sites,
www.mandtbank.com for M&T, and www.keyfin.com for Keystone.

                                        i
<PAGE>   4

                           PROXY STATEMENT-PROSPECTUS
                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                        PAGE
                                        ----
<S>                                     <C>
WHERE YOU CAN FIND MORE INFORMATION...    i
SUMMARY...............................    1
MARKET PRICES AND DIVIDEND
  INFORMATION.........................    8
COMPARATIVE PER SHARE DATA............   10
SELECTED CONSOLIDATED FINANCIAL
  DATA................................   11
  Selected Pro Forma Combined
     Financial Data...................   12
  Selected Historical Consolidated
     Financial Data...................   13
THE COMPANIES.........................   15
THE KEYSTONE SHAREHOLDERS' MEETING....   19
  Date, Place and Time................   19
  Record Date; Voting Rights..........   19
  Voting and Revocation of Proxies....   19
  Solicitation of Proxies.............   20
THE M&T SHAREHOLDERS' MEETING.........   20
  Date, Place and Time................   20
  Record Date; Voting Rights..........   20
  Voting and Revocation of Proxies....   21
  Solicitation of Proxies.............   22
THE MERGER............................   22
  Background and Reasons for the
     Merger: Recommendations of the
     Boards of Directors..............   22
  M&T's Reasons for the Merger........   24
  Keystone's Reasons for the Merger;
     Recommendation of the Keystone
     Board............................   25
  Opinion of Keystone's Financial
     Advisor..........................   26
  Opinion of M&T's Financial
     Advisor..........................   32
  Terms of the Merger.................   40
  For Keystone Shareholders: Election
     Procedures; Surrender of Stock
     Certificates.....................   43
  For M&T Shareholders: Retention of
     Stock Certificates...............   44
  Representations and Warranties;
     Conditions to the Merger;
     Waiver...........................   44
  Regulatory Approvals Needed to
     Complete the Merger..............   46
  Covenants; Conduct of Business
     Pending the Merger...............   47
  Amending the Agreement..............   48
</TABLE>

<TABLE>
<CAPTION>
                                        PAGE
                                        ----
<S>                                     <C>
  Effective Date of the Merger;
     Terminating the Agreement........   48
  Management and Operations After the
     Merger...........................   49
  Interests of Directors and Officers
     in the Merger that are Different
     from Yours.......................   51
  Certain Federal Income Tax
     Consequences.....................   55
  Accounting Treatment of the
     Merger...........................   59
  Stock Option Agreement..............   59
  Dissenters' Rights of Keystone
     Shareholders.....................   60
  No Dissenters' Rights of M&T
     Shareholders.....................   62
COMPARISON OF CERTAIN RIGHTS OF
  HOLDERS OF M&T COMMON STOCK AND
  KEYSTONE COMMON STOCK...............   63
PRO FORMA CONDENSED COMBINED FINANCIAL
  INFORMATION.........................   71
PROPOSED AMENDMENT TO THE M&T
  CORPORATION CERTIFICATE OF
  INCORPORATION.......................   78
EXPERTS...............................   79
LEGAL OPINION.........................   79
SUBMISSION OF SHAREHOLDER PROPOSALS...   79
DOCUMENTS INCORPORATED BY REFERENCE...   80
A WARNING ABOUT FORWARD-LOOKING
  STATEMENTS..........................   80
APPENDIX A -- AGREEMENT AND PLAN OF
  REORGANIZATION (INCLUDING AGREEMENT
  AND PLAN OF MERGER).................  A-1
APPENDIX B -- STOCK OPTION
  AGREEMENT...........................  B-1
APPENDIX C -- OPINION OF KEEFE,
  BRUYETTE & WOODS, INC...............  C-1
APPENDIX D -- OPINION OF MERRILL
  LYNCH, PIERCE, FENNER & SMITH
  INCORPORATED........................  D-1
APPENDIX E -- SUBCHAPTER D OF
  PENNSYLVANIA BUSINESS CORPORATION
  LAW.................................  E-1
APPENDIX F -- PROPOSED CERTIFICATE OF
  AMENDMENT TO CERTIFICATE OF
  INCORPORATION OF M&T BANK
  CORPORATION.........................  F-1
</TABLE>

                                       ii
<PAGE>   5

                                    SUMMARY

     This summary does not contain all of the information that is important to
you. You should carefully read this entire document and the documents to which
we have referred you in order to understand fully the merger and to obtain a
more complete description of the merger. See "Where You Can Find More
Information" (Page i).

THE COMPANIES (PAGE 15)

M&T BANK CORPORATION
One M&T Plaza
Buffalo, New York 14203
(716) 842-5445

     M&T Bank Corporation is a bank holding company incorporated under New York
law in 1969. As of June 30, 2000, M&T had total assets of approximately $21.7
billion and total shareholders' equity of approximately $1.9 billion.

     M&T's principal banking subsidiary is Manufacturers and Traders Trust
Company, which is headquartered in Buffalo, New York. Manufacturers and Traders
Trust Company is commonly known by its trade name, M&T Bank, and is referred to
by that name in this document. M&T Bank accounted for 96% of M&T's consolidated
assets on June 30, 2000 and for virtually all of its net income in 1999. M&T
also owns M&T Bank, N.A., which offers certain banking products on behalf of M&T
on a national basis. Collectively, the M&T banks and their subsidiaries offer a
wide range of commercial banking, trust, investment and financial services to a
diverse base of consumers, businesses, professional clients, governmental
entities and financial institutions located in their markets.

KEYSTONE FINANCIAL, INC.
One Keystone Plaza
Front and Market Streets
Harrisburg, Pennsylvania 17105
(717) 233-1555

     Keystone Financial, Inc. is a bank holding company incorporated under
Pennsylvania law in 1983. As of June 30, 2000, Keystone had total assets of
approximately $7.0 billion and total shareholders' equity of approximately $566
million.

     Keystone's bank subsidiary is Keystone Financial Bank, N.A. The bank
operates in 31 Pennsylvania counties, three Maryland counties and one county in
West Virginia. Nonbank subsidiaries offer a variety of financial services
including discount brokerage services, sales of mutual funds and annuities,
investment advisory services, brokerage, mortgage banking and community
development.

THE MERGER (PAGE 22)

     We have attached the merger agreement to this document as Appendix A.
Please read this agreement. It is the legal document that governs the merger.

M&T AND M&T BANK WILL BE THE SURVIVING
  HOLDING COMPANY AND BANK (PAGE 40)

     In the merger Keystone will merge into Olympia Financial Corp., which will
continue in existence as a wholly owned subsidiary of M&T. We hope to complete
this merger during October 2000. Also, Keystone Financial Bank, N.A. will merge
into M&T Bank, which will be the surviving bank and will continue the banking
operations of the combined bank.

FOR KEYSTONE SHAREHOLDERS: YOU WILL
  RECEIVE EITHER $21.50 IN CASH OR 0.05 OF
  A SHARE OF M&T COMMON STOCK FOR
  EACH OF YOUR KEYSTONE SHARES
  (PAGE 40)

     Keystone Shareholders. As a result of the merger, you will receive for each
of your Keystone shares either (i) $21.50 in cash or (ii) 0.05 of a share of M&T
common stock and cash, based on the market price of M&T common stock the day
before the merger, for any fractional share left over. You may elect either of
these options for each Keystone common share that you own. Since the merger
agreement provides that M&T intends to split its stock 10-for-1 in connection
with completing the merger, the 0.05 exchange ratio will be adjusted before we
complete the merger so that each Keystone share converted into M&T stock will
entitle you

                                        1
<PAGE>   6

to receive 0.5 of a share of M&T common stock following the split.

     The amount of cash and/or stock that you receive may differ from the
amounts that you elect due to the allocation and proration procedures in the
merger agreement. These procedures generally provide that 65% of the shares of
Keystone common stock outstanding when M&T and Keystone agreed to the merger
will be converted into M&T common stock and the remaining Keystone shares will
be converted into the right to receive cash.

     The market price of M&T common stock will fluctuate, altering the value of
the shares of M&T common stock that you may receive in the merger. In addition,
because the tax consequences of receiving cash will differ from the tax
consequences of receiving stock, you should carefully read the tax information
beginning on page 55.

M&T EXPECTS TO INCREASE ITS QUARTERLY
  DIVIDEND

     In connection with the merger, M&T has announced its intention to increase
the amount of its regular quarterly dividend, taking into account the 10-for-1
split of M&T's common stock, to $0.25 per share. Any change in the dividends
payable on M&T common stock will be subject to further action by M&T's board of
directors.

FOR KEYSTONE SHAREHOLDERS: HOW TO ELECT
  TO RECEIVE CASH OR STOCK AND
  EXCHANGE YOUR KEYSTONE STOCK
  CERTIFICATES (PAGE 43)

     Keystone Shareholders. A transmittal form for making an election is
enclosed with this document. The election form allows you to elect to receive
cash or stock, to make a mixed election (M&T stock for some of your Keystone
shares, cash for the others) or to make no election.

     For your election to be effective, you must return your properly completed
election form, along with your Keystone stock certificates (or an appropriate
guarantee that those certificates will be delivered) to EquiServe, M&T's
transfer agent, on or before 5:00 p.m., Eastern time, on September 20, 2000.
Shortly after the merger, EquiServe will allocate cash and stock among Keystone
shareholders, consistent with their elections and the allocation and proration
procedures. If you do not submit an election form, you will receive instructions
on where to surrender your Keystone stock certificates to EquiServe after the
merger is completed. In any event, you should not forward your Keystone stock
certificates with your proxy cards.

     If you have a preference for receiving either M&T stock or cash for your
Keystone stock, you should complete and return the enclosed election form.
Keystone shareholders who make an election will be accorded priority in
instances where the stock and cash consideration must be re-allocated among
Keystone shares to achieve the required ratio of Keystone shares to be converted
into M&T stock and into cash. If you do not make an election you will be
allocated M&T common stock and/or cash depending on the elections made by other
shareholders. However, even if you do make an election, you might not receive
the amount of cash and/or stock that you elect as described in the previous
section.

     No one associated with M&T or Keystone is recommending whether you should
elect to receive cash or stock in the merger. You must make your own decision
about your election.

DIFFERENCES IN THE RIGHTS OF M&T AND
  KEYSTONE SHAREHOLDERS (PAGE 63)

     The rights of Keystone shareholders currently are governed by Keystone's
restated articles of incorporation and bylaws, and by Pennsylvania law. After
the merger is completed, shareholders of Keystone who receive M&T common stock
in the merger will become shareholders of M&T, and therefore their rights as
shareholders of M&T will be governed by M&T's certificate of incorporation and
bylaws, and by New York law. This means that, as a result of the merger, the
rights of shareholders of Keystone will change, as the rights of M&T
shareholders differ in some ways from those of Keystone shareholders.

                                        2
<PAGE>   7

THE KEYSTONE SHAREHOLDERS' MEETING
  (PAGE 19)

     The special meeting of Keystone shareholders will be held at the Harrisburg
Hilton Hotel, Market Square, Harrisburg, Pennsylvania on Tuesday, September 5,
2000 at 10:00 a.m., local time. At the special meeting, you will be asked to
approve the merger. You may vote at the special meeting if you owned Keystone
common stock at the close of business on July 27, 2000. You may vote in person
or by proxy, either by returning the proxy card accompanying this document or
via the internet by using the voting link found at www.keyfin.com.

FOR KEYSTONE SHAREHOLDERS: MAJORITY VOTE
  REQUIRED (PAGE 19)

     Shareholder approval of the merger will require the affirmative vote of the
majority of the votes cast by Keystone shareholders eligible to vote on the
merger at the special meeting. A majority of the issued and outstanding shares
of Keystone common stock must be present either in person or by proxy for any
vote to be valid.

     As of July 27, 2000, Keystone's directors and executive officers and
related parties had the power to vote 2,499,559 shares of Keystone common stock,
representing approximately 5% of the shares of Keystone common stock then issued
and outstanding. Each of the directors and executive officers is expected to
vote his or her shares for approval of the merger.

     In addition, as of the same date, the trust department of Keystone
Financial Bank, N.A., as fiduciary, custodian or agent, had the power to vote
1,181,148 shares of Keystone common stock, representing approximately 2% of the
issued and outstanding shares of Keystone common stock. The trust department
will vote these shares in accordance with the terms of the respective governing
documents, applicable law and the trust department's fiduciary policies. The
trust department will make a determination as to how it will vote these shares
following receipt of this document.

FOR M&T SHAREHOLDERS: THE M&T
  SHAREHOLDER'S MEETING (PAGE 20)
     The special meeting of M&T shareholders will be held at M&T Center, One
Fountain Plaza, Buffalo, New York on September 19, 2000 at 11:00 a.m. local
time. At the special meeting, you will be asked to approve the issuance of M&T
shares in the merger and to authorize the amendment of M&T's certificate of
incorporation to increase the number of authorized shares of common stock to 150
million; to decrease the par value to $0.50 per share and to split the M&T
common stock on a 10-for-1 basis. You may vote at the special meeting if you
owned M&T common stock at the close of business on July 27, 2000. You may vote
in person or by returning the proxy card accompanying this document.

FOR M&T SHAREHOLDERS: VOTES REQUIRED
  (PAGE 20)

     M&T Shareholders. Your approval of the merger agreement, including the
issuance of M&T shares in the merger, will require the affirmative vote of the
holders of a majority of the votes cast on this proposal at the M&T special
meeting. Your authorization of the amendment to M&T's certificate of
incorporation will require the vote of a majority of all of the M&T shares
entitled to vote at the M&T special meeting. The amendment is necessary to allow
M&T to carry out the 10-for-1 stock split of M&T common stock described in the
merger agreement and will still leave additional authorized shares of M&T common
stock available for M&T to issue in the future. Keystone's obligation to
complete the merger is conditioned on the 10-for-1 split of M&T's stock. If the
merger does not occur M&T may still put the amendment into effect, but has not
yet decided whether it will do so. A majority of the issued and outstanding
shares of M&T common stock entitled to vote must be present either in person or
by proxy for any vote to be valid.

     As of July 27, 2000, M&T's directors and executive officers and related
parties had the power to vote 1,096,247 shares of M&T common stock, representing
approximately 14% of the

                                        3
<PAGE>   8

shares of M&T common stock then issued and
outstanding. Each of the directors and executive officers is expected to vote
his or her shares for approval of the merger.

     In addition, as of the same date, the trust department of M&T Bank, as
fiduciary, custodian or agent, had the power to vote 285,952 shares of M&T
common stock, representing approximately 4% of the issued and outstanding shares
of M&T common stock. The trust department will vote these shares in accordance
with the terms of the respective governing documents, applicable law and the
trust department's fiduciary policies. The trust department will make a
determination as to how it will vote these shares following receipt of this
document.

OUR REASONS FOR THE MERGER
  (PAGES 24 AND 25)

     Our companies are proposing to merge because we believe that by combining
them we can create a new, stronger company that will provide significant
benefits to shareholders and customers. Combining the companies should enable us
to reduce duplicative costs and to provide a broader range of products and
services throughout our combined service area. We believe that, together, we can
do a better job of increasing our combined revenues than if we did not merge. We
also believe that the merger will make us a stronger competitor in the
increasingly changing and more competitive financial services industry. To
review our reasons for the merger in greater detail, as well as how we came to
agree on the merger, please see pages 20 through 24.

OUR RECOMMENDATIONS TO SHAREHOLDERS
  (PAGES 25 AND 26)

     Keystone Shareholders. Keystone's board of directors has approved the
merger. The Keystone board believes that the merger is fair to and in the best
interests of our company and our shareholders. We unanimously recommend that you
vote FOR approval of the merger.

     M&T Shareholders. M&T's board of directors has unanimously approved the
merger and the split of M&T's common stock. The M&T board believes that the
merger and the stock split are fair to and in the best interests of our company
and our shareholders. We unanimously recommend that you vote FOR approval of the
merger and FOR approval of the stock split.

FOR KEYSTONE SHAREHOLDERS: THE
  TRANSACTION IS FAIR TO SHAREHOLDERS
  ACCORDING TO KEYSTONE'S INVESTMENT
  ADVISOR (PAGE 26)

     Among other factors considered in deciding to approve the merger, the
Keystone board of directors has received the written opinion of its financial
advisor, Keefe, Bruyette & Woods, Inc., that, as of May 15, 2000 (the date that
Keystone's board of directors voted on the merger), and updated through the date
of this document, the merger consideration was fair to Keystone's shareholders
from a financial point of view. We have attached the updated opinion to this
document as Appendix C. You should read this opinion completely to understand
the assumptions made, matters considered and limitations of the review
undertaken by KBW in providing its opinion.

FOR M&T SHAREHOLDERS: THE TRANSACTION IS
  FAIR TO M&T ACCORDING TO M&T'S
  INVESTMENT ADVISOR (PAGE 32)

     Among other factors considered in deciding to approve the merger, the M&T
board of directors has received the written opinion of its financial advisor,
Merrill Lynch, Pierce, Fenner & Smith Incorporated, that, as of May 16, 2000
(the date that M&T's board of directors voted on the merger) and updated through
the date of this document, the merger consideration was fair to M&T from a
financial point of view. We have attached the updated opinion to this document
as Appendix D. You should read this opinion completely to understand the
assumptions made, matters considered and limitations of the review undertaken by
Merrill Lynch in providing its opinion.

ROLE OF KEYSTONE MANAGEMENT AFTER THE
  MERGER (PAGE 49)

     Immediately following the merger, M&T will appoint Carl L. Campbell,
Chairman, President, Chief Executive Officer and a Director of

                                        4
<PAGE>   9

Keystone, and four other individuals designated by Mr. Campbell, who are
reasonably acceptable to M&T, to the board of directors of M&T and M&T Bank. M&T
will also elect Mr. Campbell as a Vice Chairman of M&T and M&T Bank. Mr.
Campbell will also serve as Chairman of M&T's Pennsylvania Division. M&T Bank
will appoint the remaining directors of Keystone and Keystone Bank as members of
regional advisory boards of M&T Bank.

WHAT WE NEED TO DO BEFORE THE MERGER IS
  COMPLETE (PAGE 44)

     Completion of the merger depends on a number of conditions being met,
including the following:

     - approval of the merger by the required votes of the shareholders of
       Keystone;

     - approval of the issuance of M&T shares in the merger and the stock split
       by the required votes of the shareholders of M&T;

     - approval by the Board of Governors of the Federal Reserve System and the
       New York State Banking Department. While we do not know of any reason why
       we would not be able to obtain these approvals in a timely manner, we
       cannot be certain when or if we will get these approvals; and

     - receipt by Keystone of an opinion from the law firm of Wachtell, Lipton,
       Rosen & Katz and receipt by M&T of an opinion from the law firm of Arnold
       & Porter that the U.S. federal income tax treatment of the merger to
       Keystone shareholders, Keystone and M&T should generally be as described
       in this document.

     Generally, M&T and Keystone can waive conditions to completion of the
merger. Some of these conditions, however, cannot be waived, including
shareholder and regulatory approvals and the absence of a government order
prohibiting the merger.

TERMINATING THE AGREEMENT (PAGE 48)

     The merger may be terminated by M&T or Keystone under some circumstances,
either before or after shareholder approval. These circumstances include:

     - the mutual consent of M&T and Keystone;

     - the other party has materially breached the merger agreement and has not
       cured the breach;

     - a government agency denies an approval needed to complete the merger;

     - a court or government agency issues an order prohibiting the merger;

     - the shareholders of Keystone fail to approve the merger; and

     - the merger has not been completed by January 31, 2001.

AMENDING THE AGREEMENT (PAGE 48)

     M&T and Keystone may amend the merger agreement at any time by mutual
written agreement, except that after approval by the shareholders of Keystone or
M&T, no waiver or amendment can change the amount of M&T common stock or cash
that Keystone shareholders would receive in the merger.

ACCOUNTING TREATMENT OF THE MERGER
  (PAGE 59)

     The merger will be accounted for as a purchase transaction under generally
accepted accounting principles. This means that M&T will treat the two companies
as one company beginning on the date of the merger. M&T will record the fair
market value of Keystone's assets and liabilities on its financial statements.
The difference between the purchase price in the merger and the fair market
value of Keystone's identifiable assets net of its liabilities will be recorded
on M&T's books as "goodwill." Approximately $609 million in goodwill and core
deposit intangible assets will result from accounting for the merger under the
purchase method of accounting and will be amortized over periods of up to 20
years as charges to M&T's earnings.

                                        5
<PAGE>   10

KEYSTONE STOCK OPTION AGREEMENT
  (PAGE 59)

     Keystone, as a condition to M&T's entering into the merger agreement,
granted M&T an option to purchase up to 9,730,070 shares of Keystone common
stock at a price of $15.125 per share. Keystone granted the option to increase
the likelihood that M&T and Keystone would complete the merger. The option could
discourage other companies from trying or proposing to combine with Keystone
before we complete the merger.

     M&T cannot exercise its option unless specified events occur that threaten
completion of the merger. These events include business combination or
acquisition transactions relating to Keystone and certain related activities,
other than the merger we are proposing in this document, like a merger or the
sale of a substantial amount of assets or stock. We do not know of any event
that has occurred as of the date of this document that would permit M&T to
exercise its option.

FOR KEYSTONE SHAREHOLDERS: INTERESTS OF
  DIRECTORS AND OFFICERS IN THE MERGER
  THAT ARE DIFFERENT FROM YOUR INTERESTS
  (PAGE 51)

     Some of Keystone's directors and officers have interests in the merger that
are different from, or in addition to, their interests as Keystone shareholders.
These interests include:

     - provisions of the merger agreement relating to service on M&T, M&T Bank
       and M&T Bank Advisory Boards after the merger;

     - provisions of the merger agreement relating to indemnification and
       insurance for Keystone directors and officers;

     - new employment agreements with M&T for some executive officers of
       Keystone; and

     - the effect of the merger on benefits and awards under existing Keystone
       employment arrangements and employee benefit plans (including accelerated
       vesting of options).

     The members of Keystone's board of directors knew about these additional
interests, and considered them, when they approved the merger.

FOR KEYSTONE SHAREHOLDERS: YOU HAVE
  DISSENTERS' RIGHTS IN THE MERGER
  (PAGE 60)

     Pennsylvania law permits you to dissent from the merger and have the fair
value of your stock paid to you in cash. In order to do this, you must follow
certain procedures, including filing notices and not voting any shares you
beneficially own in favor of the merger. You will not receive any of the merger
consideration if you dissent and follow the required procedures. Instead, you
will receive the appraised value of your stock in cash. The relevant sections of
Pennsylvania law governing this process are attached to this document as
Appendix E.

FOR M&T SHAREHOLDERS: YOU DO NOT HAVE
  DISSENTERS' RIGHTS IN THE MERGER
  (PAGE 62)

     You do not have dissenters' rights in connection with the merger or in
connection with the M&T stock split.

FOR KEYSTONE SHAREHOLDERS: YOUR
  EXPECTED TAX TREATMENT AS A RESULT OF
  THE MERGER (PAGE 55)

     M&T and Keystone have structured the merger to be treated as a
reorganization for U.S. federal income tax purposes. Each of M&T and Keystone
have conditioned the consummation of the merger on its receipt of a legal
opinion that this will be the case. Those opinions, however, will not bind the
Internal Revenue Service, which could take a different view. Your federal income
tax treatment will depend primarily on whether you exchange your Keystone common
stock solely for M&T common stock with cash received instead of a fractional
share of M&T common stock, solely for cash, or for a combination of M&T common
stock and cash. The following summary assumes that you hold your Keystone common
stock as a capital asset.

                                        6
<PAGE>   11

     EXCHANGE SOLELY FOR CASH: You generally will recognize capital gain or loss
equal to the difference between the amount of cash you receive and your adjusted
tax basis in the shares of Keystone common stock you surrender. However, if you
own any shares of M&T stock immediately after the merger, either actually or
through the constructive ownership rules of the Internal Revenue Code, part or
all of the cash you receive may be treated as ordinary income.

     EXCHANGE SOLELY FOR STOCK WITH CASH RECEIVED INSTEAD OF A FRACTIONAL SHARE
OF M&T COMMON STOCK: You will not recognize gain or loss except with respect to
the cash you receive instead of a fractional share of M&T common stock.

     EXCHANGE FOR A COMBINATION OF STOCK AND CASH: You will recognize income or
gain equal to the amount of cash you receive -- not counting cash received
instead of a fractional share of M&T common stock -- or the amount of gain you
realize, whichever is lower. The amount of gain you realize equals the amount of
cash you receive plus the fair market value of the M&T common stock you receive
minus your adjusted tax basis in the shares of Keystone common stock that you
surrender. You will not recognize any loss.

     In addition, if you receive cash instead of a fractional share of M&T
common stock, you will recognize income, gain or loss on your receipt of that
cash.

     Exceptions to these conclusions or other considerations may apply. Some of
them are discussed beginning on page 55. Determining the actual tax consequences
of the merger to you can be complicated. Those consequences will depend on your
specific situation, on whether you elect to receive stock, cash or a mix of
stock and cash, on whether your election is effective or must be changed under
the proration provisions of the merger agreement, and on many variables which
are not within our control. You should consult your own tax advisor for a full
understanding of the merger's federal income tax and other tax consequences as
they apply specifically to you.

                                        7
<PAGE>   12

                     MARKET PRICES AND DIVIDEND INFORMATION

     M&T common stock is listed and traded on the New York Stock Exchange under
the symbol "MTB." As of July 27, 2000 there were 4,859 shareholders of record of
M&T common stock. Keystone common stock is traded in the over-the-counter market
and price quotations are reported in the Nasdaq National Market under the symbol
"KSTN." As of July 27, 2000 there were 14,898 shareholders of record of Keystone
common stock.

     The table below sets forth for the periods indicated the high and low sale
prices and the dividends declared per share for M&T common stock and Keystone
common stock.

<TABLE>
<CAPTION>
                                                      M&T                          KEYSTONE
                                         -----------------------------   -----------------------------
                                          HIGH       LOW     DIVIDENDS    HIGH      LOW      DIVIDENDS
                                         -------   -------   ---------   ------   --------   ---------
<S>                                      <C>       <C>       <C>         <C>      <C>        <C>
2000 Quarters
  Third (through July 27, 2000)........  $497.00   $445.00     $1.25     $23.50    $21.19      $0.29
  Second...............................   475.00    399.50      1.25      22.75     14.69       0.29
  First................................   458.13    357.00      1.25      21.00     14.06       0.29
1999 Quarters
  Fourth...............................  $512.00   $406.00     $1.25     $25.56    $19.75      $0.29
  Third................................   575.00    412.50      1.25      30.25     23.63       0.29
  Second...............................   582.50    462.50      1.00      33.31     28.94       0.29
  First................................   518.75    464.00      1.00      37.50     32.25       0.29
1998 Quarters
  Fourth...............................  $539.50   $400.00     $1.00     $37.25    $25.25      $0.29
  Third................................   582.00    410.00      1.00      37.13     27.00       0.28
  Second...............................   554.00    480.00      1.00      41.75     33.56       0.28
  First................................   504.00    429.00      0.80      42.13     36.00       0.28
</TABLE>

     The information presented in the following table reflects:

     (1) the closing price for M&T common stock and the last reported sale price
         for Keystone common stock on May 16, 2000, the last trading day
         preceding the public announcement of the proposed merger;

     (2) the same information on July 27, 2000 which was the latest trading day
         practicable before the printing of this document; and

     (3) the Keystone common stock equivalent pro forma per share price as of
         May 16, 2000 and July 27, 2000. The equivalent pro forma per share
         price is calculated by multiplying the closing price of M&T common
         stock on each of these dates by the exchange ratio of 0.05.

     The merger agreement provides that the number of shares of Keystone common
stock converted into shares of M&T common stock in the merger will equal 65% of
the total number of outstanding Keystone shares on the date the merger agreement
was signed, less the total number of shares of Keystone common stock acquired by
M&T or Keystone prior to the merger. The remaining shares of Keystone common
stock will be converted into the right to receive $21.50 in cash per share. See
"THE MERGER -- Terms of the Merger."

<TABLE>
<CAPTION>
                                                            M&T      KEYSTONE     KEYSTONE
                                                          COMMON      COMMON     EQUIVALENT
                                                           STOCK      STOCK      PRO FORMA
                                                          -------    --------    ----------
<S>                                                       <C>        <C>         <C>
Market value per share:
  May 16, 2000..........................................  $415.00     $15.75       $20.75
  July 27, 2000.........................................  467.00       22.13        23.35
</TABLE>

                                        8
<PAGE>   13

     We do not know what the market price of M&T common stock will be if and
when the merger is completed. Because the exchange ratio is fixed and because
the market price of the M&T common stock is subject to fluctuation, the value of
the M&T common stock that you may receive in the merger may increase or decrease
before or after the merger and could be less than or greater than $21.50, which
is the amount available in a cash election. You should obtain current market
quotations for M&T common stock and Keystone common stock.
                                        9
<PAGE>   14

                           COMPARATIVE PER SHARE DATA

     The following table shows information about our income per share, dividends
per share and book value per share, and similar information reflecting the
merger (which we refer to as "pro forma" information).

     The information listed under the heading "Keystone Pro Forma Equivalent"
was obtained by multiplying the pro forma combined amounts by the exchange ratio
of 0.05. We expect that we will incur reorganization and restructuring expenses
as a result of combining our companies. We also anticipate that the merger will
provide the new company with financial benefits that include reduced operating
expenses and the opportunity to earn more revenue. The pro forma information,
while helpful in illustrating the financial characteristics of the new company,
does not reflect these expenses or benefits and does not attempt to predict or
suggest future results. In connection with the merger, M&T has announced its
intention to increase its regular quarterly dividend to $0.25 on a post-split
basis. Any change in the dividends payable on M&T common stock will be subject
to further action by M&T's board of directors. The pro forma combined and pro
forma equivalent dividend amounts in the table do not reflect this expected
change in M&T's regular quarterly dividend.

     The information in the following table is based on the historical financial
information that we have presented in our prior Securities and Exchange
Commission filings. We have incorporated this material into this document by
reference. See "WHERE YOU CAN FIND MORE INFORMATION" and "DOCUMENTS INCORPORATED
BY REFERENCE."

<TABLE>
<CAPTION>
                                                   HISTORICAL
                                        --------------------------------                PRO FORMA      KEYSTONE
                                                      M&T                  PRO FORMA    COMBINED       PRO FORMA
           PER SHARE DATA:                M&T     ADJUSTED(1)   KEYSTONE   COMBINED    ADJUSTED(1)   EQUIVALENT(2)
           ---------------              -------   -----------   --------   ---------   -----------   -------------
<S>                                     <C>       <C>           <C>        <C>         <C>           <C>
BASIC EARNINGS
Three months ended March 31, 2000.....  $  8.85       0.88        0.41        7.94         0.79         $ 0.40
Twelve months ended December 31,
  1999................................    34.05       3.41        0.76       26.17         2.62           1.31
DILUTED EARNINGS
Three months ended March 31, 2000.....     8.61       0.86        0.41        7.76         0.78           0.39
Twelve months ended December 31,
  1999................................    32.83       3.28        0.75       25.39         2.54           1.27
CASH DIVIDENDS (3)
Three months ended March 31, 2000.....     1.25      0.125        0.29        1.25        0.125           0.06
Twelve months ended December 31,
  1999................................     4.50       0.45        1.16        4.50         0.45           0.23
BOOK VALUE
At March 31, 2000.....................  $238.26      23.83       11.39      269.63        26.96         $13.48
</TABLE>

-------------------------
(1) M&T adjusted and pro forma combined adjusted amounts have been adjusted as
    though the proposed 10-for-1 stock split had already occurred.

(2) The Keystone pro forma equivalent represents the pro forma combined amount
    multiplied by the exchange ratio of 0.05. See "PRO FORMA CONDENSED COMBINED
    FINANCIAL INFORMATION (Unaudited)."

(3) Pro Forma combined dividends per share represents historical dividends per
    common share paid by M&T. M&T plans to increase its quarterly dividend after
    the merger to not less than $0.25 per share, after giving effect to the
    10-for-1 split of M&T common stock. The declaration and payment of dividends
    is subject to a number of factors, including M&T board approval and the
    level of earnings at M&T. The pro forma combined and pro forma equivalent
    dividend amounts in the table do not reflect this expected change in M&T's
    regular quarterly dividend.
                                       10
<PAGE>   15

                      SELECTED CONSOLIDATED FINANCIAL DATA

     The following tables set forth certain selected historical and selected pro
forma consolidated financial data for M&T and Keystone. The historical selected
financial data for the five years ending December 31, 1999 are derived from the
respective audited consolidated financial statements of M&T and Keystone. The
selected financial data for the three-month periods ending March 31, 2000 and
1999 are derived from unaudited consolidated interim financial statements and
are not necessarily indicative of the results for the remainder of the year or
any future period. We believe that our respective consolidated interim financial
statements reflect all adjustments, which are of a normal recurring nature,
necessary for a fair statement of the results for the interim period presented.
You should read this summary in connection with the financial statements and
other financial information included in documents incorporated in this document
by reference. See "WHERE YOU CAN FIND MORE INFORMATION" and "DOCUMENTS
INCORPORATED BY REFERENCE."

     The pro forma selected financial data were developed giving effect to the
merger using the purchase method of accounting. Per share data has also been
shown as adjusted as though the proposed 10-for-1 stock split had already
occurred. For a description of the purchase method of accounting with respect to
the merger and the related effects on the historical financial statements of M&T
and Keystone, see "THE MERGER -- Accounting Treatment." The pro forma selected
financial data may not be indicative of the financial position or results that
actually would have occurred had the merger been completed on the dates or at
the beginning of the periods indicated, or which will be attained in the future.
See "SUMMARY -- Comparative Per Share Data" and "PRO FORMA CONDENSED COMBINED
FINANCIAL INFORMATION (Unaudited)."
                                       11
<PAGE>   16

                   SELECTED PRO FORMA COMBINED FINANCIAL DATA
                 (DOLLARS IN THOUSANDS, EXCEPT PER SHARE DATA)
                                  (UNAUDITED)

<TABLE>
<CAPTION>
                                                         FOR THE THREE
                                                          MONTHS ENDED     FOR THE YEAR ENDED
                                                         MARCH 31, 2000    DECEMBER 31, 1999
                                                         --------------    ------------------
<S>                                                      <C>               <C>
SUMMARIZED INCOME STATEMENT DATA:
  Net interest income..................................   $   249,084         $   987,052
  Provision for credit losses..........................        12,788              67,876
  Other income.........................................        96,010             388,024
  Other expense........................................       217,356             918,989
  Income taxes.........................................        41,095             142,447
                                                          -----------         -----------
  Net income...........................................   $    73,855         $   245,764
PER SHARE DATA:
  Basic earnings.......................................   $      7.94         $     26.17
  Diluted earnings.....................................          7.76               25.39
  Book value at end of period..........................        269.63              263.96
  Cash dividends.......................................          1.25                4.50
  Adjusted basic earnings(1)...........................          0.79                2.62
  Adjusted diluted earnings(1).........................          0.78                2.54
  Adjusted book value at end of period(1)..............         26.96               26.40
  Adjusted cash dividends(1)...........................         0.125                0.45
WEIGHTED AVERAGE NUMBER OF SHARES:
  Basic................................................   $     9,301         $     9,391
  Diluted..............................................         9,512               9,681
  Adjusted basic(1)....................................        93,015              93,905
  Adjusted diluted(1)..................................        95,124              96,807
AVERAGE BALANCE SHEET DATA:
  Total assets.........................................   $29,830,406         $28,341,785
  Total borrowings.....................................     6,073,994           5,151,082
  Shareholders' equity.................................     2,489,445           2,435,835
</TABLE>

------------------

(1) Amounts have been adjusted as though the proposed 10-for-1 stock split had
    already occurred.
                                       12
<PAGE>   17

                              M&T BANK CORPORATION
                SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA
                     (IN THOUSANDS, EXCEPT PER SHARE DATA)

<TABLE>
<CAPTION>
                                     THREE MONTHS ENDED
                                          MARCH 31,                                YEARS ENDED DECEMBER 31,
                                  -------------------------   -------------------------------------------------------------------
                                     2000          1999          1999          1998          1997          1996          1995
                                  -----------   -----------   -----------   -----------   -----------   -----------   -----------
<S>                               <C>           <C>           <C>           <C>           <C>           <C>           <C>
SUMMARIZED INCOME STATEMENT
 DATA:
 Net interest income............  $   195,127   $   181,307   $   759,397   $   671,947   $   559,406   $   533,522   $   488,744
 Provision for credit losses....        9,000         8,500        44,500        43,200        46,000        43,325        40,350
 Other income...................       71,998        72,716       282,375       262,939       190,529       167,750       147,218
 Other expense..................      150,597       139,466       578,958       566,123       421,776       408,978       374,439
 Income taxes...................       39,293        39,151       152,688       117,589       105,918        97,866        90,137
                                  -----------   -----------   -----------   -----------   -----------   -----------   -----------
   Net income...................  $    68,235   $    66,906   $   265,626   $   207,974   $   176,241   $   151,103   $   131,036
PER COMMON SHARE DATA:(1)
 Basic net income...............  $      8.85   $      8.65   $     34.05   $     27.30   $     26.60   $     22.54   $     19.61
 Diluted net income.............         8.61          8.34         32.83         26.16         25.26         21.08         17.98
 Book value at end of period....       238.26        215.34        232.41        207.94        155.86        135.45        125.33
 Cash dividends.................         1.25          1.00          4.50          3.80          3.20          2.80          2.50
WEIGHTED AVERAGE NUMBER OF
 SHARES:(1)
 Basic..........................        7,711         7,731         7,800         7,619         6,625         6,663         6,499
 Diluted........................        7,922         8,023         8,090         7,950         6,977         7,170         7,288
AVERAGE BALANCE SHEET DATA:
 Total assets...................  $22,438,135   $20,297,739   $21,057,080   $18,309,436   $13,308,559   $12,478,666   $11,484,754
 Total borrowings...............    4,526,649     3,785,053     3,804,625     2,758,130     1,184,864     1,310,784     1,569,514
 Shareholders' equity...........    1,812,769     1,638,086     1,736,087     1,500,677       953,021       863,133       782,520
</TABLE>

-------------------------

(1) Amounts have not been adjusted for the proposed 10-for-1 stock split.
                                       13
<PAGE>   18

                              KEYSTONE FINANCIAL, INC.
                  SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA
                       (IN THOUSANDS, EXCEPT PER SHARE DATA)

<TABLE>
<CAPTION>
                                         THREE MONTHS ENDED
                                              MARCH 31,                             YEARS ENDED DECEMBER 31,
                                       -----------------------   --------------------------------------------------------------
                                          2000       1999(1)      1999(1)        1998         1997         1996         1995
                                       ----------   ----------   ----------   ----------   ----------   ----------   ----------
<S>                                    <C>          <C>          <C>          <C>          <C>          <C>          <C>
SUMMARIZED INCOME STATEMENT DATA:
  Net interest income................  $   61,386   $   64,630   $  257,373   $  276,965   $  278,244   $  262,119   $  246,011
  Provision for credit losses........       3,788        2,663       23,376       17,150       15,316       10,713        8,568
  Other income.......................      24,012       26,451      105,649      110,036       90,424       71,862       58,234
  Other expense......................      54,495       77,204      290,978      224,412      226,482      196,582      182,227
  Income taxes.......................       7,260        2,899       11,592       45,692       38,953       37,180       34,001
                                       ----------   ----------   ----------   ----------   ----------   ----------   ----------
    Net income.......................  $   19,855   $    8,315   $   37,076   $   99,747   $   87,917   $   89,506   $   79,449
PER COMMON SHARE DATA:
  Basic net income...................  $     0.41   $     0.17   $     0.76   $     1.94   $     1.70   $     1.72   $     1.60
  Diluted net income.................        0.41         0.17         0.75         1.92         1.68         1.70         1.59
  Book value at end of period........       11.39        11.99        11.29        13.12        13.18        12.70        11.96
  Cash dividends.....................        0.29         0.29         1.16         1.13         1.06         0.98         0.93
WEIGHTED AVERAGE NUMBER OF SHARES:
  Basic..............................      48,805       49,595       48,856       51,446       51,693       52,119       49,557
  Diluted............................      48,870       50,114       49,186       52,042       52,320       52,481       49,846
AVERAGE BALANCE SHEET DATA:
  Total assets.......................  $6,894,746   $6,787,002   $6,787,180   $6,874,316   $6,630,002   $6,232,648   $5,871,236
  Total borrowings...................   1,198,873      905,236      997,985      866,541      676,194      487,010      441,478
  Shareholders' equity...............     563,023      613,603      586,095      681,812      662,320      635,351      567,362
</TABLE>

-------------------------

(1) Where applicable, amounts include special charges relating to settlement of
    certain litigation and restructuring-related charges that reduced net income
    by $46.6 million or $0.95 per share for the year ended December 31, 1999 and
    by $12.8 million and $0.25 per share for the three months ended March 31,
    1999.
                                       14
<PAGE>   19

                                 THE COMPANIES

M&T BANK CORPORATION

     M&T Bank Corporation ("M&T") is a New York business corporation registered
as a bank holding company under the Bank Holding Company Act of 1956, as
amended, and under Article III-A of the New York State Banking Law. M&T was
incorporated in November 1969. As of June 30, 2000, M&T had total consolidated
assets of approximately $21.7 billion and total shareholders' equity of
approximately $1.9 billion. M&T's two wholly owned banking subsidiaries are
Manufacturers and Traders Trust Company, with its principal executive offices in
Buffalo, New York, and M&T Bank, National Association, with its main office at
Oakfield, New York. Collectively, the banks and their subsidiaries offer a wide
range of commercial banking, trust and investment services to their customers.

     M&T Bank is a banking corporation incorporated and chartered under New York
law. M&T Bank is a member of the Federal Reserve System and the Federal Home
Loan Bank System, and its deposits are insured by the Federal Deposit Insurance
Corporation ("FDIC") up to applicable limits. As of June 30, 2000, M&T Bank
represented 96% of the consolidated assets of M&T. As of June 30, 2000, M&T Bank
had 247 banking offices located throughout New York State and 19 banking offices
located in northeastern Pennsylvania plus a branch in Nassau, the Bahamas. As a
commercial bank, M&T Bank offers a broad range of financial services to a
diverse base of consumers, businesses, professional clients, governmental
entities and financial institutions located in its markets. Lending is largely
focused on consumers residing in New York State and Northeastern Pennsylvania
and on small and medium-size businesses. However, certain of M&T Bank's
subsidiaries conduct lending activities in markets outside of New York State,
including Northeastern Pennsylvania. M&T Bank also provides other financial
services through its operating subsidiaries, including a consumer lending and
commercial leasing and lending company, a mortgage banking subsidiary, a company
specializing in capital equipment leasing, a company engaged in commercial real
estate lending and servicing activities, a company providing securities
brokerage and investment advisory services and a consumer leasing company.

     M&T Bank, N.A. is a national bank and a member of the Federal Reserve
System, and its deposits are insured by the FDIC up to applicable limits. M&T
Bank, N.A. commenced operations on October 2, 1995 and offers selected deposit,
loan and insurance products on a nationwide basis, primarily through telephone
marketing and direct mail marketing techniques. Insurance products are also
offered by M&T Bank, N.A. through the banking offices of M&T Bank. As of June
30, 2000, M&T Bank, N.A. had total assets of $918 million.

     On July 9, 2000, M&T agreed to acquire Premier National Bancorp, Inc.
("Premier"), a bank holding company headquartered in Lagrangeville, New York. As
of June 30, 2000, Premier reported, on a consolidated basis, total assets of
approximately $1.6 billion, total deposits of approximately $1.3 billion and
total shareholders equity of approximately $139 million. Its principal
subsidiary, Premier National Bank, operates branches primarily in New York's
Hudson Valley region.

     Under the agreement, Premier will merge into Olympia and Premier National
Bank will merge into M&T Bank. The outstanding shares of Premier common stock
will be converted into shares of M&T common stock and cash having an aggregate
value of approximately $342 million. The Premier merger is conditioned upon,
among other things, receipt of necessary shareholder and regulatory approvals.
M&T and Premier expect to complete the merger in the first quarter of 2001.
Additional information about the Premier merger is included in documents
incorporated in this document by reference, which are available as described on
page 80.

     From time to time, M&T investigates and holds discussions and negotiations
in connection with possible strategic transactions with other banks and
financial services entities. As of the date of this

                                       15
<PAGE>   20

document, M&T has not entered into any material agreements or mutual
understandings in any transactions of the type referred to above except for the
transactions described in this document and in documents incorporated in this
document by reference. See "WHERE YOU CAN FIND MORE INFORMATION" and "DOCUMENTS
INCORPORATED BY REFERENCE." If required under applicable law or New York Stock
Exchange policy, any such transactions would be subject to regulatory approval
and the approval of shareholders.

                                       16
<PAGE>   21

M&T SECOND QUARTER 2000 FINANCIAL RESULTS

     On July 11, 2000, M&T announced unaudited results of its operations for the
three and six months ended June 30, 2000. The following unaudited financial
results are derived from the unaudited consolidated financial statements for the
three and six month periods ended June 30, 2000 and 1999. Such financial
statements, in the opinion of M&T management, contain the adjustments all of
which are normal and recurring in nature, necessary to present fairly M&T's
consolidated financial position, results of operations, and changes in cash
flows.

<TABLE>
<CAPTION>
                                               FOR THE THREE MONTHS   FOR THE SIX MONTHS ENDED
                                                  ENDED JUNE 30,              JUNE 30,
                                               --------------------   ------------------------
                                                 2000        1999        2000          1999
                                               --------    --------   ----------    ----------
                                                (THOUSANDS, EXCEPT     (THOUSANDS, EXCEPT PER
                                                 PER SHARE DATA)            SHARE DATA)
<S>                                            <C>         <C>        <C>           <C>
Net interest income..........................  $198,754    $188,051    $393,881      $369,358
Income before income tax.....................   110,426     100,810     217,954       206,867
Net income...................................    71,538      65,038     139,773       131,944
Net income per common share (basic)..........  $   9.33    $   8.35    $  18.18      $  17.00
Net income per common share (diluted)........  $   9.07    $   8.00    $  17.68      $  16.33
Weighted average common shares outstanding
  (diluted)..................................     7,888       8,132       7,905         8,078
</TABLE>

     At June 30, 2000, M&T had consolidated total assets of $21.7 billion,
consolidated total deposits of $15.2 billion and consolidated total
stockholders' equity of $1.9 billion.

KEYSTONE SECOND QUARTER 2000 FINANCIAL RESULTS

     On July 18, 2000, Keystone announced unaudited results of its operations
for the three and six months ended June 30, 2000. The following unaudited
financial results are derived from the unaudited consolidated financial
statements for the three and six month periods ended June 30, 2000 and 1999.
Such financial statements, in the opinion of Keystone management, contain the
adjustments all of which are normal and recurring in nature, necessary to
present fairly Keystone's consolidated financial position, results of
operations, and changes in cash flows.

<TABLE>
<CAPTION>
                                               FOR THE THREE MONTHS   FOR THE SIX MONTHS ENDED
                                                  ENDED JUNE 30,              JUNE 30,
                                               --------------------   ------------------------
                                                 2000      1999(1)       2000        1999(1)
                                               --------    --------   ----------    ----------
                                                (THOUSANDS, EXCEPT     (THOUSANDS, EXCEPT PER
                                                 PER SHARE DATA)            SHARE DATA)
<S>                                            <C>         <C>        <C>           <C>
Net interest income..........................  $ 63,834    $ 64,744    $125,220      $129,374
Income before income tax.....................    28,560      35,423      55,675        46,637
Net income...................................    20,194      24,204      40,049        32,519
Net income per common share (basic)..........  $   0.41    $   0.49    $   0.82      $   0.66
Net income per common share (diluted)........  $   0.41    $   0.49    $   0.82      $   0.66
Weighted average common shares outstanding
  (diluted)..................................    48,990      48,927      48,930        49,522
</TABLE>

------------------

(1) Where applicable, amounts include restructuring-related charges that reduced
    net income by $423 thousand or $0.01 per share and $13.2 million or $0.26
    per share for the three months ended and six months ended June 30, 1999,
    respectively.

     At June 30, 2000, Keystone had consolidated total assets of $7.0 billion,
consolidated total deposits of $5.0 billion and consolidated total stockholders'
equity of $566 million.

     For additional information concerning the business of M&T and its financial
condition, you should refer to the M&T documents incorporated in this document
by reference. See "WHERE YOU CAN FIND MORE INFORMATION" and "DOCUMENTS
INCORPORATED BY REFERENCE."

                                       17
<PAGE>   22

OLYMPIA FINANCIAL CORP.

     Olympia Financial Corp. ("Olympia"), a wholly owned subsidiary of M&T, is a
Delaware corporation that holds the stock of M&T Bank and is registered as a
bank holding company under the Bank Holding Company Act. Its registered office
is located at 1209 Orange Street, Wilmington, Delaware 19801.

KEYSTONE FINANCIAL, INC.

     Keystone is a Pennsylvania corporation registered as a bank holding company
under the Bank Holding Company Act. As of June 30, 2000, Keystone had total
assets of $7 billion and shareholders' equity of $566 million. Keystone has one
wholly owned subsidiary bank, Keystone Financial Bank, N.A. ("Keystone Bank"), a
national banking association. Keystone Bank is a member of the Federal Reserve
System and the Federal Home Loan Bank of Pittsburgh, and its deposits are
insured by the FDIC up to applicable limits.

     Keystone Bank offers diversified financial services through 177 community
banking offices in 31 Pennsylvania counties, three Maryland counties and one
county in West Virginia. The principal business of Keystone Bank is to accept
deposits from the general public and to invest those deposits, together with
funds from borrowings and ongoing operations, in commercial, consumer and
residential mortgage loans. Keystone Bank concentrates its efforts in the
retail, municipal and commercial banking businesses. Keystone Bank offers a
variety of deposit and loan products and trust services designed to meet the
needs of residents and businesses of its market areas. Keystone also offers
brokerage services, investment advisory services and sales of noninsured mutual
funds, employee benefits consulting and annuities through subsidiaries and
affiliates of Keystone Bank, including Governors Group Advisors, Inc.,
Martindale, Andres & Company, Inc., MMC&P Retirement Benefits Services, Inc. and
Keystone Brokerage, L.L.C.

     For additional information concerning the business of Keystone and its
financial condition, you should refer to Keystone's documents incorporated in
this document by reference. See "WHERE YOU CAN FIND MORE INFORMATION" and
"DOCUMENTS INCORPORATED BY REFERENCE."

THE COMBINED COMPANY

     Combining M&T and Keystone will create a company that will rank first,
based on deposit share, in both Central Pennsylvania and Upstate New York. On a
pro forma basis as of June 30, 2000, the combined company would have
approximately $20 billion in deposits. The combined company will offer a broader
range of products and services to current Keystone customers and will benefit
from greater geographic diversity and the benefits of scale associated with a
larger company. Because of the lack of overlap between the two companies, the
merger is not expected to result in the consolidation of any Keystone branches
into M&T branches. M&T also expects that the merger will result in significant
opportunities for cost savings and for revenue enhancement. See "THE
MERGER -- Management and Operations After the Merger -- Operations."

                                       18
<PAGE>   23

                       THE KEYSTONE SHAREHOLDERS' MEETING

DATE, PLACE AND TIME

     The special meeting of Keystone shareholders is held at the Harrisburg
Hilton Hotel, Market Square, Harrisburg, Pennsylvania on September 5, 2000 at
10:00 a.m., local time.

RECORD DATE; VOTING RIGHTS

     The Keystone record date is the close of business on July 27, 2000. The
Keystone record date has been fixed as the date for purposes of determining
shareholders entitled to notice of, and to vote at, the Keystone special
meeting. On the Keystone record date, there were issued and outstanding
49,114,469 shares of Keystone common stock. You, as a shareholder of Keystone on
the Keystone record date, will be entitled to one vote for each share of
Keystone common stock held of record with respect to the merger and any other
matter properly submitted at the special meeting. The affirmative vote of a
majority of the votes cast by all shareholders of Keystone common stock entitled
to vote at the special meeting is required to approve the merger agreement. In
order for the special meeting to take place, holders of a majority of the
outstanding Keystone common stock must attend the meeting either in person or by
proxy.

     Keystone intends to count shares of Keystone common stock present in person
at the special meeting but not voting, and shares of Keystone common stock for
which it has received proxies but with respect to which holders of such shares
have abstained on any matter, as present at the special meeting for purposes of
determining whether a quorum exists. Because approval of the merger requires the
affirmative vote of a majority of the votes cast by all shareholders of Keystone
common stock entitled to vote on the merger, such nonvoting shares and
abstentions will not be counted in determining whether or not the required
number of shares have been voted to approve the merger. In addition, under
applicable NASDAQ rules, brokers who hold shares of Keystone common stock in
street name for customers who are the beneficial owners of such shares are
prohibited from giving a proxy to vote shares held for such customers in favor
of the approval of the merger without specific instructions to that effect from
such customers. Accordingly, the failure of such customers to provide
instructions with respect to their shares of Keystone common stock to their
broker will have the effect of the shares not being voted and will not be
counted as a vote for or against the merger. Such "broker non-votes," if any,
will be counted as present for determining the presence or absence of a quorum
for the transaction of business.

     As of July 27, 2000, Keystone's directors and executive officers and
related parties had the power to vote 2,499,559 shares of Keystone common stock,
representing approximately 5% of the shares of Keystone common stock then
outstanding. Each of the directors and executive officers is expected to vote
for approval of the merger.

     In addition, as of the same date, the trust department of Keystone Bank, as
fiduciary, custodian or agent, had the power to vote 1,181,148 shares of
Keystone common stock, representing approximately 2% of the then outstanding
Keystone common stock. The trust department of Keystone Bank will vote these
shares in accordance with the terms of the respective governing documents,
applicable law and the trust department's fiduciary policies. The trust
department will make a determination as to how it will vote these shares
following receipt of this document.

VOTING AND REVOCATION OF PROXIES

     Shares of Keystone common stock represented by a proxy properly signed and
returned at or prior to, or submitted via the internet proxy link you can find
at www.keyfin.com prior to, the special meeting, and not subsequently revoked
prior to the vote on the merger, will be voted at the special meeting in

                                       19
<PAGE>   24

accordance with the instructions on the proxy. If a proxy is signed and returned
without indicating any voting instructions, the shares of Keystone common stock
represented by the proxy will be voted FOR approval of the merger.

     You may revoke your proxy at any time before it is exercised. In order to
revoke a proxy, you must either give written notice of such revocation to the
Secretary of Keystone or vote the shares of Keystone common stock subject to
such proxy by a later-dated proxy or by written ballot at the special meeting.
Written notices of revocation should be directed to: Ben G. Rooke, Vice
Chairman, General Counsel and Secretary, Keystone Financial, Inc., One Keystone
Plaza, Front and Market Streets, Harrisburg, PA 17105. Your presence at the
special meeting, if you have given a proxy, will not, in and of itself, revoke
the proxy. Any shareholder of record attending the special meeting may vote in
person whether or not a proxy has been previously given.

     The board of directors of Keystone is not aware of any business to be acted
upon at the special meeting other than the merger. If other matters are properly
brought before the special meeting, or any adjournments or postponements
thereof, the persons appointed as proxies will have discretion to vote or act on
these matters according to their best judgment. The persons named as proxies by
a shareholder may propose and vote for one or more adjournments or postponements
of the special meeting to permit additional solicitation of proxies in favor of
the merger, but no proxy voted against the merger will be voted in favor of any
such adjournment or postponement.

SOLICITATION OF PROXIES

     In addition to solicitation of proxies by mail, Keystone's directors,
officers and regular employees may also solicit proxies without additional
compensation to such directors, officers or regular employees and at a nominal
cost to Keystone. Brokerage houses, nominees, fiduciaries and other custodians
have been requested to forward proxy materials to beneficial owners of Keystone
common stock and such parties will be reimbursed for the expenses incurred by
them. Keystone will bear its own expenses in connection with the solicitation of
proxies, except that M&T and Keystone each will bear half of all printing and
mailing costs and filing fees associated with this document.

                         THE M&T SHAREHOLDERS' MEETING

DATE, PLACE AND TIME

     The special meeting of M&T shareholders will be held at M&T Center, One
Fountain Plaza on Tuesday, September 19, 2000 at 11:00 a.m., local time.

RECORD DATE; VOTING RIGHTS

     The M&T record date is the close of business on July 27, 2000. The M&T
record date will be used for purposes of determining shareholders entitled to
notice of, and to vote at, the special meeting. On the M&T record date, there
were issued and outstanding 7,653,915 shares of M&T common stock entitled to
vote at the special meeting. You, as a shareholder of M&T on the M&T record
date, will be entitled to one vote for each share of M&T common stock held of
record with respect to the merger, the M&T stock split and any matter properly
submitted at the special meeting. Although neither applicable New York law nor
the certificate of incorporation of M&T requires M&T's shareholders' approval of
the merger, the rules and regulations of the NYSE require M&T's shareholders'
approval of the issuance of M&T common stock in connection with the merger. The
affirmative vote of the holders of a majority of the votes cast by the holders
of M&T common stock eligible to vote thereon at a meeting at which a quorum is
present is required to approve the merger. In addition, the affirmative vote of
a majority of all

                                       20
<PAGE>   25

of the outstanding shares of M&T common stock entitled to vote at the special
meeting is required to authorize the M&T stock split. In order for the special
meeting to take place, holders of a majority of M&T common stock outstanding on
the M&T record date must attend the meeting either in person or by proxy.

     M&T intends to count shares of M&T common stock present in person at the
special meeting but not voting, and shares of M&T common stock for which it has
received proxies but with respect to which holders of such shares have abstained
on any matter, as present at the special meeting for purposes of determining
whether a quorum exists. Because the approval of the merger requires the
affirmative vote of a majority of the votes cast by holders of M&T common stock
eligible to vote at the special meeting, such abstentions will have no effect on
the vote for the merger. Because authorization of the M&T stock split requires
the affirmative vote of a majority of all of the outstanding shares of M&T
common stock entitled to vote at the special meeting, nonvoting shares and
abstentions will have the same effect as a vote against the M&T stock split. In
addition, under applicable exchange rules, brokers who hold shares of M&T common
stock in street name for customers who are the beneficial owners of such shares
are prohibited from giving a proxy to vote shares held for such customers in
favor of the approval of the issuance of M&T common stock in the merger or the
amendment to the M&T certificate of incorporation without specific instructions
to that effect from such customers. Accordingly, the failure of such customers
to provide instructions with respect to their shares of M&T common stock to
their broker will have no effect on the vote for the merger and will have the
effect of a vote against the M&T stock split. Such "broker non-votes," if any,
will be counted as present for determining the presence or absence of a quorum
for the transaction of business.

     As of July 27, 2000, M&T's directors and executive officers and related
parties had the power to vote 1,096,247 shares of M&T common stock, representing
approximately 14% of the shares of M&T common stock then issued and outstanding.
Each of the directors has indicated his or her intention to vote for approval of
the merger. Other than compensation paid in connection with their executive
duties or service as directors of M&T, no compensation has been paid to any
person who has indicated an intention to vote in favor of the merger.

     In addition, as of the same date, the trust department of M&T Bank, as
fiduciary, custodian or agent, had the power to vote 285,952 shares of M&T
common stock, representing approximately 4% of the then issued and outstanding
M&T common stock. The trust department of M&T Bank will vote these shares in
accordance with the terms of the respective governing documents, applicable law
and the trust department's fiduciary policies. The trust department will make a
determination as to how it will vote these shares following receipt of this
document.

VOTING AND REVOCATION OF PROXIES

     Shares of M&T common stock represented by a proxy properly signed and
returned at or prior to the special meeting and not subsequently revoked prior
to the vote will be voted at the special meeting, or submitted by internet or
telephone using the procedures described on the proxy, in accordance with the
instructions on the proxy. If a proxy is signed and returned without indicating
any voting instructions, the shares of M&T common stock represented by the proxy
will be voted FOR approval of the merger and FOR approval of the M&T stock
split.

     If you are giving a proxy, you may revoke it at any time before it is
exercised. In order to revoke a proxy, you must either give written notice of
such revocation to the Secretary of M&T or to the Secretary of the special
meeting or vote the shares of M&T common stock subject to such proxy by a later
dated proxy or by written ballot at the special meeting. Written notices of
revocation should be directed to: Marie King, Corporate Secretary, M&T, One M&T
Plaza, Buffalo, New York 14203. The

                                       21
<PAGE>   26

presence at the special meeting of any shareholder who has given a proxy will
not, in and of itself, revoke the proxy. Any shareholder of record attending the
special meeting may vote in person whether or not a proxy has been previously
given.

     The board of directors of M&T is not aware of any business to be acted upon
at the special meeting other than the issuance of M&T common stock in the merger
and the M&T stock split. According to New York law, no business may be brought
before the M&T special meeting other than business related to the matters set
forth in M&T's notice of special meeting to shareholders, which is provided in
the beginning of this document. The persons named as proxies by a shareholder
may propose and vote for one or more adjournments or postponements of the
special meeting to permit another solicitation of proxies in favor of the
issuance of M&T common stock in the merger or the M&T stock split, but no proxy
voted against the issuance of M&T common stock in the merger or the M&T stock
split will be voted in favor of any adjournment or postponement for the purpose
of soliciting additional votes for such proposal.

SOLICITATION OF PROXIES

     In addition to solicitation of proxies by mail, M&T's directors, officers
and regular employees may also solicit proxies, without additional compensation
to such directors, officers or regular employees and at a nominal cost to M&T.
Brokerage houses, nominees, fiduciaries and other custodians have been requested
to forward proxy materials to beneficial owners of M&T common stock and such
parties will be reimbursed for the expenses incurred by them. M&T will bear its
own expenses in connection with the solicitation of proxies, except that M&T and
Keystone each will bear 50% of all printing and mailing costs and filing fees
associated with this document.

                                   THE MERGER

     This section describes material aspects of the merger. The description of
the merger agreement and the stock option agreement contained in this section
does not purport to be complete and is qualified in its entirety by reference to
the merger agreement and the stock option agreement, which are attached to this
document as Appendix A and Appendix B, respectively, and are incorporated by
reference. You are urged to read the merger agreement and the stock option
agreement carefully and in their entirety.

BACKGROUND AND REASONS FOR THE MERGER: RECOMMENDATIONS OF THE BOARDS OF
DIRECTORS

Background

     During 1999, M&T informally considered strategic alternatives for
geographic and overall franchise expansion, focusing on contiguous states,
including Pennsylvania, given M&T's previous entry into Pennsylvania through its
acquisition of ONBANCorp.

     On March 17, 2000, Ben G. Rooke, Vice Chairman, General Counsel and
Secretary of Keystone, met informally with senior executives of M&T and
discussed with them general conditions in the banking and financial services
industry and the current environment in which Keystone and M&T were operating.
During this discussion, it was determined that a strategic relationship between
Keystone and M&T could potentially be advantageous to both companies, and the
executives present agreed to contact the chief executive officers of their
respective companies to determine whether further discussions might be fruitful.

     On April 1, 2000, Robert G. Wilmers, President and Chief Executive Officer
of M&T, met in Harrisburg, Pennsylvania with Carl L. Campbell, Chairman,
President and Chief Executive Officer of Keystone. Messrs. Wilmers and Campbell
discussed a possible transaction between the two companies

                                       22
<PAGE>   27

including the possible terms of such a transaction. Mr. Campbell indicated that
he would discuss a possible transaction with M&T with the executive committee of
the Keystone board of directors at its next meeting.

     Later in April, 2000, senior executives of Keystone had informal,
exploratory discussions regarding a possible business combination with senior
executives of M&T. The executive committee of Keystone's board of directors met
on April 19, 2000. The matter of a possible strategic transaction between
Keystone and M&T was discussed, and Mr. Campbell was authorized to proceed with
exploratory discussions with M&T. Keystone retained Keefe, Bruyette & Woods as
its financial advisor in connection with a possible transaction with M&T. On
April 25, 2000, M&T and Keystone signed a mutual confidentiality agreement.

     Conversations continued between Messrs. Campbell and Wilmers. Information
relating to both companies was exchanged, and a meeting between Messrs. Campbell
and Wilmers to discuss the key terms of an agreement was arranged for April 30,
2000 in New York City. At that meeting, financial, transaction structure and
other terms of a potential transaction were discussed, including M&T's splitting
its stock and increasing its dividend. Following the meeting with Mr. Wilmers,
Mr. Campbell and representatives from KBW met with the executive committee of
the Keystone board and reviewed the progress of discussions with M&T, as well as
the preliminary terms of a possible agreement that Mr. Campbell had discussed
with Mr. Wilmers. Following Mr. Campbell's presentation and discussion among the
members of the executive committee, the executive committee determined to refer
the matter to the Keystone board of directors for continued discussion and
deliberation.

     On May 4, 2000, the Keystone board of directors met, with Mr. Campbell and
other executive officers of Keystone describing the background of discussions
with M&T and the potential terms of a business combination as they had developed
to date. Following these presentations and discussion among the members of the
board, the Keystone board of directors authorized continued discussions with M&T
regarding a possible business combination and authorized Keystone management to
conduct mutual due diligence with M&T.

     Following this meeting, representatives of Keystone and M&T commenced
mutual due diligence investigations. During this period, legal counsel to each
company began to negotiate the terms of the definitive documentation with
respect to a possible merger between the two companies, including drafts of a
reorganization agreement, a plan of merger, a stock option agreement and
employment agreements. On May 11, 2000, M&T retained Merrill Lynch, Pierce,
Fenner & Smith Incorporated as its financial advisor in connection with a
possible transaction with Keystone.

     On May 15, 2000, the Keystone board of directors met to consider the
proposed merger. Mr. Campbell updated the board on the status of discussions
with M&T and gave an overview of the proposed transaction. KBW outlined the
terms of the proposed transaction with M&T, provided information on Keystone and
M&T and discussed the merger's financial terms and certain financial information
about the combined company on a pro forma basis. During the meeting, the
Keystone board received the opinion of KBW that, as of that date, the merger
consideration contemplated by the merger agreement was fair, from a financial
point of view, to the holders of Keystone common stock. Keystone's legal
counsel, Wachtell, Lipton, Rosen & Katz, discussed with the board of directors
its legal and fiduciary responsibilities in connection with its consideration of
the merger proposal and reviewed the terms of the merger agreement, the stock
option agreement and the employment agreements. Mr. Campbell and other members
of the Keystone management then summarized the results of Keystone's due
diligence investigation of M&T, and Mr. Wilmers and Robert E. Sadler, Jr.,
President of M&T Bank, addressed the Keystone board of directors. After further
discussion of matters relating to the proposed transaction and questions from
the directors, the Keystone board determined that the

                                       23
<PAGE>   28

merger was fair to, and in the best interests of, Keystone and its shareholders,
approved the merger and the merger agreement and the related agreements,
resolved to submit the merger to Keystone shareholders for their approval, and
authorized senior management of Keystone to take such action as needed to
finalize the definitive documentation and, if satisfactorily finalized, to
execute and deliver the documents and effect the transactions contemplated in
them.

     On May 16, 2000, at a meeting of the M&T board, the merger was discussed.
The meeting was also attended by several members of M&T management and by
representatives from Merrill Lynch. M&T management summarized the results of due
diligence, and Merrill Lynch presented its opinion on the fairness of the
transaction. Following further discussion, the merger was approved by M&T's
board. Definitive agreements were executed after the close of business on May
16, 2000. On May 17, 2000, M&T and Keystone issued a joint press release
announcing the execution of the merger agreement.

M&T'S REASONS FOR THE MERGER

     In reaching its decision to approve the merger and the merger agreement,
the M&T board consulted with, and received advice from, senior management and
its financial advisors and considered a number of factors. In reaching its
determination to approve the merger, the M&T board considered the following:

          (1) its belief that the combination of the two banking franchises will
     create additional scale, and significant deposit share in new markets for
     M&T, and will allow operating efficiencies to be realized that would
     otherwise be unattainable; that the demographics of Keystone's markets are
     similar to M&T's, allowing M&T to apply its business model across a larger
     geographic footprint; and that Keystone's mix of commercial and retail
     banking is a good match with M&T's mix, making for an easier integration of
     the two companies;

          (2) its belief that the Keystone franchise would enhance the future
     earnings and growth prospects of the combined entity; and that the
     combination of the two banking franchises will generate incremental
     earnings and cash flow and related benefits for M&T shareholders;

          (3) the combined company's leading position, based upon deposits, in
     both Upstate New York and Central Pennsylvania;

          (4) the anticipated annual pretax cost savings of approximately $43
     million resulting from the merger. See "-- Management and Operations after
     the Merger -- Operations.

          (5) the opinion of Merrill Lynch, delivered at the May 16, 2000 M&T
     board of directors meeting, that, as of such date, the merger consideration
     was fair to M&T from a financial point of view;

          (6) historical information concerning M&T's and Keystone's respective
     businesses, financial performance and condition, operations, technology,
     management and competitive position, including filings with the Securities
     and Exchange Commission concerning the financial condition, results of
     operations, businesses and prospects of M&T and Keystone before and after
     giving effect to the merger, the performance of the companies' common stock
     relative to selected comparable companies and the terms of transactions
     comparable to the merger;

          (7) current financial market conditions and historical market prices,
     volatility and trading information about M&T and Keystone common stock;

          (8) the tax treatment of the merger as a reorganization and accounting
     treatment of the merger as a purchase;

                                       24
<PAGE>   29

          (9) the terms of the merger agreement and the stock option agreement,
     including the 10-for-1 split of M&T stock and the proposed increase in
     M&T's regular quarterly dividend; and

          (10) the anticipated impact of the merger on M&T customers, employees
     and other constituencies.

     The foregoing discussion of the information and factors considered by the
M&T board is not intended to be exhaustive, but reflects all material factors
considered by the M&T board. In reaching its determination to approve and
recommend the merger, the M&T board did not assign any relative or specific
weights to the foregoing factors and individual directors may have weighed
factors differently.

     THE M&T BOARD BELIEVES THAT THE MERGER IS IN THE BEST INTERESTS OF M&T AND
ITS SHAREHOLDERS AND UNANIMOUSLY RECOMMENDS THAT M&T'S SHAREHOLDERS VOTE FOR
APPROVAL OF THE MERGER AGREEMENT, INCLUDING THE ISSUANCE OF M&T COMMON STOCK IN
THE MERGER, AND THE AUTHORIZATION OF THE AMENDMENT TO THE M&T CERTIFICATE OF
INCORPORATION.

KEYSTONE'S REASONS FOR THE MERGER; RECOMMENDATION OF THE KEYSTONE BOARD

     The Keystone board believes that the proposed merger with M&T is fair to,
and in the best interests of, Keystone and its shareholders. Accordingly, the
Keystone board has approved the merger agreement and unanimously recommends that
Keystone shareholders vote for the adoption of the merger agreement.

     In making this determination, the board considered a number of factors,
including the following:

          (1) the Keystone board's familiarity with Keystone's business,
     operations, financial condition, earnings and prospects;

          (2) the board's conclusion that, in view of the trend toward
     consolidation in the financial services industry, the merger would provide
     Keystone shareholders with an opportunity for continued equity
     participation in a larger enterprise.

          (3) the board's understanding of the business, operations, financial
     condition, earnings and prospects of M&T. In making its determination, the
     Keystone board took into account the result of Keystone's due diligence
     review of M&T;

          (4) the consideration Keystone shareholders will receive if the merger
     is completed and the likelihood that the merger would deliver greater value
     to Keystone shareholders than what would be reasonable to expect if
     Keystone remained independent;

          (5) the presentation of KBW to the board on May 15, 2000, including
     KBW's opinion that the consideration in the merger is fair to Keystone
     shareholders from a financial point of view as of that date;

          (6) the absence of substantial geographical overlap between the M&T
     and Keystone franchises and the anticipated impact of the merger on various
     Keystone constituencies, including Keystone employees and the communities
     in which Keystone does business;

          (7) the complementary nature of M&T's and Keystone's businesses,
     services and products, and the opportunity to create a combined business
     that offers a wider variety of services to Keystone customers and an
     enhanced ability to attract new clients;

          (8) the historical performance of M&T's common stock and M&T's
     historical financial performance;

          (9) the board's review of other strategic alternatives potentially
     available to Keystone;

                                       25
<PAGE>   30

          (10) the terms and conditions of the merger agreement, including the
     fact that Keystone's obligation to consummate the merger is conditioned
     upon M&T effecting a 10-for-1 stock split of its common stock and the
     receipt of an opinion from Keystone's legal counsel that, with respect to
     the portion of the merger consideration to be paid in M&T common stock, the
     merger will be accomplished on a tax-free basis for Keystone shareholders
     for U.S. federal income tax purposes to the extent that they receive M&T
     common stock (except for cash received instead of fractional shares), and
     of the stock option agreement;

          (11) M&T's announcement that, in connection with the merger, it
     intends to increase (on a post-split basis) its regular quarterly cash
     dividend to $0.25;

          (12) the likelihood that the merger will be approved by the
     appropriate regulatory authorities;

          (13) the likelihood of a smooth integration of Keystone's business
     with that of M&T;

          (14) the employment, benefit and retention arrangements involving
     various employees of Keystone agreed to in connection with the merger,
     including the employment agreements with Messrs. Campbell, Pulaski and
     Rooke; and

          (15) the judgment and advice of Keystone's senior management.

     This discussion of the factors considered by the Keystone board is not
intended to be exhaustive. However, it does include all of the material factors
considered by the Keystone board in approving the merger agreement and
recommending that Keystone shareholders vote to adopt the merger agreement. In
reaching this determination, the Keystone board did not assign any relative or
specific weights to the individual factors. Individual directors may have
weighed the individual factors differently.

     The Keystone board believes that the merger is in the best interests of
Keystone and its shareholders. ACCORDINGLY, THE KEYSTONE BOARD UNANIMOUSLY
RECOMMENDS THAT KEYSTONE'S SHAREHOLDERS VOTE FOR APPROVAL AND ADOPTION OF THE
MERGER AGREEMENT.

OPINION OF KEYSTONE'S FINANCIAL ADVISOR

     Keystone engaged Keefe, Bruyette & Woods, Inc. to act as its exclusive
financial advisor in connection with the merger. KBW agreed to assist Keystone
in analyzing, structuring, negotiating and effecting a transaction with M&T.
Keystone selected KBW because KBW is a nationally recognized investment banking
firm with substantial experience in transactions similar to the merger and is
familiar with Keystone and its business. As part of its investment banking
business, KBW is continually engaged in the valuation of businesses and their
securities in connection with mergers and acquisitions.

     As part of its engagement, representatives of KBW attended the meeting of
Keystone's board of directors held on May 15, 2000 at which the Board considered
and approved the merger agreement. At the May 15, 2000 meeting, KBW rendered an
oral opinion (subsequently confirmed in writing) that, as of that date, the
consideration to be paid in the merger was fair to Keystone and its shareholders
from a financial point of view. That opinion was reconfirmed in writing as of
the date of this document.

     The full text of KBW's updated written opinion is attached as Appendix C to
this document and is incorporated herein by reference. You are urged to read the
opinion in its entirety for a description of the procedures followed,
assumptions made, matters considered, and qualifications and limitations on the
review undertaken by KBW.

     KBW'S OPINION IS DIRECTED TO THE BOARD AND ADDRESSES ONLY THE FAIRNESS,
FROM A FINANCIAL POINT OF VIEW, OF THE MERGER CONSIDERATION TO YOU. IT DOES NOT
ADDRESS THE UNDERLYING BUSINESS DECISION TO

                                       26
<PAGE>   31

PROCEED WITH THE MERGER AND DOES NOT CONSTITUTE A RECOMMENDATION TO YOU AS TO
HOW YOU SHOULD VOTE AT THE KEYSTONE SPECIAL MEETING ON THE MERGER OR ANY RELATED
MATTER.

     In rendering its opinion, KBW:

     - reviewed, among other things,

       - the merger agreement,

       - Annual Reports to shareholders and Annual Reports on Form 10-K of M&T,

       - Annual Reports to shareholders and Annual Reports on Form 10-K of
         Keystone,

       - Quarterly Reports on Form 10-Q of M&T, and

       - Quarterly Reports on Form 10-Q of Keystone;

     - held discussions with members of senior management of Keystone and M&T
       regarding

       - past and current business operations,

       - regulatory relationships,

       - financial condition, and

       - future prospects of the respective companies;

     - compared financial and stock market information for M&T and Keystone with
       similar information for other companies with publicly traded securities;

     - reviewed the financial terms of certain recent business combinations in
       the banking industry; and

     - performed other studies and analyses that it considered appropriate.

     In conducting its review and arriving at its opinion, KBW relied upon and
assumed the accuracy and completeness of all of the financial and other
information provided to it or publicly available. KBW did not attempt to verify
such information independently. KBW relied upon the management of Keystone as to
the reasonableness and achievability of the financial and operating forecasts
and projections (and assumptions and bases therefor) provided to KBW. KBW
assumed, without independent verification, that the aggregate allowances for
loan and lease losses for M&T and Keystone are adequate to cover those losses.
KBW did not make or obtain any evaluations or appraisals of any assets or
liabilities of M&T or Keystone, and KBW did not examine any books and records or
review individual credit files.

     The projections furnished to KBW and used by it in certain of its analyses
were prepared by Keystone's senior management. Keystone does not publicly
disclose internal management projections of the type provided to KBW in
connection with its review of the merger. As a result, such projections were not
prepared with a view towards public disclosure. The projections were based on
numerous variables and assumptions which are inherently uncertain, including
factors related to general economic and competitive conditions. Accordingly,
actual results could vary significantly from those set forth in the projections.

     The following is a summary of the material analyses presented by KBW to the
Keystone board on May 15, 2000 in connection with its May 15, 2000 oral opinion:

     TRANSACTION SUMMARY. KBW calculated the merger consideration to be paid as
a multiple of Keystone's book value per share, last twelve months' earnings per
share as well as 2000 and 2001 consensus estimated earnings per share. The
merger consideration was based on exchange ratio of 0.05 M&T shares for 65% of
Keystone shares and $21.50 for the remaining 35% of Keystone shares. In

                                       27
<PAGE>   32

addition, this computation assumed the KBW estimates of Keystone's earnings per
share of $0.75 for the last twelve months ended March 31, 2000 and an estimated
$1.75 in 2000 and an estimated $1.83 in 2001. Based on those assumptions, this
analysis indicated that you would receive shares of M&T common stock and cash
worth $20.95 for each share of Keystone common stock held, and that this amount
would represent a multiple of 1.8 times book value per share, 27.9 times last
twelve months' earnings per share, 12.0 times estimated 2000 earnings per share
and 11.4 times estimated 2001 earnings per share.

     SELECTED TRANSACTION ANALYSIS. KBW reviewed certain financial data related
to a set of comparable nationwide bank transactions with announced value over
$450 million since December 31, 1998 (13 transactions).

     KBW compared multiples of price to various factors for the merger to the
same multiples for the comparable group's mergers at the time those mergers were
announced. In addition, KBW repeated this analysis using acquiror stock prices
current as of KBW's presentation to the Keystone board. The results were as
follows:

     Multiple of Price to Factor

<TABLE>
<CAPTION>
                                                 COMPARABLE GROUP   COMPARABLE GROUP   M&T-KEYSTONE
RATIO OF PRICE PER SHARE TO:                     ANNOUNCED MEDIAN    CURRENT MEDIAN       MERGER
----------------------------                     ----------------   ----------------   ------------
<S>                                              <C>                <C>                <C>
Estimated Earnings per Share for 2000..........       16.8x              14.3x            12.0x
Trailing 12 Months Earnings per Share..........       23.8x              16.6x            21.2x
Book Value per Share...........................       2.61x              2.07x            1.84x
Tangible Book Value per Share..................       3.47x              2.24x            2.03x
</TABLE>

     KBW also reviewed certain financial data related to a set of comparable
nationwide bank transactions with announced value over $450 million since
December 31, 1999 (four transactions).

     KBW compared multiples of price to various factors for the merger to the
same multiples for the comparable group's mergers at the time those mergers were
announced. In addition, KBW repeated this analysis using acquiror stock prices
current as of KBW's presentation to the Keystone board. The results were as
follows:

<TABLE>
<CAPTION>
                                                 COMPARABLE GROUP   COMPARABLE GROUP   M&T-KEYSTONE
RATIO OF PRICE PER SHARE TO:                     ANNOUNCED MEDIAN    CURRENT MEDIAN       MERGER
----------------------------                     ----------------   ----------------   ------------
<S>                                              <C>                <C>                <C>
Estimated Earnings per Share for 2000..........       13.5x              13.5x            12.0x
Trailing 12 Months Earnings per Share..........       14.4x              13.7x            21.2x
Book Value per Share...........................       1.84x              1.89x            1.84x
Tangible Book Value per Share..................       1.97x              2.15x            2.03x
</TABLE>

     No company or transaction used as a comparison in the above analysis is
identical to M&T, Keystone or the merger. Accordingly, an analysis of these
results is not mathematical. Rather, it involves complex considerations and
judgments concerning differences in financial and operating characteristics of
the companies and other factors that could affect the public trading value of
the companies to which they are being compared.

     DISCOUNTED DIVIDEND ANALYSIS -- M&T STAND-ALONE. KBW estimated the present
value of future cash flows that would accrue to a holder of a share of M&T
common stock assuming that the stockholder held the stock for five years and
then sold it. The analysis was based on First Call consensus earnings per share
forecasts on a stand-alone and independent basis for the year 2001 and an annual
net income growth rate of 10.5% for the years 2002 through 2005. A 12.0%
dividend payout ratio was assumed for M&T through the year 2005. An estimated
year end stock price was estimated for each year by multiplying the projected
annual earnings by a price to generally accepted accounting

                                       28
<PAGE>   33

principles ("GAAP") earnings multiple of 11.0 times. In addition, the estimated
net income for the years 2002 through 2005 were calculated using growth rates of
11.0% and 12.0%. The estimated stock price for each year and the estimated
dividends were discounted at a rate of 11.5%, which KBW viewed as an appropriate
discount rate for a company with M&T's risk characteristics. On the basis of
these assumptions, KBW calculated a range of present values ranging from $417.08
to $431.90.

     KBW repeated the analysis based on cash earnings forecasts for the year
2001 and with annual net income growth rates of 11.0% and 12.0% for the years
2002 through 2005. A 11.0% dividend payout ratio was assumed for M&T through the
year 2005. An estimated year end stock price was estimated for each year by
multiplying the projected annual cash earnings by the current M&T cash earnings
multiple of 9.8 times. The estimated stock price for each year and the estimated
dividends were discounted at a rate of 11.5 % producing present values ranging
from $421.48 to $436.47. KBW repeated the analysis based on the current M&T peer
cash earnings multiple of 11.7 times. The estimated stock price for each year
and the estimated dividends were also discounted at a rate of 11.5% producing
present values ranging from $498.89 to $516.70.

     The discounted cash flow present value analysis is a widely used valuation,
methodology, but relies on numerous assumptions, including asset and earnings
growth rates, terminal values and discount rates. The analysis does not purport
to be indicative of the actual values or expected values of M&T common stock.

     SELECTED PEER GROUP ANALYSIS. KBW compared the financial performance and
market performance of M&T to those of a group of comparable holding companies.
The comparisons were based on:

     - various financial measures:

       - earnings performance

       - operating efficiency

       - capital

       - asset quality

     - various measures of market performance including:

       - price/book value

       - price to earnings

       - dividend yields

     To perform this analysis, KBW used financial information as of and for the
quarter ended March 31, 2000 and market price information as of May 12, 2000.
The 15 companies in the peer group were US regional banks with total market
capitalizations ranging from $1.5 billion to $25.0 billion.

     KBW's analysis showed the following concerning M&T's financial performance:

<TABLE>
<CAPTION>
                                                                      PEER GROUP
                    PERFORMANCE MEASURE:                       M&T      MEDIAN
                    --------------------                      -----   ----------
<S>                                                           <C>     <C>
Return on Equity, annualized................................  15.10%    18.49%
Return on Assets, annualized................................   1.22%     1.50%
Net Interest Margin, annualized.............................   3.88%     4.18%
Efficiency Ratio, annualized (Non-interest Expense to Net
  Operating Revenue)........................................  50.57%    53.36%
Leverage Ratio (Tier I Capital to Average Tangible
  Assets)...................................................   7.05%     7.74%
Non-Performing Assets to Total Loans & Other Real Estate
  Owned.....................................................   0.43%     0.47%
Loan Loss Reserve to Total Gross Loans......................   1.80%     1.37%
</TABLE>

                                       29
<PAGE>   34

     KBW's analysis showed the following concerning M&T's market performance:

<TABLE>
<CAPTION>
                                                                      PEER GROUP
                    PERFORMANCE MEASURE                        M&T      MEDIAN
                    -------------------                       -----   ----------
<S>                                                           <C>     <C>
Price to 2000 GAAP Estimated Earnings per Share.............   11.3x     12.3x
Price to 2000 Cash Estimated Earnings per Share.............    9.8x     11.7x
Price to 2001 GAAP Estimated Earnings per Share.............   10.0x     11.0x
Price to 2001 Cash Estimated Earnings per Share.............    8.8x     10.6x
Price to Book Value per Share...............................   1.73x     2.21x
Price to Tangible Book Value per Share......................   2.66x     2.43x
Dividend Yield (prior to M&T's anticipated dividend
  increase).................................................   1.21%     3.39%
</TABLE>

     KBW also compared the financial performance and market performance of
Keystone to those of a group of comparable holding companies. The comparisons
were based on:

     - various financial measures:

     - earnings performance

     - operating efficiency

     - capital

     - asset quality

     - various measures of market performance including:

     - price/book value

     - price to earnings

     - dividend yields

     To perform this analysis, KBW used financial information as of and for the
quarter ended March 31, 2000 and market price information as of May 12, 2000.
The eight companies in the peer group were Mid-Atlantic region banks with total
market capitalizations ranging from $500 million to $2.0 billion.

     KBW's analysis showed the following concerning Keystone's financial
performance:

<TABLE>
<CAPTION>
                                                                         PEER GROUP
                    PERFORMANCE MEASURE:                      KEYSTONE     MEDIAN
                    --------------------                      --------   ----------
<S>                                                           <C>        <C>
Return on Equity, annualized................................   14.18%      16.27%
Return on Assets, annualized................................    1.16%       1.51%
Net Interest Margin, annualized.............................    3.99%       4.31%
Efficiency Ratio, annualized (Non-Interest Expense to Net
  Operating Revenue)........................................   62.14%      48.73%
Leverage Ratio (Tier I Capital to Average Tangible
  Assets)...................................................    7.63%       8.74%
Non-Performing Assets to Total Loans and Other Real Estate
  Owned.....................................................    0.86%       0.45%
Loan Loss Reserve to Total Gross Loans......................    1.34%       1.27%
</TABLE>

                                       30
<PAGE>   35

     KBW's analysis showed the following concerning Keystone's market
performance:

<TABLE>
<CAPTION>
                                                                         PEER GROUP
                    PERFORMANCE MEASURE:                      KEYSTONE     MEDIAN
                    --------------------                      --------   ----------
<S>                                                           <C>        <C>
Price to 2000 GAAP Estimated Earnings per Share.............     8.9x       11.7x
Price to 2000 Cash Estimated Earnings per Share.............     8.4x       11.4x
Price 2001 GAAP Estimated Earnings per Share................     8.2x       10.7x
Price Cash Estimated Earnings per Share.....................     7.8x       10.5x
Price to Book Value per Share...............................    1.36x       2.01x
Price to Tangible Book Value per Share......................    1.50x       2.19x
Dividend Yield..............................................    7.48%       4.27%
</TABLE>

     For purposes of the above calculations, all earnings estimates are based
upon the KBW estimates for M&T and Keystone.

     CONTRIBUTION ANALYSIS. KBW analyzed the relative contribution of each of
Keystone and M&T to the pro forma balance sheet and income statement items of
the combined entity, including assets, common equity, tangible equity, deposits,
loans, market capitalization, and estimated 2001 net income. KBW relied on First
Call projections for 2001 net income. KBW compared the relative contribution of
balance sheet and income statement items with the estimated pro forma ownership
for Keystone based on an exchange ratio of 0.05 for 100% of Keystone's shares.
The results of KBW's analysis are set forth in the following table:

<TABLE>
<CAPTION>
                          CATEGORY                            M&T        KEYSTONE
                          --------                            ----       --------
<S>                                                           <C>        <C>
Total Assets................................................  76.4%        23.6%
Gross Loans.................................................  79.6%        20.4%
Total Deposits..............................................  75.0%        25.0%
Common Equity...............................................  76.7%        23.3%
Tangible Common Equity......................................  70.3%        29.7%
2000 Estimated Net Income...................................  77.2%        22.8%
2001 Estimated Net Income...................................  78.4%        21.6%
Market Capitalization.......................................  80.7%        19.3%
Ownership (based on 100% stock).............................  76.3%        23.7%
</TABLE>

     FINANCIAL IMPACT ANALYSIS. KBW performed pro forma merger analysis that
combined projected income statement and balance sheet information. Assumptions
regarding the accounting treatment, acquisition adjustments and cost savings
were used to calculate the financial impact that the merger would have on
certain projected financial results of pro forma company. This analysis
indicated that the merger is expected to be accretive to Keystone's estimated
GAAP earnings per share and accretive to Keystone's estimated cash earnings per
share in 2001 and 2002. The analysis also indicated that the merger is expected
to be accretive to Keystone's book value per share and dilutive to tangible book
value per share. This analysis was based on First Call 2001 published earnings
estimates, the First Call long-term estimated growth rates, and on Keystone
management's estimates of the expected savings. For all of the above analyses,
the actual results achieved by pro forma company following the merger will vary
from the projected results, and the variations may be material.

     OTHER ANALYSES. KBW reviewed the relative financial and market performance
of Keystone and M&T to a variety of relevant industry peer groups and indices.
KBW also reviewed earnings estimates, balance sheet composition, historical
stock performance and other financial data for M&T.

     In connection with its opinion dated as of the date of this document, KBW
performed procedures to update, as necessary, certain of the analyses described
above. KBW reviewed the assumptions on which the analyses described above were
based and the factors considered in connection therewith.

                                       31
<PAGE>   36

KBW did not perform any analyses in addition to those described above in
updating its May 15, 2000 opinion.

     The Keystone board has retained KBW as an independent contractor to act as
financial adviser to Keystone regarding the merger. As part of its investment
banking business, KBW is continually engaged in the valuation of banking
businesses and their securities in connection with mergers and acquisitions,
negotiated underwritings, competitive biddings, secondary distributions of
listed and unlisted securities, private placements and valuations for estate,
corporate and other purposes. As specialists in the securities of banking
companies, KBW has experience in, and knowledge of, the valuation of banking
enterprises. In the ordinary course of its business as a broker-dealer, KBW may,
from time to time, purchase securities from, and sell securities to, Keystone
and M&T. As a market maker in securities KBW may from time to time have a long
or short position in, and buy or sell, debt or equity securities of Keystone and
M&T for KBW's own account and for the accounts of its customers.

     Keystone and KBW have entered into an agreement relating to the services to
be provided by KBW in connection with the merger. Keystone agreed to pay KBW a
cash fee of $250,000 concurrently with the execution of the definitive
agreement, the transaction, and a cash fee of $250,000 promptly after the
mailing of this document to Keystone shareholders. In addition, Keystone has
agreed to pay KBW at the time of closing a cash fee ("contingent fee") equal to
0.40% of the market value of the aggregate consideration offered in exchange for
the outstanding shares of common stock of Keystone in the transaction. The fees
paid prior to the contingent fee payment will be credited against the contingent
fee. Pursuant to the KBW engagement agreement, Keystone also agreed to reimburse
KBW for reasonable out-of-pocket expenses and disbursements incurred in
connection with its retention and to indemnify against certain liabilities,
including liabilities under the federal securities laws.

OPINION OF M&T'S FINANCIAL ADVISOR

     M&T retained Merrill Lynch to act as its financial advisor in connection
with the merger. On May 16, 2000, the board of directors of M&T held a meeting
to evaluate the proposed merger. At this meeting, Merrill Lynch rendered its
written opinion that, as of that date and based upon and subject to the factors
and assumptions set forth in its opinion, the merger consideration was fair,
from a financial point of view, to M&T. Merrill Lynch subsequently confirmed and
updated its opinion in writing by delivering to the board of directors of M&T a
written opinion dated as of the date of this document. In connection with its
written opinion, Merrill Lynch confirmed the appropriateness of its reliance on
the analyses used to render its earlier opinion. It also performed procedures to
update certain of its analyses and reviewed the assumptions used in its analyses
and the factors considered in connection with its earlier opinion.

     The full text of the Merrill Lynch opinion, which describes, among other
things, the assumptions made, matters considered, and qualifications and
limitations on the review undertaken by Merrill Lynch is attached as Appendix D
to this document and is incorporated in this document by reference. M&T
shareholders are urged to, and should, read Merrill Lynch's opinion carefully
and in its entirety.

     Merrill Lynch's opinion is directed to the board of directors of M&T and
addresses only the fairness, from a financial point of view, of the merger
consideration to M&T. The opinion does not address any other aspect of the
merger or any related transaction, nor does it constitute a recommendation to
any shareholder as to how to vote at the M&T special meeting. The summary of the

                                       32
<PAGE>   37

fairness opinion set forth in this document is qualified in its entirety by
reference to the full text of the opinion.

     In arriving at its opinion, Merrill Lynch, among other things:

     - reviewed certain publicly available business and financial information
       relating to M&T and Keystone that Merrill Lynch deemed to be relevant;

     - reviewed certain information, including financial forecasts, relating to
       the respective businesses, earnings, assets, liabilities and prospects of
       M&T and Keystone furnished to Merrill Lynch by the senior management of
       M&T and Keystone, as well as the amount and timing of the cost savings,
       revenue enhancements and related expenses expected to result from the
       merger furnished to Merrill Lynch by senior management of M&T and
       Keystone;

     - conducted discussions with members of senior management and
       representatives of M&T and Keystone concerning the matters described in
       the bullet points set forth above, as well as their respective businesses
       and prospects before and after giving effect to the merger and the
       expected synergies;

     - reviewed the market prices and valuation multiples for M&T common stock
       and Keystone common stock and compared them with those of certain
       publicly traded companies that Merrill Lynch deemed to be relevant;

     - reviewed the respective publicly reported financial condition and results
       of operations of M&T and Keystone and compared them with those of certain
       publicly traded companies that Merrill Lynch deemed to be relevant;

     - compared the proposed financial terms of the merger with the financial
       terms of certain other transactions that Merrill Lynch deemed to be
       relevant;

     - participated in certain discussions among representatives of M&T and
       Keystone and their financial and legal advisors with respect to the
       merger;

     - reviewed the potential pro forma impact of the merger on M&T;

     - reviewed the merger agreement; and

     - reviewed such other financial studies and analyses and took into account
       such other matters as Merrill Lynch deemed necessary, including Merrill
       Lynch's assessment of general economic, market and monetary conditions.

     In rendering its opinion, Merrill Lynch assumed and relied on the accuracy
and completeness of all information supplied or otherwise made available to
Merrill Lynch, or that was discussed with, or reviewed by or for Merrill Lynch,
or that was publicly available, and Merrill Lynch did not assume any
responsibility for independently verifying this information or undertake an
independent evaluation or appraisal of the assets or liabilities of M&T or
Keystone nor has Merrill Lynch been furnished any such evaluation or appraisal.

     Merrill Lynch is not an expert in the evaluation of allowances for loan
losses, and neither made an independent evaluation of the adequacy of the
allowances for loan losses of M&T or Keystone, nor reviewed any individual
credit files of M&T or Keystone or has been requested to conduct such a review
and, as a result, Merrill Lynch has assumed that the aggregate allowances for
loan losses for both M&T and Keystone are adequate to cover such losses and will
be adequate on a pro forma basis for the combined company. In addition, Merrill
Lynch did not assume any obligation to conduct, nor did Merrill Lynch conduct,
any physical inspection of the properties or facilities of M&T or Keystone. With
respect

                                       33
<PAGE>   38

to the financial and operating forecast information furnished to or discussed
with Merrill Lynch by M&T or Keystone, including without limitation, financial
forecasts, valuations of contingencies and projections regarding
under-performing and non-performing assets, net charge-offs, adequacy of
reserves, future economic conditions and information on the cost savings,
revenue enhancements and related expenses expected to result from the merger,
Merrill Lynch assumed that the information was reasonably prepared and reflects
the best currently available estimates and judgments of the senior management of
each of M&T and Keystone as to the future financial and operating performance of
M&T, Keystone or the combined entity, as the case may be, and the expected
synergies. Merrill Lynch's opinion is necessarily based upon market, economic
and other conditions as in effect on, and on the information made available to
Merrill Lynch as of, the date of its opinion.

     For purposes of rendering its opinion, Merrill Lynch assumed that, in all
respects material to its analyses:

     - the merger will be completed substantially in accordance with the terms
       set forth in the merger agreement;

     - the representations and warranties of each party in the merger agreement
       and in all related documents and instruments referred to in the merger
       agreement are true and correct;

     - each party to the merger agreement and all related documents will perform
       all of the covenants and agreements required to be performed by such
       party under such documents;

     - all conditions to the completion of the merger will be satisfied without
       any waivers; and

     - in the course of obtaining the necessary regulatory, contractual, or
       other consents or approvals for the merger, no restrictions, including
       any divestiture requirements, termination or other payments or amendments
       or modifications, will be imposed that will have a material adverse
       effect on the future results of operations or financial condition of M&T,
       Keystone or the combined entity or the contemplated benefits of the
       merger, including the cost savings, revenue enhancements and related
       expenses expected to result from the merger.

     Merrill Lynch further assumed that the merger would be accounted for as a
purchase under GAAP and that the merger will qualify as a tax-free
reorganization for U.S. federal income tax purposes. Merrill Lynch's opinion is
not an expression of an opinion as to the prices at which shares of M&T common
stock or shares of Keystone common stock will trade following the announcement
of the merger, or the actual value of the shares of common stock of M&T when
issued pursuant to the merger, or the prices at which the shares of common stock
of M&T will trade following the completion of the merger.

ANALYSES OF MERRILL LYNCH

     In performing its analyses, Merrill Lynch made numerous assumptions with
respect to industry performance, general business, economic, market and
financial conditions and other matters, many of which are beyond the control of
Merrill Lynch, M&T and Keystone. Any estimates contained in the analyses
performed by Merrill Lynch are not necessarily indicative of actual values or
future results, which may be significantly more or less favorable than suggested
by these analyses. Additionally, estimates of the value of businesses or
securities do not purport to be appraisals or to reflect the prices at which
such businesses or securities might actually be sold. Accordingly, these
analyses and estimates are inherently subject to substantial uncertainty. In
addition, the Merrill Lynch opinion was among several factors taken into
consideration by the board of directors of M&T in making its determination to
approve the merger agreement and the merger. Consequently, the analyses
described below should not

                                       34
<PAGE>   39

be viewed as determinative of the decision of the board of directors of M&T or
management of M&T with respect to the fairness of the merger consideration.

     The following is a summary of the material financial analyses presented by
Merrill Lynch to the board of directors of M&T on May 16, 2000, in connection
with the rendering of its written opinion on that date. The summary is not a
complete description of the analyses underlying the Merrill Lynch opinion or the
presentation made by Merrill Lynch to the board of directors of M&T, but
summarizes the material analyses performed and presented in connection with its
opinion. The preparation of a fairness opinion is a complex analytic process
involving various determinations as to the most appropriate and relevant methods
of financial analysis and the application of those methods to the particular
circumstances. Therefore, a fairness opinion is not readily susceptible to
partial analysis or summary description.

     In arriving at its opinion, Merrill Lynch did not attribute any particular
weight to any analysis or factor that it considered, but rather made qualitative
judgments as to the significance and relevance of each analysis and factor. The
financial analyses summarized below includes information presented in tabular
format. Accordingly, Merrill Lynch believes that its analyses and the summary of
its analyses must be considered as a whole and that selecting portions of its
analyses and factors or focusing on the information presented below in tabular
format, without considering all analyses and factors or the full narrative
description of the financial analyses, including the methodologies and
assumptions underlying the analyses, could create a misleading or incomplete
view of the process underlying its analyses and opinion. The tables alone do not
constitute a complete description of the financial analyses.

     CALCULATION OF TRANSACTION VALUE OF THE MERGER CONSIDERATION. Merrill Lynch
reviewed the terms of the merger. It noted that the transaction had an implied
value of approximately $21.08 per share for shares of Keystone common stock
based on the closing price of M&T common stock on May 15, 2000 and an implied
aggregate value of $1.03 billion.

     COMPARABLE TRANSACTION PRICING MULTIPLE ANALYSIS. Merrill Lynch performed a
comparable transaction pricing multiple analysis by comparing the transaction
value in the merger to all traditional bank acquisition transactions announced
since January 1, 1999 that exceeded $1 billion and that Merrill Lynch determined
were comparable to the merger (seven such transactions). Merrill Lynch based
this analysis on financial results for Keystone at or for the twelve months
ended March 31, 2000, except for the analyses for price-to-forward cash earnings
per share and price-to-forward GAAP earnings per share, which are based on
quarterly First Call estimates as of May 15, 2000 for the next four quarters
through March 31, 2001, with the forward year GAAP estimate for Keystone equal
to $1.86. First Call is a recognized data service that monitors and publishes
compilations of earnings estimates by selected research analysts regarding
companies of interest to institutional investors. The following table compares
certain transaction pricing multiples of the merger to corresponding data in
comparable transactions:

<TABLE>
<CAPTION>
                                                              PRICE/LAST
                                       PRICE/LAST   PRICE/      TWELVE     PRICE/               PRICE/     TANGIBLE
                                         TWELVE     FORWARD     MONTHS     FORWARD   PRICE/    TANGIBLE      BOOK
                                         MONTHS      CASH        GAAP       GAAP      BOOK       BOOK      PREMIUM/
                                        CASH EPS      EPS        EPS         EPS     VALUE      VALUE      DEPOSITS
                                       ----------   -------   ----------   -------   ------   ----------   --------
<S>                                    <C>          <C>       <C>          <C>       <C>      <C>          <C>
Implied M&T/Keystone Multiple........     11.9x       10.8x      12.5x       11.3x    1.85x      2.05x       10.4%
Comparable Transactions Average......     17.3        15.2       18.9        16.3     2.69       3.08        26.1
</TABLE>

     As part of its comparable transaction analysis, Merrill Lynch also analyzed
the per share price to be paid in the merger as a premium to the closing price
of Keystone common stock at selected intervals prior to the announcement of the
merger. Merrill Lynch determined that the price to be paid in the merger as a
premium to (i) the per share closing price of Keystone common stock on May 15,
2000 (one day prior to the date of Merrill Lynch's presentation to the M&T board
of directors), was 32.8% compared to an average premium of 29.4% (representing
the average premium over the closing price

                                       35
<PAGE>   40

one day prior to the date of the public announcement for the comparable
transactions) paid in comparable transactions, and (ii) the average per share
closing price of Keystone common stock for the 30-trading-day period prior to
Merrill Lynch's presentation to the M&T board was 31.2% compared to an average
premium over such period of 27.9% paid in comparable transactions. Merrill Lynch
also determined that, under each of the premium analyses referred to above, the
premium being paid in the merger when expressed as a percentage of the premiums
paid in the comparable transactions over such periods was 112%.

     DISCOUNTED DIVIDEND ANALYSIS -- KEYSTONE. Merrill Lynch performed a
discounted dividend analysis to estimate a range of present values per share of
Keystone common stock assuming Keystone's affiliation with M&T. This range was
determined by adding (1) the present value of the estimated future dividend
stream that Keystone could generate through 2006, and (2) the present value at
March 31, 2000 of the "terminal value" of Keystone common stock at the end of
this period.

     In calculating a terminal value of Keystone common stock, Merrill Lynch
applied multiples of 8.0x, 9.0x and 10.0x to year 2006 forecasted cash earnings.
The dividend stream and terminal value were then discounted back to March 31,
2000 using discount rates of 11.0%, 12.0% and 13.0%, which rates Merrill Lynch
viewed as the appropriate range of discount rates for a company with Keystone's
risk characteristics.

     In performing this analysis, Merrill Lynch used First Call consensus
earnings per share estimates for 2000 and 2001. For periods after 2001, earnings
were assumed to increase at I/B/E/S estimated annual long-term earnings growth
rate of 8.5%. I/B/E/S is an industry service provider of global earnings
information based on an average of earnings estimates published by selected
research analysts regarding companies of interest to institutional investors.
Merrill Lynch also assumed an annual asset growth rate of 5.0%, and further
assumed that earnings in excess of those necessary to maintain Keystone's
tangible common equity ratio at 5.4% (the tangible common equity ratio of M&T)
could be paid out as dividends. Merrill Lynch further assumed that Keystone's
dividend payout ratio would remain constant at its current ratio of 64.1%.
Merrill Lynch's analysis also assumed that: (i) synergies equal to $43.4 million
pre-tax, or approximately 20% of Keystone's non-interest expenses, would be
fully realized in the merger; (ii) a restructuring charge equal to $52 million
after-tax would be incurred in the merger; and (iii) no revenue enhancements
would result from the merger. Merrill Lynch also noted that Keystone's current
price-to-2000 estimated cash earnings per share was 8.8x, and that the current
average price-to-2000 estimated cash earnings per share for companies in
Keystone's peer group was 9.8x. Based on the above assumptions, Merrill Lynch
determined that the present value of the Keystone common stock ranged from
$21.63 to $27.23 per share.

     DISCOUNTED DIVIDEND ANALYSIS -- M&T STAND-ALONE. Merrill Lynch also
performed a discounted dividend analysis to estimate a range of present values
per share of M&T common stock assuming M&T continued to operate as a stand-alone
entity. As was the analysis performed with regard to Keystone, this range was
determined by adding (1) the present value of the estimated future dividend
stream that M&T could generate through 2006, and (2) the present value at March
31, 2000 of the "terminal value" of M&T common stock at the end of this period.

     In calculating a terminal value of M&T common stock, Merrill Lynch applied
multiples of 8.50x, 9.50x and 10.50x to year 2006 forecasted cash earnings. The
dividend stream and terminal value were then discounted back to March 31, 2000
using discount rates of 11.5%, 12.5% and 13.5%, which rates Merrill Lynch viewed
as the appropriate range of discount rates for a company with M&T's risk
characteristics.

     In performing this analysis, Merrill Lynch used First Call consensus
earnings per share estimates for 2000 and 2001. For periods after 2001, earnings
were assumed to increase at I/B/E/S estimated

                                       36
<PAGE>   41

annual long-term earnings growth rate of 10.5%. Merrill Lynch also assumed an
annual asset growth rate of 7.0%, and further assumed that earnings in excess of
those necessary to maintain M&T's tangible common equity ratio at 5.4% could be
paid out as dividends. Merrill Lynch adjusted M&T's dividend payout ratio to
reflect the 100% increase in the annual dividend that is expected to occur as
part of the merger. In performing this analysis, Merrill Lynch also noted that
M&T's current price-to-2000 estimated cash earnings per share was 9.8x, and that
the current average price-to-2000 estimated cash earnings per share for
companies in M&T's peer group also was 9.8x. Based on the above assumptions,
Merrill Lynch determined that the per share stand-alone present value of the M&T
common stock ranged from $373.69 to $472.69 per share.

     The analyses set forth in each of the preceding six paragraphs does not
necessarily indicate actual values or actual future results and does not purport
to reflect the prices at which any securities may trade at the present or at any
time in the future. The discount rates applied to Keystone and M&T referred to
in such paragraphs were based on several factors, including the financial
advisor's knowledge of each of Keystone and M&T and the industry in which they
operate, the business risk of each company and the overall interest rate
environment as of May 16, 2000. The asset growth rates applied for Keystone and
M&T took into consideration several factors, including the historical asset
growth of each of Keystone and M&T as well as projected long-term growth rates.
Dividend discount analysis is a widely used valuation methodology, but the
results of this methodology are highly dependent upon the numerous assumptions
that must be made, including earnings growth rates, dividend payout ratios,
terminal values and discount rates.

     RELATIVE STOCK PRICE PERFORMANCE -- LAST FIVE YEARS. Merrill Lynch also
analyzed the price performance of the M&T common stock over the five-year period
from May 15, 1995 to May 15, 2000 and compared that performance to the
performance of the Keystone common stock and the Standard & Poors Regional Bank
Index over the same period. Based on information from FactSet Datasystems, this
analysis indicated the following cumulative changes in price over the period:

<TABLE>
<S>                                                           <C>
M&T common stock............................................  +156.6%
Standard & Poors Regional Bank Index........................  +120.9%
Keystone common stock.......................................   -17.2%
</TABLE>

     Merrill Lynch also noted that, as of May 15, 2000, the per share price of
Keystone's common stock was $15.88, and that the 52-week high and low of such
stock was $32.50 and $14.06, respectively.

     PEER GROUP ANALYSIS -- TOTAL STOCK RETURNS. Merrill Lynch compared the
total stock returns of M&T to publicly available corresponding data for selected
banks with a market capitalization between $1.75 billion and $10 billion that
Merrill Lynch determined were comparable to M&T. These selected banks are
referred to in this document as the M&T peer group. The following table compares
the stock returns of M&T with corresponding average data for the M&T peer group
("CAGR" denotes "Compound Annual Growth Rate" and includes dividends paid over
the relevant periods):

<TABLE>
<CAPTION>
                                          ONE-YEAR   TWO-YEAR   THREE-YEAR   FOUR-YEAR   FIVE-YEAR
                                            CAGR       CAGR        CAGR        CAGR        CAGR
                                          --------   --------   ----------   ---------   ---------
<S>                                       <C>        <C>        <C>          <C>         <C>
M&T Common Stock........................   (23.25)%    (8.63)%     9.91%       16.18%      21.14%
M&T Peer Group Average..................   (27.92)    (15.57)      3.51        12.11       15.57
</TABLE>

     Merrill Lynch also compared the total stock returns of Keystone to publicly
available corresponding data for selected banks with a market capitalization
between $500 million and $1 billion that Merrill Lynch determined were
comparable to Keystone. These selected banks are referred to in this document

                                       37
<PAGE>   42

as the Keystone peer group. The following table compares the stock returns of
Keystone, including dividends paid over the relevant periods, with corresponding
average data for the Keystone peer group:

<TABLE>
<CAPTION>
                                          ONE-YEAR   TWO-YEAR   THREE-YEAR   FOUR-YEAR   FIVE-YEAR
                                            CAGR       CAGR        CAGR        CAGR        CAGR
                                          --------   --------   ----------   ---------   ---------
<S>                                       <C>        <C>        <C>          <C>         <C>
Keystone Common Stock...................   (46.35)%   (32.49)%    (9.52)%      (2.23)%      1.85%
Keystone Peer Group Average.............   (12.88)    (15.67)      3.30        10.66       15.15
</TABLE>

     PEER GROUP ANALYSIS -- CURRENT TRADING MULTIPLES. Merrill Lynch compared
selected operating and stock market results of M&T to publicly available
corresponding data for the M&T peer group.

     The following table compares selected financial data of M&T with
corresponding average data for the M&T peer group. The multiples listed are
based on the market value of M&T common stock using the closing price as of May
15, 2000 (one trading day prior to the date of Merrill Lynch's presentation to
the M&T board). Financial data is as of March 31, 2000. The calculation of
price-to-2000 and price-to-2001 estimated earnings per share are based on
estimated earnings per share calculated in accordance with GAAP. The calculation
of price-to-2000 and price-to-2001 estimated cash earnings per share are based
on First Call estimated earnings per share plus amortization of intangible
assets per share.

<TABLE>
<CAPTION>
                                                        PRICE/                  PRICE/
                                                         2000       PRICE/       2001       PRICE/
                                            PRICE/     ESTIMATED     2000      ESTIMATED     2001
                               PRICE/      TANGIBLE      GAAP      ESTIMATED     GAAP      ESTIMATED
                             BOOK VALUE   BOOK VALUE      EPS      CASH EPS       EPS      CASH EPS
                             ----------   ----------   ---------   ---------   ---------   ---------
<S>                          <C>          <C>          <C>         <C>         <C>         <C>
M&T........................     1.74x        2.67x       11.46x       9.82x      10.34x       8.99x
M&T Peer Group Average.....     1.93         2.47        10.69        9.78        9.59        8.85
</TABLE>

     Merrill Lynch also compared selected operating and stock market results of
Keystone to publicly available corresponding data for the Keystone peer group.
The following table compares selected financial data of Keystone with
corresponding average data for the Keystone peer group. The multiples listed are
based on the market value of Keystone common stock using the closing price as of
May 15, 2000 (one trading day prior to the date of Merrill Lynch's presentation
to the M&T board). Financial data is as of March 31, 2000. The calculations of
price-to-2000 and price-to-2001 estimated earnings per share are based on
estimated earnings per share calculated in accordance with GAAP. The
calculations of price-to-2000 and price-to-2001 estimated cash earnings per
share are based on First Call estimated earnings per share plus amortization of
intangible assets per share.

<TABLE>
<CAPTION>
                                                        PRICE/                  PRICE/
                                                         2000       PRICE/       2001       PRICE/
                                            PRICE/     ESTIMATED     2000      ESTIMATED     2001
                               PRICE/      TANGIBLE      GAAP      ESTIMATED     GAAP      ESTIMATED
                             BOOK VALUE   BOOK VALUE      EPS      CASH EPS       EPS      CASH EPS
                             ----------   ----------   ---------   ---------   ---------   ---------
<S>                          <C>          <C>          <C>         <C>         <C>         <C>
Keystone...................     1.39x        1.54x        9.23x       8.80x       8.67x       8.29x
Keystone Peer Group
  Average..................     1.66         1.87        10.46        9.82        9.77        9.25
</TABLE>

     PEER GROUP ANALYSIS -- OPERATING RATIOS. Merrill Lynch compared certain
operating ratios of M&T and Keystone to publicly available corresponding data
for the M&T peer group and the Keystone peer group, respectively. For the two
following tables, operating measures represent the most recent quarter
annualized, based on data received from SNL Securities, LP, and exclude
nonrecurring charges.

                                       38
<PAGE>   43

The following table compares certain operating ratios of M&T with corresponding
average data for the M&T peer group:

<TABLE>
<CAPTION>
                                                           CASH                                FEE
                                                         RETURN ON     NET         CASH      INCOME/
                                 RETURN ON   RETURN ON   TANGIBLE    INTEREST   EFFICIENCY    TOTAL
                                  ASSETS      EQUITY      EQUITY      MARGIN      RATIO      REVENUES
                                 ---------   ---------   ---------   --------   ----------   --------
<S>                              <C>         <C>         <C>         <C>        <C>          <C>
M&T............................    1.22%       15.06%      27.19%      3.92%      50.57%       27.0%
M&T Peer Group Average.........    1.34        16.95       23.59       4.11       52.82        27.8
</TABLE>

     The following table compares certain operating ratios of Keystone with
corresponding average data for the Keystone peer group:

<TABLE>
<CAPTION>
                                                           CASH                                FEE
                                                         RETURN ON     NET         CASH      INCOME/
                                 RETURN ON   RETURN ON   TANGIBLE    INTEREST   EFFICIENCY    TOTAL
                                  ASSETS      EQUITY      EQUITY      MARGIN      RATIO      REVENUES
                                 ---------   ---------   ---------   --------   ----------   --------
<S>                              <C>         <C>         <C>         <C>        <C>          <C>
Keystone.......................    1.15%       14.11%      16.40%      3.98%       60.3%       27.8%
Keystone Peer Group Average....    1.16        15.46       18.86       4.10        59.9        27.2
</TABLE>

     PEER GROUP ANALYSIS -- FINANCIAL CONDITION. Merrill Lynch also compared
certain balance sheet and asset quality ratios of M&T and Keystone to publicly
available data for the M&T peer group and the Keystone peer group, respectively.
Financial data for the two following tables is as of March 31, 2000. The
following table compares certain balance sheet and asset quality ratios of M&T
with corresponding average data for the M&T peer group:

<TABLE>
<CAPTION>
                                             TANGIBLE                 NON-      RESERVES/
                                              COMMON     GROSS     PERFORMING      NON-
                                   EQUITY/   EQUITY/     LOANS/     ASSETS/     PERFORMING   RESERVES/
                                   ASSETS     ASSETS    DEPOSITS     ASSETS       LOANS        LOANS
                                   -------   --------   --------   ----------   ----------   ---------
<S>                                <C>       <C>        <C>        <C>          <C>          <C>
M&T..............................   8.05%      5.40%     116.84%      0.33%       475.73%      1.80%
M&T Peer Group Average...........   8.09       6.47       97.72       0.39        286.00       1.38
</TABLE>

     The following table compares certain balance sheet and asset quality ratios
of Keystone with corresponding average data for the Keystone peer group:

<TABLE>
<CAPTION>
                                             TANGIBLE                 NON-      RESERVES/
                                              COMMON     GROSS     PERFORMING      NON-
                                   EQUITY/   EQUITY/     LOANS/     ASSETS/     PERFORMING   RESERVES/
                                   ASSETS     ASSETS    DEPOSITS     ASSETS       LOANS        LOANS
                                   -------   --------   --------   ----------   ----------   ---------
<S>                                <C>       <C>        <C>        <C>          <C>          <C>
Keystone.........................   7.93%      7.23%      89.73%      0.56%       168.90%      1.34%
Keystone Peer Group Average......   7.59       6.87       81.22       0.36        352.52       1.37
</TABLE>

     No company or transaction used in the comparable company analyses described
above is identical to M&T, Keystone, the pro forma combined company, or the
merger, as the case may be. Accordingly, an analysis of the results of the
foregoing necessarily involves complex considerations and judgments concerning
financial and operating characteristics and other factors that could affect the
merger, public trading or other values of the companies to which they are being
compared. Mathematical analysis (such as determining the average or median) is
not in itself a meaningful method of using comparable transaction data or
comparable company data.

     PRO FORMA MERGER ANALYSIS. Merrill Lynch also analyzed the pro forma per
share financial impact of the merger on (1) M&T's cash earnings per share as
projected by First Call for each of 2001, 2002 and 2003, and (2) M&T's GAAP
earnings per share as projected by First Call for each of 2001, 2002 and 2003.

     The analyses performed indicated that, on a per share basis, the merger
would be accretive to M&T's estimated cash earnings per share in each of 2001,
2002 and 2003 based on consensus First Call

                                       39
<PAGE>   44

earnings estimates and after-tax synergies of $14.1 million in 2001, $28.2
million in 2002, and $29.3 million in 2003. Merrill Lynch also assumed that pro
forma cash earnings per share would be $46.92 in 2001, $53.29 in 2002 and $58.76
in 2003 and pro forma GAAP earnings per share would be $37.60 in 2001, $44.02 in
2002 and $49.53 in 2003. Using the same assumptions set forth above, the
analysis further revealed that, on a per share basis, the merger would be
dilutive to M&T's First Call estimated GAAP earnings per share in both 2001 and
2002 and would be accretive to M&T's First Call estimated GAAP earnings per
share in 2003.

     The actual operating and financial results achieved by the pro forma
combined company may vary from projected results and variations may be material
as a result of business and operational risks, and the timing, amount and costs
associated with achieving cost savings and revenue enhancements, if any, as well
as other factors.

     M&T retained Merrill Lynch based upon its experience and expertise. Merrill
Lynch is an internationally recognized investment banking and advisory firm. As
part of its investment banking business, Merrill Lynch is regularly engaged in
the valuation of businesses and securities in connection with mergers and
acquisitions, negotiated underwritings, competitive biddings, secondary
distributions of listed and unlisted securities, private placements and
valuations for estate, corporate and other purposes.

     In addition, in the ordinary course of its business, Merrill Lynch and its
affiliates may actively trade the debt and equity securities of M&T and Keystone
for their own account and/or the accounts of their respective customers, and,
accordingly, may at any time hold long or short positions in these securities.
In the past two years, Merrill Lynch has provided to M&T financial advisory,
investment banking and other services unrelated to the proposed merger, and has
received fees for the rendering of these services. Merrill Lynch may provide
these types of services to the combined company in the future and receive fees
for those services.

     Pursuant to a letter agreement between M&T and Merrill Lynch, dated as of
May 11, 2000, M&T agreed to pay Merrill Lynch for financial advisory services
rendered through the closing of the merger (1) a fee of $100,000 payable in cash
on the date Merrill Lynch delivered its opinion, and (2) a fee of $400,000
payable in cash upon the closing of the merger. M&T also agreed, among other
things, to reimburse Merrill Lynch for certain expenses incurred in connection
with the services provided by Merrill Lynch, and to indemnify Merrill Lynch and
its affiliates from and against certain liabilities and expenses, which may
include certain liabilities under federal securities laws, in connection with
its engagement.

TERMS OF THE MERGER

     Under the terms of the merger agreement and applicable Delaware,
Pennsylvania and New York law, M&T will acquire Keystone through the merger of
Keystone with and into Olympia, a direct wholly owned subsidiary of M&T. The
separate existence of Keystone will cease, and Olympia will continue as the
surviving entity. SHAREHOLDERS OF KEYSTONE WILL BE ENTITLED TO STATUTORY
DISSENTERS' RIGHTS IN CONNECTION WITH THE MERGER. SHAREHOLDERS OF M&T WILL NOT
BE ENTITLED TO STATUTORY DISSENTERS' RIGHTS IN CONNECTION WITH THE MERGER OR THE
M&T STOCK SPLIT. Immediately following the merger, Keystone Bank will merge with
and into M&T Bank.

     CONVERSION OF KEYSTONE COMMON STOCK

     When the merger becomes effective, each share of Keystone common stock
issued and outstanding immediately prior to the completion of the merger will
automatically be converted into the right to receive, at the holder's election,
either (a) $21.50 in cash without interest or (b) 0.05 of a share of M&T common
stock and cash instead of fractional shares (collectively, the "merger
consideration"). A

                                       40
<PAGE>   45

Keystone shareholder's receipt of either cash and/or stock, however, is subject
to the allocation and proration procedures in the merger agreement.

     Under the terms of the merger agreement, Keystone shareholders may elect to
convert their shares into M&T common stock, cash or a mixture of cash and M&T
common stock. Keystone shareholders may also choose not to indicate a preference
for stock or cash and make no election. The allocation and proration procedures
in the merger agreement provide that the number of shares of Keystone common
stock to be converted into M&T common stock in the merger must equal 65% of the
total number of shares of Keystone common stock issued and outstanding on May
16, 2000, the date of the merger agreement (or 31,804,500) less the total number
of shares of Keystone common stock acquired by M&T or Keystone prior to the
completion of the merger (no shares as of July 27 2000).

     It is unlikely that Keystone shareholders will make elections in the exact
proportions of stock and cash required by the merger agreement. As a result, the
merger agreement includes procedures to be followed if Keystone shareholders in
the aggregate elect to receive more or less of the M&T common stock than M&T has
agreed to issue. These procedures are summarized below and are described in more
detail in the election form accompanying this document.

     NO GUARANTEE CAN BE MADE THAT YOU WILL RECEIVE THE AMOUNTS OF CASH AND/OR
STOCK YOU ELECT. AS A RESULT OF THE ALLOCATION AND PRORATION PROCEDURES AND
OTHER LIMITATIONS IN THE MERGER AGREEMENT, YOU MAY RECEIVE M&T COMMON STOCK OR
CASH IN AMOUNTS THAT VARY FROM THE AMOUNTS YOU ELECT. CHANGES IN THE AMOUNT OF
CASH AND/OR STOCK YOU RECEIVE AS A RESULT OF THESE PROCEDURES WILL HAVE NO
IMPACT ON YOUR VOTE ON THE MERGER.

     Because the market price of M&T common stock will fluctuate prior to and
following the completion of the merger and could be greater than or less than
$430.00 per share -- the approximate price at which the market value of 0.05 of
a share of M&T common stock would equal $21.50 -- the value of 0.05 of a share
of M&T common stock upon completion of the merger could be less than or greater
than $21.50. As of July 27 2000, the price of M&T common stock was $467.00. No
assurance can be given as to what the market price of M&T common stock will be
if and when the merger is completed, and Keystone shareholders are advised to
obtain current market quotations for the M&T common stock and Keystone common
stock. In addition, because the tax consequences of receiving cash will differ
from the tax consequences of receiving M&T common stock, you should carefully
read the information included below under "Certain Federal Income Tax
Consequences."

     - WHEN STOCK IS OVERSUBSCRIBED:
       If Keystone shareholders elect to receive M&T common stock for more than
       the 65% of Keystone shares that M&T has agreed will be converted into M&T
       common stock, then:

       - All shares for which a cash election or no election has been made will
         be converted into the right to receive cash.

       - Shares for which an M&T common stock election has been made will be
         converted into the right to receive M&T common stock until M&T common
         stock has been issued for 65% of the Keystone common shares.

       - Shares electing to receive M&T common stock in excess of 65% of
         Keystone common shares will be converted into the right to receive
         cash.

     Each shareholder's "stock election" shares will be reduced on a pro rata
basis. For example, if the actual percentage of outstanding Keystone shares
electing to receive M&T common stock is 75%, then approximately 13% of each
Keystone shareholder's "stock election" shares will be converted into the right
to receive $21.50 in cash, instead of M&T common stock.

                                       41
<PAGE>   46

     - WHEN STOCK IS UNDERSUBSCRIBED:
       If Keystone shareholders elect to receive M&T common stock for fewer than
       the 65% of Keystone shares that M&T has agreed will be converted into M&T
       common stock, then:

       - All Keystone shares for which a "stock election" has been made will be
         converted into the right to receive M&T common stock.

       - If the number of Keystone shares for which no election has been made,
         when added to the number of "stock election" shares, is equal to 65% or
         more of the Keystone shares, then all "cash election" shares will be
         converted into the right to receive cash; enough "no election" shares
         will be converted into the right to receive M&T common stock to reach
         the 65% level; and the rest of the "no election" shares will be
         converted into the right to receive cash.

       - If the number of Keystone shares for which no election has been made,
         when added to the number of "stock election" shares, is less than 65%
         of the Keystone shares, then all of these "no election" shares will be
         converted into the right to receive M&T common stock; enough "cash
         election" shares will be converted into the right to receive M&T common
         stock to reach, when combined with the "stock election" and no
         election" shares, the 65% level; and the rest of the "cash election"
         shares will be converted into the right to receive cash.

     Allocation of your "no election" shares and "cash election" shares between
the right to receive cash and M&T common stock will be done on a pro rata basis.
This means that each Keystone shareholder will, as nearly as possible, have the
same percentage of his or her "no election" or "cash election" shares converted
into the right to receive cash or M&T common stock as every other Keystone
shareholder holding these types of shares.

     Notwithstanding these rules, in order that the tax opinions described under
"Certain Federal Income Tax Consequences" can be rendered, it may be necessary
for M&T to reduce the percentage of Keystone common shares that will be
converted into the right to receive cash and correspondingly increase the
percentage of Keystone common shares that will be converted into M&T common
stock above 65%. If this is necessary, the allocation and proration procedures
described above will remain the same except that they will be based on this
higher percentage of Keystone common stock to be converted into M&T common
stock, instead of 65%.

     NO FRACTIONAL SHARES

     Each holder of shares of Keystone common stock who would otherwise have
been entitled to receive a fraction of a share of M&T common stock (after taking
into account all shares of Keystone common stock owned by such holder) will
receive, instead of M&T common stock, cash in an amount equal to the value of
such fractional share based on the closing price of M&T common stock on the NYSE
Composite Transactions List (as reported by The Wall Street Journal or, if not
reported in this publication, other comparable authoritative source) for the
trading day immediately preceding the date on which the merger is completed. No
such holder will be entitled to dividends, voting rights or any other
shareholder rights in respect of such fractional share. Under the terms of the
merger agreement, the 10-for-1 split of M&T common stock will be effected before
the merger is completed, so the determination of fractional shares will be on a
post-split basis.

     KEYSTONE STOCK OPTIONS

     M&T has agreed to assume each outstanding option, vested or unvested,
granted by Keystone to purchase shares of Keystone common stock that is
outstanding prior to the effective date of the merger. Each Keystone option
assumed by M&T will continue to have, and to be subject to, the same terms and

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<PAGE>   47

conditions set forth in the Keystone plan under which the option had been
granted and as in existence immediately prior to the effective date, except that
(i) the option will be exercisable (when vested) for that number of whole shares
of M&T common stock equal to the product of the number of shares of Keystone
common stock covered by the option multiplied by the exchange ratio, except that
any fractional shares of M&T common stock resulting from this multiplication
will be rounded down to the nearest share and (ii) the exercise price per share
of M&T common stock will be equal to the exercise price per share of Keystone
common stock divided by the exchange ratio, except that such exercise price will
be rounded up to the nearest cent. The terms under which the Keystone options
will be assumed are subject to adjustment to reflect, among other things,
increases or decreases in the number of outstanding shares of M&T common stock
to reflect recapitalizations, reclassifications, stock dividends, stock splits
or other like changes in M&T's capitalization, including M&T's anticipated
10-for-1 stock split in connection with the merger.

     CAPITAL ADJUSTMENTS

     If prior to the merger M&T increases, decreases, changes or exchanges its
common stock for a different number or kind of shares or securities through
reorganization, recapitalization, reclassification, stock dividend, stock split
or other like changes in M&T's capitalization, then a proportionate adjustment
will be made to the exchange ratio. In connection with the merger, M&T will
split its common stock 10-for-1, which will result in the exchange ratio of
Keystone common stock for M&T common stock being changed from 0.05 to 0.5.

FOR KEYSTONE SHAREHOLDERS: ELECTION PROCEDURES; SURRENDER OF STOCK CERTIFICATES

     Along with this document, an election form is being mailed to holders of
shares of Keystone common stock, together with other customary transmittal
materials, which specify that delivery will be effected, and risk of loss and
title to the certificates representing Keystone common stock will pass, only
upon proper delivery of certificates to the exchange agent, currently EquiServe.

     Each election form entitles the holder of the Keystone common stock to
elect to receive cash, M&T common stock, or a combination of both as outlined
above. See "Conversion of Keystone Common Stock."

     TO MAKE AN EFFECTIVE ELECTION, YOU MUST SUBMIT A PROPERLY COMPLETED
ELECTION FORM TO THE EXCHANGE AGENT ON OR BEFORE THE ELECTION DEADLINE, WHICH
HAS BEEN SET AS 5:00 P.M., EASTERN TIME, ON SEPTEMBER 20, 2000. An election form
will be deemed properly completed only if accompanied by one or more stock
certificates representing all shares of Keystone common stock covered by such
election form (or an appropriate guarantee of delivery), together with the duly
executed transmittal materials included in the election form. Keystone
shareholders may change their election at any time prior to the election
deadline by written notice accompanied by a properly completed and signed,
revised election form received by the exchange agent prior to the election
deadline or by withdrawal of their stock certificates prior to the election
deadline. All elections will be revoked automatically if the merger agreement is
terminated.

     If certificates for Keystone common stock are not immediately available, or
time will not permit the election form and other required documents to reach the
exchange agent prior to the election deadline, Keystone shares may be properly
exchanged if (i) such exchanges are made by or through a member firm of a
registered national securities exchange or of the National Association of
Securities Dealers, Inc., or by a commercial bank or trust company having an
office, branch or agency in the United States; (ii) the exchange agent receives,
prior to the election deadline, a properly completed and duly executed Notice of
Guaranteed Delivery substantially in the form provided with this document
(delivered by hand,

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<PAGE>   48

mail, telegram, telex or facsimile transmission); and (iii) the exchange agent
receives, within three business days after the election deadline, the
certificates for all exchanged Keystone shares, or confirmation of the delivery
of all such certificates into the exchange agent's account with the Depository
Trust Company in accordance with the proper procedures for such transfer,
together with a properly completed and duly executed election form and any other
documents required by the election form.

     Keystone shareholders who do not submit a properly completed election form
or revoke their election form prior to the election deadline will have their
shares of Keystone common stock designated as "no election" shares for purposes
of the allocation procedures described above. See "Conversion of Keystone Common
Stock." Keystone stock certificates represented by elections that have been
revoked will be promptly returned without charge to the Keystone shareholder
submitting the election form upon written request. After the completion of the
merger, the exchange agent will allocate cash and M&T common stock among the
shareholders of Keystone common stock according to the allocation procedures
outlined above.

     After the completion of the merger, the exchange agent will mail to
shareholders who did not submit election forms a letter of transmittal, together
with instructions for the exchange of their Keystone common stock certificates
for the merger consideration. Until so exchanged, each certificate representing
shares of Keystone common stock that have been converted into shares of M&T
common stock will be deemed for all purposes to evidence ownership of the number
of shares of M&T common stock into which such shares have been converted; except
that no dividends or other distributions declared after the completion of the
merger with respect to M&T common stock will be paid to the holder of any
unsurrendered certificate until the holder surrenders that certificate.

     Keystone shareholders will not be entitled to change the amount of M&T
common stock and/or cash allocated to them in accordance with the merger
agreement. Nevertheless, Keystone shareholders having a preference as to the
form of merger consideration to be received in exchange for their shares of
Keystone common stock should make an election, because shares as to which an
election has been made will be given priority in allocating the merger
consideration over shares as to which no election is made. No one is making any
recommendation as to whether shareholders should elect to receive cash or M&T
common stock in the merger. Each holder of Keystone common stock must make his
or her own decision with respect to such election.

FOR M&T SHAREHOLDERS: RETENTION OF STOCK CERTIFICATES

     As a result of the stock split, each issued and outstanding share of M&T
common stock will be subdivided into 10 shares. If you currently hold a stock
certificate for M&T shares, that certificate will represent the post-split
shares. If that certificate is surrendered, any new certificate issued will show
the number of shares on a post-split basis. You are not obligated to surrender
your certificate for replacement merely because of the occurrence of the stock
split.

REPRESENTATIONS AND WARRANTIES; CONDITIONS TO THE MERGER; WAIVER

     The merger agreement contains representations and warranties by M&T and
Keystone regarding various legal, financial, business and regulatory matters.
The representations and warranties will not survive after the merger except to
the limited extent provided for in the merger agreement.

     The respective obligations of M&T, Olympia and Keystone to complete the
merger are subject to the fulfillment of the following conditions:

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<PAGE>   49

     - all corporate actions necessary to complete the merger having been taken
       by the parties, including obtaining the approval of the merger by the
       requisite vote of the shareholders of Keystone and approval by the
       necessary vote of M&T shareholders of the issuance of M&T common stock in
       the merger and of the M&T stock split;

     - receipt of all required regulatory approvals, expiration of all notice
       and waiting periods required after the grant of any such approvals and
       the satisfaction of all pre-consummation conditions contained in any such
       approval; except that no such approval will have imposed any condition or
       requirement which, in the reasonable opinion of the board of directors of
       M&T or Keystone, so materially and adversely affects the anticipated
       economic and business benefits to M&T or Keystone, respectively, of the
       transactions contemplated by the merger agreement as to render
       consummation of such transaction inadvisable. In the merger agreement,
       each of M&T and Keystone represented that at the date of the merger
       agreement, it was not aware of any reason that this regulatory condition
       would not be satisfied without the imposition of any such material,
       adverse conditions. While no assurances can be given, neither M&T nor
       Keystone is aware of any such reason as of the date of this document;

     - the effectiveness of the registration statement, of which this document
       forms a part, and the absence of any threatened or pending proceeding by
       the Securities and Exchange Commission to suspend the effectiveness of
       the registration statement;

     - receipt of all state securities "Blue Sky" permits or other
       authorizations, or confirmations as to the availability of an exemption
       from registration requirements as may be necessary;

     - receipt of all third-party consents or waivers required in connection
       with the merger under agreements to which Keystone or any subsidiary of
       Keystone is a party, unless the failure to obtain any such consents or
       waivers, individually or in the aggregate, would not have a material
       adverse effect on Keystone;

     - the absence of any court or agency order prohibiting completion of the
       transactions contemplated by the merger agreement;

     - approval for listing on the NYSE of the shares of M&T common stock to be
       issued in the merger;

     - receipt by M&T and Keystone of the tax opinions described in "Certain
       Federal Income Tax Consequences";

     - the material accuracy of the representations and warranties of the other
       party to the merger agreement as of the date of the merger agreement and
       as of the closing date;

     - material compliance by the other party with all covenants required to be
       performed at or prior to the closing date;

     - receipt of customary officer's certificates as to the preceding two
       items; and

     - in the case of Keystone's obligation to complete the merger, the 10-for-1
       split of M&T common stock having become effective; and

     - in the case of M&T's obligation to complete the merger, dissenters rights
       not having been exercised by holders of more than 15% of Keystone's
       outstanding common stock.

     Except with respect to any required shareholder or regulatory approval and
certain other conditions described below, M&T and Keystone, respectively, may at
any time, whether before or after approval of the merger agreement by the
shareholders of Keystone or M&T, extend the time for the performance of

                                       45
<PAGE>   50

any of the obligations or other acts of Keystone, on the one hand, or M&T or
Olympia, on the other hand, and may waive any inaccuracies in the
representations or warranties made by the other party, compliance with any of
the covenants, undertakings or agreements of such party, or satisfaction of any
of the conditions precedent to its obligations, or the performance by such other
party of any of its obligations set out in the merger agreement. No waiver
executed after approval of the shareholders of Keystone or M&T may change the
number of shares of M&T common stock or the amount of cash into which shares of
Keystone common stock will be converted pursuant to the merger. Certain
conditions to the consummation of the merger cannot be waived as a matter of
law, including the existence of an effective registration statement, the absence
of a government order enjoining or prohibiting consummation of the merger or any
other transaction contemplated by the merger agreement and the receipt of any
required "Blue Sky" permits or other authorizations.

REGULATORY APPROVALS NEEDED TO COMPLETE THE MERGER

     The merger is subject to the approval of the Board of Governors of the
Federal Reserve System ("Federal Reserve") under the Bank Holding Company Act
and the New York State Banking Department under the New York State Banking Law
and will require prior notice to the Pennsylvania Banking Department. The merger
of Keystone Bank into M&T Bank (the "bank merger") is subject to the approval of
the Federal Reserve under the Bank Merger Act and the Federal Reserve Act. The
bank merger also is subject to the approval of the New York State Banking
Department under the New York State Banking Law. In addition, the bank merger
will require prior notice to the Pennsylvania Banking Department and the
acquisition of Keystone Bank's branches in Maryland and West Virginia will
require prior notice to the Maryland Commissioner of Financial Regulation and
the West Virginia Commissioner of Banking, respectively. Also, Keystone Bank
must give notice to the Office of the Comptroller of the Currency in order to
facilitate the termination of Keystone Bank's status as a national banking
association.

     The Federal Reserve, in reviewing applications under the Bank Holding
Company Act and the Bank Merger Act, must consider, among other factors, the
competitive effect of the contemplated transaction, the managerial and financial
resources and future prospects of the institutions involved and the effect of
the contemplated transaction on the convenience and needs of the communities to
be served. Under the Community Reinvestment Act of 1977, as amended, the Federal
Reserve also must take into account the record of performance of each of M&T
Bank, Keystone Bank and M&T Bank, N.A. in meeting the credit needs of its
assessment area, including low and moderate income neighborhoods. In addition,
each of the Bank Holding Company Act and the Bank Merger Act provides that a
transaction approved by the Federal Reserve under these statutes generally may
not be consummated until 30 days after approval by such agency, during which
time the U.S. Department of Justice may challenge the transaction on antitrust
grounds. If the U.S. Department of Justice and the Federal Reserve agree, this
30-day period may be reduced to not less than 15 days.

     In considering whether to approve the merger under the New York Banking
Law, the New York State Banking Department will generally consider factors
similar to those considered by the Federal Reserve under the Bank Holding
Company Act and the Bank Merger Act, including whether the transaction is
consistent with adequate or sound banking, the competitive effects of the
transaction, and the public interest and the needs and convenience thereof. The
Banking Department will also consider the institutions' performance under the
New York State equivalent of the Community Reinvestment Act.

     All of the applications and notices required to be filed with the relevant
state and federal agencies described above have been filed.

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<PAGE>   51

     We are not aware of any governmental approvals or actions that are required
for completion of the merger and the bank merger except as described above and
except as related to activities of the Keystone subsidiaries involving
insurance, acting as broker dealers, registered investment advisers and advisors
to registered investment funds and with respect to which M&T and Keystone are
seeking the appropriate approvals. Should any additional governmental approval
or action be required, it is presently contemplated that such approval or action
would be sought. We will not proceed with the merger and the bank merger in the
absence of the required regulatory approvals, and there can be no assurance that
all such approvals will be obtained. Further, if approved, there can be no
assurance as to the date of such approvals, or that such approvals will not be
conditioned upon matters that would cause the Keystone board or the M&T board to
abandon the merger, although as of the date of this document, neither M&T nor
Keystone is aware of any reason why these approvals would be denied or such
condition imposed. Likewise, there can be no assurance that there will be no
legal challenges to the merger or the bank merger, including attempts by the
Department of Justice or any state attorney general to challenge these
transactions on antitrust grounds, or if such a challenge is made, as to the
result of the challenge. See "Representations and Warranties; Conditions to the
Merger; Waiver" and "Effective Date of the Merger; Terminating the Agreement."

     The approval of any application merely implies satisfaction of regulatory
criteria for approval, which do not include a review of the merger from the
standpoint of the adequacy of the consideration that Keystone shareholders are
to receive. Furthermore, regulatory approvals do not constitute an endorsement
or recommendation of the merger.

COVENANTS; CONDUCT OF BUSINESS PENDING THE MERGER

     Under the terms of the merger agreement, we have agreed to use our
reasonable best efforts in good faith to obtain as soon as practicable all
consents and approvals of any persons necessary or desirable for the
consummation of the merger and the bank merger, including obtaining the
requisite approvals of our respective shareholders and all requisite regulatory
approvals. Neither of us may take any action that would substantially impair the
prospects of completing, or would materially delay, the merger or that would
adversely affect the desired income tax consequences of the merger.

     The merger agreement provides that Keystone will, and will cause each of
its subsidiaries to, use its reasonable best efforts to preserve its properties,
business and relationships with customers, employees and others and to carry on
its respective business in the usual, regular and ordinary course in
substantially the same manner as conducted prior to the execution of the merger
agreement. In addition, Keystone may not, without the prior written consent of
M&T, except as otherwise provided in the merger agreement, increase the
compensation or fringe benefits of its directors, officers or employees except
in a manner consistent with past practice; declare or pay any dividends or other
distributions on capital stock other than its regular quarterly cash dividend on
Keystone common stock in an amount not in excess of $0.29 per share; or take
other specified actions, other than in the ordinary course of business, that
might impact its financial condition or business.

     In addition, the merger agreement provides that neither Keystone nor its
subsidiaries or any of its officers, directors, employees or agents may directly
or indirectly solicit, initiate or encourage any inquiries relating to, or the
making of any proposal which would constitute a "takeover proposal" (as defined
below). The merger agreement also provides that, except to the extent legally
required for the discharge of the fiduciary duties of the Keystone board,
Keystone, its subsidiaries or any of these individuals may not recommend or
endorse any takeover proposal, or participate in any discussions or
negotiations, or provide third parties with any nonpublic information, relating
to any such inquiry or proposal, or otherwise facilitate any effort or attempt
to make or implement a takeover proposal. The merger agreement allows Keystone
to communicate information about a takeover proposal to its

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<PAGE>   52

shareholders if, in the judgment of the Keystone board, based on the advice of
outside counsel, that communication is required under applicable law. Keystone
has agreed to notify M&T immediately if any such inquiries or takeover proposals
are received by, any such information is requested from, or any such
negotiations or discussions are sought to be initiated or continued with
Keystone. The merger agreement defines a "takeover proposal" as any tender or
exchange offer, proposal for a merger, consolidation or other business
combination involving Keystone or any subsidiary of Keystone or any proposal or
offer to acquire in any manner a substantial equity interest in, or a
substantial portion of, the assets of Keystone or any subsidiary of Keystone
other than the transactions contemplated or permitted by the merger agreement or
the stock option agreement.

AMENDING THE AGREEMENT

     M&T and Keystone may amend the merger agreement at any time by mutual
written agreement, except that after approval by the shareholders of Keystone or
M&T, no waiver or amendment can change the amount of M&T common stock or cash
that Keystone shareholders are to receive in the merger.

EFFECTIVE DATE OF THE MERGER; TERMINATING THE AGREEMENT

     The effective date will be the date and time as described in the
certificates of merger that are to be delivered and filed on the closing date
with the Delaware Secretary of State and the Pennsylvania Secretary of the
Commonwealth according to the respective laws of Delaware and Pennsylvania. The
closing date will be the first business day following the satisfaction of the
conditions to the consummation of the merger (other than conditions relating to
the receipt of officers' certificates and legal opinions) or such later date
during such month in which such business day occurs (or, if such business day
occurs within ten days prior to the end of such month, during the following
month) thereafter as may be mutually specified by M&T and Keystone.

     M&T and Keystone each anticipate that the merger will be completed during
October 2000. However, consummation of the merger could be delayed as a result
of delays in obtaining the requisite regulatory approvals or the satisfaction of
the closing conditions. There can be no assurances as to if or when such
approvals will be obtained or that the merger will be completed. See "Regulatory
Approvals Needed to Complete the Merger."

     The merger agreement may be terminated, either before or after approval by
the shareholders of Keystone or M&T:

     - by the mutual consent in writing of M&T and Keystone;

     - by Keystone, on one hand, or M&T, on the other hand, if the other party
       has breached any covenant or agreement or representation or warranty
       contained in the merger agreement if such breach has not been cured as
       permitted by the merger agreement and the materiality of the breach would
       excuse the terminating party's obligation to complete the merger;

     - by either party if any application for regulatory approval has been
       denied, or if a court or agency has issued an order prohibiting the
       merger;

     - by either party if the shareholders of Keystone do not approve the
       merger; and

     - by either party if the closing has not occurred by January 31, 2001.

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<PAGE>   53

MANAGEMENT AND OPERATIONS AFTER THE MERGER

     BOARD OF DIRECTORS; MANAGEMENT

     The merger agreement provides that, following the merger, those persons
serving as directors of M&T and Olympia immediately prior to the effective date
will continue as directors of those respective entities, except that, as of the
effective date, the M&T board will elect Mr. Campbell and four other individuals
that Mr. Campbell designates, who are reasonably acceptable to M&T, as members
of the M&T board. See "Interests of Directors and Officers in the Merger that
are Different from Your Interests -- M&T Board of Directors."

     The merger agreement also provides that, following the consummation of the
merger, Keystone Bank will be merged with and into M&T Bank and Mr. Campbell and
the four other individuals will be appointed to the board of directors of M&T
Bank. In addition, M&T and Keystone have agreed that, as of the completion of
the merger, Mr. Campbell will be elected Vice Chairman of M&T and M&T Bank.

     The merger agreement further provides that members of the Keystone board,
the boards of directors of Keystone Bank and the members of Keystone's advisory
boards (other than Mr. Campbell and the four other Keystone directors described
above) will be appointed as members of the regional advisory boards of M&T Bank.
See "Interests of Directors and Officers in the Merger that are Different from
Your Interests -- Regional Advisory Boards."

     Information regarding the current directors of M&T and Keystone is included
in documents incorporated in this document by reference. See "WHERE YOU CAN FIND
MORE INFORMATION" and "DOCUMENTS INCORPORATED BY REFERENCE."

     OPERATIONS

     M&T believes that the merger will allow M&T to establish a leading position
in the Central Pennsylvania market, as well as enter Maryland and West Virginia.
M&T believes that the new, combined M&T/Keystone entity will have even greater
financial strength, operational efficiencies, profitability, cash flow and
potential for growth than M&T or Keystone would have on its own. M&T also
believes the merger will provide Keystone customers with a greater range of
services and products than is currently available to them.

     M&T believes that the merger will enable M&T to significantly expand its
presence in Pennsylvania. After the merger, M&T will rank first in deposit share
in both Upstate New York -- with approximately $12.4 billion in deposits -- and
in Central Pennsylvania -- with approximately $4.2 billion in deposits. Together
with the addition of Keystone's branches in Maryland and West Virginia, M&T
would have total pro forma deposits of approximately $20.2 billion after the
merger. M&T also expects to be able to benefit from the experience it already
has acquired in Pennsylvania as a result of the acquisition of ONBANCorp and its
Franklin First subsidiary, as well as from the similar demographics between the
current Keystone and M&T franchises. M&T also believes that the geographic
expansion into Keystone's market will provide benefits of geographic
diversification, as well as the benefits of scale associated with a larger
company.

     M&T believes that the merger presents significant opportunities for cost
savings and operating efficiencies through, among other things, the
consolidation of systems, business lines and administrative and back office
functions. Currently, M&T estimates that the merger will produce annual pre-tax
cost savings of approximately $43 million. These estimated savings are expected
to be achieved in the areas of technology and operations, corporate overhead,
business line consolidation and facilities expense. Because of the lack of
overlap between Keystone's and M&T's markets, M&T expects no branch

                                       49
<PAGE>   54

consolidations or loss of front-line personnel in the merger. M&T estimates that
approximately half of these cost savings would be realized in 2001, and all of
the savings would be realized in 2002.

     These cost savings do not take into account the cost of the amortization of
intangibles created in purchase accounting and also exclude various one-time
items, including purchase accounting adjustments. These adjustments include an
estimated $41.4 million in after-tax merger related charges.

     There can be no assurance that any specific level of cost savings will be
achieved or that these cost savings will be achieved within the time period
contemplated. Merger and conversion-related charges also could differ from those
M&T anticipates.

     While there can be no assurance, M&T also believes that the merger will
create significant revenue enhancement opportunities compared with what the two
companies could have achieved separately. The combined franchise is expected to
provide new small business and middle market lending opportunities for M&T and
provide a new market for M&T's automated banking, loan and trust products and
investment services.

     EMPLOYEES

     Upon completion of the merger, all persons employed by Keystone or any of
its subsidiaries will be employed upon terms and conditions (including benefits)
which in the aggregate are no less favorable with respect to their employment by
M&T and its subsidiaries after the effective date than those generally afforded
to other employees of M&T holding similar positions, subject to the terms and
conditions under which those employee benefits are made available to such
employees. For purposes of determining eligibility for and vesting of such
employee benefits only (and not for pension benefit accrual purposes),
determining levels of short-term disability benefits, vacation benefits and
severance benefits under any severance pay arrangement and, if applicable, for
purposes of satisfying any waiting periods concerning preexisting conditions,
service with Keystone or a subsidiary of Keystone or any predecessor thereto
prior to the effective date will be treated as service with an "employer" to the
same extent as if such persons had been employees of M&T. In addition, any
copayments and expenses paid by Keystone employees prior to the effective date
under Keystone's medical benefit plans will be treated as if paid under M&T's
medical benefit plans for purposes of determining satisfaction of copayment and
deductible requirements under M&T's medical benefit plans. M&T will provide
employees or former employees of Keystone or its subsidiaries with
post-retirement medical benefits on the same basis as those provided to new
hires at M&T. M&T has agreed to honor, or to cause the appropriate subsidiaries
of M&T to honor, in accordance with their terms, all employment, severance and
employee benefit plans, contracts, agreements, arrangements and understandings
of Keystone or any of its subsidiaries as provided in the merger agreement. M&T
may, however, amend or terminate any such plan, contract, agreement, arrangement
or understanding in accordance with its terms other than the Keystone severance
plan following a change of control which will remain in effect without amendment
for one year following the effective date. M&T has agreed that following the
effective date the sales and performance targets for the cash incentive awards
under the Keystone bonus and incentive plans and agreements shall be doubled
relative to the award levels in effect prior to the effective date for the
annual performance period in which the effective date occurs and the quarterly
or other performance periods within such annual period, up to a maximum
aggregate additional cost of $2.5 million.

     The continued coverage of the Keystone employees under the employee benefit
plans maintained by Keystone and/or any Keystone subsidiary immediately prior to
the effective date will be deemed to provide the Keystone employees with
benefits that are on the same basis as those offered to other employees of M&T
and any M&T subsidiary, provided that after the effective date there is no
material

                                       50
<PAGE>   55

reduction (determined on an overall basis) in the benefits provided under the
Keystone employee benefit plans.

     RETENTION POOL

     M&T and Keystone have agreed that Keystone will establish an employee
retention cash pool in an aggregate amount of up to $1.5 million. The cash in
the retention pool will be available for allocation among key employees of
Keystone. Allocation of the retention pool among those Keystone employees will
be determined mutually by Keystone and M&T.

INTERESTS OF DIRECTORS AND OFFICERS IN THE MERGER THAT ARE DIFFERENT FROM YOURS

     In considering the recommendation of the Keystone board of directors that
you vote in favor of adopting the merger agreement, Keystone shareholders should
be aware that some Keystone executive officers and Keystone's directors have
interests in the merger with M&T that are different from, or in addition to,
your interest as a shareholder generally. The Keystone board of directors knew
about these additional interests, and considered them, in making its decisions
to approve the merger agreement and to recommend adoption of the merger
agreement to you.

     EMPLOYMENT AGREEMENTS WITH M&T

     In connection with the signing of the merger agreement, M&T entered into
employment agreements with Carl L. Campbell, the current Chairman, President and
Chief Executive Officer of Keystone, Mark L. Pulaski, the current President of
the Wealth Management Division of Keystone Financial Bank and Ben G. Rooke, Vice
Chairman, General Counsel and Secretary of Keystone.

     Employment Agreement with Mr. Campbell. The term of Mr. Campbell's
employment agreement begins on the effective date of the merger and expires on
the third anniversary of that date. Pursuant to Mr. Campbell's employment
agreement, Mr. Campbell will serve as Vice Chairman of M&T and as Chairman of
M&T's Pennsylvania operations. During the employment period, Mr. Campbell will
serve as a member of M&T's board of directors. Following the termination of this
three-year period and until his 65th birthday, Mr. Campbell will continue
employment on a part-time basis on terms to be agreed to between him and M&T.

     Under Mr. Campbell's employment agreement, for each year during the initial
three-year employment period, he will receive (1) an annual base salary no less
than $460,000, and (2) an annual cash bonus of no less than $168,505. During the
part-time employment period, he will receive an annual base salary of $400,000.
If Mr. Campbell dies before his 65th birthday, 50% of the annual base salary he
would have otherwise received during the remainder of the part-time employment
period will be paid to his current spouse, if she survives him.

     Upon completion of the merger, M&T will grant Mr. Campbell an option to
acquire 50,000 shares of M&T's common stock (on a post-split basis) which will
vest in three equal installments on each of the first, second and third
anniversaries of the completion of the merger (or, if earlier, upon the
occurrence of a change of control of M&T) and will have a term of ten years from
the date of grant without regard to Mr. Campbell's earlier termination of
employment. Mr. Campbell will also receive upon completion of the merger a lump
sum payment of $1,250,000 (provided he is employed on such date).

     Mr. Campbell's employment agreement provides for a lifetime annual
retirement benefit of $350,000, less any amounts payable under qualified and
non-qualified defined benefit retirement plans, commencing upon his 65th
birthday. Upon the death of Mr. Campbell, his current spouse, if she

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survives him, will receive an annual benefit for the rest of her life in an
amount equal to 50% of this retirement benefit. During the initial three-year
employment period, Mr. Campbell will be entitled to participate in all employee
benefit, welfare and other plans, practices, policies and programs that apply
generally to senior executives of M&T on a basis no less favorable than that
provided to those executives, except that if Mr. Campbell's employment is
terminated for any reason other than for cause by M&T, M&T will continue to
provide him and his current spouse with medical and dental benefits for the
remainder of their lives on a basis no less favorable than that on which those
benefits were provided immediately before the termination. The employment
agreement contains confidentiality, non-competition and non-solicitation
provisions that apply while Mr. Campbell is employed and for specified periods
thereafter.

     In the event that Mr. Campbell's employment is terminated prior to the end
of the initial three-year employment period by M&T other than for "cause" or
"disability" or by Mr. Campbell for "good reason" (each as defined in Mr.
Campbell's employment agreement), Mr. Campbell will be entitled to receive the
following payments and benefits:

     - annual base salary through the date of termination and a pro-rata annual
       bonus through the date of termination (based on the minimum annual bonus
       under the employment agreement);

     - a lump sum payment equal to the product of (1) the number of months and
       portions thereof from the date of termination until the end of the
       initial three-year employment period, divided by 12, and (2) the sum of
       Mr. Campbell's annual base salary and the minimum annual bonus;

     - the retirement benefit described above, payable in accordance with the
       terms of the employment agreement;

     - a lump sum payment of $2 million; and

     - the stock options granted to Mr. Campbell, as described above, will vest
       immediately.

     If any amounts payable to Mr. Campbell under the employment agreement or
otherwise would be subject to the excise tax under Section 4999 of the Internal
Revenue Code, an additional payment will be made so that after the payment of
all income and excise taxes, Mr. Campbell will be in the same after-tax position
as if no excise tax under Section 4999 had been imposed. However, if these
additional payments (excluding any additional amounts payable due to the excise
tax) do not exceed 110% of the greatest amount that could be paid without
requiring payment of the excise tax, no additional payments will be made on
account of the excise tax. Instead, the payments otherwise due will be reduced
as necessary to prevent the application of the excise tax. On completion of the
merger, Mr. Campbell's new employment agreement will supersede Mr. Campbell's
current employment agreement with Keystone.

     Employment Agreements with Messrs. Pulaski and Rooke. The terms of Mr.
Pulaski's and Mr. Rooke's employment agreements begin on the effective date of
the merger and expire on the third anniversary of that date. The terms of Mr.
Pulaski's and Mr. Rooke's employment agreements with M&T are substantially the
same and accordingly, for purposes of this section, Mr. Pulaski and Mr. Rooke
are each referred to as the "executive." Pursuant to each executive's employment
agreement, the executive will serve in a senior executive capacity.

     Under each executive's employment agreement, for each year during the
initial three-year employment period, he will receive (1) an annual base salary
no less than the annual base salary payable to the executive immediately prior
to the completion of the merger, and (2) an annual cash bonus no less than
$83,694 for Mr. Pulaski and $57,531 for Mr. Rooke.

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<PAGE>   57

     Upon completion of the merger, M&T will grant each executive an option to
acquire 20,000 shares of M&T's common stock (on a post-split basis) which will
vest in three equal installments on each of the first, second and third
anniversaries of the completion of the merger (or, if earlier, upon the change
of control of M&T) and will have a term of ten years from the date of grant
without regard to the executive's earlier termination of employment. Each
executive will also receive upon completion of the merger a lump sum payment of
$750,000 and, upon the one-year anniversary of the merger, a lump sum payment of
$500,000 (in each case, provided that the executive remains employed on the date
the payment is due).

     During the three-year employment period, each executive will be entitled to
participate in all employee benefit, welfare and other plans, practices,
policies and programs that apply generally to senior executives of M&T on a
basis no less favorable than that provided to those executives, except that if
the executive's employment is terminated for any reason other than for cause by
M&T, M&T will continue to provide him and his current spouse with medical and
dental benefits for the remainder of their lives on a basis no less favorable
than that on which those benefits were provided immediately before the
termination. The employment agreements contain confidentiality, non-competition
and non-solicitation provisions that apply while the executive is employed and
for specified periods thereafter.

     In the event that an executive's employment is terminated prior to the end
of the three-year employment period by M&T other than for cause or disability,
or by the executive for good reason (each as defined in the executive's
employment agreement), the executive will be entitled to receive the following
payments and benefits:

     - annual base salary through the date of termination and a pro-rata annual
       bonus through the date of termination (based on the minimum annual bonus
       under the employment agreement);

     - a lump sum payment equal to the product of (1) the number of months and
       portions thereof from the date of termination until the end of the
       initial three-year employment period, divided by 12, and (2) the sum of
       the executive's annual base salary and the minimum annual bonus under the
       employment agreement;

     - the lump sum payment due upon the one-year anniversary of the merger, if
       not already paid; and

     - the stock options granted to the executive, as described above, will vest
       immediately.

     If any amounts payable to the executive under the employment agreement or
otherwise would be subject to the excise tax under Section 4999 of the Internal
Revenue Code, an additional payment will be made so that after the payment of
all income and excise taxes, the executive will be in the same after-tax
position as if no excise tax under Section 4999 had been imposed. However, if
these additional payments (excluding any additional amounts payable due to the
excise tax) do not exceed 110% of the greatest amount that could be paid without
requiring payment of the excise tax, no additional payments will be made on
account of the excise tax. Instead, the payments otherwise due will be reduced
as necessary to prevent the application of the excise tax. On completion of the
merger, the executive's new employment agreement will supersede the executive's
current employment agreement with Keystone.

     EXISTING EMPLOYMENT AGREEMENTS

     Messrs. Campbell, Pulaski and Rooke are parties to employment agreements
with Keystone. The employment agreements into which those executives entered
with M&T in connection with the execution of the merger agreement provide that
the new M&T employment agreements will, upon completion of the merger, supersede
their existing employment agreements with Keystone.

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<PAGE>   58

     Keystone has also entered into employment agreements with five other
executive officers, William J. Rossman, Robert R. Wozniewicz, George R. Barr,
Jr., Edwin R. Eckberg and Donald F. Holt. These agreements provide that if,
within 24 months following the later of a "change of control" of Keystone (as
defined in the employment agreements) or the consummation of the transactions
resulting in the change of control, the executive is terminated other than for
cause or terminates his employment for good reason (in each case, as defined in
the employment agreements), then the executive is entitled to a lump-sum cash
payment. The amount of the cash payment is 2.5 times the sum of the executive's
highest annual base salary during the three-year period ending before the date
of termination and the executive's highest annual bonus award under the Keystone
Management Incentive Compensation Plan during that three-year period. In such a
case, Keystone would also be obligated to maintain in full force and effect, for
at least 18 months following the termination, all employee benefit plans and
programs to which the executive was entitled before the date of termination (or
to provide compensating cash payments or equivalent coverage if continued
participation by the executive is not permitted). If any amounts payable to the
executive under the change of control agreement or otherwise would be subject to
the excise tax under Section 4999 of the Internal Revenue Code, an additional
payment will be made so that after the payment of all income and excise taxes,
the executive will be in the same after-tax position as if no excise tax under
Section 4999 had been imposed. The merger will constitute a "change of control"
for purposes of these employment agreements.

     MEMBERSHIP ON BOARDS OF DIRECTORS AND ADVISORY BOARDS AFTER THE MERGER

     Under the merger agreement, M&T has agreed that, as of the date the merger
is completed, it will elect Mr. Campbell and four other individuals designated
by Mr. Campbell, who are reasonably acceptable to M&T, as directors of M&T and
also cause them to be elected as directors of M&T Bank. The merger agreement
also provides that Mr. Campbell will be Vice Chairman of M&T and of M&T Bank
following the merger.

     In addition, M&T has agreed to continue, for at least 24 months following
completion of the merger, Keystone's five regional advisory boards. Each
regional advisory board will advise M&T Bank on deposit and lending activities
within the board's geographical area. Each current member of the Keystone
advisory boards and of the boards of directors of Keystone and Keystone Bank,
other than those who will serve as directors of M&T or M&T Bank after the
merger, will be appointed to serve on one of the advisory boards. M&T has agreed
that, during this 24-month period, members of the advisory boards will be paid
fees for their participation as advisory directors. The annual fee for an
advisory director will approximate the current aggregate fees for that
individual in his capacities as a Keystone director, Keystone bank director and
Keystone advisory board member, will depend upon the satisfaction of the
attendance requirements set forth in the merger agreement and will not exceed
$50,000 per year for any individual.

     KEYSTONE STOCK-BASED RIGHTS; PERFORMANCE UNIT PLAN

     Under Keystone's employee and non-employee director stock-based plans,
unvested stock options will become fully vested and exercisable on a change of
control of Keystone. In addition, under Keystone's 1996 Performance Unit Plan,
upon a change of control, awards are deemed earned and payable for each
uncompleted performance period at the maximum performance dollar amount. The
transactions provided for by the merger agreement will constitute a change of
control under the Keystone stock-based plans and under the 1996 Performance Unit
Plan.

     The merger agreement provides that options under the Keystone stock-based
plans that are outstanding immediately before the merger is completed will be
assumed by M&T and will continue to be governed by the terms of the relevant
Keystone plan, except that the options will become exercisable

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<PAGE>   59

for shares of M&T common stock, and the number of shares for which an option may
be exercised and the exercise price of the option will be adjusted to reflect
the exchange ratio in the merger.

     INDEMNIFICATION AND INSURANCE OF DIRECTORS AND OFFICERS

     The merger agreement provides that, following the completion of the merger,
M&T will indemnify, to the fullest extent permitted by law, any then-current or
former Keystone director or officer for any claims or lawsuits against them that
relate to:

     - their status as an employee, officer or director of Keystone or its
       subsidiaries or

     - the merger agreement, the stock option agreement or any transaction
       contemplated by those agreements.

     M&T has also agreed that any rights to indemnification, or limitations on
liability, that currently exist in the articles of incorporation or bylaws of
Keystone or its subsidiaries in favor of any of the employees, officers or
directors of Keystone or its subsidiaries will continue unchanged and will be
honored for six years after the merger is completed.

     M&T has further agreed that, for a period of at least four years after the
effective date, it will use its reasonable best efforts to cause Keystone
directors and officers to continue to be covered by Keystone's existing
directors and officers liability insurance policy or an equivalent policy,
except that M&T will not be required to spend more than 200% of Keystone's
current premium to secure this coverage.

     OTHER RIGHTS

     Pursuant to the merger agreement and, in the case of Messrs. Campbell,
Pulaski and Rooke, their employment agreements with M&T, M&T has agreed to
assume, and continue in effect after the completion of the merger, the split
dollar insurance policy arrangements (which provide for payment by the employer
of a portion of the applicable insurance premiums) currently in effect between
Keystone and certain of its executive officers, including Messrs. Campbell,
Pulaski and Rooke. Under these split dollar agreements, if an executive becomes
entitled to severance benefits under a severance plan of or employment agreement
with Keystone for a termination following a change of control, then the
executive will no longer be required to reimburse Keystone for the split dollar
life insurance premium payments made by Keystone. The transactions contemplated
by the merger agreement will constitute a change of control under the split
dollar agreements.

     In connection with entering into the merger agreement and contingent upon
completion of the merger, the Keystone board of directors extended for 10 years
after the completion of the merger the term of loans made to Keystone officers
to purchase Keystone common stock under the Management Stock Ownership Program,
subject to the other terms and provisions of the Program.

CERTAIN FEDERAL INCOME TAX CONSEQUENCES

     The following is a summary of the anticipated material U.S. federal income
tax consequences of the merger to a holder of Keystone common stock. This
discussion is based on laws, regulations, rulings and judicial decisions as they
exist on the date of this document. These authorities are all subject to change
and any such change may be made with retroactive effect.

     This discussion is not a complete description of the U.S. federal income
tax consequences of the merger and may not apply to a holder subject to special
treatment under the Internal Revenue Code of 1986, as amended, such as a holder
that is

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     - a financial institution,

     - an insurance company,

     - a dealer in securities or foreign currencies,

     - a trader in securities,

     - a tax-exempt organization,

     - a person who holds shares of Keystone common stock in an individual
       retirement account (IRA), 401(k) plan or similar tax-favored account,

     - a person who acquired shares of Keystone common stock pursuant to the
       exercise of an employee stock option or otherwise as compensation or

     - a person who holds shares of Keystone common stock as part of a hedge,
       straddle, conversion or constructive sale transaction.

     In addition, this discussion applies only to a holder of Keystone common
stock who is holding such stock as a capital asset and who is a U.S. person (as
defined in Section 7701(a)(30) of the Internal Revenue Code). No ruling will be
requested from the Internal Revenue Service regarding the tax consequences of
the merger. Moreover, the opinions of counsel described in this discussion are
not binding on the Internal Revenue Service, and none of those opinions would
prevent the Internal Revenue Service from challenging the U.S. federal income
tax treatment of the merger. In addition, this discussion does not address the
state, local or foreign tax consequences of the merger.

     BECAUSE OF THE COMPLEXITIES OF THE TAX LAWS IN GENERAL, AND THE
COMPLEXITIES OF THE TAX CONSEQUENCES ASSOCIATED WITH THE RECEIPT OF CASH IN THE
MERGER IN PARTICULAR, YOU SHOULD CONSULT YOUR TAX ADVISOR WITH RESPECT TO THE
FEDERAL, STATE, LOCAL AND FOREIGN TAX CONSEQUENCES OF THE MERGER AS THEY APPLY
TO YOUR SPECIFIC SITUATION.

     In connection with the filing with the Securities and Exchange Commission
of the registration statement of which this document is a part, Arnold & Porter,
special counsel to M&T, and Wachtell, Lipton, Rosen & Katz, special counsel to
Keystone, have delivered their respective opinions addressing the U.S. federal
income tax consequences of the merger described below. These opinions are based
upon facts, representations and assumptions set forth or referred to in each
opinion. In rendering these opinions, Arnold & Porter and Wachtell, Lipton,
Rosen & Katz have relied upon representations and facts provided by M&T and
Keystone. These opinions are to the effect that the merger will be treated as a
reorganization within the meaning of Section 368(a) of the Internal Revenue Code
and that:

     - Keystone, M&T and Olympia will each be a party to the reorganization
       within the meaning of Section 368(b) of the Internal Revenue Code;

     - No gain or loss will be recognized by M&T, Olympia or Keystone as a
       result of the merger (except for amounts resulting from any required
       change in accounting methods or any income or deferred gain recognized
       under the relevant consolidated return regulations);

     - Keystone shareholders who receive only M&T common stock for all of their
       shares of Keystone stock will not recognize any gain or loss with respect
       to shares of M&T stock received (except with respect to cash received
       instead of a fractional share interest in M&T common stock);

     - Each Keystone shareholder who receives M&T common stock and cash (other
       than cash instead of a fractional share interest in M&T common stock) in
       exchange for the shareholder's shares of Keystone common stock will
       recognize the gain, if any, realized by the shareholder, but in an

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<PAGE>   61

       amount not in excess of the amount of cash received, but will not
       recognize any loss on the exchange;

     - Each Keystone shareholder's aggregate tax basis in any shares of M&T
       common stock received in the transaction (including fractional shares
       deemed received and redeemed as described below) will be the same as the
       aggregate tax basis of the shares of Keystone common stock the Keystone
       shareholder surrendered in exchange therefor, decreased by the amount of
       any cash received by the shareholder and increased by the amount of
       income or gain recognized by the shareholder in the exchange; and

     - Each Keystone shareholder's holding period in any shares of M&T common
       stock received in the transaction (including any fractional shares deemed
       received and redeemed as described below) will, in each instance, include
       the period during which the shares of Keystone common stock surrendered
       in exchange therefor were held.

     For purposes of the opinions described above, a Keystone shareholder's
realized gain is equal to the sum of the amount of cash and the fair market
value of M&T common stock received minus the holder's adjusted tax basis in the
Keystone shares surrendered.

     Our obligations to consummate the merger are conditioned upon the receipt
by M&T and Keystone of additional opinions of Arnold & Porter and Wachtell,
Lipton, Rosen & Katz, respectively, each dated as of the effective date of the
merger, substantially to the foregoing effect. Each of those opinions will be
subject to and based on facts, representations and assumptions set forth or
referred to in the opinion. In rendering those opinions, Arnold & Porter and
Wachtell, Lipton, Rosen & Katz may rely upon representations and facts as
provided by M&T and Keystone.

     CHARACTER OF GAIN WHERE KEYSTONE COMMON STOCK EXCHANGED SOLELY FOR CASH. In
general, if, pursuant to the merger, all of the shares of Keystone common stock
actually owned by a shareholder are exchanged solely for cash, the shareholder
generally will recognize capital gain or loss equal to the difference between
the amount of cash received and the shareholder's adjusted tax basis in the
shares of Keystone common stock surrendered, which gain or loss will be
long-term capital gain or loss if the shareholder's holding period with respect
to the shares of Keystone common stock surrendered is more than one year as of
the effective date of the merger. If, however, any such shareholder actually or
constructively (through the constructive ownership rules of the Internal Revenue
Code) owns shares of M&T stock immediately after the merger, part or all of the
cash received may be treated as ordinary income if the exchange has the effect
of a distribution of a dividend with respect to the shareholder. The application
of the law to a shareholder described in the previous sentence is particularly
complex; accordingly, any such shareholder should consult its tax advisor.

     CALCULATION AND CHARACTER OF GAIN WHERE KEYSTONE COMMON STOCK IS EXCHANGED
FOR M&T COMMON STOCK AND CASH. For purposes of calculating gain in this
transaction, if a shareholder receives M&T common stock and cash, gain or loss
must be calculated by the shareholder separately for each identifiable block of
shares surrendered in the exchange, and is equal to the sum of the amount of
cash and the fair market value of M&T common stock received with respect to that
block of shares minus the shareholder's adjusted tax basis in that block of
shares. In addition, a loss realized on one block of shares may not be used to
offset a gain realized on another block of shares.

     In general, in the case of a Keystone shareholder that exchanges his or her
shares of Keystone common stock for a combination of M&T common stock and cash
pursuant to the merger, the determination of whether any gain recognized in the
exchange should be treated as capital gain or has the effect of a distribution
of a dividend depends upon whether, and to what extent, the exchange reduces the
shareholder's deemed percentage stock ownership of M&T. For purposes of this

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determination, the shareholder is treated as if it first exchanged all of its
shares of Keystone common stock solely for M&T common stock and then M&T
immediately redeemed (in a "deemed redemption") a portion of such M&T common
stock in exchange for the cash the shareholder actually received. The gain
recognized in the exchange will be treated as capital gain if the deemed
redemption (i) is "substantially disproportionate" with respect to the
shareholder or (ii) is not essentially equivalent to a dividend.

     The deemed redemption should generally be "substantially disproportionate"
with respect to a shareholder if the percentage of the outstanding stock of M&T
the shareholder owns, actually and constructively, immediately after the deemed
redemption is less than 80% of the percentage of the outstanding stock of M&T
the shareholder is deemed to own, actually and constructively, immediately
before the deemed redemption.

     Whether the deemed redemption is "not essentially equivalent to a dividend"
with respect to a shareholder will depend upon the shareholder's particular
circumstances. In order for the deemed redemption to be "not essentially
equivalent to a dividend," the deemed redemption must result in a "meaningful
reduction" in the shareholder's actual and constructive percentage stock
ownership of M&T. In general, that determination requires a comparison of the
percentage of the outstanding stock of M&T the shareholder is deemed to own,
actually and constructively, immediately before the deemed redemption and the
percentage of the outstanding stock of M&T the shareholder actually and
constructively owns immediately after the deemed redemption. The Internal
Revenue Service has ruled that a minority shareholder (i.e., a shareholder whose
relative stock interest is minimal in relation to the number of shares
outstanding and who exercises no control with respect to corporate affairs)
generally is treated as having a "meaningful reduction" in interest if a cash
payment results in a relatively minor reduction in the shareholder's actual and
constructive percentage ownership.

     CASH RECEIVED INSTEAD OF A FRACTIONAL SHARE. Cash received by a Keystone
shareholder instead of a fractional share of M&T common stock will be treated as
though the fractional share had been received and then redeemed for cash, and in
general gain or loss will be recognized, measured by the difference between the
amount of cash received and the portion of the basis of the shares of Keystone
common stock allocable to such fractional interest. Such gain or loss generally
will be long-term capital gain or loss if the holding period for such shares of
Keystone common stock was more than one year as of the effective date of the
merger. If, however, the receipt of cash instead of a fractional share of M&T
common stock has the effect of the distribution of a dividend with respect to a
shareholder, part or all of the cash received may be treated as a dividend.

     BACKUP WITHHOLDING. Unless an exemption applies under the applicable law
and regulations, the exchange agent will be required to withhold 31% of any cash
payments to which a Keystone shareholder or other payee is entitled pursuant to
the merger unless the shareholder or other payee provides its taxpayer
identification number (social security number or employer identification number)
and certifies, among other things, that such number is correct. Each shareholder
and, if applicable, each other payee should complete and sign the substitute
Form W-9 included as part of the transmittal letter that accompanies the
election form, so as to provide the information and certification necessary to
avoid backup withholding, unless an applicable exemption exists and is
established in a manner satisfactory to the exchange agent.

     RESALE OF M&T COMMON STOCK

     The M&T common stock issued pursuant to the merger will be freely
transferable under the Securities Act of 1933, except for shares issued to any
Keystone shareholder who may be deemed to be an affiliate of M&T for purposes of
Rule 144 promulgated under the Securities Act of 1933 or who may

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be deemed an affiliate of Keystone for purposes of Rule 145 promulgated under
the Securities Act of 1933 (each an "affiliate"). affiliates will include
persons (generally executive officers, directors and 10% or greater
shareholders) who control, are controlled by or are under common control with
(i) M&T or Keystone at the time of the special meeting or (ii) M&T on or after
the effective date.

     Rules 144 and 145 will restrict the sale of M&T common stock received in
the merger by affiliates and certain of their family members and related
interests. Generally speaking, during the 12 months following the effective
date, those persons who are affiliates of Keystone at the time of the special
meeting (provided they are not affiliates of M&T on or following the effective
date) may publicly resell any M&T common stock received by them in the merger,
subject to certain limitations as to, among other things, the amount of M&T
common stock sold by them in any three-month period and as to the manner of
sale. After such one-year period, such affiliates may resell their M&T common
stock received in the merger without such restrictions so long as there is
adequate current public information with respect to M&T as required by Rule 144.
Persons who are affiliates of M&T after the Effective Date may publicly resell
the M&T common stock received by them in the merger, subject to similar
limitations and to certain filing requirements specified in Rule 144.

     The ability of affiliates to resell shares of M&T common stock received in
the merger under Rule 144 or 145 as summarized in this document generally will
be subject to M&T's having satisfied its Securities Exchange Act of 1934
reporting requirements for specified periods prior to the time of sale.
affiliates also would be permitted to resell M&T common stock received in the
merger pursuant to an effective registration statement under the Securities Act
of 1933 or another available exemption from the Securities Act of 1933
registration requirements. This document does not cover any resales of M&T
common stock received in the merger by persons who may be deemed to be
affiliates of M&T or Keystone and M&T has not contractually undertaken to
register any such shares for resale.

ACCOUNTING TREATMENT OF THE MERGER

     The merger will be accounted for as a purchase transaction under GAAP. This
means that, for financial accounting purposes, M&T will treat the two companies
as one company beginning as of the date of the combination. Under this method of
accounting, M&T will record the fair market value of Keystone's assets and
liabilities on its financial statements. The difference between the purchase
price of the merger and the fair market value of Keystone's identifiable assets
net of its liabilities will be recorded on M&T's books as "goodwill."
Approximately $609 million in goodwill and core deposit intangible assets will
result from accounting for the merger under the purchase method of accounting.
The $609 million for goodwill and core deposit intangible assets will be
amortized over periods of up to 20 years as charges to M&T's earnings.

STOCK OPTION AGREEMENT

     THE SUMMARY INFORMATION BELOW CONCERNING THE MATERIAL TERMS OF THE STOCK
OPTION AGREEMENT IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO THE FULL TEXT OF
SUCH AGREEMENT, WHICH IS ATTACHED TO THIS DOCUMENT AS APPENDIX B.

     The Stock Option Agreement provides for the grant by Keystone to M&T of an
unconditional irrevocable option to purchase up to 9,730,070 shares (such number
subject to adjustment upon changes in capitalization or in certain other
circumstances) of Keystone common stock, at an exercise price of $15.125 per
share (the "option").

     The purpose of the option is to increase the likelihood that the merger
will be completed by making it more difficult and more expensive for a third
party to gain control of Keystone. Accordingly, the option is exercisable only
on the occurrence of certain events that generally involve the acquisition

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or attempted acquisition by a third party of Keystone, a significant portion of
the then-issued and outstanding Keystone common stock or all or a significant
portion of Keystone's assets. Upon the occurrence of certain triggering events
in connection with an acquisition or attempted acquisition, M&T can compel
Keystone to repurchase the option for cash. This would have the effect of
disqualifying the other acquisition from the use of the pooling-of-interests
method of accounting, even if that method would otherwise have been available.

     Although the shares issuable upon exercise of the option represent
approximately 16.6% of the Keystone common stock that would be outstanding after
such exercise (or 19.9% without giving effect to the exercise), M&T may not
acquire more than 5% of the stock of Keystone, pursuant to the exercise of the
option or otherwise, without prior approval of the Federal Reserve. M&T has not
yet received such approval, but intends to request such approval in its
application to the Federal Reserve to acquire control of Keystone. Unless and
until the option is exercised, M&T disclaims beneficial ownership of the
Keystone common stock subject to the option.

DISSENTERS' RIGHTS OF KEYSTONE SHAREHOLDERS

     Pursuant to Sections 1930 and 1571 to 1580 (Subchapter D of Chapter 15) of
the Pennsylvania Business Corporation Law ("PBCL"), if you, as a holder of
Keystone common stock, do not wish to accept the merger consideration, you may
dissent from the merger and elect to have the fair value of your shares of
Keystone common stock, as determined under Sections 1571 to 1580 of the PBCL,
and paid in cash to you, provided that you comply with the procedural
requirements set forth in the PBCL.

     If you are contemplating making demand for the fair value of your Keystone
common stock, you are urged to review carefully the provisions of Sections 1571
to 1580 of the PBCL, particularly the procedural steps required to perfect your
dissenters' rights. Sections 1571 to 1580 are set forth in Appendix E to this
document. YOUR DISSENTERS' RIGHTS WILL BE LOST IF THE PROCEDURAL REQUIREMENTS OF
SECTIONS 1571 TO 1580 OF THE PBCL ARE NOT FULLY AND PRECISELY SATISFIED. THE
FOLLOWING SUMMARY DOES NOT PURPORT TO BE A COMPLETE STATEMENT OF THE PROVISIONS
OF SECTIONS 1571 TO 1580 OF THE PBCL AND IS QUALIFIED IN ITS ENTIRETY BY
REFERENCE TO APPENDIX E.

     FILING NOTICE OF INTENTION TO DEMAND FAIR VALUE

     If you wish to dissent from the merger, you must deliver to Keystone,
before the vote of Keystone shareholders is taken on the merger, a written
notice of intention to demand that you be paid the fair value of your shares if
the merger is completed. Such written notice may be sent to the Secretary of
Keystone at the address of Keystone set forth on the first page of this
document. Neither the return of a proxy by you with instructions to vote your
shares against the merger, nor a vote against the merger, is sufficient to
satisfy the requirement of delivering a written notice to Keystone. In addition,
you must not change beneficial ownership of your shares from the date of filing
the notice with Keystone through the effective date and shares for which payment
of fair value is sought must not be voted in favor of the merger. The submission
of a signed blank proxy will serve to waive dissenters' rights if not revoked,
but a failure to vote will not waive your rights to dissent. Proper revocation
of a signed blank proxy or a signed proxy instructing a vote for approval and
adoption of the merger will also preserve dissenters' rights under the PBCL.
FAILURE TO COMPLY WITH ANY OF THE FOREGOING WILL RESULT IN THE FORFEITURE OF ANY
RIGHT TO PAYMENT OF FAIR VALUE FOR YOUR SHARES UNDER THE PBCL, AND YOUR SHARES
WILL BE CONVERTED INTO THE MERGER CONSIDERATION IN THE MANNER DESCRIBED IN THIS
DOCUMENT.

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     RECORD AND BENEFICIAL OWNERS

     If you are a record holder of shares, you may assert your dissenters'
rights as to fewer than all of the shares of Keystone common stock registered in
your name only if you dissent with respect to all the shares of Keystone common
stock beneficially owned by any one person and disclose the name and address of
the person or persons on whose behalf you dissent. If you are a beneficial owner
of shares who is not the record holder, you may assert your dissenters' rights
with respect to shares held on your behalf if you submit to Keystone the written
consent of the record holder not later than the time of assertion of dissenters'
rights. If you are a beneficial owner, you may not dissent with respect to less
than all of the shares of Keystone common stock owned by you, whether or not
such shares are registered in your name.

     NOTICE TO DEMAND PAYMENT

     If the merger is approved at the Keystone special meeting, Keystone will
mail to all dissenters who gave due notice of their intention to demand payment
of fair value and who refrained from voting in favor of the merger, a notice
stating where and when a demand for payment must be sent and certificates for
shares deposited in order to obtain payment. The notice will be accompanied by a
copy of Sections 1571 to 1580 and a form for demanding payment. This form will
include a request for certification of the date that beneficial ownership of the
dissenting shares was acquired by the shareholder or the person on whose behalf
the shareholder dissents. The time set for the receipt of demands and the
deposit of certificates will not be less than 30 days from the mailing of the
notice. Failure by you as a dissenting shareholder to timely demand payment or
timely deposit certificates pursuant to such notice will cause you to lose all
right to receive payment of the fair value of your shares. If the merger has not
been completed within sixty (60) days after the date set for demanding payment
and depositing certificates, Keystone will return any certificates that have
been deposited. Keystone, however, may at any later time send a new notice
regarding demand for payment and deposit of certificates.

     PAYMENT OF FAIR VALUE OF SHARES

     Promptly after the effective date, or upon timely receipt of demand for
payment if the merger has already been completed, Keystone will either remit to
dissenters who have made demand and deposited their Certificates the amount
Keystone estimates to be the fair value of their shares or give written notice
that no remittance will be made under Section 1577. Such remittance or notice
will be accompanied by (i) the closing balance sheet and statement of income of
Keystone for a fiscal year ending not more than 16 months prior to the date of
the remittance or notice together with the latest available interim financial
statements, (ii) a statement of Keystone's estimate of the fair value of the
shares, and (iii) a notice of the right of the dissenting shareholder to demand
payment or supplemental payment, as the case may be, accompanied by a copy of
Section 1571 to 1580. If Keystone does not remit the amount of its estimate of
the fair value of the shares it will return all certificates that have been
deposited and may make a notation on them that a demand for payment has been
made.

     ESTIMATE BY YOU OF FAIR VALUE OF SHARES

     If you, as a dissenting shareholder, believe that the amount estimated or
paid by Keystone for your shares is less than their fair value, you may send to
Keystone your own estimate of the fair value which will be deemed a demand for
payment of the amount or the deficiency. If Keystone gives notice of its
estimate of the fair value of the shares without remitting such amount, or has
remitted payment of its estimated value of the shares and you do not file your
own estimate of fair value within 30 days after

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the mailing of such notice or remittance, you will be entitled to no more than
the amount stated in the notice or remitted to you by Keystone.

     VALUATION PROCEEDINGS

     Within 60 days after the latest of (i) the effective date, (ii) timely
receipt of any demands for payment, and (iii) timely receipt of any shareholder
estimates of fair value, if any demands for payment remain unsettled, Keystone
may file in court an application for relief requesting that the fair value of
the shares be determined by the court. If your demands have not been settled,
you will be made a party to the proceeding and will be entitled to recover the
amount by which the fair value of your shares is found to exceed the amount, if
any, previously remitted. You, as a dissenter, will also be entitled to interest
on such amount from the effective date until the date of payment as is fair and
equitable under the circumstances, taking into account all relevant factors
including the average rate currently paid by Keystone on its principal bank
loans. If Keystone fails to file an application within the 60-day period and you
have not settled your claim, you may file an application in Keystone's name
within 30 days after the expiration of the 60-day period. If no dissenter files
an application within such 30-day period and you have not settled your claim,
you will be paid no more than Keystone's estimate of the fair value of your
shares and may bring an action to recover any amount not previously remitted.

     COSTS AND EXPENSES OF VALUATION PROCEEDINGS

     The costs and expenses of any valuation proceedings, including the
reasonable compensation and expenses of any appraiser appointed by the court,
will be determined by the court and assessed against Keystone except that any
part of such costs and expenses may be assessed as the court deems appropriate
against all or some of the dissenters whose action in demanding supplemental
payment is found by the court to be dilatory, obdurate, arbitrary, vexatious or
in bad faith. The court may also assess the fees and expenses of counsel and
experts for any or all of the dissenters against Keystone if Keystone fails to
comply substantially with Sections 1571 to 1580 or acts in bad faith or in a
dilatory, obdurate, arbitrary or vexatious manner. The court can also assess any
such fees or expenses incurred by Keystone against a dissenter if the dissenter
is found to have acted in bad faith or in a dilatory, obdurate, arbitrary or
vexatious manner. If the court finds that the services of counsel for any
dissenter were of substantial benefit to the other dissenters and should not be
assessed against Keystone, it may award to such counsel reasonable fees to be
paid out of the amounts awarded to the dissenters who were benefited.

     OTHER

     You should be aware that certain courts have disagreed as to whether
dissenters' rights are the exclusive remedy available to a shareholder who is
opposed to a corporate transaction, such as the merger. You should note that
Section 1572 of the PBCL defines "fair value" as: The fair value of shares
immediately before the effectuation of the corporate action to which the
dissenter objects taking into account all relevant factors, but excluding any
appreciation or depreciation in anticipation of the corporate action. In view of
the complexities of these provisions of the PBCL, if you are considering
dissenting from the merger, you should consult your own counsel.

NO DISSENTERS' RIGHTS OF M&T SHAREHOLDERS

     You, as an M&T shareholder, do not have dissenters' rights in connection
with the merger or in connection with the M&T stock split.

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                   COMPARISON OF CERTAIN RIGHTS OF HOLDERS OF
                   M&T COMMON STOCK AND KEYSTONE COMMON STOCK

     M&T is a New York corporation subject to the provisions of the New York
Business Corporation Law ("New York law"). Keystone is a Pennsylvania
corporation subject to the provisions of the PBCL. Upon consummation of the
merger, shareholders of Keystone who receive M&T common stock in exchange for
some or all of their shares of Keystone common stock in the merger, and whose
rights as such currently are governed by Keystone's Restated Articles of
Incorporation and Bylaws and the PBCL, will become shareholders of M&T, and
their rights as such will be governed by the M&T Certificate of Incorporation
and Bylaws and by New York law.

     The following is a summary of the material differences between the rights
of shareholders of M&T and Keystone. This summary does not purport to be a
complete discussion of all of the differences between the rights of shareholders
of M&T and Keystone, and the identification of certain differences is not meant
to indicate that other differences do not exist. The following summary is
qualified in its entirety by reference to the PBCL, New York law, and the
certificate or articles of incorporation and bylaws of each corporation.

AUTHORIZED COMMON STOCK

     Under its certificate of incorporation, M&T is authorized to issue
15,000,000 shares of M&T common stock, par value $5.00 per share, 7,653,915
shares of which were issued and outstanding and 447,674 shares of which were
held in treasury as of July 27, 2000. In connection with the 10-for-1 stock
split M&T has agreed to effect prior to completing the merger, M&T will, subject
to the receipt of shareholder approval, amend its certificate of incorporation
to provide for the authority to issue up to 150 million shares of common stock.
Keystone is authorized by its restated articles of incorporation to issue
100,000,000 shares of Keystone common stock, par value $2.00 per share,
48,930,000 shares of which were issued and outstanding as of May 16, 2000. Both
the M&T and Keystone boards may, subject to applicable law and rules of the NYSE
and the Nasdaq Market (and, in the case of Keystone, the merger agreement),
approve the issuance of additional shares of authorized common stock at such
times, for such purposes, and for such consideration as they may deem advisable
without further shareholder approval.

ISSUANCE OF AUTHORIZED PREFERRED STOCK

     Under its certificate of incorporation, M&T is authorized to issue, without
shareholder approval, up to 1,000,000 shares of preferred stock, par value $1.00
per share, none of which is issued and outstanding. Keystone is authorized under
its restated articles of incorporation to issue in one or more series and,
without shareholder approval, up to 8,000,000 shares of preferred stock, par
value $1.00 per share, none of which is issued and outstanding. Both the M&T and
Keystone boards may, subject to applicable law and rules of their respective
exchanges, approve the issuance of shares of authorized preferred stock at such
times, for such purposes, and for such consideration as they may deem advisable,
without further shareholder approval. The ability of M&T and Keystone to issue
shares of preferred stock up to the prescribed amounts in its respective
articles or certificate of incorporation could have a possible anti-takeover
effect.

AMENDMENT OF CHARTER

     Under New York law, a corporation may amend its certificate of
incorporation, if the amendment contains only provisions that could be lawfully
contained in a certificate of incorporation. An amendment or change of the
certificate of incorporation may be authorized by a vote of the board,

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<PAGE>   68

followed by a vote of the holders of a majority of all outstanding shares
entitled to vote thereon at a meeting of shareholders.

     Under New York law, a proposed amendment must also be authorized by a vote
of the holders of a majority of all outstanding shares of the affected class or
series when it would:

     - exclude or limit their right to vote on any matter;

     - reduce par value, change the number of authorized shares or fix, change
       or abolish, the designation of such class or series, or any of the
       relative rights, preferences, limitations or the conversion rights of
       such class or series; or

     - subordinate their rights by authorizing shares having preferences which
       would be superior to their rights.

     Under New York law, where any proposed amendment would adversely affect or
subordinate the rights of holders of shares of a series of any class, but not
the entire class, then only the holders of the series whose rights would be
adversely affected or subordinated would be considered a separate class for
purposes of voting on the authorization of the proposed amendment.

     Also, New York law provides that when a provision of the certificate of
incorporation requires action by a vote of a greater proportion than is required
by New York law, that provision may only be altered, amended or modified by such
greater vote.

     Under New York law, an amendment to the certificate of incorporation does
not require the approval of the shareholders if shares have not been issued or
if the amendment only:

     - changes the location of the corporation's office;

     - changes the address of the corporation's designated office for service of
       process; or

     - makes, revokes or changes the designation of the corporation's registered
       agent, or specifies or changes the address of the corporation's
       registered agent.

     The M&T certificate of incorporation does not vary from the statutory
provisions.

     Keystone's restated articles of incorporation require the votes of the
holders of (1) 75% of the voting power of all outstanding voting stock of
Keystone and (2) a majority of the voting power of the voting stock not
beneficially owned by an interested shareholder to approve any amendment to
Keystone's restated articles of incorporation or bylaws. The special voting
requirement does not apply to any amendment approved by a majority of the
disinterested directors if at the time of the such approval the disinterested
directors constitute a majority of the Keystone board. Except as required by the
PBCL, Keystone's board may also amend the bylaws without shareholder approval by
a vote including a majority of the disinterested directors then in office.

ANNUAL AND SPECIAL MEETINGS OF SHAREHOLDERS

     M&T's bylaws provide that the chief executive officer or the M&T board may
call special meetings, and that such a special meeting must be called if
requested in writing by the holders of at least 25% of the outstanding shares.
Written notice of every special and annual meeting of shareholders must be given
either personally or by mail to each shareholder at least 10 and not more than
60 days prior to the meeting, stating the place, date, and hour of the meeting,
the purpose for which the meeting is called, and, other than the annual meeting,
by whom it is being called.

     Keystone's bylaws provide that only the Chairman of the Keystone board, the
President or the Keystone board may call special meetings. Written notice of the
date, place, and hour of every annual

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and special meeting must be given either in person or by mail to each
shareholder at least 10 days prior to such meetings. No business may be
transacted at any special meeting other than that stated in the notice of the
meeting and business that is relevant to such stated business.

BOARD OF DIRECTORS

     Under New York law, a corporation may have one or more directors on its
board. The bylaws or the shareholders may fix the number of directors. The board
of directors may determine the number of directors if specifically permitted by
a shareholder-adopted bylaw.

     Like New York, the PBCL allows a corporation to have one or more directors
on its board. Under the PBCL, the bylaws or articles of incorporation govern the
size of the board. If neither the articles of incorporation nor the bylaws
provide for the size of the board, the PBCL fixes the number of directors on the
board at three.

     The bylaws of M&T require that the M&T board consist of a minimum of three
directors, the exact number to be fixed by the shareholders or the vote of a
majority of the board. The M&T board is currently comprised of 21 directors.
Prior to the merger, M&T will increase the size of its board to 26 directors to
accommodate the election of Mr. Campbell and the other four Keystone designees
as directors of M&T. The restated articles of incorporation of Keystone provide
that the number of directors will be fixed by vote reflecting a majority of the
disinterested directors (as defined under "-- Vacancies on the Board of
Directors" below) on the Keystone board. Under the Keystone bylaws, the number
of directors will not be less than five or more than 25. The Keystone board is
currently comprised of 18 directors.

CLASSIFICATION OF THE BOARD OF DIRECTORS

     New York law provides that a corporation's certificate of incorporation or
a shareholder-adopted bylaw may provide that the directors be divided into two,
three or four classes. All classes must be as nearly equal in number as
possible. M&T's board of directors is not classified. The directors must be
elected at each annual meeting of M&T shareholders.

     The PBCL provides that, unless otherwise specified in the articles of
incorporation, a corporation's board of directors may be divided into various
classes with staggered terms of office. All classes must be nearly equal in
number as possible, the terms of office of at least one class must expire in
each year and the members of a class may not be elected for a period longer than
four years. If the directors are to be otherwise classified, the classification
must be done in the articles of incorporation. Keystone's board of directors is
divided into three classes, each consisting of one-third (or near as may be) of
the whole number of the board of directors. One class of directors is elected at
each annual meeting of Keystone shareholders, and each class serves a term of
three years.

VACANCIES ON THE BOARD OF DIRECTORS

     New York law provides that newly created directorships resulting from an
increase in the number of directors and vacancies occurring on the board for any
reason, except the removal of directors without cause, may be filled by the vote
of the board, and if the number of directors remaining in office is less than a
quorum, by the vote of a majority of the directors then in office. The
certificate of incorporation or the bylaws may provide that such newly created
directorships or vacancies must be filled by the vote of shareholders and the
certificate of incorporation may impose greater requirements relating to the
quorum and vote of directors needed to fill such newly created directorships or
vacancies. Unless the certificate of incorporation or the specific provisions of
the bylaws adopted by the shareholders provide

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otherwise, vacancies occurring on the board by reason of the removal of
directors without cause may not be filled by the board of directors and may only
be filled by the shareholders.

     M&T's bylaws provide that newly created directorships resulting from an
increase in the number of directors and vacancies occurring for any reason other
than removal may be filled by the majority vote of the then remaining directors,
although less than a quorum exists. Any vacancy attributable to removal by the
shareholders may be filled by the vote of the shareholders at the meeting at
which the removal action is taken or at any special meeting notice of which
referred to the proposed election. Any newly created directorship or vacancy not
filled prior to the annual shareholders meeting is to be filled at the next
annual shareholders meeting. Any director elected to fill a vacancy will hold
office for the unexpired term of his or her predecessor.

     Keystone's restated articles of incorporation provide that any vacancies on
the Keystone board or newly created directorships will be filled by the majority
vote of the then remaining disinterested directors then in office, though less
than a quorum. Such newly elected directors will hold office for the full
remainder of the term of the class to which they have been elected. A
"disinterested director" is any member of the Keystone board of directors who is
not a 20% shareholder or an affiliate, associate or representative of a 20%
shareholder, and who was a director before the 20% shareholder became such or is
a successor to a disinterested director and was recommended for election by a
majority of disinterested directors then on the board.

REMOVAL OF DIRECTORS

     New York law provides that any or all of the directors may be removed for
cause by a vote of the shareholders, and, if the certificate of incorporation or
the specific provision of a bylaw adopted by the shareholders provides,
directors may be removed for cause by action of the board of directors or
without cause by the vote of the shareholders. Pursuant to M&T's bylaws, any
director may be removed for cause by the shareholders holding the majority of
the votes cast at any shareholders meeting, notice of which referred to the
proposed removal, or by three-fourths vote of the M&T board at any M&T board
meeting where the notice of the meeting referred to the proposed action. M&T's
bylaws further provide that any director may be removed without cause by
majority vote of the shares entitled to vote at any shareholders meeting notice
of which referred to the proposed removal. Keystone's restated articles of
incorporation provide that a director, any class of directors or the entire
Keystone board may be removed from office by shareholder vote only for cause and
only if, in addition to any other vote required by law, such removal is approved
by a majority of the voting power of the outstanding voting stock of Keystone
that is not beneficially owned by a 20% shareholder.

DIRECTOR NOMINATIONS AND PROPOSALS FOR BUSINESS

     New York law does not contain any provision establishing procedures that
must be followed in order for a shareholder to nominate directors or propose
items of business at any annual or special shareholders meeting. The M&T bylaws
provide that the deadline for proposals to be included in M&T's proxy statement
for its annual meetings or for proposals to be presented at a shareholder's
meeting is 120 days prior to the day of the month on which M&T first mailed its
proxy materials for the prior year's annual meeting. For other shareholder
meetings or annual meetings held on a date that is more than 30 days from the
date of the proceeding year's annual meeting, the deadline for submission of
shareholder proposals is the close of business on the tenth day following the
date public disclosure of the date of such meeting is first made. Keystone's
restated articles of incorporation require that any shareholder intending to
nominate a candidate for election as a director must give the corporation
advance written notice of the nomination, containing certain specified
information. Keystone's restated articles of incorporation require that the
notice be given not later than 120 days in advance of the

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meeting at which the election is to be held. In order to propose business at the
annual meeting of Keystone shareholders, Keystone's bylaws provide that a
Keystone shareholder must give notice that is received at Keystone's principal
executive offices not less than 120 days before the date of the proxy statement
released to the shareholders in connection with the previous year's annual
meeting. For special meetings of Keystone shareholders, Keystone's bylaws
provide that the only business that will be conducted is the business stated in
Keystone's notice of the meeting and other matters germane to that business.

SHAREHOLDER ELECTION OF DIRECTORS AND OTHER CORPORATE ACTION

     Generally, M&T's and Keystone's directors are elected by plurality vote,
whereas all other corporate actions taken by shareholder vote are to be by
majority of the votes cast, except as otherwise provided by law, in the
certificate of incorporation, or in the bylaws. M&T's bylaws further provide
that, unless the person presiding at such meeting or any shareholder so demands,
voting will not be by ballot. Keystone's restated articles of incorporation
contain provisions requiring special shareholder votes to approve certain types
of transactions. In the absence of these provisions, either no shareholder vote
would be required or the PBCL would require approval of the transaction by a
majority of the shares of Keystone common stock voted at a meeting.

INDEMNIFICATION

     Under New York law, a corporation may indemnify any person made, or
threatened to be made, a party to any action or proceeding except for
shareholder derivative suits, by reason of the fact that he or she was a
director or officer of the corporation, provided such director or officer acted
in good faith for a purpose which he or she reasonably believed to be in the
best interests of the corporation and, in criminal proceedings, in addition, had
no reasonable cause to believe his or her conduct was unlawful. In the case of
shareholder derivative suits, the corporation may indemnify any person who was a
director or officer of the corporation if he or she acted in good faith for a
purpose which he or she reasonably believed to be in the best interests of the
corporation, except that no indemnification may be made for (i) a threatened
action, or a pending action which is settled or otherwise disposed of, or (ii)
any claim, issue or matter as to which such person had been adjudged to be
liable to the corporation, unless and only to the extent that the court in which
the action was brought or, if no action was brought, any court of competent
jurisdiction, determines upon application that, in view of all circumstances the
person is fairly and reasonably entitled to indemnity for such portion of the
settlement amount and expenses as the court deems proper.

     Indemnification under New York law is not exclusive of other
indemnification rights to which a director or officer may be entitled, whether
contained in the certificate of incorporation or bylaws, or, when authorized by
such certificate of incorporation or bylaws, (i) a resolution of shareholders or
directors, or (ii) an agreement providing for such indemnification, provided
that no indemnification may be made to or on behalf of any director or officer
if a judgment or other final adjudication adverse to the director or officer
establishes that his or her acts were committed in bad faith or were the result
of active and deliberate dishonesty and were material to the cause of action so
adjudicated, or that he or she personally gained a financial profit or other
advantage to which he or she was not legally entitled. The M&T bylaws provide
that M&T will indemnify to the maximum extent permissible under New York law its
directors and officers, and any person whose testator or intestate was such a
director or officer; provided, however, that M&T will provide indemnification in
connection with an action or proceeding (or part thereof) initiated by such
director or officer only if such action or proceeding (or part thereof) was
authorized by the M&T board.

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     Under New York law, any person to whom such provisions in New York law
regarding indemnification apply who has been successful on the merits or
otherwise in the defense of a civil or criminal action or proceeding is entitled
to indemnification. Except as provided in the preceding sentence, unless ordered
by a court pursuant to New York law, indemnification under New York law, the
certificate of incorporation, the bylaws, any resolution of shareholders or
directors, or any agreement pursuant to the above paragraphs, may be made only
if authorized in the specific case and after a finding that the director or
officer met the requisite standard of conduct (i) by the board acting by a
quorum of disinterested directors or (ii) if such quorum is not available, or
even if available, if so directed by a quorum of disinterested directors by
either (A) the board upon the written opinion of counsel or (B) by the
shareholders.

BUSINESS COMBINATIONS WITH INTERESTED SHAREHOLDERS

     Keystone is subject to provisions of the PBCL prohibiting "business
combination" transactions with a person that becomes a "beneficial owner" of
shares representing 20% or more of the voting power in an election of directors
of Keystone unless (1) the business combination or the acquisition of the 20%
interest is approved by the board of Keystone prior to the date the 20% interest
is acquired, (2) the person beneficially owns at least 80% of the outstanding
shares and the business combination (a) is approved by a majority vote of the
disinterested shareholders and (b) satisfies certain minimum price and other
conditions prescribed in the PBCL, (3) the business combination is approved by a
majority vote of the disinterested shareholders at a meeting called no earlier
than five years after the date the 20% interest is acquired or (4) the business
combination (a) is approved by shareholder vote at a meeting called no earlier
than five years after the date the 20% interest is acquired and (b) satisfies
certain minimum price and other conditions prescribed in the PBCL.

     New York law contains provisions governing "business combinations" with
"interested shareholders" (as those terms are defined in the law). Under these
provisions, a New York corporation may not engage in a business combination with
an interested shareholder for a period of five years after the interested
shareholder became an interested shareholder, unless the business combination or
the purchase of stock by the interested shareholder causing the shareholder to
become an interested shareholder was approved in advance by the board of
directors. Other business combinations with an interested shareholder are
prohibited at any time, unless certain requirements are met. As permitted by
Section 912 of New York law, M&T has expressly elected in its bylaws not to be
governed by the provisions of New York law governing business combinations with
interested shareholders.

     Keystone's restated articles of incorporation require that certain
transactions between Keystone and "interested shareholder" be approved by the
votes of the holders of (1) 75% of the voting power of all outstanding voting
shares of Keystone and (2) a majority of the voting power of the voting shares
not beneficially owned by the interested shareholder. An "interested
shareholder" is generally defined by Keystone's restated articles of
incorporation as a person or a group acting in concert that beneficially owns
more than 20% of the voting power of Keystone's outstanding voting shares. The
transactions subject to Keystone's special vote requirements include mergers,
consolidations or share exchanges of Keystone with an interested shareholder.
The special voting requirements do not apply to any transaction approved by a
majority of the disinterested directors.

PENNSYLVANIA "CONTROL TRANSACTIONS" STATUTE

     Subchapter 25E of the PBCL (relating to "control transactions") provides
that if any person, or group acting in concert acquires 20% or more of the
voting power of a covered corporation, the remaining stockholders may demand
from that person or group the fair value of their shares, including a

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proportionate amount of any control premium. Keystone is subject to Subchapter
25E of the PBCL. There is no comparable provision in New York law.

STATUTORY PROVISIONS RELATING TO FIDUCIARY DUTIES OF DIRECTORS IN TAKEOVERS

     The PBCL contains a number of detailed provisions delineating the fiduciary
duties of the board of a Pennsylvania corporation, such as Keystone, in the
takeover context. The fiduciary duty standards applicable to the Keystone board
under the PBCL:

- explicitly give the Keystone board the authority to weigh, in addition to
  consideration of employees, suppliers, customers and creditors of Keystone,
  the communities in which Keystone is located and other pertinent factors) the
  short- and long-term interests of Keystone and the possibility that they may
  be best served by the independence of the corporation, and the resources,
  intent and past and potential conduct of a potential acquiror;

- do not require the Keystone board to regard shareholder interests as dominant
  or controlling;

- explicitly give the Keystone board the discretion to refuse to redeem a
  stockholder rights plan or to refuse to take certain specified actions
  relating to potential acquisitions of control of the corporation;

- declare actions by directors with respect to a takeover bid to be subject to
  the same standard of conduct for directors that is applicable to all other
  conduct; and

- establish a presumption that actions relating to a takeover bid by the
  "disinterested directors" (essentially, all directors except certain Keystone
  officers and persons associated with a potential acquiror) are lawful unless
  it is proved under a clear and convincing evidence standard that the director
  did not act in good faith after reasonable investigation.

     New York law does not contain comparable statutory provisions, and, under
current New York law, the principal guidance as to the fiduciary obligations of
directors in specific situations, including in the takeover context, is found in
judicial decisions interpreting New York law.

DISSENTER'S APPRAISAL RIGHTS

     In the case of Keystone, the PBCL generally provides dissentor's rights to
shareholders with respect to:

- mergers, consolidations, divisions, conversions and certain share exchanges
  that would require shareholder approval,

- sales of all or substantially all of the assets,

- amendments or plans containing a provision for special treatment of certain
shareholders, and

- any corporate action taken pursuant to a shareholder vote to the extent the
  articles of incorporation, bylaws or a resolution of the board of directors
  entitles stockholders to dissent.

     Generally, under the PBCL, a shareholder opposing a plan will not have
dissenters' rights if the shares of the corporation are listed on a national
securities exchange or are held of record by more than 2,000 stockholders. This
exception will not apply, however, in situations where the plan of merger does
not provide that shares will be converted solely into shares of the acquiring,
surviving, new or other corporation, or solely into such shares and money in
lieu of fractional shares. Also, in the case of certain corporations like
Keystone that are "registered corporations" under the PBCL, dissenter's rights
are not available under the PBCL where the corporation transfers all or
substantially all of its assets outside of the ordinary course under a plan of
transfer.

                                       69
<PAGE>   74

     In addition, Subchapter 25E of the PBCL provides for certain
quasi-appraisal rights, under particular circumstances, upon specified
acquisitions of 20% or more of a corporation's voting shares.

     Under New York law, dissenters rights are available to shareholders
entitled to vote on

- a plan of merger or consolidation to which the corporation is a party

- with limited exceptions, a disposition of all or substantially all of the
  corporation's assets that requires shareholder approval under New York law

- a share exchange

and are also available in certain mergers, consolidations and share exchanges
where the shareholder is not entitled to vote on the transaction. However, under
New York law, a shareholder entitled to vote on a merger is not entitled to
appraisal rights if the shares of the New York corporation are listed on
national securities exchange or quoted on Nasdaq, without regard for the type of
consideration into which those shares are to be converted in the merger.

                                       70
<PAGE>   75

                                   PRO FORMA
                    CONDENSED COMBINED FINANCIAL INFORMATION
                                  (UNAUDITED)

     The following unaudited Pro Forma Condensed Combined Financial Information
and explanatory notes are presented to show you the pro forma impact of the
merger on the historical financial position and results of operations of M&T.

     In accordance with the merger agreement, each share of Keystone's common
stock will be converted in the merger into the right to receive, at your
election as a holder of Keystone common stock, but subject to the election and
allocation procedures set forth in the merger agreement, either 0.05 of a share
of M&T common stock or $21.50 in cash. The merger agreement provides that a
number of shares of Keystone common stock equal to 65%, of the shares of
Keystone common stock outstanding as of May 16, 2000 (or 31,804,500), are to be
exchanged for 1,590,225 shares of M&T common stock (subject to adjustment under
certain circumstances). See "THE MERGER -- Terms of the Merger." In addition,
the number of shares of Keystone common stock used in calculating the total
market value of M&T common stock to be issued in connection with the merger
reflects an exchange of M&T common stock for 65% of the outstanding shares of
Keystone common stock outstanding on that date.

     The unaudited Pro Forma Condensed Combined Financial Information reflects
the merger using the purchase method of accounting. The cash component of the
merger consideration is expected to be funded by the liquidation of investment
securities and the issuance of subordinated debentures.

     The unaudited Pro Forma Condensed Combined Financial Information assumes
that the merger was completed on the dates or at the beginning of the periods
indicated. Certain amounts in Keystone's historical financial information as
shown have been reclassified to conform to M&T's presentation. The unaudited Pro
Forma Condensed Combined Statements of Income reflect the consolidation of the
results of operations of M&T and Keystone for the three months ended March 31,
2000 and for the 12 months ended December 31, 1999.

     The unaudited Pro Forma Condensed Combined Financial Information reflects
the merger based on preliminary purchase accounting adjustments. Estimates
relating to the fair value of certain assets, liabilities and other items have
been made as more fully described in the Notes to the unaudited Pro Forma
Condensed Combined Financial Information. Actual adjustments, which may include
adjustments to additional assets, liabilities and other items, will be made on
the basis of appraisals and evaluations as of the effective date of the merger
and, therefore, may differ from those reflected in the unaudited Pro Forma
Condensed Combined Financial Information.

     The combined company expects to achieve substantial merger benefits
primarily through operating cost savings. The unaudited Condensed Combined
Statements of Income, which do not reflect any direct costs or potential savings
which are expected to result from the consolidation of operations of M&T and
Keystone, are not indicative of the results of future operations. No assurances
can be given with respect to the ultimate level of cost savings or other merger
synergies to be realized. See "THE MERGER -- Management and Operations After the
Merger -- Operations."

     The following information should be read in conjunction with and is
qualified in its entirety by the consolidated financial statements and
accompanying notes of M&T and Keystone included in the documents described under
"WHERE YOU CAN FIND MORE INFORMATION" and "DOCUMENTS INCORPORATED BY REFERENCE."

     The unaudited Pro Forma Condensed Combined Financial Information is
intended for information purposes and is not necessarily indicative of the
future financial position or future results of the combined company or of the
financial position or the results of operations of the combined company that
would have actually occurred had the merger been in effect as of the date or for
the periods presented.

                                       71
<PAGE>   76

                              M&T BANK CORPORATION
                   PRO FORMA CONDENSED COMBINED BALANCE SHEET
                             (DOLLARS IN THOUSANDS)
                                  (UNAUDITED)

     The following unaudited pro forma condensed combined balance sheet, as of
March 31, 2000, is presented to show the impact of the merger on M&T's
historical financial condition. The merger has been reflected under the purchase
method of accounting.

<TABLE>
<CAPTION>
                                                                   MARCH 31, 2000
                                             -----------------------------------------------------------
                                                                            PRO FORMA
                                                 M&T       KEYSTONE        ADJUSTMENTS        PRO FORMA
                                             -----------   ---------   -------------------   -----------
<S>                                          <C>           <C>         <C>       <C>         <C>
                  ASSETS
Cash and due from banks....................  $   476,969     207,764                         $   684,733
Money-market assets........................    1,238,957     172,118                           1,411,075
Investment securities......................    2,078,949   1,658,970   (18,925)  (1)(2)(3)     3,718,994
Loans and leases...........................   17,860,069   4,684,590   (29,507)  (4)          22,515,152
  Unearned discount........................     (157,406)    (32,155)                           (189,561)
  Allowance for credit losses..............     (318,595)    (60,614)                           (379,209)
                                             -----------   ---------   -------               -----------
  Loans and leases, net....................   17,384,068   4,591,821   (29,507)               21,946,382
                                             -----------   ---------   -------               -----------
Premises and equipment.....................      169,194     117,960   (14,900)  (5)             272,254
Goodwill and core deposit
  intangible...............................      638,245      53,109   555,804   (1)-(11)      1,247,158
Accrued interest and other assets..........      775,172     210,604     5,053   (6)             990,829
                                             -----------   ---------   -------               -----------
    Total assets...........................  $22,761,554   7,012,346   497,525               $30,271,425
                                             ===========   =========   =======               ===========
   LIABILITIES AND SHAREHOLDERS' EQUITY
Interest-bearing deposits..................  $13,010,656   4,339,856    (7,132)  (7)         $17,343,380
Short-term borrowings......................    3,068,547     389,410                           3,457,957
Long-term borrowings.......................    1,774,456     879,655   348,472   (2)(8)        3,002,583
                                             -----------   ---------   -------               -----------
  Interest-bearing liabilities.............   17,853,659   5,608,921   341,340                23,803,920
                                             -----------   ---------   -------               -----------
Non-interest bearing deposits..............    2,140,782     711,793                           2,852,575
Other liabilities..........................      934,857     135,281    42,532   (9)           1,112,670
                                             -----------   ---------   -------               -----------
    Total liabilities......................   20,929,298   6,455,995   383,872                27,769,165
                                             -----------   ---------   -------               -----------
Common equity..............................    1,832,256     556,351   113,653   (1)(10)       2,502,260
                                             -----------   ---------   -------               -----------
    Total shareholders' equity.............    1,832,256     556,351   113,653                 2,502,260
                                             -----------   ---------   -------               -----------
    Total liabilities and shareholders'
       equity..............................  $22,761,554   7,012,346   497,525               $30,271,425
                                             ===========   =========   =======               ===========
</TABLE>

  See accompanying Notes to Pro Forma Condensed Combined Financial Information

                                       72
<PAGE>   77

                              M&T BANK CORPORATION
                PRO FORMA CONDENSED COMBINED STATEMENT OF INCOME
                 (DOLLARS IN THOUSANDS, EXCEPT PER SHARE DATA)
                                  (UNAUDITED)

     The following unaudited pro forma condensed combined statements of income
are presented to show the impact of the merger on M&T's historical results of
operation. These statements assume that the companies had been combined during
each period presented.

<TABLE>
<CAPTION>
                                                                  FOR THE THREE MONTHS ENDED MARCH 31, 2000
                                                             ----------------------------------------------------
                                                                                       PRO FORMA
                                                               M&T      KEYSTONE      ADJUSTMENTS       PRO FORMA
                                                             --------   --------   ------------------   ---------
<S>                                                          <C>        <C>        <C>       <C>        <C>
Interest income
  Loans and leases, including fees.........................  $358,802    97,102      2,459   (12)       $458,363
  Money-market assets......................................     9,709     1,420                           11,129
  Investment securities
    Fully taxable..........................................    27,801    23,185      1,011   (13)(14)     51,997
    Exempt from federal taxes..............................     2,546     3,429                            5,975
                                                             --------   -------    -------              --------
      Total interest income................................   398,858   125,136      3,470               527,464
                                                             --------   -------    -------              --------
Interest expense
  Deposits.................................................   134,325    46,265      1,621   (15)        182,211
  Short-term borrowings....................................    39,759     4,573                           44,332
  Long-term borrowings.....................................    29,647    12,912      9,278   (16)(17)     51,837
                                                             --------   -------    -------              --------
      Total interest expense...............................   203,731    63,750     10,899               278,380
                                                             --------   -------    -------              --------
Net interest income........................................   195,127    61,386     (7,429)              249,084
Provision for credit losses................................     9,000     3,788                           12,788
                                                             --------   -------    -------              --------
Net interest income after provision for credit losses......   186,127    57,598     (7,429)              236,296
Other income
  Mortgage banking revenues................................    14,559     1,772                           16,331
  Service charges on deposit accounts......................    20,460     4,833                           25,293
  Trust income.............................................     9,980     6,705                           16,685
  Brokerage services income................................     9,408     2,019                           11,427
  Trading account and foreign exchange gains...............       294        --                              294
  Gain on sales of bank investment
    securities.............................................        --        85                               85
  Other revenues from operations...........................    17,297     8,598                           25,895
                                                             --------   -------                         --------
      Total other income...................................    71,998    24,012                           96,010
Other expense
  Salaries and employee benefits...........................    76,701    26,087                          102,788
  Equipment and net occupancy..............................    18,119    10,880                           28,999
  Printing, postage and supplies...........................     4,494     1,986                            6,480
  Amortization of goodwill and core deposit intangible.....    14,407     1,039     11,948   (18)         27,394
  Other costs of operations................................    36,876    14,503        316   (19)         51,695
                                                             --------   -------    -------              --------
      Total other expense..................................   150,597    54,495     12,264               217,356
                                                             --------   -------    -------              --------
Income before income taxes.................................   107,528    27,115    (19,693)              114,950
Income taxes...............................................    39,293     7,260     (5,458)  (20)         41,095
                                                             --------   -------    -------              --------
Net income.................................................  $ 68,235    19,855    (14,235)             $ 73,855
                                                             ========   =======    =======              ========
Net income per common share (21)
  Basic....................................................  $   8.85      0.41                         $   7.94
  Diluted..................................................      8.61      0.41                         $   7.76
  Adjusted basic (22)......................................      0.88      0.41                             0.79
  Adjusted diluted (22)....................................      0.86      0.41                             0.78
</TABLE>

  See accompanying Notes to Pro Forma Condensed Combined Financial Information

                                       73
<PAGE>   78

                              M&T BANK CORPORATION
                PRO FORMA CONDENSED COMBINED STATEMENT OF INCOME
                  (DOLLARS IN THOUSANDS EXCEPT PER SHARE DATA)
                                  (UNAUDITED)

<TABLE>
<CAPTION>
                                                                     FOR THE TWELVE MONTHS ENDED DECEMBER 31, 1999
                                                       --------------------------------------------------------------------------
                                                                                   PRO FORMA
                                                          M&T       KEYSTONE      ADJUSTMENTS                 PRO FORMA
                                                       ----------   --------   ------------------   -----------------------------
<S>                                                    <C>          <C>        <C>       <C>        <C>
Interest income
  Loans and leases, including fees...................  $1,323,262   379,538      9,836   (12)                $1,712,636
  Money-market assets................................      27,731     5,031                                      32,762
  Investment securities
    Fully taxable....................................     118,741    89,357      4,042   (13)(14)               212,140
    Exempt from federal taxes........................       8,897    12,105                                      21,002
                                                       ----------   -------    -------                       ----------
      Total interest income..........................   1,478,631   486,031     13,878                        1,978,540
                                                       ----------   -------    -------                       ----------
Interest expense
  Deposits...........................................     506,476   173,942      6,484   (15)                   686,902
  Short-term borrowings..............................     104,911    15,844                                     120,755
  Long-term borrowings...............................     107,847    38,872     37,112   (16)(17)               183,831
                                                       ----------   -------    -------                       ----------
      Total interest expense.........................     719,234   228,658     43,596                          991,488
                                                       ----------   -------    -------                       ----------
Net interest income..................................     759,397   257,373    (29,718)                         987,052
Provision for credit losses..........................      44,500    23,376                                      67,876
                                                       ----------   -------    -------                       ----------
Net interest income after provision for credit
  losses.............................................     714,897   233,997    (29,718)                         919,176
Other income
  Mortgage banking revenues..........................      71,819    12,765                                      84,584
  Service charges on deposit accounts................      73,612    19,173                                      92,785
  Trust income.......................................      40,751    26,422                                      67,173
  Brokerage services income..........................      27,140     8,158                                      35,298
  Trading account and foreign exchange gains.........         315        --                                         315
  Gain (loss) on sales of bank investment
    securities.......................................       1,575      (338)                                      1,237
  Other revenues from operations.....................      67,163    39,469                                     106,632
                                                       ----------   -------                                  ----------
      Total other income.............................     282,375   105,649                                     388,024
Other expense
  Salaries and employee benefits.....................     284,822   106,850                                     391,672
  Equipment and net occupancy........................      73,131    39,272                                     112,403
  Printing, postage and supplies.....................      17,510     8,079                                      25,589
  Amortization of goodwill and core deposit
    intangible.......................................      49,715     4,324     47,790   (18)                   101,829
  School districts' settlement expense...............          --    43,658                                      43,658
  Special charges....................................          --    26,917                                      26,917
  Other costs of operations..........................     153,780    61,878      1,263   (19)                   216,921
                                                       ----------   -------    -------                       ----------
      Total other expense............................     578,958   290,978     49,053                          918,989
                                                       ----------   -------    -------                       ----------
Income before income taxes...........................     418,314    48,668    (78,771)                         388,211
Income taxes.........................................     152,688    11,592    (21,833)  (20)                   142,447
                                                       ----------   -------    -------                       ----------
Net income...........................................  $  265,626    37,076    (56,938)                      $  245,764
                                                       ==========   =======    =======                       ==========
Net income per common share (21)
  Basic..............................................  $    34.05      0.76                                  $    26.17
  Diluted............................................       32.83      0.75                                       25.39
  Adjusted basic (22)................................        3.41      0.76                                        2.62
  Adjusted diluted (22)..............................        3.28      0.75                                        2.54
</TABLE>

  See accompanying Notes to Pro Forma Condensed Combined Financial Information

                                       74
<PAGE>   79

                             NOTES TO THE PRO FORMA
              CONDENSED COMBINED FINANCIAL INFORMATION (UNAUDITED)
                (DOLLARS IN THOUSANDS, EXCEPT PER SHARE AMOUNTS)

     The unaudited Pro Forma Condensed Combined Financial Information is based
on the following adjustments and related assumptions. The actual purchase
accounting adjustments will be made on the basis of appraisals and evaluations
as of the effective date of the merger and, therefore, may differ from those
reflected in the unaudited Pro Forma Condensed Combined Financial Information.

     A summary of the purchase accounting adjustments to record the merger used
in preparation of the unaudited Pro Forma Condensed Combined Balance Sheet is as
follows:

                              INCREASE (DECREASE)
<TABLE>
<CAPTION>
                                                PREMISES    GOODWILL AND     ACCRUED      INTEREST
        NOTE           INVESTMENT   LOANS AND      AND      CORE DEPOSIT   INTEREST AND   BEARING    LONG-TERM       OTHER
      REFERENCE        SECURITIES    LEASES     EQUIPMENT    INTANGIBLE    OTHER ASSETS   DEPOSITS   BORROWINGS   LIABILITIES
      ---------        ----------   ---------   ---------   ------------   ------------   --------   ----------   -----------
<S>                    <C>          <C>         <C>         <C>            <C>            <C>        <C>          <C>
     (1)(2)(10)         $ (3,198)                             481,851                                 365,000
         (3)             (15,727)                              15,727
         (4)                         (29,507)                  29,507
         (5)                                     (14,900)      14,900
         (6)                                                   (5,053)        5,053
         (7)                                                   (7,132)                     (7,132)
         (8)                                                  (16,528)                                (16,528)
         (9)                                                   42,532                                               42,532
                        --------     -------     -------      -------         -----        ------     -------       ------
                        $(18,925)    (29,507)    (14,900)     555,804         5,053        (7,132)    348,472       42,532

<CAPTION>

        NOTE           SHAREHOLDERS'
      REFERENCE           EQUITY
      ---------        -------------
<S>                    <C>
     (1)(2)(10)          $113,653
         (3)
         (4)
         (5)
         (6)
         (7)
         (8)
         (9)
                         --------
                         $113,653
</TABLE>

 (1) The purchase accounting adjustments to record the merger used in the
     preparation of the unaudited Pro Forma Condensed Combined Balance Sheet
     are:

<TABLE>
<CAPTION>
                                                             MARCH 31, 2000
                                                       --------------------------
                                                          CASH           STOCK         TOTAL
                                                       -----------    -----------    ----------
    <S>                                    <C>         <C>            <C>            <C>
    Keystone common stock outstanding (a)                              48,930,000
    Allocation...........................                       35%            65%
    Keystone shares exchanged............               17,125,500     31,804,500
    Exchange ratio.......................                                    0.05
    Cash consideration per share.........              $     21.50
    M&T common stock to be issued........                               1,590,225
    M&T common stock price...............                             $    415.00
                                                       -----------    -----------    ----------
                                                       $   368,198    $   659,943    $1,028,141
    Fair value of stock options..........                                                10,061
                                                                                     ----------
    Assumed total consideration..........                                            $1,038,202
    Financing of the cash consideration:
      Investment securities..............  $  3,198
      Subordinated debt..................   365,000
                                           --------
                                           $368,198
    Assumed historical net assets
      acquired (b).......................                                            $  556,351
                                                                                     ----------
    Assumed premium to allocate..........                                            $  481,851
                                                                                     ==========
</TABLE>

                                       75
<PAGE>   80

 (1) continued

<TABLE>
    <S>                                    <C>         <C>            <C>            <C>
    Adjustments to fair value of net
      assets acquired:
      Assets:
         Investment securities...........                             $   (15,727)
         Loans and leases................                                 (29,507)
         Premises and equipment..........                                 (14,900)
         Mortgage servicing rights.......                                   5,053
         Core deposit intangible.........                                 100,000
         Goodwill........................                                 455,804
      Liabilities:
         Interest-bearing deposits.......                                  (7,132)
         Long-term borrowings............                                 (16,528)
         Deferred income taxes...........                                  11,409
         Other liabilities...............                                  31,123
    Assumed adjustments to fair value of
      net assets acquired................                                            $  481,851
</TABLE>

-------------------------
     (a) For pro forma purposes, 65% of the number of Keystone's shares
         outstanding as of May 16, 2000 has been used in the calculations.
     (b) The historical net assets acquired will be determined as of the
         effective date. The historical net assets, as adjusted, for Keystone as
         of the indicated date has been used in the pro forma calculations.

 (2) The unaudited Pro Forma Condensed Combined Financial Information assumes
     the funding of the cash consideration is provided by liquidation of
     investment securities and issuance of subordinated debentures.

 (3) Reflects the preliminary estimate of the adjustment to mark investment
     securities to market.

 (4) Reflects the preliminary estimate of the adjustment to mark loans to
     market.

 (5) Reflects the preliminary estimate of the writedowns associated with
     duplicate facilities, equipment and other fixed assets of Keystone.

 (6) Reflects the preliminary estimate of the adjustment to mark mortgage
     servicing rights and other assets to fair value.

 (7) Reflects the preliminary estimate of the adjustment to mark
     interest-bearing deposits to market.

 (8) Reflects the preliminary estimate of the adjustment to mark medium term
     notes and Federal Home Loan Bank ("FHLB") borrowings to market.

 (9) Reflects the preliminary estimates of legal, accounting and investment
     bankers' fees associated with the merger, severance benefits associated
     with the elimination of duplicate employment positions at Keystone, the
     fair value for stock options and the estimated net tax liability associated
     with the adjustments to fair value of net assets acquired assuming an
     income tax rate of 39%.

(10) Reflects the issuance of 1,590,225 shares of M&T common stock with a market
     value of $659,943,000 and the elimination of Keystone's March 31, 2000
     equity of $556,351,000.

(11) Represents preliminary estimates of core deposit intangible and goodwill.
     Since the final determination of adjustments to assets and liabilities will
     be based upon fair values as of the effective date and after appraisals and
     evaluations are complete, the final amounts may differ from the estimates
     provided herein.

                                       76
<PAGE>   81

    The Purchase Accounting Adjustments to record the Merger used in the
    preparation of the Unaudited Pro Forma Condensed Combined Statements of
    Income are summarized below:

<TABLE>
<CAPTION>
                                                               THREE MONTHS    FULL YEAR ENDED
                                                                  ENDED         DECEMBER 31,
                                                              MARCH 31, 2000        1999
                                                              --------------   ---------------
<S>                                                           <C>              <C>

(12) Reflects the estimated amortization of net discount         $ 2,459           $ 9,836
     related to loans and leases on an accelerated basis
     using an estimated maturity of 5 years.

(13) Reflects the estimated reduction in interest income              52               209
     from investment securities liquidated to fund portion
     of the cash component of the merger consideration
     assuming an interest rate of 6.54%.

(14) Reflects the estimated amortization of discount related       1,063             4,251
     to investment securities assumed to be retained on a
     straight-line basis over the estimated maturities of
     the affected securities using an estimated life of 3.7
     years.

(15) Reflects the estimated amortization of the related            1,621             6,484
     mark-to-market adjustments to deposits on an
     accelerated basis using an estimated maturity of 1.2
     years.

(16) Reflects the estimated increase in interest expense           7,510            30,040
     from the issuance of subordinated debt issued to fund
     portion of the cash component of the merger
     consideration assuming a fixed interest rate of 8.23%.

(17) Reflects the estimated amortization of the related            1,768             7,072
     mark-to-market adjustments to FHLB borrowings and
     medium term notes on a straight-line basis using an
     estimated maturity of 1.75 years and 5 years,
     respectively.

(18) Reflects the amortization on an accelerated basis of
     the core deposit intangible and on a straight-line
     basis for goodwill
</TABLE>

<TABLE>
<CAPTION>
                                                       ESTIMATED LIFE
                                                       --------------
     <S>                                               <C>              <C>              <C>
     Core deposit intangible.........................         7              6,250            25,000
     Goodwill........................................        20              5,698            22,790
                                                                           -------           -------
     Total amortization..............................                       11,948            47,790
</TABLE>

<TABLE>
<S>                                                           <C>              <C>

(19) Reflects the amortization on an accelerated basis of        $   316           $ 1,263
     the mark-to-market adjustment on mortgage servicing
     rights using an estimated life of 7 years.

(20) Income tax expense on pro forma adjustments is reflected using a 39% tax rate.

(21) The pro forma net income per common share amounts include the effect of the adjustments
     described above and the issuance of 1,590,225 shares of M&T common stock.

(22) The M&T and pro forma net income per common share amounts have been adjusted as though
     the proposed 10-for-1 stock split has already occurred.
</TABLE>

                                       77
<PAGE>   82

                 PROPOSED AMENDMENT TO THE M&T BANK CORPORATION
                          CERTIFICATE OF INCORPORATION

     On July 18, 2000, the M&T board authorized, subject to shareholder
authorization, an amendment to M&T's certificate of incorporation to effect a
10-for-1 split of the M&T common stock. The effect of this amendment would be to
increase the number of authorized shares of M&T common stock from 15,000,000 to
150,000,000 shares and to reduce the par value of the M&T Common Stock from
$5.00 to $0.50 per share. [Attached as Appendix E to this document is a copy of
the certificate of amendment to M&T's certificate of incorporation, in the form
approved by the M&T board.] The certificate of amendment will be filed with the
New York Secretary of State prior to the effective date. In the event the merger
does not occur, M&T may still file the certificate of amendment, but has not yet
decided whether it will do so.

     As of July 27, 2000, M&T had 7,346,085 authorized but unissued shares of
common stock, including shares held as treasury stock. Of that amount, there
were 1,240,861 shares reserved for issuance pursuant to various employee
compensation and benefit plans maintained by M&T. If the amendment becomes
effective, M&T will have (based on the number of shares issued and outstanding
as of July 27, 2000) 73,460,850 authorized but unissued shares of common stock,
including shares held as treasury stock, including 12,408,610 shares reserved
for issuance pursuant to employee compensation and benefit plans.

PURPOSES

     Completion of a 10-for-1 split of the M&T common stock prior to the
effective date is a condition to Keystone's obligation to consummate the merger.
In the future, the additional shares of uncommitted authorized but unissued
shares will be available for issue from time to time to such persons and for
such consideration as the M&T board may determine, including acquisitions,
financings, employee benefit plan issuances, equity incentives and such other
corporate purposes as may arise.

     The rules of the New York Stock Exchange currently require shareholder
approval of issuances of common stock under certain circumstances, including
those in which the number of shares to be issued is equal to or exceeds 20
percent of the voting power outstanding. In other instances, the issuance of
additional shares of authorized M&T common stock would be within the discretion
of the M&T board, without shareholder approval. M&T believes that the proposed
increase in the number of authorized shares would give M&T greater flexibility
in responding to business and financing opportunities by allowing shares of M&T
common stock to be issued without the need to obtain shareholders' approval. The
M&T board will determine whether, when and upon what terms, the issuance of
shares of M&T common stock may be warranted in connection with any of the
foregoing purposes.

EFFECT

     All newly authorized shares of M&T common stock would have the same rights
as the presently authorized shares, including the right to cast one vote per
share and to participate in dividends when and to the extent declared and paid.
Approval of the amendment and subsequent issuances of M&T common stock as a
result of the 10-for-1 split will not affect the proportional common stock
ownership of current M&T shareholders, although they will result in a reduction
in the trading price per share. The split will not affect the rights of the
holders of currently issued and outstanding M&T common stock, except for effects
incidental to increasing the number of shares of M&T common stock outstanding,
such as the dilution of earnings per share in some cases. Shareholders of M&T
currently do not have preemptive rights to subscribe for or purchase additional
shares of M&T common stock and will have no preemptive rights to subscribe for
or purchase any of the newly authorized shares.

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<PAGE>   83

     If the amendment to M&T certificate of incorporation is authorized, the
authority of the M&T board to issue the authorized but unissued shares of M&T
common stock might be considered as having the effect of discouraging an attempt
by another person or entity to effect a takeover or otherwise gain control of
M&T since the issuance of additional shares of M&T common stock would dilute the
voting power of the common stock then outstanding. Although the issuance of any
additional shares will be on terms deemed to be in the best interests of M&T and
its shareholders, under certain circumstances the issuance of additional shares
of M&T common stock could have an adverse effect on the market price per share
of M&T common stock.

     THE M&T BOARD RECOMMENDS A VOTE FOR THE PROPOSAL TO AMEND M&T'S CERTIFICATE
OF INCORPORATION TO REDUCE THE PAR VALUE OF M&T COMMON STOCK TO $0.50 PER SHARE
AND TO EFFECT THE 10-FOR-1 STOCK SPLIT.

                                    EXPERTS

     The consolidated financial statements of M&T included in M&T's Annual
Report on Form 10-K for the year ended December 31, 1999, have been audited by
PricewaterhouseCoopers LLP, independent accountants, as outlined in their report
thereon incorporated in this document by reference. Such consolidated financial
statements are incorporated in this document by reference in reliance upon such
report given upon the authority of such firm as experts in accounting and
auditing.

     The consolidated financial statements of Keystone and subsidiaries included
in the Annual Report on Form 10-K of Keystone for the year ended December 31,
1999, have been audited by Ernst & Young LLP, independent auditors, as set forth
in their report thereon incorporated by reference therein and incorporated
herein by reference. Such consolidated financial statements are incorporated
herein by reference in reliance upon such report given on the authority of such
firm as experts in accounting and auditing.

                                 LEGAL OPINION

     A legal opinion which states that the issuance of the shares of M&T common
stock offered hereby, when issued in accordance with the terms of the merger
agreement, will be validly issued, fully paid and nonassessable, has been
rendered by Richard A. Lammert, Esq., Senior Vice President and General Counsel
of M&T. As of July 27, 2000, Mr. Lammert was the beneficial owner of 6,180
shares of M&T common stock and held options granted under the M&T Bank
Corporation 1983 Stock Option Plan covering 12,500 shares of M&T common stock,
9,000 of which are currently exercisable.

                      SUBMISSION OF SHAREHOLDER PROPOSALS

     Keystone intends to hold an annual meeting of Keystone shareholders in 2001
only if the merger is not completed. To the extent that an annual meeting of
Keystone shareholders is held in 2001, a shareholder proposal to be timely for
purposes of Rule 14a-8 of the Securities and Exchange Commission under the
Securities Exchange Act of 1934 or for purposes of Keystone's bylaws must be
received by December 8, 2000.

     Under M&T's bylaws, no business may be brought before an annual meeting of
shareholders unless it is specified in the notice of the meeting or is otherwise
brought before the meeting by the board of directors or by you, if you are
entitled to vote and have delivered notice to M&T (containing information
specified in the bylaws) not less than 120 days prior to the anniversary of the
preceding year's annual meeting of shareholders. These requirements are separate
from and in addition to the

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<PAGE>   84

SEC's requirements that a shareholder must meet in order to have a shareholder
proposal included in M&T's proxy statement.

     If you wish to submit a proposal for consideration at the 2001 annual
meeting of shareholders, either under SEC Rule 14a-8 or otherwise, you must do
so no later than November 8, 2000.

                      DOCUMENTS INCORPORATED BY REFERENCE

     This document incorporates by reference the documents listed below that M&T
and Keystone have previously filed with the Commission:

     - M&T's Annual Report on Form 10-K for the year ended December 31, 1999;

     - Keystone's Annual Report on Form 10-K for the year ended December 31,
       1999;

     - M&T's Quarterly Report on Form 10-Q for the quarter ended March 31, 2000;

     - Keystone's Quarterly Report on Form 10-Q for the quarter ended March 31,
       2000;

     - M&T's Current Reports on Form 8-K dated as of May 23, 2000 and July 9,
       2000;

     - Keystone's Current Reports on Form 8-K dated as of January 18, 2000,
       March 23, 2000, April 18, 2000, May 16, 2000, May 18, 2000, May 24, 2000,
       May 25, 2000 (filed May 30, 2000), May 25, 2000 (filed June 9, 2000),
       July 18, 2000, and July 20, 2000; and

     - the description of M&T common stock contained in a registration statement
       on Form 8-A dated May 20, 1998 filed by M&T pursuant to Section 12 of the
       Securities Exchange Act of 1934, and any amendment or report filed for
       the purpose of updating such description.

     M&T and Keystone also incorporate by reference additional documents that
either company may file with the Commission between the date of this document
and the date of the last special meeting or, if later, the expiration of the
election period for Keystone shareholders to elect to receive M&T common stock
or cash for their shares of Keystone common stock in the merger. These documents
may include Quarterly Reports on Form 10-Q and Current Reports on Form 8-K, as
well as proxy statements.

                   A WARNING ABOUT FORWARD-LOOKING STATEMENTS

     This document and the documents that have been incorporated by reference
into this document include statements that reflect projections or expectations
of future financial condition, results of operations and business of each of
M&T, Keystone and the combined company following the merger. These statements
are subject to risk and uncertainty. We believe such statements to be "forward-
looking" statements within the meaning of Section 27A of the Securities Act of
1933 and Section 21E of the Securities Exchange Act of 1934. M&T and Keystone
have made, and may continue to make, various forward-looking statements with
respect to earnings per share, cash earnings per share, cost savings related to
acquisitions, credit quality and other financial and business matters for 2001
and, in certain instances, subsequent periods. We caution that these
forward-looking statements are subject to numerous assumptions, risks and
uncertainties, and that statements for periods after 2001 are subject to greater
uncertainty because of the increased likelihood of changes in underlying factors
and assumptions. Actual results could differ materially from those expressed in
forward-looking statements. In addition to factors disclosed in documents
incorporated by reference in this document and factors identified elsewhere in
this document, the following factors could cause actual results to differ
materially from those expressed in forward-looking statements:

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<PAGE>   85

     - expected cost savings from the merger cannot be fully realized or cannot
       be realized within the expected time frame;

     - revenues following the merger are lower than expected;

     - competitive pressure among financial services institutions increases
       significantly;

     - costs or difficulties related to the integration of the business of M&T
       and Keystone are greater than expected;

     - changes in the interest rate environment reduce interest margins;

     - general economic conditions, either nationally or in the markets in which
       the combined company will be doing business, are less favorable than
       expected;

     - legislation or regulatory requirements or changes that adversely affect
       the business in which the combined company would be engaged; and

     - other "Future Factors" enumerated in M&T's Annual Report on Form 10-K
       with respect to M&T, or enumerated under "Forward-Looking Statements" in
       Keystone's Annual Report with respect to Keystone, in each case for the
       year ended December 31, 1999 and incorporated in this document by
       reference.

     Our forward-looking statements speak only as of the dates on which they are
made. By making forward-looking statements, we assume no duty to update them to
reflect new, changing or unanticipated events or circumstances, except as may be
required by applicable law or regulation.

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<PAGE>   86

                                   APPENDIX A

                      AGREEMENT AND PLAN OF REORGANIZATION

                    (INCLUDING AGREEMENT AND PLAN OF MERGER)

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<PAGE>   87

                      AGREEMENT AND PLAN OF REORGANIZATION

     AGREEMENT AND PLAN OF REORGANIZATION ("Reorganization Agreement" or
"Agreement") dated as of May 16, 2000, by and among Keystone Financial, Inc.
("Seller"), a Pennsylvania corporation having its principal executive office at
One Keystone Plaza, Front and Market Streets, Harrisburg, Pennsylvania 17105,
M&T Bank Corporation ("Purchaser"), a New York corporation having its principal
executive office at One M&T Plaza, Buffalo, New York 14614, and Olympia
Financial Corp. ("Merger Sub"), a Delaware corporation having its registered
office at 1209 Orange Street, Wilmington, Delaware.

                              W I T N E S S E T H

     WHEREAS, the parties hereto desire that Seller shall be acquired by
Purchaser through the merger ("Merger") of Seller with and into Merger Sub, with
Merger Sub as the surviving corporation ("Surviving Corporation") pursuant to an
Agreement and Plan of Merger substantially in the form attached hereto as Annex
A ("Plan of Merger"); and

     WHEREAS, following the consummation of the Merger, Keystone Financial Bank,
N.A. ("Seller Bank"), a banking subsidiary of Seller, which shall be a
wholly-owned subsidiary of the Surviving Corporation following the Merger, shall
merge with and into Manufacturers and Traders Trust Company ("Purchaser Bank"),
a bank subsidiary of Purchaser ("Bank Merger"), pursuant to an Agreement and
Plan of Merger ("Bank Merger Agreement") in a form to be specified by Purchaser;
and

     WHEREAS, the parties hereto desire to provide for certain undertakings,
conditions, representations, warranties and covenants in connection with the
transactions contemplated hereby;

     NOW, THEREFORE, in consideration of the premises and of the mutual
representations, warranties and covenants herein contained and intending to be
legally bound hereby, the parties hereto do hereby agree as follows:

                                   ARTICLE 1.
                                  DEFINITIONS

     1.1 "Agreement" is defined in the preamble hereto.

     1.2 "Bank Holding Company Act" shall mean the Bank Holding Company Act of
1956, as amended.

     1.3 "Banking Board" shall mean the New York State Banking Board.

     1.4 "Bank Merger" is defined in the recitals hereto.

     1.5 "Bank Merger Agreement" is defined in the recitals hereto.

     1.6 "Cash Consideration" is defined in the Plan of Merger.

     1.7 "Claim" is defined in Section 4.11(e) hereof.

     1.8 "Closing Date" shall mean the date specified pursuant to Section 4.9
hereof as the date on which the parties hereto shall close the transactions
contemplated herein.

     1.9 "Code" shall mean the Internal Revenue Code of 1986, as amended.

     1.10 "Commission" or "SEC" shall mean the Securities and Exchange
Commission.

     1.11 "Confidentiality Agreement" is defined in Section 4.5 hereof.

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<PAGE>   88

     1.12 "Covered Parties" is defined in Section 4.11(e) hereof.

     1.13 "DPC Shares" is defined in the Plan of Merger.

     1.14 "Dividend Increase" is defined in Section 4.14 hereof.

     1.15 "Effective Date" shall mean the date specified pursuant to Section 4.9
hereof as the effective date of the Merger.

     1.16 "ERISA" shall mean the Employee Retirement Income Security Act of
1974, as amended.

     1.17 "ERISA affiliate" is defined in Section 2.13 hereof.

     1.18 "Exchange Act" shall mean the Securities Exchange Act of 1934, as
amended.

     1.19 "FDIA" shall mean the Federal Deposit Insurance Act.

     1.20 "FDIC" shall mean the Federal Deposit Insurance Corporation.

     1.21 "Federal Reserve Board" shall mean the Board of Governors of the
Federal Reserve System.

     1.22 "Indemnified Parties" is defined in Section 4.11(d) hereof.

     1.23 "Insurance Amount" is defined in Section 4.11(f) hereof.

     1.24 "Intellectual Property" means domestic and foreign letters patent,
patents, patent applications, patent licenses, software licensed or owned,
know-how licenses, trade names, common law and other trademarks, service marks,
licenses of trademarks, trade names and/or service marks, trademark
registrations and applications, service mark registrations and applications and
copyright registrations and applications.

     1.25 "KBW" is defined in Section 2.18 hereof.

     1.26 "Material Adverse Effect" shall mean, with respect to Seller or
Purchaser, as the case may be, a material adverse effect on the business,
results of operations or financial condition of such party and any Subsidiary of
the party taken as a whole or a material adverse effect on such party's ability
to consummate the transactions contemplated hereby; provided, however, that in
determining whether a Material Adverse Effect has occurred there shall be
excluded any effect on the referenced party the cause of which is (i) any change
in banking or similar laws, rules or regulations of general applicability or
interpretations thereof by courts or governmental authorities, (ii) any change
in generally accepted accounting principles or regulatory accounting
requirements applicable to banks or their holding companies generally, (iii)
general changes in conditions, including interest rates, in the banking industry
or in the global or United States economy or financial markets, with respect to
clause (i), (ii) or (iii), to the extent that a change does not materially
affect the referenced party to a materially different extent than other
similarly situated banking organizations, and (iv) any action or omission of
Seller or Purchaser or any Subsidiary of either of them taken with the prior
written consent of Purchaser or Seller, as applicable, in contemplation of the
Merger.

     1.27 "Merger" is defined in the recitals hereto.

     1.28 "Merger Consideration" is defined in the Plan of Merger.

     1.29 "Merger Sub" is defined in the preamble of this Agreement.

     1.30 "Merrill Lynch" is defined in Section 3.14 hereof.

     1.31 "Nasdaq" shall mean the Nasdaq Stock Market.

     1.32 "NYSE" shall mean the New York Stock Exchange.

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     1.33 "OCC" shall mean the Office of the Comptroller of Currency.

     1.34 "Option Agreement" shall mean the Stock Option Agreement dated of even
date herewith between Seller and Purchaser pursuant to which Seller will grant
Purchaser the right to purchase certain shares of Seller Common Stock.

     1.35 "Plan of Merger" is defined in the recitals hereto.

     1.36 "Previously Disclosed" shall mean disclosed prior to the execution
hereof in (i) an SEC Document filed with the SEC subsequent to January 1, 2000
and prior to the date hereof or (ii) a letter dated of even date herewith from
the party making such disclosure and delivered to the other party prior to the
execution hereof. Any information disclosed by one party to the other for any
purpose hereunder shall be deemed to be disclosed for all purposes hereunder.
The inclusion of any matter in information Previously Disclosed shall not be
deemed an admission or otherwise to imply that any such matter is material for
purposes of this Agreement.

     1.37 "Proxy Statement" shall mean the joint proxy statement/prospectus (or
similar documents) together with any supplements thereto sent to the
shareholders of Purchaser and Seller to solicit their votes in connection with
this Agreement and the Plan of Merger.

     1.38 "Purchaser" is defined in the preamble of this Agreement.

     1.39 "Purchaser Bank" is defined in the recitals hereof.

     1.40 "Purchaser Common Stock" is defined in Section 3.1 hereof.

     1.41 "Purchaser Financial Statements" shall mean (i) the consolidated
balance sheets of Purchaser as of March 31, 2000 and as of December 31, 1999 and
1998 and the related consolidated statements of income, cash flows and changes
in shareholders' equity (including related notes, if any) for the three months
ended March 31, 2000 and each of the three years ended December 31, 1999, 1998
and 1997, respectively, as filed by Purchaser in SEC Documents and (ii) the
consolidated balance sheets of Purchaser and related consolidated statements of
income, cash flows and changes in shareholders' equity (including related notes,
if any) as filed by Purchaser in SEC Documents as of dates or with respect to
periods ended subsequent to March 31, 2000.

     1.42 "Purchaser Plan" is defined in Section 3.10 hereof.

     1.43 "Purchaser Preferred Stock" is defined in Section 3.1 hereof.

     1.44 "Registration Statement" shall mean the registration statement with
respect to the Purchaser Common Stock to be issued in connection with the Merger
as declared effective by the Commission under the Securities Act.

     1.45 "Rights" shall mean warrants, options, rights, convertible securities
and other arrangements or commitments which obligate an entity to issue or
dispose of any of its capital stock, and stock appreciation rights, performance
units and other similar stock-based rights whether they obligate the issuer
thereof to issue stock or other securities or to pay cash.

     1.46 "Reorganization Agreement" is defined in the recitals hereto.

     1.47 "SEC Documents" shall mean all reports and registration statements
filed, or required to be filed, by a party hereto pursuant to the Securities
Laws.

     1.48 "Securities Act" shall mean the Securities Act of 1933, as amended.

                                       A-4
<PAGE>   90

     1.49 "Securities Laws" shall mean the Securities Act; the Exchange Act; the
Investment Company Act of 1940, as amended; the Investment Advisers Act of 1940,
as amended; the Trust Indenture Act of 1939, as amended; and the rules and
regulations of the Commission promulgated thereunder.

     1.50 "Seller" is defined in the preamble of this Agreement.

     1.51 "Seller Bank" is defined in the recitals hereto.

     1.52 "Seller Common Stock" is defined in Section 2.1 hereof.

     1.53 "Seller Designees" is defined in Section 4.11(b) hereof.

     1.54 "Seller Employees" is defined in Section 4.11(a) hereof.

     1.55 "Seller Financial Statements" shall mean (i) the consolidated
statements of condition of Seller as of March 31, 2000 and as of December 31,
1999 and 1998 and the related consolidated statements of income, cash flows and
changes in shareholders' equity (including related notes, if any) for the three
months ended March 31, 2000 and each of the three years ended December 31, 1999,
1998 and 1997, respectively, as filed by Seller in SEC Documents and (ii) the
consolidated statements of condition of Seller and related consolidated
statements of income, cash flows and changes in shareholders' equity (including
related notes, if any) as filed by Seller in SEC Documents with respect to
periods ended subsequent to March 31, 2000.

     1.56 "Seller Plans" is defined in Section 2.13(a) hereof.

     1.57 "Seller Preferred Stock" is defined in Section 2.1 hereof.

     1.58 "Seller Stock Option Plans" is defined in the Plan of Merger.

     1.59 "Settled Litigation" is defined in Section 2.15(b) hereof.

     1.60 "Stock Consideration" is defined in the Plan of Merger hereof.

     1.61 "Stock Split" is defined in Section 4.13 hereof.

     1.62 "Subsidiary" or "Subsidiaries" shall mean with respect to any party,
any bank, corporation, partnership or other organization, whether incorporated
or unincorporated, which is consolidated with such party for financial reporting
purposes; provided, however, that "Subsidiary" or "Subsidiaries" shall not
include any subsidiary trust formed for the purpose of issuing trust preferred
or similar securities.

     1.63 "Surviving Corporation" is defined in the recitals hereto.

     1.64 "Takeover Laws" is defined in Section 2.28 hereof.

     1.65 "Takeover Proposal" is defined in Section 4.7(b)(13) hereof.

     1.66 "Tax," collectively, "Taxes" shall mean all taxes, however
denominated, including any interest, penalties, criminal sanctions or additions
to tax (including, without limitation, any underpayment penalties for
insufficient estimated tax payments) or other additional amounts that may become
payable in respect thereof (or in respect of a failure to file any Tax Return
when and as required), imposed by any federal, state, local or foreign
government or any agency or political subdivision of any such government, which
taxes shall include, without limiting the generality of the foregoing, all
income taxes, payroll and employment taxes, withholding taxes (including
withholding taxes in connection with amounts paid or owing to any employee,
independent contractor, creditor, stockholder or other person or entity),
unemployment insurance taxes, social security (or similar) taxes, sales and use
taxes, excise taxes, franchise taxes, gross receipts taxes, occupation taxes,
real and personal property taxes, stamp taxes, value added taxes, transfer
taxes, profits or windfall profits taxes, licenses in the nature of taxes,

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estimated taxes, severance taxes, duties (custom and others), workers'
compensation taxes, premium taxes, environmental taxes (including taxes under
Section 59A of the Code), disability taxes, registration taxes, alternative or
add-on minimum taxes, estimated taxes, and other fees, assessments, charges or
obligations of the same or of a similar nature.

     1.67 "Tax Return," collectively, "Tax Returns" shall mean all returns,
reports, estimates, information statements or other written submissions, and any
schedules or attachments thereto, required or permitted to be filed pursuant to
the statutes, rules and regulations of any federal, state, local or foreign
government Tax authority, including but not limited to, original returns and
filings, amended returns, claims for refunds, information returns and accounting
method change requests.

     1.68 "Trust Account Shares" is defined in the Plan of Merger.

                                   ARTICLE 2.
                    REPRESENTATIONS AND WARRANTIES OF SELLER

     Except as Previously Disclosed, Seller hereby represents and warrants to
Purchaser and Merger Sub as follows:

     2.1.  CAPITAL STRUCTURE OF SELLER

     The authorized capital stock of Seller consists of (i) 8,000,000 shares of
preferred stock, par value $1.00 per share ("Seller Preferred Stock") none of
which is issued and outstanding and (ii) 100,000,000 shares of common stock, par
value $2.00 per share ("Seller Common Stock"), of which, as of the date hereof,
48,930,000 shares are issued and outstanding and no shares are held in treasury.
As of the date hereof, no shares of Seller Preferred Stock or Seller Common
Stock are reserved for issuance, except as Previously Disclosed and except for
9,737,070 shares of Seller Common Stock reserved for issuance pursuant to the
Option Agreement. Schedule 2.1 hereto sets forth a list of all currently
outstanding options for the purchase of Seller Common Stock, the number of
shares of Seller Common Stock subject to such options, whether such options are
vested or unvested, the vesting schedule for unvested options and the vesting or
other treatment of all unvested options in the event of a change of control of
Seller. All outstanding shares of Seller Common Stock have been duly authorized
and validly issued and are fully paid and nonassessable. Seller does not have
and is not bound by any Rights which are authorized, issued or outstanding with
respect to the capital stock of Seller except (i) for the Option Agreement, (ii)
as Previously Disclosed, and (iii) as set forth above. None of the shares of
Seller's capital stock has been issued in violation of the preemptive rights of
any person.

     2.2.  ORGANIZATION, STANDING AND AUTHORITY OF SELLER

     Seller is a duly organized corporation, validly existing and in good
standing under the laws of the Commonwealth of Pennsylvania with full corporate
power and authority to carry on its business as now conducted and is duly
licensed or qualified to do business in the states of the United States and
foreign jurisdictions where its ownership or leasing of property or the conduct
of its business requires such qualification, except where the failure to be so
licensed or qualified would not have a Material Adverse Effect on Seller. Seller
is registered as a bank holding company under the Bank Holding Company Act.

     2.3.  OWNERSHIP OF SELLER SUBSIDIARIES; CAPITAL STRUCTURE OF SELLER
SUBSIDIARIES

     As of the date hereof, Seller does not own, directly or indirectly, 5% or
more of the outstanding capital stock or other voting securities of any
corporation, bank or other organization except the Seller Subsidiaries as
Previously Disclosed. In the letter from Seller to Purchaser delivered pursuant
to Section 1.32(ii) hereof, Seller has Previously Disclosed to Purchaser a list
of all of the Subsidiaries,

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including a summary description of each Subsidiary's activities and the
authority under which each Subsidiary is held by Seller or Seller Bank, as the
case may be. Except as Previously Disclosed, the outstanding shares of capital
stock or other equity interests of each Seller Subsidiary have been duly
authorized and validly issued and are fully paid and (except as provided by
applicable law) nonassessable and all such shares or equity interests are
directly or indirectly owned by Seller free and clear of all liens, claims and
encumbrances. No Seller Subsidiary has or is bound by any Rights which are
authorized, issued or outstanding with respect to the capital stock or other
equity interests of any Seller Subsidiary and, except as Previously Disclosed,
there are no agreements, understandings or commitments relating to the right of
Seller to vote or to dispose of said shares. None of the shares of capital stock
or other equity interests of any Seller Subsidiary has been issued in violation
of the preemptive rights of any person.

     2.4.  ORGANIZATION, STANDING AND AUTHORITY OF SELLER SUBSIDIARIES

     Each Seller Subsidiary is a duly organized corporation, banking association
or other organization, validly existing and in good standing under applicable
laws. Each Seller Subsidiary (i) has full power and authority to carry on its
business as now conducted, and (ii) is duly licensed or qualified to do business
in the states of the United States and foreign jurisdictions where its ownership
or leasing of property or the conduct of its business requires such licensing or
qualification, except where failure to be so licensed or qualified would not
have a Material Adverse Effect on Seller. Each Seller Subsidiary has all
federal, state, local and foreign governmental authorizations necessary for it
to own or lease its properties and assets and to carry on its business as it is
now being conducted, except where the failure to be so authorized would not have
a Material Adverse Effect on Seller. Seller Bank is a member in good standing of
the Federal Home Loan Bank of Pittsburgh and owns the requisite amount of shares
therein and is a qualified seller and servicer for the Federal Home Loan
Mortgage Corporation.

     2.5. AUTHORIZED AND EFFECTIVE AGREEMENT

     (a) Seller has all requisite corporate power and authority to enter into
and perform all of its obligations under this Reorganization Agreement, the Plan
of Merger and the Option Agreement. The execution and delivery of this
Reorganization Agreement, the Plan of Merger and the Option Agreement and the
consummation of the transactions contemplated hereby and thereby have been duly
and validly authorized by all necessary corporate action in respect thereof on
the part of Seller, except for the affirmative vote of the majority of the votes
cast by the holders of Seller Common Stock entitled to vote thereon, which is
the only shareholder vote required to approve the Plan of Merger pursuant to the
Pennsylvania Business Corporation Law and Seller's Restated Articles of
Incorporation, as amended, and Seller's Bylaws. The Board of Directors of Seller
has directed that this Agreement and the Plan of Merger be submitted to Seller's
stockholders for approval at a special meeting to be held as soon as
practicable. The Board of Directors of Seller has approved the Merger as
contemplated by Section 9.2 of Seller's Articles of Incorporation.

     (b) Assuming the accuracy of the representation contained in Section 3.5(b)
hereof, this Reorganization Agreement and the Plan of Merger constitute legal,
valid and binding obligations of Seller, enforceable against it in accordance
with their respective terms, subject as to enforceability, to bankruptcy,
insolvency and other laws of general applicability relating to or affecting
creditors' rights and to general equity principles.

     (c) Neither the execution and delivery of this Reorganization Agreement,
the Plan of Merger or the Option Agreement, nor consummation of the transactions
contemplated hereby or thereby, nor compliance by Seller with any of the
provisions hereof or thereof shall (i) conflict with or result in a breach of
any provision of the articles or certificate of incorporation or association,
charter or bylaws of

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<PAGE>   93

Seller or any Seller Subsidiary, (ii) assuming the consents and approvals
contemplated by Section 4.3 hereof and the consents and approvals which are
Previously Disclosed are duly obtained, constitute or result in a breach of any
term, condition or provision of, or constitute a default under, or give rise to
any right of termination, cancellation or acceleration with respect to, or
result in the creation of any lien, charge or encumbrance upon any property or
asset of Seller or any Seller Subsidiary pursuant to, any note, bond, mortgage,
indenture, license, agreement or other instrument or obligation, or (iii)
assuming the consents and approvals contemplated by Section 4.3 hereof and the
consents and approvals which are Previously Disclosed are duly obtained, violate
any order, writ, injunction, decree, statute, rule or regulation applicable to
Seller or any Seller Subsidiary, except (in the case of clauses (ii) and (iii)
above) for such violations, rights, conflicts, breaches, creations or defaults
which, either individually or in the aggregate, would not have a Material
Adverse Effect on Seller.

     (d) Other than as contemplated by Section 4.3 hereof, no consent, approval
or authorization of, or declaration, notice, filing or registration with, any
governmental or regulatory authority, or any other person, is required to be
made or obtained by Seller or any Seller Subsidiary on or prior to the Closing
Date in connection with the execution, delivery and performance of this
Agreement and the Plan of Merger or the consummation of the transactions
contemplated hereby or thereby. As of the date hereof, Seller is not aware of
any reason that the condition set forth in Section 5.1(b) of this Agreement,
including the proviso thereto, would not be satisfied.

     2.6.  SEC DOCUMENTS; REGULATORY FILINGS

     Seller has filed all SEC Documents required by the Securities Laws and such
SEC Documents complied, as of their respective dates, in all material respects
with the Securities Laws. Seller and each Seller Subsidiary has filed all
reports required by statute or regulation to be filed with any federal or state
bank regulatory agency, except where the failure to so file would not have a
Material Adverse Effect on Seller, and such reports were prepared in accordance
with the applicable statutes, regulations and instructions in existence as of
the date of filing of such reports in all material respects.

     2.7.  FINANCIAL STATEMENTS; BOOKS AND RECORDS; MINUTE BOOKS

     The Seller Financial Statements filed by Seller in SEC Documents prior to
the date of this Agreement fairly present, and the Seller Financial Statements
filed by Seller after the date of this Agreement will fairly present, the
consolidated financial position of Seller and its consolidated Subsidiaries as
of the dates indicated and the consolidated income, changes in shareholders'
equity and cash flows of Seller and its consolidated Subsidiaries for the
periods then ended and each such financial statement has been or will be, as the
case may be, prepared in conformity with generally accepted accounting
principles applicable to financial institutions applied on a consistent basis
except as disclosed therein and except, in the case of unaudited statements, as
permitted by Form 10-Q. The books and records of Seller and each Seller
Subsidiary fairly reflect in all material respects the transactions to which it
is a party or by which its properties are subject or bound. Such books and
records have been properly kept and maintained and are in compliance with all
applicable legal and accounting requirements in all material respects. The
minute books of Seller and each Seller Subsidiary contain records which are
accurate in all material respects of all corporate actions of its shareholders
and Board of Directors (including committees of its Board of Directors).

     2.8.  MATERIAL ADVERSE CHANGE

     Seller has not, on a consolidated basis, suffered any change in its
financial condition, results of operations or business since December 31, 1999
which individually or in the aggregate with any other such changes would
constitute a Material Adverse Effect with respect to Seller.

                                       A-8
<PAGE>   94

     2.9.  ABSENCE OF UNDISCLOSED LIABILITIES

     Neither Seller nor any Seller Subsidiary has any liability (contingent or
otherwise), excluding contractually assumed contingencies, that is material to
Seller on a consolidated basis, or that, when combined with all similar
liabilities, would be material to Seller on a consolidated basis, except as
disclosed in the Seller Financial Statements filed with the SEC prior to the
date hereof and except for liabilities incurred in the ordinary course of
business subsequent to December 31, 1999.

     2.10.  PROPERTIES

     Seller and the Seller Subsidiaries have good and marketable title free and
clear of all liens, encumbrances, charges, defaults or equitable interests to
all of the properties and assets, real and personal, which, individually or in
the aggregate, are material to the business of Seller and its Subsidiaries taken
as a whole, and which are reflected on the Seller Financial Statements as of
December 31, 1999 or acquired after such date, except (i) liens for taxes not
yet due and payable, (ii) pledges to secure deposits and other liens incurred in
the ordinary course of banking business, (iii) such imperfections of title,
easements and encumbrances, if any, as are not material in character, amount or
extent and (iv) dispositions and encumbrances for adequate consideration in the
ordinary course of business. All leases pursuant to which Seller or any Seller
Subsidiary, as lessee, leases real and personal property which, individually or
in the aggregate, are material to the business of Seller and its Subsidiaries
taken as a whole are valid and enforceable in accordance with their respective
terms except where the failure of such lease or leases to be valid and
enforceable would not, individually or in the aggregate, have a Material Adverse
Effect on Seller. All tangible property used in the business of Seller and its
Subsidiaries is in good condition, reasonable wear and tear excepted, and is
usable in the ordinary course of business consistent with Seller's past
practices.

     2.11.  LOANS

     (a) Each loan reflected as an asset in the Seller Financial Statements (i)
is evidenced by notes, agreements or other evidences of indebtedness which are
true, genuine and what they purport to be, (ii) to the extent secured, has been
secured by valid liens and security interests which have been perfected, and
(iii) is the legal, valid and binding obligation of the obligor named therein,
enforceable in accordance with its terms, subject to bankruptcy, insolvency,
fraudulent conveyance and other laws of general applicability relating to or
affecting creditors' rights and to general equity principles, in each case other
than loans as to which the failure to satisfy the foregoing standards,
individually or in the aggregate, would not have a Material Adverse Effect on
Seller.

     (b) The allowance for loan losses reflected on the Seller Financial
Statements, as of their respective dates, is in all material respects consistent
with the requirements of generally accepted accounting principles to provide for
reasonably anticipated losses with respect to Seller's loan portfolio based upon
information reasonably available at the time.

     2.12.  TAX MATTERS

     (a) Seller and each Seller Subsidiary have timely filed federal income tax
returns for each year through December 31, 1998 and have timely filed, or caused
to be filed, all other Tax Returns required to be filed with respect to Seller
or any Seller Subsidiary, except where the failure to file timely such federal
income and other Tax Returns would not, in the aggregate, have a Material
Adverse Effect on Seller. All Taxes due by or on behalf of Seller or any Seller
Subsidiary have been paid or adequate reserves have been established on the
Seller Financial Statements for the payment of such Taxes, except where any such
failure to pay or establish adequate reserves would not, in the aggregate, have
a Material

                                       A-9
<PAGE>   95

Adverse Effect on Seller. Neither Seller nor any Seller Subsidiary will have any
liability for any such Taxes in excess of the amounts so paid or reserves or
accruals so established except where such liability would not have a Material
Adverse Effect on Seller.

     (b) All Tax Returns filed by Seller and each Seller Subsidiary are complete
and accurate in all material respects. Neither Seller nor any Seller Subsidiary
is delinquent in the payment of any material Tax, and, except as Previously
Disclosed, none of them has requested any extension of time within which to file
any Tax Returns which have not since been filed. Except as Previously Disclosed
or as fully settled and paid or accrued on the Seller Financial Statements, no
material audit examination, deficiency, adjustment, refund claim or litigation
with respect to Tax Returns, paid Taxes, unpaid Taxes or Tax attributes of
Seller or any Seller Subsidiary has been proposed, asserted or assessed
(tentatively or otherwise). Except as Previously Disclosed, there are currently
no agreements in effect with respect to Seller or any Seller Subsidiary to
extend the period of limitations for the assessment or collection of any Tax.

     (c) Neither the transactions contemplated hereby nor the termination of the
employment of any employees of Seller or any Seller Subsidiary prior to or
following consummation of the transactions contemplated hereby will result in
Seller or any Seller Subsidiary (or any successor thereof) making or being
required to make any "excess parachute payment" as that term is defined in
Section 280G of the Code.

     (d) Neither Seller nor any Seller Subsidiary is a party to any agreement
(other than an agreement exclusively among Seller and the Seller Subsidiaries)
providing for the allocation or sharing of, or indemnification for, Taxes.

     (e) Neither Seller nor any Seller Subsidiary is required to include in
income any adjustment in any taxable period ending after the date hereof
pursuant to Section 481(a) of the Code.

     (f) Neither Seller nor any Seller Subsidiary has executed or entered into
any written agreement with any Tax authority conceding or agreeing to any
treatment of Taxes or Tax attributes, including, without limitation, an Internal
Revenue Service Form 870 or Form 870-AD, closing agreement or special closing
agreement, affecting the Seller or any Seller Subsidiary pursuant to Section
7121 of the Code or any predecessor provision thereof or any similar provision
of state, local or foreign law, which agreement would have a material impact on
the calculation of the Taxes of Purchaser or any Purchaser Subsidiary after the
Effective Date.

     (g) For purposes of this Section 2.12 and Section 2.27, (i) references to
Seller and any Seller Subsidiary shall include predecessors thereof and (ii)
"Seller Subsidiary"shall include each Subsidiary (as defined in Article 1
hereof) of Seller, and each corporation, partnership, limited liability company,
joint venture or other entity which Seller controls directly or indirectly
(through one or more intermediaries). For purposes of the previous sentence,
"control" means the possession, direct or indirect, of the power either (1) to
vote fifty percent (50%) or more of the voting interests of a corporation,
partnership, limited liability company, joint venture or other entity, or (2) to
direct or cause the direction of the management and policies of a corporation,
partnership, limited liability company, joint venture or other entity, whether
by contract or otherwise.

     2.13.  EMPLOYEE BENEFIT PLANS

     (a) Schedule 2.13(a) hereto sets forth a true and complete list of each
Seller Plan. For purposes of this Section 2.13, the term "Seller Plan"means each
bonus, deferred compensation, incentive compensation, stock purchase, stock
option, severance pay, medical, life or other insurance, profit-sharing, or
pension plan, program, agreement or arrangement, and each other employee benefit
plan,

                                      A-10
<PAGE>   96

program, agreement or arrangement, sponsored, maintained or contributed to or
required to be contributed to by Seller or by any trade or business, whether or
not incorporated, that together with Seller would be deemed a "single employer"
under Section 414 of the Code (an "ERISA affiliate") for the benefit of any
employee or director or former employee or former director of Seller or any
ERISA affiliate of Seller.

     (b) With respect to each of the Seller Plans, Seller has made available to
Purchaser true and complete copies of each of the following documents: (a) the
Seller Plan and related documents (including all amendments thereto); (b) the
most recent annual reports, financial statements, and actuarial reports, if any;
(c) the most recent summary plan description, together with each summary of
material modifications, required under ERISA with respect to such Seller Plan
and all material communications relating to each such Seller Plan; and (d) the
most recent determination letter received from the IRS with respect to each
Seller Plan that is intended to be qualified under the Code and all material
communications to or from the IRS or any other governmental or regulatory agency
or authority relating to each Seller Plan.

     (c) No liability under Title IV of ERISA has been incurred by Seller or any
ERISA affiliate of Seller that has not been satisfied in full, and no condition
exists that presents a material risk to Seller or any ERISA affiliate of Seller
of incurring a liability under such Title, other than liability for premium
payments to the Pension Benefit Guaranty Corporation, which premiums have been
or will be paid when due.

     (d) Neither Seller nor, to the knowledge of Seller, any ERISA affiliate of
Seller, nor any of the Seller Plans, nor, to the knowledge of Seller, any trust
created thereunder, nor any trustee or administrator thereof has engaged in a
prohibited transaction (within the meaning of Section 406 of ERISA and Section
4975 of the Code) in connection with which Seller or any ERISA affiliate of
Seller could reasonably be expected to, either directly or indirectly, incur any
material liability or material cost.

     (e) Full payment has been made, or will be made in accordance with Section
404(a)(6) of the Code, of all amounts that Seller or any ERISA affiliate of
Seller is required to pay under Section 412 of the Code or under the terms of
the Seller Plans.

     (f) The fair market value of the assets held under each Seller Plan that is
subject to Title IV of ERISA equals or exceeds the actuarial present value of
all accrued benefits under each such Seller Plan. No reportable event under
Section 4043 of ERISA has occurred with respect to any Seller Plan other than
any reportable event occurring by reason of the transactions contemplated by
this Agreement or a reportable event for which the requirement of notice to the
PBGC has been waived.

     (g) None of the Seller Plans is a "multiemployer pension plan," as such
term is defined in Section 3(37) of ERISA, a "multiple employer welfare
arrangement," as such term is defined in Section 3(40) of ERISA, or a single
employer plan that has two or more contributing sponsors, at least two of whom
are not under common control, within the meaning of Section 4063(a) of ERISA.

     (h) A favorable determination letter has been issued by the Internal
Revenue Service with respect to each of the Seller Plans that is intended to be
"qualified" within the meaning of Section 401(a) of the Code to the effect that
such plan is so qualified and, to the knowledge of Seller, no condition exists
that could adversely affect the qualified status of any such Seller Plan. Each
of the Seller Plans that is intended to satisfy the requirements of Section 125
or 501(c)(9) of the Code satisfies such requirements in all material respects.
Each of the Seller Plans has been operated and administered in all material
respects in accordance with its terms and applicable laws, including but not
limited to ERISA and the Code.

                                      A-11
<PAGE>   97

     (i) There are no actions, suits or claims pending, or, to the knowledge of
Seller, threatened or anticipated (other than routine claims for benefits)
against any Seller Plan, the assets of any Seller Plan or against Seller or any
ERISA affiliate of Seller with respect to any Seller Plan. There is no judgment,
decree, injunction, rule or order of any court, governmental body, commission,
agency or arbitrator outstanding against or in favor of any Seller Plan or any
fiduciary thereof (other than rules of general applicability). There are no
pending or, to the knowledge of Seller, threatened audits, examinations or
investigations by any governmental body, commission or agency involving any
Seller Plan.

     (j) The consummation of the transactions contemplated by this Agreement
will not result in, and is not a precondition to, (i) any current or former
employee or director of Seller or any ERISA affiliate of Seller becoming
entitled to severance pay, unemployment compensation or any similar payment,
(ii) any acceleration in the time of payment or vesting, or increase in the
amount, of any compensation due to any such current or former employee or
director, or (iii) any renewal or extension of the term of any agreement
regarding compensation for any such current or former employee or director.

     2.14.  CERTAIN CONTRACTS

     (a) Neither Seller nor any Seller Subsidiary is a party to, or is bound by,
(i) any material contract as defined in Item 601(b)(10) of Regulation S-K of the
SEC or any other material contract or similar arrangement whether or not made in
the ordinary course of business (other than loans or loan commitments and
funding transactions in the ordinary course of business of any Seller
Subsidiary) or any agreement restricting the nature or geographic scope of its
business activities in any material respect, (ii) any agreement, indenture or
other instrument relating to the borrowing of money by Seller or any Seller
Subsidiary or the guarantee by Seller or any Seller Subsidiary of any such
obligation, other than instruments relating to transactions entered into in the
ordinary course of business, (iii) any agreement, arrangement or commitment
relating to the employment of a consultant who was formerly a director or
executive officer or the employment, election, retention in office or severance
of any present or former director or officer, or (iv) any contract, agreement or
understanding with a labor union, in each case whether written or oral.

     (b) Neither Seller nor any Seller Subsidiary is in default under any
material agreement, commitment, arrangement, lease, insurance policy or other
instrument whether entered into in the ordinary course of business or otherwise
and whether written or oral, and there has not occurred any event that, with the
lapse of time or giving of notice or both, would constitute such a default,
except for such defaults which would not, individually or in the aggregate, have
a Material Adverse Effect on Seller.

     2.15.  LEGAL PROCEEDINGS

     (a) There are no actions, suits or proceedings instituted, pending or, to
the knowledge of Seller or any Seller Subsidiary, threatened (or unasserted but
considered probable of assertion and which if asserted would have at least a
reasonable probability of an unfavorable outcome) against Seller or any Seller
Subsidiary or against any asset, interest or right of Seller or any Seller
Subsidiary as to which there is a reasonable probability of an unfavorable
outcome and which, if such an unfavorable outcome was rendered, would,
individually or in the aggregate, have a Material Adverse Effect on Seller. To
the knowledge of Seller or any Seller Subsidiary, there are no actual or
threatened actions, suits or proceedings which present a claim to restrain or
prohibit the transactions contemplated herein or to impose any material
liability in connection therewith as to which there is a reasonable probability
of an unfavorable outcome and which, if such an unfavorable outcome was
rendered, would, individually or in the aggregate, have a Material Adverse
Effect on Seller. There are no actions, suits or proceedings instituted, pending
or, to the knowledge of Seller or any Seller Subsidiary, threatened (or
unasserted but

                                      A-12
<PAGE>   98

considered probable of assertion and which if asserted would be reasonably
expected to have an unfavorable outcome) against any present or, to Seller's
knowledge, former director or officer of Seller or any Seller Subsidiary, that
would reasonably be expected to give rise to a claim for indemnification and
that (i) has a reasonable probability of an unfavorable outcome and (ii) in the
event of an unfavorable outcome, would, individually or in the aggregate, have a
Material Adverse Effect on Seller.

     (b) With respect to certain litigation Previously Disclosed to Purchaser by
Seller as having been the subject of settlement agreements (the "Settled
Litigation"), to Seller's knowledge, there is no remaining liability with
respect to the Settled Litigation that would have a Material Adverse Effect on
Seller.

     2.16.  COMPLIANCE WITH LAWS

     Except as Previously Disclosed, Seller and each Seller Subsidiary is in
compliance in all material respects with all statutes and regulations applicable
to the conduct of its business, and neither Seller nor any Seller Subsidiary has
received notification from any agency or department of federal, state or local
government (i) asserting a material violation of any such statute or regulation,
(ii) threatening to revoke any license, franchise, permit or government
authorization or (iii) restricting or in any way limiting its operations, except
for such noncompliance, violations, revocations and restrictions which would
not, individually or in the aggregate, have a Material Adverse Effect on Seller.
Neither Seller nor any Seller Subsidiary is subject to any regulatory or
supervisory cease and desist order, agreement, directive, memorandum of
understanding or commitment which would be reasonably expected to have a
Material Adverse Effect on Seller, and none of them has received any
communication requesting that they enter into any of the foregoing.

     2.17.  LABOR MATTERS

     With respect to their employees, neither Seller nor any Seller Subsidiary
is a party to any labor agreement with any labor organization, group or
association and has not engaged in any unfair labor practice. Since January 1,
2000 and prior to the date hereof, Seller and the Seller Subsidiaries have not
experienced any attempt by organized labor or its representatives to make Seller
or any Seller Subsidiary conform to demands of organized labor relating to their
employees or to enter into a binding agreement with organized labor that would
cover the employees of Seller or any Seller Subsidiary. To the knowledge of
Seller and the Seller Subsidiaries, there is no unfair labor practice charge or
other complaint by any employee or former employee of Seller or any Seller
Subsidiary against any of them pending before any court, arbitrator or
governmental agency arising out of Seller's or such Seller Subsidiary's
activities, which charge or complaint (i) has a reasonable probability of an
unfavorable outcome and (ii) in the event of an unfavorable outcome would,
individually or in the aggregate, have a Material Adverse Effect on Seller;
there is no labor strike or labor disturbance pending or, to the knowledge of
Seller and the Seller Subsidiaries, threatened against any of them; and neither
Seller nor any Seller Subsidiary has experienced a work stoppage or other
material labor difficulty since January 1, 2000.

     2.18.  BROKERS AND FINDERS

     Neither Seller nor any Seller Subsidiary, nor any of their respective
officers, directors or employees, has employed any broker, finder or financial
advisor or incurred any liability for any fees or commissions in connection with
the transactions contemplated herein or the Plan of Merger, except for Seller's
retention of Keefe, Bruyette & Woods, Inc. ("KBW") to perform certain financial
advisory services as Previously Disclosed. Prior to the execution and delivery
of this Agreement, KBW has delivered to the Board of Directors of Seller an
opinion that the Merger Consideration is fair from a financial point of view to
the shareholders of Seller.

                                      A-13
<PAGE>   99

     2.19.  INSURANCE

     Seller and the Seller Subsidiaries each currently maintains insurance in
amounts considered by Seller and any Seller Subsidiary as applicable, to be
reasonably necessary for their operations. Neither Seller nor any Seller
Subsidiary has received any notice of a material premium increase over current
rates or cancellation with respect to any of its insurance policies or bonds,
and within the last three years, neither Seller nor any Seller Subsidiary has
been refused any insurance coverage sought or applied for, and Seller has no
reason to believe that existing insurance coverage cannot be renewed as and when
the same shall expire, upon terms and conditions as favorable as those presently
in effect, other than possible increases in premiums or unavailability in
coverage that have not resulted from any extraordinary loss experience of Seller
or any Seller Subsidiary. Seller has Previously Disclosed a list of all
outstanding claims as of the date hereof by Seller or any Seller Subsidiary
under any insurance policy. The deposits of Seller Bank are insured by the FDIC
in accordance with the FDIA, and Seller Bank and its predecessors have paid all
assessments and filed all reports required by the FDIA.

     2.20.  ENVIRONMENTAL LIABILITY

     Neither Seller nor any Seller Subsidiary has received any written notice of
any legal, administrative, arbitral or other proceeding, claim or action and, to
the knowledge of Seller and the Seller Subsidiaries, there is no governmental
investigation of any nature ongoing, in each case that would reasonably be
expected to result in the imposition, on Seller or any Seller Subsidiary of any
liability arising under any local, state or federal environmental statute,
regulation or ordinance including, without limitation, the Comprehensive
Environmental Response, Compensation and Liability Act of 1980, as amended,
which liability would have a Material Adverse Effect on Seller; except as
Previously Disclosed, there are no facts or circumstances which would reasonably
be expected to form the basis for any such proceeding, claim, action or
governmental investigation that would impose any such liability; and neither
Seller nor any Seller Subsidiary is subject to any agreement, order, judgment,
decree or memorandum by or with any court, governmental authority, regulatory
agency or third party imposing any such liability.

     2.21.  ADMINISTRATION OF TRUST ACCOUNTS

     Each Seller Subsidiary has properly administered all common trust funds and
collective investment funds and all accounts for which it acts as a fiduciary or
agent, including but not limited to accounts for which it serves as a trustee,
agent, custodian, personal representative, guardian, conservator or investment
advisor, in accordance with the terms of the governing documents and applicable
state and federal law and regulation and common law, except where the failure to
do so would not, individually or in the aggregate, have a Material Adverse
Effect on Seller. Neither Seller, any Seller Subsidiary, nor any director,
officer or employee of Seller or any Seller Subsidiary acting on behalf of
Seller or a Seller Subsidiary, has committed any breach of trust with respect to
any such common trust fund or collective investment fund or fiduciary or agency
account, and the accountings for each such common trust fund or collective
investment fund or fiduciary or agency account are true and correct in all
material respects and accurately reflect the assets of such common trust fund or
collective investment fund or fiduciary or agency account, except for such
breaches and failures to be true, correct and accurate which would not,
individually or in the aggregate, have a Material Adverse Effect on Seller.

     2.22.  INTELLECTUAL PROPERTY

     Except as Previously Disclosed, Seller or a Seller Subsidiary owns the
entire right, title and interest in and to, or has valid licenses with respect
to, all of the Intellectual Property necessary in all material respects to
conduct the business and operations of Seller and the Seller Subsidiaries as
presently conducted, except where the failure to do so would not, individually
or in the aggregate, have a Material

                                      A-14
<PAGE>   100

Adverse Effect on Seller. The ownership, licensing or use of Intellectual
Property by Seller or its Subsidiaries does not conflict with, infringe,
misappropriate or otherwise violate the Intellectual Property rights of any
other person or entity. None of such Intellectual Property is subject to any
outstanding order, decree, judgment, stipulation, settlement, lien, charge,
encumbrance or attachment, which order, decree, judgment, stipulation,
settlement, lien, charge, encumbrance or attachment would have a Material
Adverse Effect on Seller. Except as Previously Disclosed, upon consummation of
the transactions contemplated by this Agreement Purchaser and the Purchaser
Subsidiaries will be entitled to continue to use all such Intellectual Property
without the payment of any fees, licenses or other payments (other than ongoing
payments required under license agreements for software used by Seller or the
Seller Subsidiaries in Previously Disclosed amounts consistent with past
practice).

     2.23.  RISK MANAGEMENT INSTRUMENTS

     All interest rate swaps, caps, floors, option agreements, futures and
forward contracts and other similar risk management arrangements to which Seller
or a Seller Subsidiary is a party, whether entered into for Seller's own
account, or for the account of one or more of the Seller Subsidiaries or their
customers, were entered into (i) in accordance with prudent business practices
and all applicable laws, rules, regulations and regulatory policies and (ii)
with counterparties believed to be financially responsible at the time; and each
of them constitutes the valid and legally binding obligation of Seller or one of
the Seller Subsidiaries, enforceable in accordance with its terms (except as
enforceability may be limited by applicable bankruptcy, insolvency,
reorganization, moratorium, fraudulent transfer and similar laws of general
equity principles), and neither Seller nor any Seller Subsidiary nor to Seller's
knowledge, any other party thereto, is in breach of any of its obligations under
any such agreement or arrangement. Seller has previously made available to
Purchaser all of such agreements and arrangements that are in effect as of the
date of this Agreement.

     2.24.  REPURCHASE AGREEMENTS

     With respect to all agreements pursuant to which Seller or any Seller
Subsidiary has purchased securities subject to an agreement to resell, if any,
Seller or such Seller Subsidiary, as the case may be, has a valid, perfected
first lien or security interest in or evidence of ownership in book entry form
of the government securities or other collateral securing the repurchase
agreements, and the value of such collateral equals or exceeds the amount of the
debt secured thereby.

     2.25.  CERTAIN INFORMATION

     When the Registration Statement or any post-effective amendment thereto
shall become effective, and at all times subsequent to such effectiveness up to
and including the time of the Seller shareholders' meeting to vote upon the
Merger, such Registration Statement and all amendments or supplements thereto,
with respect to all information set forth or incorporated by reference therein
furnished by Seller relating to Seller and the Seller Subsidiaries, (i) shall
comply in all material respects with the applicable provisions of the Securities
Laws, and (ii) shall not contain any untrue statement of a material fact or omit
to state a material fact required to be stated therein or necessary to make the
statements contained therein not misleading. All information concerning Seller
and its directors, officers, shareholders and any Subsidiaries included (or
submitted for inclusion) in any application and furnished by it pursuant to
Section 4.3 of this Agreement shall be true, correct and complete in all
material respects.

     2.26.  YEAR 2000

     The computer software operated by Seller and any Seller Subsidiary which is
material to the conduct of the business of Seller and any Seller Subsidiary is
capable of providing uninterrupted

                                      A-15
<PAGE>   101

millennium functionality to record, store, process and present calendar dates
falling on or after January 1, 2000 in substantially the same manner and with
the same functionality as such software records, stores, processes and presents
such calendar dates falling on or before December 31, 1999, and such software
and Seller and any Seller Subsidiary currently are otherwise in compliance with
all relevant Regulatory Authority guidance and requirements relating to the Year
2000 computer issues including the statements of the Federal Financial
Institutions Examination Council, dated May 5, 1997, entitled "Year 2000 Project
Management Awareness,"and December 1997, entitled "Safety and Soundness
Guidelines Concerning the Year 2000 Business Risk." The costs of the adaptations
referred to in this clause have not and will not have a Material Adverse Effect
on Seller.

     2.27.  TAX TREATMENT

     As of the date of this Agreement, Seller knows of no reason relating to it
or any of the Seller Subsidiaries which would reasonably cause it to believe
that the Merger will not qualify as a reorganization under Section 368(a) of the
Code.

     2.28.  TAKEOVER LAWS

     Seller has taken all action required to by taken by it in order to exempt
this Reorganization Agreement, the Plan of Merger and the Option Agreement and
the transactions contemplated hereby and thereby from, and this Reorganization
Agreement, the Plan of Merger and the Option Agreement and the transactions
contemplated hereby and thereby are exempt from, the requirements of any
"moratorium," "control share," "fair price," "affiliate transaction," "business
combination," or other antitakeover laws and regulations of any state
(collectively, "Takeover Laws"), including, without limitation, the Commonwealth
of Pennsylvania.

                                   ARTICLE 3.
                       REPRESENTATIONS AND WARRANTIES OF
                            PURCHASER AND MERGER SUB

     Except as Previously Disclosed, Purchaser and Merger Sub hereby jointly and
severally represent and warrant to Seller as follows:

     3.1.  CAPITAL STRUCTURE OF PURCHASER

     The authorized capital stock of Purchaser consists at March 31, 2000 of (i)
1,000,000 shares of preferred stock, par value $1.00 per share ("Purchaser
Preferred Stock"), none of which were issued and outstanding and (ii) 15,000,000
shares of common stock, par value $5.00 per share ("Purchaser Common Stock"), of
which, as of the date hereof, 7,640,239 shares were issued and outstanding and
461,300 shares were held in treasury. All outstanding shares of Purchaser
capital stock have been duly authorized and validly issued and are fully paid
and nonassessable. None of the shares of Purchaser's capital stock has been
issued in violation of the preemptive rights of any person. The shares of
Purchaser Common Stock to be issued in connection with the Merger have been duly
authorized and, when issued in accordance with the terms of this Reorganization
Agreement and the Plan of Merger, will be validly issued, fully paid,
nonassessable and free and clear of any preemptive rights.

     3.2.  ORGANIZATION, STANDING AND AUTHORITY OF PURCHASER

     Purchaser is a duly organized corporation, validly existing and in good
standing under the laws of New York, with full corporate power and authority to
carry on its business as now conducted and is duly licensed or qualified to do
business in the states of the United States and foreign jurisdictions

                                      A-16
<PAGE>   102

where its ownership or leasing of property or the conduct of its business
requires such qualification, except where the failure to be so licensed or
qualified would not have a Material Adverse Effect on Purchaser. Purchaser is
registered as a bank holding company under the Bank Holding Company Act.

     3.3.  OWNERSHIP OF PURCHASER SUBSIDIARIES; CAPITAL STRUCTURE OF PURCHASER
SUBSIDIARIES

     Purchaser has no Subsidiary other than those disclosed in its Annual Report
on Form 10-K for the year ended December 31, 1999, Merger Sub or any Subsidiary
that is not a significant subsidiary under the SEC's Regulation S-X. Except as
Previously Disclosed, the outstanding shares of capital stock of the Purchaser
Subsidiaries have been duly authorized and validly issued and are fully paid and
(except as provided in 12 U.S.C. sec. 55 or Section 114 of the New York Banking
Law) nonassessable and all such shares are directly or indirectly owned by
Purchaser free and clear of all liens, claims and encumbrances. No Purchaser
Subsidiary has or is bound by any Rights which are authorized, issued or
outstanding with respect to the capital stock of any Purchaser Subsidiary and,
except as Previously Disclosed, there are no agreements, understandings or
commitments relating to the right of Purchaser to vote or to dispose of said
shares. None of the shares of capital stock of any Purchaser Subsidiary has been
issued in violation of the preemptive rights of any person.

     3.4.  ORGANIZATION, STANDING AND AUTHORITY OF PURCHASER SUBSIDIARIES

     Each Purchaser Subsidiary is a duly organized corporation or banking
corporation, validly existing and in good standing under applicable laws. Each
Purchaser Subsidiary (i) has full power and authority to carry on its business
as now conducted, and (ii) is duly licensed or qualified to do business in the
states of the United States and foreign jurisdictions where its ownership or
leasing of property or the conduct of its business requires such licensing or
qualification and where failure to be licensed or qualified would have a
Material Adverse Effect on Purchaser. Each Purchaser Subsidiary has all federal,
state, local and foreign governmental authorizations necessary for it to own or
lease its properties and assets and to carry on its business as it is now being
conducted, except where the failure to be so authorized would not have a
Material Adverse Effect on Purchaser.

     3.5.  AUTHORIZED AND EFFECTIVE AGREEMENT

     (a) Each of Purchaser and Merger Sub has all requisite corporate power and
authority to enter into and perform all of its obligations under this
Reorganization Agreement and the Plan of Merger. The execution and delivery of
this Reorganization Agreement and the Plan of Merger and the consummation of the
transactions contemplated hereby and thereby have been duly and validly
authorized by all necessary corporate action in respect thereof on the part of
Purchaser and Merger Sub, except (i) that the affirmative vote of the holders of
a majority of the votes cast by the holders of Purchaser capital stock eligible
to vote thereon is required to authorize an amendment to Purchaser's Certificate
of Incorporation to increase the number of authorized shares of Purchaser Common
Stock to 150,000,000, in accordance with the applicable provisions of the New
York Business Corporation Law, and (ii) the affirmative vote of the holders of a
majority of the votes cast at a meeting of Purchaser shareholders at which a
quorum is present is required to authorize the issuance of Purchaser Common
Stock pursuant to this Reorganization Agreement and the Plan of Merger in
accordance with the rules of the NYSE. The Board of Directors of Purchaser has
directed that the issuance of Purchaser Common Stock pursuant to this
Reorganization Agreement and Plan of Merger and the increase in the number of
authorized shares of Purchaser Common Stock be submitted to Purchaser's
stockholders for approval at a special meeting to be held as soon as
practicable.

     (b) Assuming the accuracy of the representation contained in Section 2.5(b)
hereof, this Reorganization Agreement and the Plan of Merger constitute legal,
valid and binding obligations of each

                                      A-17
<PAGE>   103

of Purchaser and Merger Sub, in each case enforceable against it in accordance
with their respective terms subject, as to enforceability, to bankruptcy,
insolvency and other laws of general applicability relating to or affecting
creditors' rights and to general equity principles.

     (c) Neither the execution and delivery of this Reorganization Agreement or
the Plan of Merger, nor consummation of the transactions contemplated hereby or
thereby, nor compliance by Purchaser or Merger Sub with any of the provisions
hereof or thereof shall (i) conflict with or result in a breach of any provision
of the articles or certificate of incorporation or association, charter or
bylaws of Purchaser or any Purchaser Subsidiary, (ii) assuming the consents and
approvals contemplated by Section 4.3 hereof and the consents and approvals
which are Previously Disclosed are duly obtained, constitute or result in a
breach of any term, condition or provision of, or constitute a default under, or
give rise to any right of termination, cancellation or acceleration with respect
to, or result in the creation of any lien, charge or encumbrance upon any
property or asset of Purchaser or any Purchaser Subsidiary pursuant to, any
note, bond, mortgage, indenture, license, agreement or other instrument or
obligation, or (iii) assuming the consents and approvals contemplated by Section
4.3 hereof and the consents and approvals which are Previously Disclosed are
duly obtained, violate any order, writ, injunction, decree, statute, rule or
regulation applicable to Purchaser or any Purchaser Subsidiary, except (in the
case of clauses (ii) and (iii) above) for such violations, rights, conflicts,
breaches, creations or defaults which, either individually or in the aggregate,
will not have a Material Adverse Effect on Purchaser.

     (d) Except for approvals specified in Section 4.3 hereof and except as
expressly referred to in this Reorganization Agreement, no consent, approval or
authorization of, or declaration, notice, filing or registration with, any
governmental or regulatory authority, or any other person, is required to be
made or obtained by Purchaser or Merger Sub on or prior to the Closing Date in
connection with the execution, delivery and performance of this Agreement and
the Plan of Merger or the consummation of the transactions contemplated hereby
or thereby. As of the date hereof, Purchaser is not aware of any reason that the
condition set forth in Section 5.1(b) of this Agreement, including the proviso
thereto, would not be satisfied.

     3.6.  SEC DOCUMENTS; REGULATORY FILINGS

     Purchaser has filed all SEC Documents required by the Securities Laws and
such SEC Documents complied, as of their respective dates, in all material
respects with the Securities Laws. Purchaser and each of the Purchaser
Subsidiaries has filed all reports required by statute or regulation to be filed
with any federal or state bank regulatory agency, except where the failure to so
file would not have a Material Adverse Effect on Purchaser, and such reports
were prepared in accordance with the applicable statutes, regulations and
instructions in existence as of the date of filing of such reports in all
material respects.

     3.7.  FINANCIAL STATEMENTS; BOOKS AND RECORDS; MINUTE BOOKS

     The Purchaser Financial Statements filed by Purchaser in SEC documents
prior to the date of this Agreement fairly present, and the Purchaser Financial
Statements filed by Purchaser in SEC Documents after the date of the Agreement
will fairly present the consolidated financial position of Purchaser and its
consolidated Subsidiaries as of the dates indicated and the consolidated results
of operations, changes in shareholders' equity and cash flows of Purchaser and
its consolidated Subsidiaries for the periods then ended and each such financial
statement has been or will be, as the case may be, prepared in conformity with
generally accepted accounting principles applicable to financial institutions
applied on a consistent basis except as disclosed therein and except in the case
of unaudited statements, as permitted by Form 10-Q. The books and records of
Purchaser and each Purchaser Subsidiary fairly reflect in all material respects
the transactions to which it is a party or by which its properties are subject
or bound.

                                      A-18
<PAGE>   104

Such books and records have been properly kept and maintained and are in
compliance in all material respects with all applicable legal and accounting
requirements. The minute books of Purchaser and the Purchaser Subsidiaries
contain records which are accurate in all material respects of all corporate
actions of its shareholders and Board of Directors (including committees of its
Board of Directors).

     3.8.  MATERIAL ADVERSE CHANGE

     Purchaser has not, on a consolidated basis, suffered any change in its
financial condition, results of operations or business since December 31, 1999
which individually or in the aggregate with any other such changes would
constitute a Material Adverse Effect with respect to Purchaser.

     3.9.  ABSENCE OF UNDISCLOSED LIABILITIES

     Neither Purchaser nor any Purchaser Subsidiary has any liability
(contingent or otherwise), excluding contractually assumed contingencies, that
is material to Purchaser on a consolidated basis, or that, when combined with
all similar liabilities, would be material to Purchaser on a consolidated basis,
except as Previously Disclosed, as disclosed in the Purchaser Financial
Statements filed with the SEC prior to the date hereof and except for
liabilities incurred in the ordinary course of business subsequent to December
31, 1999.

     3.10.  EMPLOYEE BENEFIT PLANS

     Each of the Purchaser Plans complies in all material respects with the
requirements of applicable law, including ERISA and the Code. For purposes of
this Agreement, the term "Purchaser Plan" means each bonus, incentive
compensation, severance pay, medical or other insurance program, retirement
plan, or other employee benefit plan program, agreement or arrangement
sponsored, maintained or contributed to by Purchaser or any trade or business,
whether or not incorporated, that together with Purchaser or any of the
Purchaser Subsidiaries would be deemed a "single employer" under Section 414 of
the Code (an "ERISA affiliate") or under which Purchaser or any ERISA affiliate
has any liability or obligation. No liability under Title IV of ERISA has been
incurred by Purchaser or any ERISA affiliate that has not been satisfied in
full, and no condition exists that presents a material risk to Purchaser or any
ERISA affiliate of incurring any such liability. Full payment has been made, or
will be made in accordance with Section 404(a)(6) of the Code of all amounts
that Purchaser or any ERISA affiliate is required to pay under Section 412 of
the Code or under the terms of the Purchaser Plans, and no accumulated funding
deficiency (within the meaning of Section 412 of the Code) exists with respect
to any Purchaser Plan.

     3.11.  LEGAL PROCEEDINGS

     There are no actions, suits or proceedings instituted, pending or, to the
knowledge of Purchaser and Merger Sub, threatened (or unasserted but considered
probable of assertion and which if asserted would have at least a reasonable
probability of an unfavorable outcome) against Purchaser, Merger Sub or any
Purchaser Subsidiary or against any asset, interest or right of Purchaser or any
Purchaser Subsidiary as to which there is a reasonable probability of an
unfavorable outcome and which, if such an unfavorable outcome was rendered,
would, individually or in the aggregate, have a Material Adverse Effect on
Purchaser. There are no actual or threatened actions, suits or proceedings which
present a claim to restrain or prohibit the transactions contemplated herein or
to impose any material liability in connection therewith as to which there is a
reasonable probability of an unfavorable outcome and which, if such an
unfavorable outcome was rendered, would, individually or in the aggregate, have
a Material Adverse Effect on Purchaser.

                                      A-19
<PAGE>   105

     3.12.  COMPLIANCE WITH LAWS

     Except as Previously Disclosed, each of Purchaser and the Purchaser
Subsidiaries is in compliance in all material respects with all statutes and
regulations applicable to the conduct of its business, and none of them has
received notification from any agency or department of federal, state or local
government (i) asserting a material violation of any such statute or regulation,
(ii) threatening to revoke any license, franchise, permit or government
authorization or (iii) restricting or in any way limiting its operations, except
for such noncompliance, violations, revocations and restrictions which would
not, individually or in the aggregate, have a Material Adverse Effect on
Purchaser. None of Purchaser or any Purchaser Subsidiary is subject to any
regulatory or supervisory cease and desist order, agreement, directive,
memorandum of understanding or commitment which could be reasonably anticipated
to have a Material Adverse Effect on Purchaser, and none of them has received
any communication requesting that they enter into any of the foregoing.

     3.13.  TAX MATTERS

     (a) Purchaser and each Purchaser Subsidiary have timely filed federal
income tax returns for each year through December 31, 1998 and have timely
filed, or caused to be filed, all other Tax Returns required to be filed with
respect to Purchaser or any Purchaser Subsidiary, except where the failure to
file timely such federal income and other Tax Returns would not, in the
aggregate, have a Material Adverse Effect on Purchaser. All Taxes due by or on
behalf of Purchaser or any Purchaser Subsidiary have been paid or adequate
reserves have been established on the Purchaser Financial Statements for the
payment of such Taxes, except where any such failure to pay or establish
adequate reserves would not, in the aggregate, have a Material Adverse Effect on
Purchaser. Neither Purchaser nor any Purchaser Subsidiary will have any material
liability for any such Taxes in excess of the amounts so paid or reserves or
accruals so established except where such liability would not have a Material
Adverse Effect on Purchaser.

     (b) All Tax Returns filed by Purchaser and each Purchaser Subsidiary are
complete and accurate in all material respects. Neither Purchaser nor any
Purchaser Subsidiary is delinquent in the payment of any material Tax, and,
except as Previously Disclosed, none of them has requested any extension of time
within which to file any Tax Returns which have not since been filed. Except as
Previously Disclosed or as fully settled and paid or accrued on the Purchaser
Financial Statements, no material audit examination, deficiency, adjustment,
refund claim or litigation with respect to Tax Returns, paid Taxes, unpaid Taxes
or Tax attributes of Purchaser or any Purchaser Subsidiary has been proposed,
asserted or assessed (tentatively or otherwise).

     (c) Neither Purchaser nor any Purchaser Subsidiary is required to include
in income any adjustment in any taxable period ending after the date hereof
pursuant to Section 481(a) of the Code other than any adjustment for which it
already has made an accrual.

     (d) For purposes of this Section 3.13 and Section 3.19, (i) references to
Purchaser and any Purchaser Subsidiary shall include predecessors thereof and
(ii) "Purchaser Subsidiary" shall include each Subsidiary (as defined in Article
1 hereof) of Purchaser, and each corporation, partnership, limited liability
company, joint venture or other entity which Purchaser controls directly or
indirectly (through one or more intermediaries). For purposes of the previous
sentence, "control" means the possession, direct or indirect, of the power
either (1) to vote fifty percent (50%) or more of the voting interests of a
corporation, partnership, limited liability company, joint venture or other
entity, or (2) to direct or cause the direction of the management and policies
of a corporation, partnership, limited liability company, joint venture or other
entity, whether by contract or otherwise.

                                      A-20
<PAGE>   106

     3.14.  BROKERS AND FINDERS

     Neither Purchaser nor any Purchaser Subsidiary, nor any of their respective
officers, directors or employees, has employed any broker, finder or financial
advisor or incurred any liability for any fees or commissions in connection with
the transactions contemplated herein or the Plan of Merger, except for
Purchaser's retention of Merrill Lynch & Co. ("Merrill Lynch") to perform
certain financial advisory services as Previously Disclosed. Prior to the
execution and delivery of this Agreement, Merrill Lynch has delivered to the
Board of Directors of Purchaser an opinion that the Merger is fair from a
financial point of view to the shareholders of Purchaser.

     3.15.  INSURANCE

     Purchaser and the Purchaser Subsidiaries each currently maintains insurance
in amounts considered by Purchaser and any Purchaser Subsidiary as applicable,
to be reasonably necessary for their operations. Neither Purchaser nor any
Purchaser Subsidiary has received any notice of a material premium increase or
cancellation with respect to any of its insurance policies or bonds, and within
the last three years, neither Purchaser nor any Purchaser Subsidiary has been
refused any insurance coverage sought or applied for, and Purchaser has no
reason to believe that existing insurance coverage cannot be renewed as and when
the same shall expire, upon terms and conditions as favorable as those presently
in effect, other than possible increases in premiums or unavailability in
coverage that have not resulted from any extraordinary loss experience of
Purchaser or any Purchaser Subsidiary.

     3.16.  ENVIRONMENTAL LIABILITY

     Neither Purchaser nor any Purchaser Subsidiary has received any written
notice of any legal, administrative, arbitral or other proceeding, claim or
action and, to the knowledge of Purchaser and the Purchaser Subsidiaries, there
is no governmental investigation of any nature ongoing, in each case that could
reasonably be expected to result in the imposition, on Purchaser or any
Purchaser Subsidiary of any liability arising under any local, state or federal
environmental statute, regulation or ordinance including, without limitation,
the Comprehensive Environmental Response, Compensation and Liability Act of
1980, as amended, which liability would have a Material Adverse Effect on
Purchaser; except as Previously Disclosed, there are no facts or circumstances
which could reasonably be expected to form the basis for any such proceeding,
claim, action or governmental investigation that would impose any such
liability; and neither Purchaser nor any Purchaser Subsidiary is subject to any
agreement, order, judgment, decree or memorandum by or with any court,
governmental authority, regulatory agency or third party imposing any such
liability.

     3.17.  CERTAIN INFORMATION

     When the Registration Statement or any post-effective amendment thereto
shall become effective, and at all times subsequent to such effectiveness up to
and including the time of the Seller shareholders' meeting to vote upon the
Merger, such Registration Statement and all amendments or supplements thereto,
with respect to all information set forth or incorporated by reference therein
furnished by Purchaser relating to Purchaser and the Purchaser Subsidiaries, (i)
shall comply in all material respects with the applicable provisions of the
Securities Laws, and (ii) shall not contain any untrue statement of a material
fact or omit to state a material fact required to be stated therein or necessary
to make the statements contained therein not misleading. All information
concerning Purchaser and its directors, officers, shareholders and any
Subsidiaries included (or submitted for inclusion) in any application and
furnished by it pursuant to Section 4.3 of this Agreement shall be true, correct
and complete in all material respects.

                                      A-21
<PAGE>   107

     3.18.  YEAR 2000

     The computer software operated by Purchaser or any Purchaser Subsidiary
which is material to the conduct of Purchaser's or any Purchaser Subsidiary's
business is capable of providing uninterrupted millennium functionality to
record, store, process and present calendar dates falling on or after January 1,
2000 in substantially the same manner and with the same functionality as such
software records, stores, processes and presents such calendar dates falling on
or before December 31, 1999, and such software and Purchaser or any Purchaser
Subsidiary currently are otherwise in compliance with all relevant Regulatory
Authority guidance and requirements relating to the Year 2000 computer issues
including the statements of the Federal Financial Institutions Examination
Council, dated May 5, 1997, entitled "Year 2000 Project Management Awareness,"
and December 1997, entitled "Safety and Soundness Guidelines Concerning the Year
2000 Business Risk." The costs of the adaptations referred to in this clause
will not have a Material Adverse Effect on Purchaser.

     3.19.  TAX TREATMENT

     As of the date of this Agreement, Purchaser knows of no reason relating to
it or any of the Purchaser Subsidiaries which would reasonably cause it to
believe that the Merger will not qualify as a reorganization under Section
368(a) of the Code.

     3.20.  MERGER CONSIDERATION

     Purchaser will have, at the Effective Time, unissued shares of Common Stock
and shares of Common Stock held in its treasury that are not reserved for any
other purpose sufficient to provide the Stock Consideration and also will have
available to it at the Effective Time funds sufficient to provide the Cash
Consideration.

                                   ARTICLE 4.
                                   COVENANTS

     4.1.  SHAREHOLDERS' MEETING

     Seller and Purchaser shall submit this Reorganization Agreement and the
Plan of Merger and, in the case of Purchaser, the issuance of Purchaser Common
Stock thereunder and the amendment to its Certificate of Incorporation to
increase the number of authorized shares of Purchaser Common Stock, to their
respective shareholders for approval at special meetings to be held as soon as
practicable. Subject to the fiduciary duties of the respective boards of
directors of Seller and Purchaser as determined after consultation with counsel,
the boards of directors of Seller and Purchaser shall recommend that the
shareholders of the respective companies vote in favor of such approval.

     4.2.  PROXY STATEMENT; REGISTRATION STATEMENT

     As promptly as practicable after the date hereof, Purchaser and Seller
shall cooperate in the preparation of the Proxy Statement to be mailed to the
shareholders of Seller and Purchaser in connection with this Agreement and the
transactions contemplated hereby and to be filed by Purchaser as part of the
Registration Statement. Purchaser will advise Seller, promptly after it receives
notice thereof, of the time when the Registration Statement or any
post-effective amendment thereto has become effective or any supplement or
amendment has been filed, of the issuance of any stop order, of the suspension
of qualification of the Purchaser Common Stock issuable in connection with the
Merger for offering or sale in any jurisdiction, or the initiation or threat of
any proceeding for any such purpose, or of any request by the SEC for the
amendment or supplement of the Registration Statement or for additional
information. Purchaser shall take all actions necessary to register or qualify
the shares of

                                      A-22
<PAGE>   108

Purchaser Common Stock to be issued in the Merger pursuant to all applicable
state "blue sky" or securities laws and shall maintain such registrations or
qualifications in effect for all purposes hereof. Purchaser shall apply for, and
shall use reasonable best efforts to obtain, approval to list the shares of
Purchaser Common Stock to be issued in the Merger on the NYSE, subject to
official notice of issuance, prior to the Effective Date.

     4.3.  APPLICATIONS

     As promptly as practicable after the date hereof, and after a reasonable
opportunity for review by counsel to Seller, Purchaser shall submit any
requisite applications for prior approval of, and notices with respect to, the
transactions contemplated herein, in the Plan of Merger and in the Bank Merger
Agreement, to (i) the Federal Reserve Board pursuant to Sections 3 and 4 of the
Bank Holding Company Act and the Bank Merger Act, (ii) the New York Banking
Board pursuant to Section 142 of the New York Banking Law, (iii) the OCC
pursuant to 12 C.F.R. sec. 5.33(g)(3), and (iv) the Pennsylvania Department of
Banking pursuant to Sections 115 and 1603 of the Pennsylvania Banking Code, and
the regulations promulgated thereunder, and each of the parties hereto shall,
and they shall cause their respective subsidiaries to, submit any applications,
notices or other filings to any other state or federal government agency,
department or body the approval of which is required for consummation of the
Merger and the Bank Merger. Seller and Purchaser each represents and warrants to
the other that all information concerning it and its directors, officers,
shareholders and subsidiaries included (or submitted for inclusion) in any such
application and furnished by it shall be true, correct and complete in all
material respects.

     4.4.  BEST EFFORTS

     (a) Subject to the terms and conditions of this Agreement, Purchaser,
Merger Sub, and Seller shall each use its reasonable best efforts in good faith,
and each of them shall cause its Subsidiaries to use their reasonable best
efforts in good faith, to (i) furnish such information as may be required in
connection with the preparation of the documents referred to in Sections 4.2 and
4.3 above, and (ii) take or cause to be taken all action necessary or desirable
on its part so as to permit consummation of the Merger at the earliest possible
date, including, without limitation, (1) obtaining the consent or approval of
each individual, partnership, corporation, association or other business or
professional entity whose consent or approval is required for consummation of
the transactions contemplated hereby, provided that neither Seller nor any
Seller Subsidiary shall agree to make any payments or modifications to
agreements in connection therewith without the prior written consent of
Purchaser, which consent shall not be unreasonably withheld and (2) requesting
the delivery of appropriate opinions, consents and letters from its counsel and
independent auditors. Subject to the terms and conditions of this Agreement, no
party hereto shall take or fail to take, or cause or permit its Subsidiaries to
take or fail to take, or to the best of its ability permit to be taken or
omitted to be taken by any third persons, any action that would substantially
impair the prospects of completing the Merger pursuant to this Reorganization
Agreement and the Plan of Merger, that would materially delay such completion,
or that would adversely affect the qualification of the Merger as a
reorganization within the meaning of Section 368(a) of the Code; provided that
nothing herein contained shall preclude Purchaser from exercising its rights
under the Option Agreement. In the event that either party has taken any action,
whether before, on or after the date hereof, that would adversely affect such
qualification, each party shall take such action as the other party may
reasonably request to cure such effect to the extent curable without a Material
Adverse Effect on either of the parties.

     (b) Seller shall give prompt notice to Purchaser, and Purchaser shall give
prompt notice to Seller, of (i) the occurrence, or failure to occur, of any
event which occurrence or failure would be reasonably

                                      A-23
<PAGE>   109

likely to cause any representation or warranty contained in this Agreement to be
untrue or inaccurate at any time from the date hereof to the Closing Date such
that the condition set forth in Section 5.2(a) or 5.3(a), as applicable, would
not be met if such failure to be true or accurate were to occur or be continuing
on the Closing Date, and (ii) any material failure of Seller or Purchaser, as
the case may be, to comply with or satisfy any covenant, condition or agreement
to be complied with or satisfied by it hereunder, and each party shall use all
reasonable best efforts to remedy such failure.

     (c) From the date of this Agreement through the Effective Date, to the
extent permitted by law, Seller shall, and shall cause the Seller Subsidiaries
to, provide such assistance to Purchaser as shall be reasonably necessary to
assist Purchaser in converting and transferring as soon as practicable after the
Effective Date all information concerning the loans, deposits and other assets
and liabilities of Seller and the Seller Subsidiaries into Purchaser's own data
processing system, with a view to facilitating the integration of Purchaser's
and Seller's systems and otherwise combining Purchaser's and Seller's operations
upon consummation of the Merger. After execution of this Agreement, to the
extent permitted by law, Seller shall provide Purchaser with computer file
instructions with respect to the information in its data processing system
regarding the assets and liabilities of Seller and the Seller Subsidiaries,
together with operational procedures designed to implement the transfer of such
information to Purchaser, with a view to facilitating the integration of
Purchaser's and Seller's systems and otherwise combining Purchaser's and
Seller's operations upon consummation of the Merger. After execution of this
Agreement, Seller and Purchaser shall each designate an individual to serve as
liaison concerning the transfer of data processing information and other similar
operational matters and to consult as to whether and when Seller will proceed
with its pending data processing conversion.

     (d) Each party shall provide and shall request its auditors to provide the
other party with such historical financial information regarding it (and related
audit reports and consents) as the other party may reasonably request for
disclosure purposes under the Securities Laws.

     4.5.  INVESTIGATION AND CONFIDENTIALITY

     Seller and Purchaser each will keep the other advised of all material
developments relevant to its business and to consummation of the transactions
contemplated herein and in the Plan of Merger. Purchaser and Seller each may
make or cause to be made such investigation of the financial and legal condition
of the other as such party reasonably deems necessary or advisable in connection
with the transactions contemplated herein and in the Plan of Merger, provided,
however, that such investigation shall be reasonably related to such
transactions and shall not interfere unnecessarily with normal operations.
Purchaser and Seller agree to furnish the other and the other's advisors with
such financial data and other information with respect to its business and
properties as such other party shall from time to time reasonably request. No
investigation pursuant to this Section 4.5 shall affect or be deemed to modify
any representation or warranty made by, or the conditions to the obligations to
consummate the Merger of, any party hereto. Each party hereto shall hold all
information furnished by the other party or any of such party's Subsidiaries or
representatives pursuant to this Agreement in confidence to the extent required
by, and in accordance with, the provisions of the confidentiality agreement,
dated April 25, 2000, between Seller and Purchaser (the "Confidentiality
Agreement").

     4.6.  PRESS RELEASES

     Seller and Purchaser shall agree with each other as to the form and
substance of any press release related to this Reorganization Agreement and the
Plan of Merger or the transactions contemplated hereby or thereby, and shall
consult each other as to the form and substance of other public disclosures
related thereto, provided, however, that nothing contained herein shall prohibit
any party, following notification to the other parties, from making any
disclosure which is required by applicable law or

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<PAGE>   110

NYSE or Nasdaq rules. The initial press release related to this Reorganization
Agreement and the Plan of Merger and the transactions contemplated hereby and
thereby will disclose Purchaser's intention to effect the Stock Split and the
Dividend Increase.

     4.7.  ACTIONS PENDING THE MERGER

     (a) Prior to the Closing Date, and except as otherwise provided for by this
Reorganization Agreement, the Plan of Merger, the Option Agreement, or consented
to or approved by the other party hereto, each of Purchaser and Seller shall,
and shall cause each of its Subsidiaries to, use its reasonable best efforts to
preserve its properties, business and relationships with customers, employees
and other persons.

     (b) Seller shall not, and shall not permit any of the Seller Subsidiaries
to, except with the prior written consent of Purchaser and except as Previously
Disclosed or expressly contemplated or permitted by this Agreement, the Plan of
Merger, or the Option Agreement:

          (1) carry on its business other than in the usual, regular and
     ordinary course in substantially the same manner as heretofore conducted;

          (2) in the case of Seller only, declare, set aside, make or pay any
     dividend or other distribution in respect of its capital stock other than
     its regular quarterly cash dividends on Seller Common Stock in amounts not
     in excess of $0.29 per share;

          (3) issue any shares of its capital stock or permit any treasury
     shares to become outstanding other than pursuant to the Option Agreement or
     Rights outstanding at the date hereof;

          (4) incur any additional debt obligation or other obligation for
     borrowed money other than in the ordinary course of business consistent
     with past practice;

          (5) issue, grant or authorize any Rights or effect any
     recapitalization, reclassification, stock dividend, stock split or like
     change in capitalization, or redeem, repurchase or otherwise acquire any
     shares of its capital stock except for Trust Account Shares and DPC Shares,
     and except for shares to be used to fulfill Seller's obligations under the
     Seller Employee Stock Purchase Plan and the Seller 401(k) Stock Purchase
     Plan or shares repurchased or acquired in connection with the exercise of
     options outstanding under the Seller Stock Option Plans; provided, however,
     that in order to fulfill such obligations, Seller shall acquire the
     necessary shares of Seller Common Stock solely through open market
     purchases;

          (6) amend its articles or certificate of incorporation or association
     or bylaws; impose, or suffer the imposition, on any share of stock of any
     Seller Subsidiary held by Seller of any lien, charge or encumbrance, or
     permit any such lien, charge or encumbrance to exist except, in each case,
     for liens, charges and encumbrances which have been Previously Disclosed;

          (7) merge with any other corporation, savings association or bank or
     permit any other corporation, savings association or bank to merge into it
     or consolidate with any other corporation, savings association or bank;
     acquire control over any other firm, bank, corporation, savings association
     or organization or create any Subsidiary;

          (8) waive or release any material right or cancel or compromise any
     material debt or claim;

          (9) liquidate or sell or dispose of any material assets or acquire any
     material assets; except as Previously Disclosed, make any capital
     expenditure in excess of $250,000 in any instance or $1,500,000 in the
     aggregate; or, except as Previously Disclosed, establish new branches or
     other

                                      A-25
<PAGE>   111

     similar facilities, close existing branches or similar facilities or enter
     into or modify any leases or other contracts relating thereto;

          (10) increase the rate of compensation of, pay or agree to pay any
     bonus to, or provide any other employee benefit or incentive to, any of its
     directors, officers or employees except in a manner consistent with past
     practice or as required by law or contractual obligation in effect as of
     the date hereof;

          (11) change its lending, investment, asset/liability management or
     other material banking policies in any material respect except as may be
     required by changes in applicable law;

          (12) change its methods of accounting in effect at December 31, 1999,
     except as required by changes in generally accepted accounting principles
     concurred in by its independent certified public accountants, or change any
     of its methods of reporting income, deductions or other items for federal
     income tax purposes from those employed in the preparation of its federal
     income tax returns for the year ended December 31, 1999, except as required
     by applicable law;

          (13) authorize or permit any of its officers, directors, employees or
     agents to directly or indirectly solicit, initiate or encourage any
     inquiries relating to, or the making of any proposal which constitutes, a
     "Takeover Proposal" (as defined below), or, except to the extent legally
     required for the discharge of the fiduciary duties of its Board of
     Directors, recommend or endorse any Takeover Proposal, or participate in
     any discussions or negotiations, or provide third parties with any
     nonpublic information, relating to any such inquiry or proposal or
     otherwise facilitate any effort or attempt to make or implement a Takeover
     Proposal; provided, however, that Seller may communicate information about
     any such Takeover Proposal to its stockholders if, in the judgment of
     Seller's Board of Directors, after consultation with outside counsel, such
     communication is necessary in order to comply with its fiduciary duties to
     Seller's shareholders required under applicable law. Seller will take all
     actions necessary or advisable to inform the appropriate individuals or
     entities referred to in the first sentence hereof of the obligations
     undertaken herein. Seller will notify Purchaser immediately if any such
     inquiries or Takeover Proposals are received by, any such information is
     requested from, or any such negotiations or discussions are sought to be
     initiated or continued with, Seller, and Seller will promptly inform
     Purchaser in writing of all of the relevant details with respect to the
     foregoing. As used in this Agreement, "Takeover Proposal" shall mean any
     tender or exchange offer, proposal for a merger, consolidation or other
     business combination involving Seller or any Seller Subsidiary or any
     proposal or offer to acquire in any manner a substantial equity interest
     in, or a substantial portion of the assets of, Seller or any Seller
     Subsidiary other than the transactions contemplated or permitted by this
     Agreement, the Plan of Merger and the Option Agreement; or

          (14) agree to do any of the foregoing.

     (c) Purchaser shall not, and shall not permit any of the Purchaser
Subsidiaries to, except with the prior written consent of Seller or as expressly
contemplated or permitted by this Agreement, the Plan of Merger or the Option
Agreement, carry on its business other than in the usual, regular and ordinary
course in substantially the same manner as heretofore conducted.

     4.8.  CERTAIN POLICIES

     Prior to the Effective Date, Seller shall, consistent with generally
accepted accounting principles and on a basis mutually satisfactory to it and
Purchaser, modify and change its loan, litigation and real estate valuation
policies and practices (including loan classifications and levels of reserves)
so as to be applied on a basis that is consistent with that of Purchaser;
provided, however, that Seller shall not be

                                      A-26
<PAGE>   112

obligated to take any such action pursuant to this Section 4.8 unless and until
(i) Purchaser irrevocably acknowledges to Seller in writing any that all
conditions to its obligation to consummate the Merger have been satisfied and
(ii) Purchaser irrevocably waives in writing any and all rights that it may have
to terminate this Agreement and Plan of Merger.

     4.9.  CLOSING; ARTICLES OF MERGER

     The transactions contemplated by this Reorganization Agreement and the Plan
of Merger shall be consummated at a closing to be held at the offices of the law
firm of Arnold & Porter, 399 Park Avenue, New York, New York on the first
business day following satisfaction of the conditions to consummation of the
Merger set forth in Article 5 hereof (other than such conditions relating to the
actions to be taken at the Closing) or such later date during such month in
which such business day shall occur (or, if such business day shall occur within
ten (10) business days prior to the end of such month, during the next following
month) as may be mutually specified by Purchaser and Seller. In connection with
such Closing, Merger Sub and Seller shall execute a certificate of merger and
shall cause such certificate to be delivered to (i) the Delaware Secretary of
State in accordance with Section 251(c) of the Delaware General Corporation Law,
and (ii) the Pennsylvania Secretary of State in accordance with Section 1927 of
the Pennsylvania Business Corporation Law. The Merger shall be effective at the
time and on the date specified in such certificate of merger.

     4.10.  AFFILIATES

     Seller and Purchaser shall cooperate and use their best efforts to identify
those persons who may be deemed to be "affiliates" of Seller within the meaning
of Rule 145 promulgated by the Commission under the Securities Act. Seller shall
use its best efforts to cause each person so identified to deliver to Purchaser,
no later than 30 days prior to the Effective Date, a written affiliate Agreement
in a form to be agreed upon by Purchaser and Seller.

     4.11.  SELLER EMPLOYEES; DIRECTORS AND MANAGEMENT; INDEMNIFICATION

     (a) On and after the Effective Date (or as soon thereafter as may be
practicable), all persons who are employed by Seller and/or any of the Seller
Subsidiaries on such date ("Seller Employees") shall be employed on terms and
conditions (including benefits) that in the aggregate are no less favorable (as
determined by Purchaser in its reasonable discretion after consultation with
Seller) with respect to their employment by Purchaser and its Subsidiaries after
the Effective Date than those generally afforded to other similarly situated
employees of Purchaser or its Subsidiaries, subject to the terms and conditions
under which those employee benefits are made available to such employees and
provided that (i) for purposes of (A) determining eligibility for and vesting of
such employee benefits (and not for pension benefit accrual purposes), (B)
determining levels of short-term disability benefits, vacation benefits and
severance benefits under any severance pay arrangement (to the extent any such
arrangement applies to employees generally and gives credit for length of
service with Purchaser or a Purchaser Subsidiary), and (C) if applicable,
satisfying any waiting periods concerning "preexisting conditions," service with
Seller or a Seller Subsidiary or any predecessor thereto prior to the Effective
Date shall be treated as service with an "employer" to the same extent as if
such persons had been employees of Purchaser, and (ii) copayments and expenses
paid by the Seller Employees prior to the Effective Date under the Seller Plans
that provide medical benefits shall be treated as if paid under Purchaser's
employee benefit plans that provide medical benefits for purposes of determining
satisfaction of copayment and deductible requirements under such Purchaser
plans, and provided, further, that this Section 4.11(a) shall not be construed
(A) to limit the ability of Purchaser and its Subsidiaries to terminate the
employment of any employee at any time for any reason or to review employee
benefits programs from time to time and to

                                      A-27
<PAGE>   113

make such changes as they deem appropriate or (B) to require Purchaser or its
Subsidiaries to provide employees or former employees of Seller or any of its
Subsidiaries with post-retirement medical benefits more favorable than those
provided to new hires at Purchaser. Purchaser agrees to honor, or to cause the
appropriate Purchaser Subsidiary to honor, in accordance with their terms all
employment, severance and employee benefit plans, contracts, agreements and
arrangements, and understandings Previously Disclosed, provided, however, that
the foregoing shall not prevent Purchaser from amending or terminating any such
plan, contract, or agreement in accordance with its terms and applicable law.
The continued coverage of the Seller Employees under the employee benefit plans
maintained by Seller and/or any Seller Subsidiary immediately prior to the
Effective Date (the "Seller Plans") during a transition period of no more than 6
months shall be deemed to provide the Seller Employees with benefits that are no
less favorable than those offered to other employees of Purchaser and any
Purchaser Subsidiary; provided, that after the Effective Date there is no
material reduction in the benefits provided under the Seller Plans. No provision
of this Section 4.11(a) shall create any third party beneficiary rights in any
employee or former employee of Seller (including any beneficiary or dependent
thereof) in respect of continued employment (or resumed employment) or any other
matter.

     (b) Prior to the Effective Date, Seller shall take all actions that may be
requested by Purchaser in writing upon advance notice of not less than 45 days
with respect to (i) causing one or more Seller Plans to terminate as of the
Effective Date or for benefit accrual and entitlements to cease as of the
Effective Date, (ii) causing the continuation on and after the Effective Date of
any contract, arrangement or insurance policy relating to any Seller Plan for
such period as may be requested by Purchaser, or (iii) cooperating with
Purchaser to facilitate the merger of any Seller Plan into any Purchaser Plan on
or following the Effective Date. Except for a purchase period commencing on July
1, 2000, Seller shall not authorize the commencement of any new purchase period
under any Seller Stock Purchase Plan between the date hereof and the termination
of this Reorganization Agreement and shall not extend any purchase period that
is in effect on the date hereof beyond its originally scheduled date of
termination. Any purchase period that would otherwise continue past the
Effective Date shall be terminated effective immediately prior to the Effective
Date.

     (c) Purchaser and Purchaser's Board of Directors shall, prior to the
Effective Date, take all requisite action to, as of the Effective Date, (i)
elect as directors of Purchaser Messrs. Carl L. Campbell and four other
individuals designated by Mr. Campbell who are reasonably acceptable to
Purchaser (Mr. Campbell and such four other individuals collectively, the
"Seller Designees") and to elect Mr. Campbell as Vice Chairman of Purchaser and
(ii) cause Purchaser Bank's Board of Directors to take all requisite action to
elect the Seller Designees as directors of Purchaser Bank and to elect Mr.
Campbell as Vice Chairman of Purchaser Bank. For a period of at least one year
following the Effective Date, Mr. Campbell shall additionally serve as Chairman
of Purchaser's Pennsylvania Division.

     (d) In the event of any threatened or actual claim, action, suit,
proceeding or investigation, whether civil, criminal or administrative,
including, without limitation, any such claim, action, suit, proceeding or
investigation in which any person who is now, or has been at any time prior to
the date of this Agreement, or who becomes prior to the Effective Date, a
director or officer of Seller (the "Indemnified Parties") is, or is threatened
to be, made a party based in whole or in part on, or arising in whole or in part
out of, or pertaining to (i) the fact that he is or was a director, officer or
employee of Seller, or any Seller Subsidiary or any of their respective
predecessors or (ii) this Agreement, the Plan of Merger, the Option Agreement or
any of the transactions contemplated hereby or thereby, whether in any case
asserted or arising before or after the Effective Date, the parties hereto agree
to cooperate and use their best efforts to defend against and respond thereto.
On and after the Effective Date, Purchaser shall indemnify and hold harmless, as
and to the fullest extent permitted by law, each such Indemnified Party against
any losses, claims, damages, liabilities, costs, expenses (including reasonable
attorney's fees and

                                      A-28
<PAGE>   114

expenses in advance of the final disposition of any claim, suit, proceeding or
investigation to each Indemnified Party to the fullest extent permitted by law
upon receipt of any undertaking required by applicable law), judgments, fines
and amounts paid in settlement in connection with any such threatened or actual
claim, action, suit, proceeding or investigation, and in the event of any such
threatened or actual claim, action, suit, proceeding or investigation (whether
asserted or arising before or after the Effective Date), the Indemnified Parties
may retain counsel reasonably satisfactory to them after consultation with
Purchaser; provided, however, that (1) Purchaser shall have the right to assume
the defense thereof and upon such assumption Purchaser shall not be liable to
any Indemnified Party for any legal expenses of other counsel or any other
expenses subsequently incurred by any Indemnified Party in connection with the
defense thereof, except that if Purchaser elects not to assume such defense or
counsel for the Indemnified Parties reasonably advises the Indemnified Parties
that there are issues which raise conflicts of interest between Purchaser and
the Indemnified Parties, the Indemnified Parties may retain counsel reasonably
satisfactory to them after notification, and Purchaser shall pay the reasonable
fees and expenses of such counsel for the Indemnified Parties, (2) Purchaser
shall be obligated pursuant to this paragraph to pay for only one firm of
counsel for all Indemnified Parties, (3) Purchaser shall not be liable for any
settlement effected without its prior written consent (which consent shall not
be unreasonably withheld), and (4) Purchaser shall have no obligation hereunder
to any Indemnified Party when and if a court of competent jurisdiction shall
ultimately determine, and such determination shall have become final and
nonappealable, that indemnification of such Indemnified Party in the manner
contemplated hereby is prohibited by applicable law. Any Indemnified Party
wishing to claim Indemnification under this Section 4.11(d), upon learning of
any such claim, action, suit, proceeding or investigation, shall promptly notify
Purchaser thereof, provided that the failure of any Indemnified Party to so
notify Purchaser shall not relieve it of its obligations hereunder except (and
only) to the extent that such failure materially prejudices Purchaser.

     (e) Purchaser agrees that all rights to indemnification and all limitations
on liability existing in favor of the directors, officers and employees of
Seller and any Seller Subsidiary (the "Covered Parties") as provided in their
respective Certificates of Incorporation, Bylaws or similar governing documents
as in effect as of the date of this Agreement with respect to matters occurring
prior to the Effective Date shall survive the Merger and shall continue in full
force and effect, and shall be honored by such entities or their respective
successors as if they were the indemnifying party thereunder, without any
amendment thereto, for a period of six years from the Effective Date; provided,
however, that all rights to indemnification in respect of any claim asserted or
made within such period ("Claim") shall continue until the final disposition of
such Claim; provided, further, however, that nothing contained in this Section
4.11(e) shall be deemed to preclude the liquidation, consolidation or merger of
Seller or any Seller Subsidiary, in which case all of such rights to
indemnification and limitations on liability shall be deemed to so survive and
continue as an obligation of Purchaser or the successor to Seller or the Seller
Subsidiary notwithstanding any such liquidation, consolidation or merger.

     (f) Purchaser, from and after the Effective Date will use its reasonable
best efforts directly or indirectly to cause the persons who served as directors
or officers of Seller on or before the Effective Date to be covered by Seller's
existing directors' and officers' liability insurance policy (provided that
Purchaser may substitute therefor policies of at least the same coverage and
amounts containing terms and conditions which are not less advantageous than
such policy) but in no event shall any insured person be entitled under this
Section 4.11(f) to insurance coverage more favorable than that provided to him
or her in such capacities as of the date hereof with respect to acts or
omissions resulting from their service as such on or prior to the Effective
Date. Such insurance coverage, if reasonably available at a reasonable cost
relative to the coverage obtained, shall commence on the Effective Date and will
be provided for a period of no less than four years after the Effective Date;
provided, however, that in no

                                      A-29
<PAGE>   115

event shall Purchaser be required to expend more than 200% of the current amount
expended by Seller (the "Insurance Amount") to maintain or procure insurance
coverage pursuant hereto and, provided, further, that the Insurance Amount shall
be deemed reasonable for purposes of this Section 4.11(f). Seller agrees to
renew any such existing insurance or to purchase any "discovery period"
insurance provided for thereunder at Purchaser's request.

     (g) In the event Purchaser or any of its successors or assigns (i)
consolidates with or merges into any other person and shall not be the
continuing or surviving corporation or entity of such consolidation or merger,
or (ii) transfers or conveys all or substantially all of its properties and
assets to any person, then, and in each such case, to the extent necessary,
proper provision shall be made so that the successors and assigns of Purchaser
assume the obligations set forth in this section.

     (h) The provisions of Section 4.11(d), (e), (f) and (g) are intended to be
for the benefit of, and shall be enforceable by, each Indemnified Party and
their respective heirs and representatives.

     (i) The parties agree to take the further actions Previously Disclosed by
     Seller.

     4.12.  SELLER SUBSIDIARIES

     Seller undertakes and agrees that, if so requested by Purchaser, it shall
take all necessary action to facilitate the merger of Seller Subsidiaries with
Subsidiaries of Purchaser or the dissolution of such Seller Subsidiaries
effective at or after the Effective Date; provided however, that in no event
shall the Closing be delayed in order to facilitate any such merger or
dissolution and provided, further, however, that Seller shall not be required to
take any action that could adversely affect the qualification of the Merger as a
reorganization within the meaning of Section 368(a) of the Code.

     4.13.  STOCK SPLIT

     Management of Purchaser shall recommend to Purchaser's Board of Directors
that it approve, and shall use best efforts to effect, a 10-for-1 split in the
number of outstanding shares of Purchaser Common Stock in the form of a stock
dividend or stock split (the "Stock Split"), such approval to be contingent upon
the consummation of the Merger and to become effective prior to the Merger on
the Effective Date.

     4.14.  DIVIDENDS

     After the date of this Agreement, each of Purchaser and Seller shall
coordinate with the other the declaration of any dividends in respect of
Purchaser Common Stock and Seller Common Stock and the record dates and payment
dates relating thereto, it being the intention of the parties hereto that
holders of Purchaser Common Stock or Seller Common Stock shall not receive two
dividends, or fail to receive one dividend, for any single calendar quarter with
respect to their shares of Purchaser Common Stock and/or Seller Common Stock and
any shares of Purchaser Common Stock any such holder receives in exchange
therefor in the Merger. In connection with the first quarterly dividend paid in
respect of Purchaser Common Stock after the Effective Date, the Management of
Purchaser shall recommend to the Purchaser Board that it approves and shall use
best efforts to effect an increase in the amount of Purchaser's regular
quarterly cash dividend to not less than $0.25 per share of Purchaser Common
Stock (the "Dividend Increase") after giving effect to the Stock Split. In
connection with approving this Reorganization Agreement and the transactions
contemplated hereby, Purchaser's Board of Directors has considered the Dividend
Increase and has agreed that, in the event that the transactions contemplated
hereby and by the Plan of Merger are consummated and, subject to the
coordination of dividends provisions of the first sentence of this Section 4.14
and to applicable law, the Dividend Increase will be implemented no later than
the first regular quarterly dividend declared after the Effective Date.

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<PAGE>   116

     4.15.  ADVISORY BOARDS

     Promptly following the Effective Date, Purchaser shall cause those regional
boards of directors of Seller for Seller's Regions One through Five to become
regional Advisory Boards of Purchaser Bank and shall cause the members of such
boards of directors as of the Effective Date, other than such members as become
directors of Purchaser pursuant to Section 4.11(d) hereof, to be appointed or
elected for a period of not less than twenty-four months after the Effective
Date as members such Advisory Boards, the function of which is to advise
Purchaser Bank on deposit and lending activities in Seller Bank's former market
area. In addition, Purchaser shall cause any person who is a member of Seller's
or Seller's Bank's Board of Directors on the Effective Date and is neither a
member of a regional board of directors of Seller nor an individual who becomes
a director of Purchaser pursuant to Section 4.11(d) hereof, to be appointed or
elected to one of the regional Advisory Boards of Purchaser Bank as mutually
agreed prior to the Effective Date by Purchaser and Seller. Each such advisory
director shall be paid for such service the greater of (i) the fees for such
service according to a fee schedule to be established by Purchaser or (ii)
directors' fees Previously Disclosed by Seller in connection with this Section
4.15; provided, however, that notwithstanding anything else in this Section
4.15, if a member has failed to attend at least 25% of the meetings called
within a year, such member will be paid pursuant to clause (i) of this sentence;
and no attendance fees shall be paid for meetings not actually attended; and
Purchaser Bank shall have no obligation to continue the services of any advisory
director who acts in a manner detrimental to Purchaser Bank. In the event that
Purchaser terminates, suspends or disbands one or more of the Advisory Boards,
fails to require or request the attendance of a member with respect to at least
10 meetings of any Advisory Board and/or committee thereof within a single year
or removes a member of an Advisory Board other than because such member acted in
a manner detrimental to Purchaser Bank, in each case prior to the end of the
24-month period contemplated by the first sentence of this Section 4.15 and
subject to the proviso of the preceding sentence, any member affected by any
such action or failure shall nonetheless be paid the full fees (assuming at
least 10 meetings annually had been held) pursuant to clause (i) of the
preceding sentence or the amount contemplated by clause (ii) thereof, which ever
is greater, with respect to such 24-month period.

     4.16.  SECTION 16

     Seller shall, reasonably promptly following the date hereof, provide to
Purchaser a list of (a) the directors and officers (as such terms are used under
Section 16 of the Exchange Act and the rules and regulations of the SEC
thereunder) of Seller, (b) the number of shares of Purchaser Common Stock and
options thereon expected to be received pursuant to the Merger, as appropriate,
by each such officer or director on the Effective Date on account of shares of
Seller Common Stock, and options thereon, reasonably expected to be held by such
directors and officers immediately prior to the Effective Date and (c) a
description of the material terms of such options. Prior to the Effective Date,
(a) the Seller Board of Directors shall take such actions consistent with the
SEC's interpretive guidance to approve the disposition of Seller Common Stock,
and options thereon, by each director and officer of Seller for purposes of Rule
16b-3(e) such that the deemed "sale" of such Seller Common Stock and options
thereon by such persons pursuant to the Merger shall be exempt from liability
pursuant to Section 16(b) of the Exchange Act, and (b) the Purchaser Board of
Directors shall take such action consistent with the SEC's interpretive guidance
to approve the acquisition of Purchaser Common Stock by each director and
officer of Purchaser for purposes of Rule 16b-3(d) under the Exchange Act such
that the deemed "purchase" of such Purchaser Common Stock, and options thereon,
by such persons pursuant to the Merger shall be exempt from liability pursuant
to Section 16(b) of the Exchange Act.

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<PAGE>   117

     4.17.  TAKEOVER LAWS

     No party hereto shall take any action that would cause the transactions
contemplated by this Reorganization Agreement, the Plan of Merger or the Option
Agreement to be subject to the requirements imposed by any Takeover Law, and
each of them shall take all necessary steps within its control to exempt (or
ensure the continued exemption of) the transactions contemplated by this
Reorganization Agreement, the Plan of Merger and the Option Agreement from, or
if necessary challenge the validity or applicability of, any applicable Takeover
Law, as now or hereafter in effect.

                                   ARTICLE 5.
                              CONDITIONS PRECEDENT

     5.1.  CONDITIONS PRECEDENT TO OBLIGATIONS OF PURCHASER, MERGER SUB AND
           SELLER

     The respective obligations of the parties to effect the Merger shall be
subject to satisfaction or waiver of the following conditions at or prior to the
Closing Date:

          (a) All corporate action necessary to authorize the execution,
     delivery and performance of this Reorganization Agreement and the Plan of
     Merger and consummation of the transactions contemplated hereby and
     thereby, including without limitation the stockholder approvals
     contemplated by Sections 2.5 and 3.5 hereof, shall have been duly and
     validly taken;

          (b) The parties hereto shall have received all regulatory approvals
     required or mutually deemed necessary in connection with the transactions
     contemplated by this Reorganization Agreement, the Plan of Merger and the
     Bank Merger Agreement, all notice periods and waiting periods required
     after the granting of any such approvals shall have passed and all
     conditions contained in any such approval required to have been satisfied
     prior to consummation of such transactions shall have been satisfied,
     provided, however, that no such approval shall have imposed any condition
     or requirement that, in the reasonable good faith opinion of the Board of
     Directors of Purchaser or Seller so materially and adversely affects the
     anticipated economic benefits to Purchaser or Seller, respectively, of the
     transactions contemplated by this Agreement as to render consummation of
     such transactions inadvisable;

          (c) The Registration Statement (including any post-effective amendment
     thereto) shall be effective under the Securities Act, and no proceeding
     shall be pending, or to the knowledge of Purchaser, threatened by the
     Commission to suspend the effectiveness of such Registration Statement, and
     Purchaser shall have received all state securities or "Blue Sky"permits or
     other authorizations, or confirmations as to the availability of an
     exemption from registration requirements as may be necessary;

          (d) To the extent that any lease, license, loan, financing agreement
     or other contract or agreement to which Seller or any Seller Subsidiary is
     a party requires the consent of or waiver from the other party thereto as a
     result of the transactions contemplated by this Agreement, such consent or
     waiver shall have been obtained, unless the failure to obtain such consents
     or waivers, individually or in the aggregate, would not have a Material
     Adverse Effect on Seller;

          (e) None of the parties hereto shall be subject to any order, decree
     or injunction of a court or agency of competent jurisdiction which enjoins
     or prohibits the consummation of the transactions contemplated by this
     Reorganization Agreement and the Plan of Merger;

          (f) The shares of Purchaser Common Stock that may be issued in the
     Merger which shall have been approved for listing on the NYSE, subject to
     official notice of issuance; and

                                      A-32
<PAGE>   118

          (g) Purchaser shall have received an opinion of Arnold & Porter, and
     Seller shall have received an opinion of Wachtell, Lipton, Rosen & Katz, in
     each case in form and substance reasonably satisfactory to Purchaser and
     Seller, as the case may be, dated as of the Effective Date, substantially
     to the effect that, on the basis of facts, representations and assumptions
     set forth or referred to in such opinion, the Merger will be treated for
     federal income tax purposes as a reorganization or part of a reorganization
     within the meaning of Section 368(a) of the Code, and that:

             (i) Seller, Purchaser and Merger Sub will each be a party to such
        reorganization within the meaning of Section 368(b) of the Code;

             (ii) No gain or loss will be recognized by Purchaser, Merger Sub or
        Seller as a result of the Merger (except for amounts resulting from any
        required change in accounting methods, any income and deferred gain
        recognized pursuant to Treasury regulations issued under Section 1502 of
        the Code, or other exceptions as set forth in such opinion);

             (iii) No gain or loss will be recognized by Seller shareholders
        with respect to shares of Purchaser Common Stock received in exchange
        for all of their shares of Seller Common Stock;

             (iv) The gain, if any, realized by Seller shareholders who receive
        Purchaser Common Stock and cash (other than cash in lieu of a fractional
        share interest of Purchaser Common Stock) in exchange for their shares
        of Seller Common Stock, will be recognized by each such shareholder, but
        in an amount not in excess of the amount of cash received. If the
        exchange has the effect of the distribution of a dividend, then the
        amount of the gain recognized shall be treated as a dividend. No loss
        will be recognized by such Seller shareholders on the exchange;

             (v) Each Seller shareholder's aggregate tax basis in any shares of
        Purchaser Common Stock received in the transaction will be the same as
        the aggregate tax basis of the shares of Seller Common Stock such
        shareholder surrendered in the exchange therefor, decreased by the
        amount of any cash received by the shareholder and increased by the
        amount any income or gain recognized by the shareholder in the exchange;
        and

             (vi) Each Seller shareholder's holding period in any shares of
        Purchaser Common Stock received in the transaction will, in each
        instance, include the period during which the shares of Seller Common
        Stock surrendered in exchange therefor were held, provided that such
        shares of Seller Common Stock were held as capital assets by the
        shareholder on the Effective Date.

     In rendering the opinion described in this subsection (g), Arnold & Porter
and Wachtell, Lipton, Rosen & Katz, as applicable, may rely on representations
and facts as provided by Purchaser and Seller, including, without limitation,
the representations set forth in Revenue Procedure 86-42, 1986-2 C.B. 722.

     5.2.  CONDITIONS PRECEDENT TO OBLIGATIONS OF SELLER

     The obligations of Seller to effect the Merger shall be subject to
satisfaction of the following additional conditions at or prior to the Closing
Date unless waived by Seller pursuant to Section 6.4 hereof:

          (a) The representations and warranties of Purchaser and Merger Sub set
     forth in Article 3 hereof shall be true and correct in all material
     respects as of the date of this Reorganization Agreement and as of the
     Closing Date as though made on and as of the Closing Date (or on the date
     when made in the case of any representation and warranty which specifically
     relates to an earlier date), except as otherwise contemplated by this
     Reorganization Agreement or consented to in

                                      A-33
<PAGE>   119

     writing by Seller; provided, however, that (i) in determining whether or
     not the condition contained in this paragraph (a) shall be satisfied, no
     effect shall be given to any exceptions in such representations and
     warranties relating to materiality or Material Adverse Effect and (ii) the
     condition contained in this paragraph (a) shall be deemed to be satisfied
     unless the failure of such representations and warranties to be so true and
     correct constitute, individually or in the aggregate, a Material Adverse
     Effect on Purchaser;

          (b) Purchaser and Merger Sub shall have in all material respects
     performed all obligations and complied with all covenants required by this
     Reorganization Agreement and the Plan of Merger to be performed or complied
     with at or prior to the Closing Date;

          (c) Each of Purchaser and Merger Sub shall have delivered to Seller a
     certificate, dated the Closing Date and signed by its respective Chairman,
     CEO, Executive Vice President or Senior Vice President to the effect that
     the conditions set forth in paragraphs (a) and (b) of this section have
     been satisfied; and

          (d) The Stock Split shall have become effective.

     5.3.  CONDITIONS PRECEDENT TO OBLIGATIONS OF PURCHASER AND MERGER SUB

     The respective obligations of Purchaser and Merger Sub to effect the Merger
shall be subject to satisfaction of the following additional conditions at or
prior to the Closing Date unless waived by Purchaser pursuant to Section 6.4
hereof:

          (a) The representations and warranties of Seller set forth in Article
     2 hereof shall be true and correct in all material respects as of the date
     of this Reorganization Agreement and as of the Closing Date as though made
     on and as of the Closing Date (or on the date when made in the case of any
     representation and warranty which specifically relates to an earlier date),
     except as otherwise contemplated by this Reorganization Agreement or
     consented to in writing by Purchaser; provided, however, that (i) in
     determining whether or not the condition contained in this paragraph (a)
     shall be satisfied, no effect shall be given to any exceptions in such
     representations and warranties relating to materiality or Material Adverse
     Effect and (ii) the condition contained in this paragraph (a) shall be
     deemed to be satisfied unless the failure of such representations and
     warranties to be so true and correct constitute, individually or in the
     aggregate, a Material Adverse Effect on Seller;

          (b) Seller shall have in all material respects performed all
     obligations and complied with all covenants required by this Reorganization
     Agreement and the Plan of Merger to be performed or complied with at or
     prior to the Closing Date;

          (c) Seller shall have delivered to Purchaser and Merger Sub a
     certificate, dated the Closing Date and signed by its Chairman, President
     and Chief Executive Officer or any Executive Vice President to the effect
     that the conditions set forth in paragraphs (a) and (b) of this section
     have been satisfied; and

          (d) Dissenters' rights shall not have been exercised with respect to
     more than 15% of the outstanding shares of Seller Common Stock.

                                      A-34
<PAGE>   120

                                   ARTICLE 6.
                       TERMINATION, WAIVER AND AMENDMENT

     6.1.  TERMINATION

     This Reorganization Agreement and the Plan of Merger may be terminated,
either before or after approval by the shareholders of Seller or Purchaser:

          (a) At any time on or prior to the Effective Date, by the mutual
     consent in writing of the parties hereto;

          (b) At any time on or prior to the Closing Date, by Purchaser in
     writing, if Seller has, or by Seller in writing, if Purchaser or Merger Sub
     has, in any material respect, breached (i) any covenant or agreement
     contained herein or in the Plan of Merger or (ii) any representation or
     warranty contained herein, and in either case if (x) such breach has not
     been cured by the earlier of 30 days after the date on which written notice
     of such breach is given to the party committing such breach or the Closing
     Date and (y) such breach would entitle the non-breaching party not to
     consummate the transactions contemplated hereby under Article V hereof;

          (c) At any time, by any party hereto in writing, if the applications
     for prior approval referred to in Section 4.3 hereof have been finally
     denied, and the time period for appeals and requests for reconsideration
     has run, or if any governmental entity of competent jurisdiction shall have
     issued a final nonappealable order enjoining or otherwise prohibiting the
     Merger;

          (d) At any time, by any party hereto in writing, if the shareholders
     of Seller do not approve the transactions contemplated herein at the
     special meetings duly called for that purpose; or

          (e) By any party hereto in writing, if the Closing Date has not
     occurred by the close of business on January 31, 2001 unless the failure of
     the Closing to occur by such date shall be due to the failure of the party
     seeking to terminate this Agreement to perform or observe the covenants and
     agreements set forth herein.

     6.2.  EFFECT OF TERMINATION

     In the event this Reorganization Agreement and the Plan of Merger is
terminated pursuant to Section 6.1 hereof, this Agreement and the Plan of Merger
shall become void and have no effect, except that (i) the provisions relating to
confidentiality and expenses set forth in Sections 4.5 and 7.1 hereof,
respectively, shall survive any such termination and (ii) a termination pursuant
to Section 6.1(b)(i) or (b)(ii) shall not relieve the breaching party from
liability for an uncured willful breach of such covenant or agreement or
representation or warranty giving rise to such termination.

     6.3.  SURVIVAL OF REPRESENTATIONS, WARRANTIES AND COVENANTS

     All representations, warranties and covenants in this Reorganization
Agreement and the Plan of Merger or in any instrument delivered pursuant hereto
or thereto shall expire on, and be terminated and extinguished at, the Effective
Date other than covenants that by their terms are to survive or be performed
after the Effective Date; provided, that no such representations, warranties or
covenants shall be deemed to be terminated or extinguished so as to deprive
Purchaser, Merger Sub or Seller (or any director, officer or controlling person
thereof) of any defense in law or equity which otherwise would be available
against the claims of any person, including, without limitation, any shareholder
or former shareholder of either Purchaser or Seller, the aforesaid
representations, warranties and covenants being material inducements to the
consummation by Purchaser, Merger Sub and Seller of the transactions
contemplated herein.

                                      A-35
<PAGE>   121

     6.4.  WAIVER

     Except where not permitted by law, Purchaser and Seller, respectively, by
written instrument signed by an executive officer of such party, may at any time
(whether before or after approval of this Reorganization Agreement and the Plan
of Merger by the shareholders of Purchaser and Seller) extend the time for the
performance of any of the obligations or other acts of Seller, on the one hand,
or Purchaser or Merger Sub, on the other hand, and may waive (i) any
inaccuracies of such parties in the representations or warranties contained in
this Agreement, the Plan of Merger or any document delivered pursuant hereto or
thereto, (ii) compliance with any of the covenants, undertakings or agreements
of such parties, or satisfaction of any of the conditions precedent to its
obligations, contained herein or in the Plan of Merger or (iii) the performance
by such parties of any of its obligations set out herein or therein; provided,
however, that no such waiver, or amendment or supplement contemplated by Section
6.5, executed after approval of this Reorganization Agreement and the Plan of
Merger by the shareholders of Purchaser or Seller shall, without the further
approval thereof, change the amount or kind of Merger Consideration.

     6.5.  AMENDMENT OR SUPPLEMENT

     This Reorganization Agreement and the Plan of Merger may be amended or
supplemented at any time only by mutual agreement of the parties hereto or
thereto. Any such amendment or supplement must be in writing and approved by
their respective boards of directors and/or officers authorized thereby and
shall be subject to the proviso in Section 6.4 hereto.

                                   ARTICLE 8.
                                 MISCELLANEOUS

     7.1.  EXPENSES

     Each party hereto shall bear and pay all costs and expenses incurred by it
in connection with the transactions contemplated in this Reorganization
Agreement, including fees and expenses of its own financial consultants,
accountants and counsel, except that Purchaser and Seller each shall bear and
pay 50% of all printing and mailing costs and filing fees associated with the
Registration Statement and the Proxy Statement.

     7.2.  ENTIRE AGREEMENT

     This Reorganization Agreement, the Plan of Merger and the Option Agreement
contain the entire agreement between the parties with respect to the
transactions contemplated hereunder and thereunder and supersede all prior
arrangements or understandings with respect thereto, written or oral, other than
documents referred to herein or therein and the Confidentiality Agreements.
Notwithstanding any provision of any of the aforementioned agreements, the
parties agree that Purchaser may purchase Seller Common Stock in open market or
negotiated transactions prior to the Effective Date, not to exceed 5% of the
outstanding Seller Common Stock and subject to any applicable legal
restrictions. The terms and conditions of this Reorganization Agreement and the
Plan of Merger shall inure to the benefit of and be binding upon the parties
hereto and thereto and their respective successors. Except as specifically set
forth herein, or in the Plan of Merger, nothing in this Reorganization Agreement
or the Plan of Merger, expressed or implied, is intended to confer upon any
party, other than the parties hereto and thereto, and their respective
successors, any rights, remedies, obligations or liabilities. This
Reorganization Agreement and the Plan of Merger, taken together, shall
constitute a plan of reorganization within the meaning of Section 368 of the
Code.

                                      A-36
<PAGE>   122

     7.3.  NO ASSIGNMENT

     No party hereto may assign any of its rights or obligations under this
Reorganization Agreement to any other person.

     7.4.  ALTERNATIVE STRUCTURE

     Notwithstanding any provision of this Reorganization Agreement to the
contrary, Purchaser may, with the written consent of Seller, which shall not be
unreasonably withheld, elect, subject to the filing of all necessary
applications and the receipt of all required regulatory approvals, to modify the
structure of the acquisition of Seller and the Seller Subsidiaries set forth
herein, provided, that (i) the federal income tax consequences of any
transactions created by such modification shall not be other than those set
forth in Section 5.1(g) hereof, (ii) the consideration to be paid to the holders
of the Seller Common Stock is not thereby changed in kind or reduced in amount
as a result of such modification and (iii) such modification will not materially
delay or jeopardize the consummation of the transactions contemplated by the
Reorganization Agreement and the Plan of Merger.

     7.5.  NOTICES

     All notices or other communications which are required or permitted
hereunder shall be in writing and sufficient if delivered personally or sent by
facsimile transmission or overnight express or by registered or certified mail,
postage prepaid, addressed as follows:

     If to Seller:

        Keystone Financial, Inc.
        One Keystone Plaza
        Front and Market Streets
        Harrisburg, PA 17105

        Attn: Ben G. Rooke
        Facsimile No: (717) 231-5759

     With a required copy to:

        Wachtell, Lipton, Rosen & Katz
        51 West 52(nd) Street
        New York, New York 10019
        Attn: Edward D. Herlihy, Esq.
        Facsimile No: (212) 403-2000

     If to Purchaser or Merger Sub:

        M&T Bank Corporation
        One M&T Plaza
        Buffalo, NY 14240
        Attn: Michael Pinto,
              Executive Vice President and Chief Financial Officer
        Facsimile No: (716) 842-5177

                                      A-37
<PAGE>   123

     With a required copy to:

        M&T Bank Corporation
        One M&T Plaza
        Buffalo, NY 14240
        Attn: Richard A. Lammert, Esquire
              Senior Vice President and General Counsel
        Facsimile No: (716) 842-5177

        and to:

        Arnold & Porter
        555 Twelfth Street, N.W.
        Washington, D.C. 20004
        Attn: Steven Kaplan, Esquire
        Facsimile No: (202) 942-5999

     7.6.  CAPTIONS

     The captions contained in this Reorganization Agreement are for reference
purposes only and are not part of this Reorganization Agreement.

     7.7.  COUNTERPARTS

     This Reorganization Agreement may be executed in any number of
counterparts, and each such counterpart shall be deemed to be an original
instrument, but all such counterparts together shall constitute but one
agreement.

     7.8.  GOVERNING LAW

     This Reorganization Agreement shall be governed by and construed in
accordance with the laws of the State of New York applicable to agreements made
and entirely to be performed within such jurisdiction, except to the extent
federal law may be applicable.

     [Remainder of this page left intentionally blank.]

                                      A-38
<PAGE>   124

     IN WITNESS WHEREOF, the parties hereto, intending to be legally bound
hereby, have caused this Reorganization Agreement to be executed in counterparts
by their duly authorized officers and their corporate seal to be hereunto
affixed and attested by their officers thereunto duly authorized, all as of the
day and year first above written.

<TABLE>
<S>                                                         <C>
Attest                                                      M&T BANK CORPORATION

/s/ MICHAEL S. PIEMONTE                                     By /s/ GARY S. PAUL
-----------------------------------------------------          --------------------------------------------------
Michael S. Piemonte                                            Gary S. Paul
Asst. Corporate Secretary                                      Senior Vice President


(SEAL)

Attest                                                      OLYMPIA FINANCIAL CORP.

/s/ MICHAEL S. PIEMONTE                                     By /s/ GARY S. PAUL
-----------------------------------------------------          --------------------------------------------------
Michael S. Piemonte                                             Gary S. Paul
Asst. Corporate Secretary                                       Treasurer and Assistant Secretary


(SEAL)

Attest                                                      KEYSTONE FINANCIAL, INC.

/s/ BEN G. ROOKE                                            By /s/ CARL L. CAMPBELL
-----------------------------------------------------          --------------------------------------------------
Ben G. Rooke                                                    Carl L. Campbell
Vice Chairman, General Counsel and Secretary                    Chairman, President and CEO


(SEAL)
</TABLE>

                                      A-39
<PAGE>   125

                                                                         ANNEX A

                        AGREEMENT AND PLAN OF MERGER OF
                            KEYSTONE FINANCIAL, INC.
                     WITH AND INTO OLYMPIA FINANCIAL CORP.

     AGREEMENT AND PLAN OF MERGER ("Plan of Merger") dated as of May 16, 2000 by
and between Keystone Financial, Inc. ("Seller"), a Pennsylvania corporation
having its principal executive office at One Keystone Plaza, Front and Market
Streets, Harrisburg, Pennsylvania 17105, and Olympia Financial Corp. ("Merger
Sub"), a Delaware corporation having its principal executive office at 1209
Orange Street, Wilmington, Delaware, and joined in by M&T Bank Corporation
("Purchaser"), a New York corporation having its principal executive office at
One M&T Plaza, Buffalo, New York 14614.

                              W I T N E S S E T H

     WHEREAS, the respective Boards of Directors of Seller, Merger Sub and
Purchaser deem the merger of Seller with and into Merger Sub, under and pursuant
to the terms and conditions herein set forth or referred to, desirable and in
the best interests of the respective corporations and their respective
shareholders, and the respective Boards of Directors of Seller, Merger Sub and
Purchaser have adopted resolutions approving this Plan of Merger and an
Agreement and Plan of Reorganization dated of even date herewith
("Reorganization Agreement"); and

     WHEREAS, the parties hereto desire that Seller shall be acquired by
Purchaser through the merger of Seller with and into Merger Sub, with Merger Sub
as the surviving corporation, subject to the terms and conditions of this Plan
of Merger and the Reorganization Agreement; and

     WHEREAS, the parties hereto intend that the Merger shall qualify as a
reorganization under Section 368(a) of the Internal Revenue Code of 1986, as
amended ("the Code").

     NOW, THEREFORE, in consideration of the premises and of the mutual
agreements herein contained, the parties hereto do hereby agree as follows:

                                   ARTICLE 1.
                                     MERGER

     Subject to the terms and conditions of this Plan of Merger, at the
Effective Time (as hereinafter defined), Seller shall be merged with and into
Merger Sub, pursuant to the provisions of, and with the effect provided in the
Pennsylvania Business Corporation Law and the Delaware General Corporation Law
(said transaction being hereinafter referred to as the "Merger"). At the
Effective Time, the separate existence of Seller shall cease and Merger Sub, as
the surviving entity, shall continue unaffected and unimpaired by the Merger.
(Merger Sub as existing at and after the Effective Time being hereinafter
sometimes referred to as the "Surviving Corporation").

                                   ARTICLE 2.
                    CERTIFICATE OF INCORPORATION AND BY-LAWS

     Subject to Section 4.11(e) of the Reorganization Agreement, the Certificate
of Incorporation and the Bylaws of Merger Sub in effect immediately prior to the
Effective Time shall be the Certificate of Incorporation and the Bylaws of the
Surviving Corporation, in each case until amended in accordance with applicable
law.

                                      A-40
<PAGE>   126

                                   ARTICLE 3.
                               BOARD OF DIRECTORS

     The directors and officers of Merger Sub immediately prior to the Effective
Time shall be the directors and officers of the Surviving Corporation, each to
hold office in accordance with the Certificate of Incorporation and Bylaws of
the Surviving Corporation.

                                   ARTICLE 4.
                                    CAPITAL

     At the Effective Time, all of the shares of capital stock of Merger Sub
issued and outstanding immediately prior to the Effective Time shall remain
outstanding and unchanged by virtue of the Merger and shall constitute all of
the issued and outstanding shares of capital stock of the Surviving Corporation.

                                   ARTICLE 5.
                           CONVERSION AND EXCHANGE OF
                   SELLER SHARES; FRACTIONAL SHARE INTERESTS

     1. At the Effective Time, each share of the common stock of Seller, par
value $2.00 per share ("Seller Common Stock"), issued and outstanding
immediately prior to the Effective Time (except as provided in Section 2 of this
Article 5, and subject to Sections 5 and 7 of this Article 5), shall, by virtue
of the Merger, automatically and without any action on the part of the holder
thereof, become and be converted into, at the election of the holder as provided
in and subject to the limitations set forth in this Article 5, either (i) the
right to receive $21.50 in cash without interest (the "Cash Consideration") or
(ii) 0.05 of a share (before giving effect to the Stock Split as defined in the
Reorganization Agreement) (the "Exchange Ratio") of common stock, par value
$5.00 per share, of Purchaser ("Purchaser Common Stock") (the "Stock
Consideration"). The Cash Consideration and the Stock Consideration are
sometimes referred to herein collectively as the "Merger Consideration."

     2. (a) At the Effective Time, all shares of Seller Common Stock held in the
treasury of Seller or owned beneficially by any Subsidiary of Seller other than
in a fiduciary capacity ("Trust Account Shares") or in connection with a debt
previously contracted ("DPC Shares") and all shares of Seller Common Stock owned
by Purchaser or owned beneficially by any subsidiary of Purchaser other than
Trust Account Shares and DPC Shares shall be canceled and no cash, stock or
other property shall be delivered in exchange therefor.

          (b) Notwithstanding any other provision contained in this Plan of
     Merger, no shares of Seller Common Stock that are issued and outstanding as
     of the Effective Time and that are held by a stockholder who has properly
     exercised his appraisal rights (any such shares being referred to herein as
     "Dissenting Shares") under applicable law shall be converted into the right
     to receive the Merger Consideration as provided in Section 1 of this
     Article 5 unless and until the holder shall have failed to perfect, or
     shall have effectively withdrawn or lost, his right to dissent from the
     Merger under applicable law and to receive such consideration as may be
     determined to be due with respect to such Dissenting Shares pursuant to and
     subject to the requirements of applicable law. If any such holder shall
     have so failed to perfect or effectively withdrawn or lost such right prior
     to the Election Deadline (as defined herein), each of such holder's shares
     of Seller Common Stock shall thereupon be deemed to be Non-Election Shares
     (as defined herein) for all purposes under this Article 5. If any holder of
     Dissenting Shares shall have so failed to perfect or effectively withdrawn
     or lost such holder's right to dissent from the Merger after the Election
     Deadline, each of such holder's shares of Seller Common Stock shall
     thereupon be deemed to have been converted

                                      A-41
<PAGE>   127

     into and to have become, as of the Effective Time, the right to receive the
     Stock Consideration or the Cash Consideration or a combination thereof as
     determined by Purchaser in its sole discretion.

     3. (a) An election form (an "Election Form") and other appropriate and
customary transmittal materials, which shall specify that delivery shall be
effected, and risk of loss and title to the certificates theretofore
representing Seller Common Stock ("Certificates") shall pass, only upon proper
delivery of such Certificates to a bank or trust company designated by Purchaser
and reasonably satisfactory to Seller (the "Exchange Agent") in such form as
Seller and Purchaser shall mutually agree shall be mailed on the Mailing Date
(as defined below) to each holder of record of shares of Seller Common Stock
(other than holders of Dissenting Shares or shares of Seller Common Stock to be
cancelled as provided in Section 2(a) of this Article 5) as of a record date
which shall be the same date as the record date for eligibility to vote on the
Merger. The "Mailing Date" shall be the date on which proxy materials relating
to the Merger are mailed to holders of shares of Seller Common Stock.

          (b) Each Election Form shall entitle the holder of shares of Seller
     Common Stock (or the beneficial owner through appropriate and customary
     documentation and instructions) to (i) elect to receive the Cash
     Consideration for all of such holder's shares (a "Cash Election"), (ii)
     elect to receive the Stock Consideration for all of such holder's shares (a
     "Stock Election"), (iii) elect to receive the Cash Consideration with
     respect to some of such holder's shares and the Stock Consideration with
     respect to such holder's remaining shares (a "Mixed Election"), or (iv)
     make no election or to indicate that such holder has no preference as to
     the receipt of the Cash Consideration or the Stock Consideration (a
     "Non-Election"). Holders of record of shares of Seller Common Stock who
     hold such shares as nominees, trustees or in other representative
     capacities (a "Representative") may submit multiple Election Forms;
     provided, that such Representative certifies that each such Election Form
     covers all the shares of Seller Common Stock held by that Representative
     for a particular beneficial owner. Shares of Seller Common Stock as to
     which a Cash Election has been made are referred to herein as "Cash
     Election Shares." Shares of Seller Common Stock as to which a Stock
     Election has been made are referred to herein as "Stock Election Shares."
     Shares of Seller Common Stock as to which no election or a Non-Election has
     been made are referred to as "Non-Election Shares." The aggregate number of
     shares of Seller Common Stock with respect to which a Stock Election has
     been made is referred to herein as the "Stock Election Number."

          (c) To be effective, a properly completed Election Form shall be
     submitted to the Exchange Agent on or before 5:00 p.m. New York City time
     on the 20th calendar day following the Mailing Date (or such other time and
     date as Seller and Purchaser may mutually agree) (the "Election Deadline").
     An election shall have been properly made only if the Exchange Agent shall
     have actually received a properly completed Election Form by the Election
     Deadline. An Election Form shall be deemed properly completed only if
     accompanied by one or more Certificates (or customary affidavits and, if
     required by Purchaser pursuant to Section 8 of this Article 5,
     indemnification regarding the loss or destruction of such Certificates or
     the guaranteed delivery of such Certificates) representing all shares of
     Seller Common Stock covered by such Election Form, together with duly
     executed transmittal materials included with the Election Form. Any Seller
     stockholder may at any time prior to the Election Deadline change his or
     her election by written notice received by the Exchange Agent prior to the
     Election Deadline accompanied by a properly completed and signed revised
     Election Form. Any Seller stockholder may, at any time prior to the
     Election Deadline, revoke his or her election by written notice received by
     the Exchange Agent prior to the Election Deadline or by withdrawal prior to
     the Election Deadline of his or her Certificates, or of the guarantee of
     delivery of such Certificates, previously deposited with the Exchange
     Agent. All elections shall be revoked automatically if the Exchange Agent
     is notified in writing by Purchaser

                                      A-42
<PAGE>   128

     and Seller that this Plan of Merger has been terminated. If a stockholder
     either (i) does not submit a properly completed Election Form by the
     Election Deadline, or (ii) revokes its Election Form and does not
     thereafter duly deliver a properly completed Election Form to the Exchange
     Agent prior to the Election Deadline, the shares of Seller Common Stock
     held by such stockholder shall be designated "Non-Election Shares."
     Purchaser shall cause the Certificates representing Seller Common Stock
     described in (ii) to be promptly returned without charge to the person
     submitting the Election Form upon written request to that effect from the
     person who submitted the Election Form. Subject to the terms of this Plan
     of Merger and of the Election Form, the Exchange Agent shall have
     reasonable discretion to determine whether any election, revocation or
     change has been properly or timely made and to disregard immaterial defects
     in any Election Form, and any good faith decisions of the Exchange Agent
     regarding such matters shall be binding and conclusive.

          (d) Notwithstanding any other provision contained in this Plan of
     Merger, 65% of the total number of shares of Seller Common Stock
     outstanding on the date hereof, less the aggregate number of shares of
     Seller Common Stock acquired by Purchaser pursuant to the Reorganization
     Agreement or Seller prior to the Effective Time (the "Stock Conversion
     Number") shall be converted into the Stock Consideration and the remaining
     outstanding shares of Seller Common Stock shall be converted into the Cash
     Consideration (in each case, excluding (x) shares of Seller Common Stock to
     be cancelled as provided in Section 2(a) of this Article 5 and (y)
     Dissenting Shares (the shares remaining outstanding after such exclusion
     constituting, for purposes of this Agreement the "Outstanding Seller
     Shares"); provided, however, that for federal income tax purposes, it is
     intended that the Merger will qualify as a reorganization under the
     provisions of Section 368(a) of the Code and, notwithstanding anything to
     the contrary contained herein, in order that the Merger will not fail to
     satisfy continuity of interest requirements under applicable federal income
     tax principles relating to reorganizations under Section 368(a) of the
     Code, as reasonably determined by Arnold & Porter and Wachtell, Lipton,
     Rosen & Katz, Purchaser shall increase the number of outstanding Seller
     shares that will be converted into the Stock Consideration and reduce the
     number of outstanding Seller shares that will be converted into the right
     to receive the Cash Consideration.

          (e) Within five (5) business days after the later to occur of the
     Election Deadline or the Effective Time, Purchaser shall cause the Exchange
     Agent to effect the allocation among holders of Seller Common Stock of
     rights to receive the Cash Consideration and the Stock Consideration as
     follows:

             (i) If the Stock Election Number exceeds the Stock Conversion
        Number, then all Cash Election Shares and all Non-Election Shares shall
        be converted into the right to receive the Cash Consideration, and,
        subject to Section 7 of this Article 5, each holder of Stock Election
        Shares will be entitled to receive the Stock Consideration in respect of
        that number of Stock Election Shares equal to the product obtained by
        multiplying (x) the number of Stock Election Shares held by such holder
        by (y) a fraction, the numerator of which is the Stock Conversion Number
        and the denominator of which is the Stock Election Number, with the
        remaining number of such holder's Stock Election Shares being converted
        into the right to receive the Cash Consideration;

             (ii) If the Stock Election Number is less than the Stock Conversion
        Number (the amount by which the Stock Conversion Number exceeds the
        Stock Election Number being referred to herein as the "Shortfall
        Number"), then all Stock Election Shares shall be converted into the

                                      A-43
<PAGE>   129

        right to receive the Stock Consideration and the Non-Election Shares and
        Cash Election Shares shall be treated in the following manner:

                (A) if the Shortfall Number is less than or equal to the number
           of Non-Election Shares, then all Cash Election Shares shall be
           converted into the right to receive the Cash Consideration and,
           subject to Section 7 of Article 5, each holder of Non-Election Shares
           shall receive the Stock Consideration in respect of that number of
           Non-Election Shares equal to the product obtained by multiplying (x)
           the number of Non-Election Shares held by such holder by (y) a
           fraction, the numerator of which is the Shortfall Number and the
           denominator of which is the total number of Non-Election Shares, with
           the remaining number of such holder's Non-Election Shares being
           converted into the right to receive the Cash Consideration; or

                (B) if the Shortfall Number exceeds the number of Non-Election
           Shares, then all Non-Election Shares shall be converted into the
           right to receive the Stock Consideration, and, subject to Section 7
           of this Article 5, each holder of Cash Election Shares shall receive
           the Stock Consideration in respect of that number of Cash Election
           Shares equal to the product obtained by multiplying (x) the number of
           Cash Election Shares held by such holder by (y) a fraction, the
           numerator of which is the amount by which (1) the Shortfall Number
           exceeds (2) the total number of Non-Election Shares and the
           denominator of which is the total number of Cash Election Shares,
           with the remaining number of such holder's Cash Election Shares being
           converted into the right to receive the Cash Consideration.

     For purposes of this Section 3(e), if Purchaser is obligated to increase
the number of Outstanding Seller Shares to be converted into shares of Purchaser
Common Stock as a result of the application of the last clause of Section 3(d)
above, then the higher number shall be substituted for the Stock Conversion
Number in the calculations set forth in this Section 3(e).

          (f) All of the shares of Seller Common Stock converted into and
     exchangeable for the Merger Consideration pursuant to this Article 5 shall
     no longer be outstanding and shall automatically be cancelled and cease to
     exist as of the Effective Time. Each Certificate previously representing
     any such shares of Seller Common Stock shall thereafter represent the right
     to receive the Merger Consideration pursuant to this Article 5, as
     allocated among the holders of Seller Common Stock in accordance with this
     Section 3.

          (g) At the Effective Time, Purchaser shall deposit, or shall cause to
     be deposited, with the Exchange Agent, for exchange in accordance with this
     Section 3, certificates representing the aggregate number of shares of
     Purchaser Common Stock into which the outstanding shares of Seller Common
     Stock shall be converted pursuant to this Article 5, and cash in the amount
     of the aggregate Cash Consideration and the aggregate amount of cash to be
     paid in lieu of fractional shares. As soon as practicable after the
     Effective Time, the Exchange Agent shall mail to all holders of record of
     Seller Common Stock who did not previously submit completed Election Forms
     letters of transmittal specifying the procedures for the delivery of such
     holders' certificates to the Exchange Agent and describing the Merger
     Consideration such holders will receive therefor. Also as soon as
     practicable after the Effective Time (with allowance for the mailing of the
     letters of transmittal described in the preceding sentence), the Exchange
     Agent shall distribute to holders of shares of Seller Common Stock, upon
     surrender to the Exchange Agent (to the extent not previously surrendered
     with an Election Form) of one or more Certificates for cancellation, (i) a
     certificate representing that number of whole shares of Purchaser Common
     Stock, if any, that such holder has the right to receive pursuant to this
     Plan of Merger, and (ii) a check for an amount

                                      A-44
<PAGE>   130

     equal to the cash, if any, which such holder has the right to receive
     pursuant to this Plan of Merger (including any cash in lieu of any
     fractional shares of Purchaser Common Stock to which such holder is
     entitled pursuant to Section 7 hereof and any dividends or other
     distributions to which such holder is entitled pursuant to the provisions
     set forth below). In no event shall the holder of any such surrendered
     Certificates be entitled to receive interest on any of the Cash
     Consideration or cash in lieu of fractional share interests to be received
     in the Merger. If a check is to be issued in the name of a person other
     than the person in whose name the Certificates surrendered for exchange
     therefor are registered, it shall be a condition of the exchange that the
     person requesting such exchange shall pay to the Exchange Agent any
     transfer taxes required by reason of issuance of such check to a person
     other than the registered holder of the Certificates surrendered, or shall
     establish to the reasonable satisfaction of the Exchange Agent that such
     tax has been paid or is not applicable. No dividends or other distributions
     declared after the Effective Time with respect to Purchaser Common Stock
     shall be paid to the holder of any unsurrendered Certificate until the
     holder thereof shall surrender such Certificate in accordance with this
     Article 5. After the surrender of a Certificate in accordance with this
     Article 5, the record holder thereof shall be entitled to receive any such
     dividends or other distributions, without any interest thereon, which
     theretofore had become payable with respect to shares of Purchaser Common
     Stock, if any, represented by such Certificate. Certificates surrendered
     for exchange by any person who is an "affiliate" of Seller for purposes of
     Rule 145(c) under the Securities Act of 1933, as amended, shall not be
     exchanged for certificates representing shares of Purchaser Common Stock
     until Purchaser has received the written agreement of such person
     contemplated by Section 4.10 of the Reorganization Agreement. If any
     certificate for shares of Purchaser Common Stock is to be issued in a name
     other than that in which a Certificate surrendered for exchange is issued,
     the Certificate so surrendered shall be properly endorsed and otherwise in
     proper form for transfer and the person requesting such exchange shall
     affix any requisite stock transfer tax stamps to the Certificate
     surrendered or provide funds for their purchase or establish to the
     reasonable satisfaction of Purchaser or its agent that such taxes have been
     paid or are not payable.

     4. At the Effective Time, the stock transfer books of Seller shall be
closed and no transfer of Seller Common Stock shall thereafter be made or
recognized. If, after the Effective Time, Certificates representing such shares
are presented for transfer to the Exchange Agent, they shall be cancelled and
exchanged for the Merger Consideration as provided in this Article 5. Any other
provision of this Plan of Merger notwithstanding, neither Purchaser or its agent
nor any party to the Merger shall be liable to a holder of Seller Common Stock
for any amount paid or properly delivered in good faith to a public official
pursuant to any applicable abandoned property, escheat or similar law.

     5. In the event that prior to the Effective Time, the outstanding shares of
Purchaser Common Stock shall have been increased, decreased or changed into or
exchanged for a different number or kind of shares or securities by
reorganization, recapitalization, reclassification, stock dividend, stock split
or other like changes in Purchaser's capitalization including, without
limitation, the Stock Split, then an appropriate and proportionate adjustment
shall be made to the Stock Consideration (including the Exchange Ratio) and the
formulas contained in Section 6 of this Article 5.

     6. At the Effective Time, each option to acquire Seller Common Stock (each
a "Seller Option") granted under 1997 Stock Incentive Plan; the 1992 Stock
Incentive Plan; the 1988 Stock Incentive Plan; the 1995 Employee Stock Purchase
Plan; the 1995 Non-Employee Directors' Stock Option Plan; the 1990 Non-Employee
Directors' Stock Option Plan; the Financial Trust Corp. Stock Option Plan of
1992; the Financial Trust Corp. Non-Employee Director Stock Option Plan of 1994;
the Amended and Restated Nonqualified Stock Option Agreement with Donald E.
Stone (WM Bancorp, Inc. options); the Elmwood Bancorp, Inc. Key Employee Stock
Compensation Program; and the Mainline Bancshares, Inc.

                                      A-45
<PAGE>   131

Stock Option Agreement (collectively, the "Seller Stock Option Plans") which is
outstanding immediately prior to the Effective Time, whether vested or unvested,
will be assumed by Purchaser. Each Seller Option so assumed by Purchaser shall
continue to have, and be subject to, the same terms and conditions set forth in
the Seller Stock Option Plan (and any agreement) under which it was granted and
as in existence immediately prior to the Effective Time, except that (i) such
Seller Option shall be exercisable (when vested) for that number of whole shares
of Purchaser Common Stock equal to the product of the number of shares of Seller
Common Stock covered by the Seller Option multiplied by the Exchange Ratio,
provided that any fractional shares of Purchaser Common Stock resulting from
such multiplication shall be rounded down to the nearest share; and (ii) the
exercise price per share of Purchaser Common Stock shall be equal to the
exercise price per share of Seller Common Stock of such Seller Option divided by
the Exchange Ratio, provided that such exercise price shall be rounded up to the
nearest cent. Notwithstanding the foregoing, the adjustment provided herein will
comply with the adjustment provisions in the Seller Stock Option Plans and with
respect to any Seller Options that are "incentive stock options"(as defined in
Section 422 of the Code) shall be and is intended to be effected in a manner
which is consistent with Section 424(a) of the Code. At the Effective Time, each
outstanding equity-based right or award under the Seller Stock Option Plans or
other equity-based plans (the "Equity-Based Rights") shall be assumed by
Purchaser and be subject to the terms and conditions of the applicable Seller
Stock Option Plan or equity-based plan and the applicable award agreement under
which it was granted. Each Equity-Based Right so assumed shall be converted into
a right to received the number of shares of Purchaser Common Stock or a payment
with a value equal to, as applicable, the product of (i) the number of shares of
Seller Common Stock subject to such Equity-Based Right and (ii) the Exchange
Ratio.

     7. Notwithstanding any other provision hereof, each holder of shares of
Seller Common Stock who would otherwise have been entitled to receive pursuant
to this Article 5 a fraction of a share of Purchaser Common Stock (after taking
into account all Certificates delivered by such holder) shall receive, in lieu
thereof, cash in an amount equal to such fraction of a share of Purchaser Common
Stock multiplied by the market value (as defined below) of Purchaser Common
Stock. The "market value" of Purchaser Common Stock shall be the closing price
of the Purchaser Common Stock on the New York Stock Exchange -- Composite
Transactions List (as reported by The Wall Street Journal or, if not reported
therein, another comparable authoritative source) for the trading day
immediately preceding the date on which the Effective Time occurs. No such
holder shall be entitled to dividends, voting rights or any other shareholder
right in respect of such fractional share.

     8. In the event any Certificate shall have been lost, stolen or destroyed,
upon the making of an affidavit of that fact by the person claiming such
Certificate to be lost, stolen or destroyed and, if required by Purchaser, the
posting by such person of a bond in such amount as Purchaser may reasonably
direct as indemnity against any claim that may be made against it with respect
to such Certificate, the Exchange Agent will issue in exchange for such lost,
stolen or destroyed Certificate the shares of Purchaser Common Stock
constituting the Stock Consideration and cash in lieu of fractional shares
and/or the cash constituting the Cash Consideration deliverable in respect
thereof pursuant to this Plan of Merger.

                                   ARTICLE 6.
                          EFFECTIVE TIME OF THE MERGER

     A certificate or articles of merger evidencing the transactions
contemplated herein shall be delivered to the Pennsylvania Department of State
and the Delaware Secretary of State for filing as provided in the Reorganization
Agreement. The Merger shall be effective at the time and on the date specified
in

                                      A-46
<PAGE>   132

such certificate or articles of merger (such date and time being herein referred
to as the "Effective Time").

                                   ARTICLE 7.
                              CONDITIONS PRECEDENT

     The obligations of Purchaser, Merger Sub and Seller to effect the Merger as
herein provided shall be subject to satisfaction, unless duly waived, of the
conditions to the obligations of such person set forth in Article 5 of the
Reorganization Agreement.

                                   ARTICLE 8.
                                  TERMINATION

     Anything contained in the Plan of Merger to the contrary notwithstanding,
and notwithstanding adoption hereof by the shareholders of Seller or Merger Sub,
this Plan of Merger may be terminated and the Merger abandoned as provided in
the Reorganization Agreement.

                                   ARTICLE 9.
                                 MISCELLANEOUS

     1. This Plan of Merger may be amended or supplemented at any time prior to
the Effective Time by mutual agreement of Merger Sub, Purchaser and Seller. Any
such amendment or supplement must be in writing and approved by their respective
Boards of Directors and/or by officers authorized thereby and shall be subject
to the proviso in Section 6.4 of the Reorganization Agreement.

     2. Any notice or other communication required or permitted under this Plan
of Merger shall be given, and shall be effective, in accordance with the
provisions of the Reorganization Agreement.

     3. The headings of the several Articles herein are inserted for convenience
of reference only and are not intended to be a part of or to affect the meaning
or interpretation of this Plan of Merger.

     4. This Plan of Merger shall be governed by and construed in accordance
with the laws of Pennsylvania and Delaware applicable to the internal affairs of
Seller and Merger Sub.

     5. This Plan of Merger, taken together with the Reorganization Agreement,
shall constitute a plan of reorganization within the meaning of Section 368 of
the Code.

               [Remainder of this page left intentionally blank.]

                                      A-47
<PAGE>   133

     IN WITNESS WHEREOF, the parties hereto, intending to be legally bound
hereby, have caused this Plan of Merger to be executed in counterparts by their
duly authorized officers and attested by their officers thereunto duly
authorized, all as of the day and year first above written.

<TABLE>
<S>                                                         <C>
Attest                                                      M&T BANK CORPORATION

/s/ MICHAEL S. PIEMONTE                                     By /s/ GARY S. PAUL
-----------------------------------------------------          -----------------------------------------------------
Michael S. Piemonte                                             Gary S. Paul
Asst. Corporate Secretary                                       Senior Vice President


Attest                                                      OLYMPIA FINANCIAL CORP.

/s/ MICHAEL S. PIEMONTE                                     By /s/ GARY S. PAUL
-----------------------------------------------------          -----------------------------------------------------
Michael S. Piemonte                                             Gary S. Paul
Asst. Corporate Secretary                                       Treasurer and Assistant Secretary


Attest                                                      KEYSTONE FINANCIAL, INC.

/s/ BEN G. ROOKE                                            By /s/ CARL L. CAMPBELL
-----------------------------------------------------          -----------------------------------------------------
Ben G. Rooke                                                   Carl L. Campbell
Vice Chairman, General Counsel and Secretary                   Chairman, President and CEO

</TABLE>

                                      A-48
<PAGE>   134

                                   APPENDIX B

                             STOCK OPTION AGREEMENT

                                       B-1
<PAGE>   135

                             STOCK OPTION AGREEMENT

                  THE TRANSFER OF THIS AGREEMENT IS SUBJECT TO
                   CERTAIN PROVISIONS CONTAINED HEREIN AND TO
                         RESALE RESTRICTIONS UNDER THE
                       SECURITIES ACT OF 1933, AS AMENDED

     STOCK OPTION AGREEMENT, dated May 16, 2000, Keystone Financial, Inc., a
Pennsylvania corporation ("Issuer"), and M&T Bank Corporation, a New York
corporation ("Grantee").

                              W I T N E S S E T H:

     WHEREAS, Grantee, Issuer and Olympia Financial Corp., a Delaware
corporation and a wholly owned subsidiary of Grantee ("Merger Sub") have entered
into an Agreement and Plan of Reorganization of even date herewith (the
"Reorganization Agreement"), which agreement has been executed by the parties
hereto immediately prior to this Stock Option Agreement (the "Agreement"), and
will enter into an Agreement and Plan of Merger to be dated as of the date of
this Agreement (the "Plan of Merger," and, together with the Reorganization
Agreement, the "Merger Agreements"); and

     WHEREAS, as a condition to Grantee's entering into the Merger Agreements
and in consideration therefor, Issuer has agreed to grant Grantee the Option (as
hereinafter defined);

     NOW, THEREFORE, in consideration of the foregoing and the mutual covenants
and agreements set forth herein and in the Merger Agreements, the parties hereto
agree as follows:

        1. (a) Issuer hereby grants to Grantee an unconditional, irrevocable
option (the "Option") to purchase, subject to the terms hereof, up to 9,730,070
fully paid and nonassessable shares of Issuer's Common Stock, par value $2.00
per share ("Common Stock"), at a price of $15.125 per share (the "Option
Price"); provided, however, that in no event shall the number of shares of
Common Stock for which this Option is exercisable exceed 19.9% of the Issuer's
issued and outstanding shares of Common Stock without giving effect to any
shares subject to or issued pursuant to the Option. The number of shares of
Common Stock that may be received upon the exercise of the Option and the Option
Price are subject to adjustment as herein set forth.

           (b) In the event that any additional shares of Common Stock are
either (i) issued or otherwise become outstanding after the date of this
Agreement (other than pursuant to this Agreement or as permitted under the terms
of the Merger Agreements) or (ii) redeemed, repurchased, retired or otherwise
cease to be outstanding after the date of the Agreement, the number of shares of
Common Stock subject to the Option shall be increased or decreased, as
appropriate, so that, after such issuance, such number equals 19.9% of the
number of shares of Common Stock then issued and outstanding without giving
effect to any shares subject or issued pursuant to the Option. Nothing contained
in this Section 1(b) or elsewhere in this Agreement shall be deemed to authorize
Issuer or Grantee to breach any provision of the Merger Agreements.

        2. (a) The Holder (as hereinafter defined) may exercise the Option, in
whole or part, and from time to time, if, but only if, both an Initial
Triggering Event (as hereinafter defined) and a Subsequent Triggering Event (as
hereinafter defined) shall have occurred prior to the occurrence of an Exercise
Termination Event (as hereinafter defined), provided, however, that the Holder
shall have sent the written notice of such exercise (as provided in subsection
(e) of this Section 2) within six months following such Subsequent Triggering
Event; provided, further, however, that if the Option cannot be exercised on any
day because of any injunction, order or similar restraint issued by a court of
competent jurisdiction, the period during which the Option may be exercised
shall be extended so that the Option shall expire

                                       B-2
<PAGE>   136

no earlier than on the 10th business day after such injunction, order or
restraint shall have been dissolved or when such injunction, order or restraint
shall have become permanent and no longer subject to appeal, as the case may be.
Each of the following shall be an "Exercise Termination Event": (i) the
Effective Time (as defined in the Plan of Merger) of the Merger; (ii)
termination of the Merger Agreements in accordance with the provisions thereof
if such termination occurs prior to the occurrence of an Initial Triggering
Event except a termination by Grantee pursuant to Section 6.1(b)(i) of the
Reorganization Agreement (unless the breach by Issuer giving rise to such right
of termination is non-volitional); or (iii) the passage of twelve months after
termination of the Merger Agreements if such termination follows the occurrence
of an Initial Triggering Event or is a termination by Grantee pursuant to
Section 6.1(b)(i) of the Reorganization Agreement (unless the breach by Issuer
giving rise to such right of termination is non-volitional). The term "Holder"
shall mean the holder or holders of the Option. Notwithstanding anything to the
contrary contained herein, the Option may not be exercised (nor may Grantee's
rights under Section 10 hereof be exercised) at any time when Grantee shall be
in willful breach of any of its covenants or agreements contained in the Merger
Agreements under circumstances that would entitle Issuer to terminate the Merger
Agreements (without regard to any grace period provided for in Section 6.1(b)(x)
of the Reorganization Agreement).

           (b) The term "Initial Triggering Event" shall mean any of the
following events or transactions occurring after the date hereof:

              (i) Issuer or any of its Subsidiaries (each an "Issuer
Subsidiary"), without having received Grantee's prior written consent, shall
have entered into an agreement to engage in an Acquisition Transaction (as
hereinafter defined) with any person (the term "person" for purposes of this
Agreement having the meaning assigned thereto in Sections 3(a)(9) and 13(d)(3)
of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and the
rules and regulations thereunder) other than Grantee or any of its Subsidiaries
(each a "Grantee Subsidiary"). For purposes of this Agreement, "Acquisition
Transaction" shall mean (w) a merger or consolidation, or any similar
transaction, involving Issuer or any Significant Subsidiary (as defined in Rule
1-02 of Regulation S-X promulgated by the Securities and Exchange Commission
(the "SEC")) of Issuer, (x) a purchase, lease or other acquisition or assumption
of all or a substantial portion of the assets or deposits of Issuer or any
Significant Subsidiary of Issuer, (y) a purchase or other acquisition (including
by way of merger, consolidation, share exchange or otherwise) of securities
representing 10% or more of the voting power of Issuer, or (z) any substantially
similar transaction; provided, however, that in no event shall any merger,
consolidation, purchase or similar transaction involving only the Issuer and one
or more of its Subsidiaries or involving only two or more of such Subsidiaries,
be deemed to be an Acquisition Transaction; provided that any such transaction
is not entered into in violation of the terms of the Merger Agreements;

              (ii) Issuer or any of its Subsidiaries, without having received
Grantee's prior written consent, shall have authorized, recommended, proposed,
or publicly announced its intention to authorize, recommend or propose to engage
in an Acquisition Transaction with any person other than Grantee or a Subsidiary
of Grantee;

              (iii) Any person (other than Grantee or any Subsidiary of Grantee)
shall have acquired beneficial ownership or the right to acquire beneficial
ownership of 10% or more of the outstanding shares of Common Stock (the term
"beneficial ownership" for purposes of this Agreement having the meaning
assigned thereto in Section 13(d) of the Exchange Act, and the rules and
regulations thereunder) or any person other than Grantee or any Subsidiary of
Grantee shall have commenced (as such term is defined under the rules and
regulations of the SEC), or shall have filed or publicly disseminated a
registration statement or similar disclosure statement with respect to, a tender
offer or

                                       B-3
<PAGE>   137

exchange offer to purchase any shares of Issuer Common Stock such that, upon
consummation of such offer, such person would beneficially own, directly or
indirectly, 10% or more of the then outstanding shares of Issuer Common Stock
(such an offer being referred to herein as a "Tender Offer" or an "Exchange
Offer," respectively);

              (iv) (A) the holders of Issuer Common Stock shall not have
approved the Merger Agreements and the transactions contemplated thereby, at the
meeting of such stockholders held for the purpose of voting on such agreement,
(B) such meeting shall not have been held or shall have been cancelled prior to
termination of the Merger Agreements, or (C) the Board of Directors of Issuer
shall have publicly withdrawn or modified, or publicly announced its intent to
withdraw or modify, in any manner adverse to Grantee, its recommendation that
the stockholders of Issuer approve the transactions contemplated by the Merger
Agreements, in each case after it shall have been publicly announced that any
person other than Grantee or any Subsidiary of Grantee shall have (x) made, or
disclosed an intention to make, a proposal to engage in an Acquisition
Transaction, (y) commenced a Tender Offer, or filed or publicly disseminated a
registration statement or similar disclosure statement with respect to an
Exchange Offer, or (z) filed an application (or given a notice), whether in
draft or final form, under any federal or state banking laws seeking regulatory
approval to engage in an Acquisition Transaction; or

              (v) After an overture is made by a third party to Issuer or its
stockholders to engage in an Acquisition Transaction, Issuer shall have breached
any covenant or obligation contained in the Reorganization Agreement and such
breach (x) would entitle Grantee to terminate the Merger Agreements and (y)
shall not have been cured prior to the Notice Date (as defined below).

           (c) The term "Subsequent Triggering Event" shall mean either of the
following events or transactions occurring after the date hereof:

              (i) The acquisition by any person of beneficial ownership of 25%
or more of the then outstanding shares of Common Stock; or

              (ii) The occurrence of the Initial Triggering Event described in
paragraph (i) of subsection (b) of this Section 2, except that the percentage
referred to in clause (y) shall be 25%.

           (d) Issuer shall notify Grantee promptly in writing of the occurrence
of any Initial Triggering Event or Subsequent Triggering Event of which it has
notice (together, a "Triggering Event"), it being understood that the giving of
such notice by Issuer shall not be a condition to the right of the Holder to
exercise the Option.

           (e) In the event the Holder is entitled to and wishes to exercise the
Option, it shall send to Issuer a written notice (the date of which being herein
referred to as the "Notice Date") specifying (i) the total number of shares it
will purchase pursuant to such exercise and (ii) a place and date not earlier
than three business days nor later than 60 business days from the Notice Date
for the closing of such purchase (the "Closing Date"); provided, that if prior
notification to or approval of the Federal Reserve Board or any other regulatory
agency is required in connection with such purchase, the Holder shall promptly
file the required notice or application for approval and shall expeditiously
process the same and the period of time that otherwise would run pursuant to
this sentence shall run instead from the date on which any required notification
periods have expired or been terminated or such approvals have been obtained and
any requisite waiting period or periods shall have passed. Any exercise of the
Option shall be deemed to occur on the Notice Date relating thereto.

           (f) At the closing referred to in subsection (e) of this Section 2,
the Holder shall pay to Issuer the aggregate purchase price for the shares of
Common Stock purchased pursuant to the exercise of the Option in immediately
available funds by wire transfer to a bank account designated by Issuer;

                                       B-4
<PAGE>   138

provided, that failure or refusal of Issuer to designate such a bank account
shall not preclude the Holder from exercising the Option.

           (g) At such closing, simultaneously with the delivery of immediately
available funds as provided in subsection (f) of this Section 2, Issuer shall
deliver to the Holder a certificate or certificates representing the number of
shares of Common Stock purchased by the Holder and, if the Option should be
exercised in part only, a new Option evidencing the rights of the Holder thereof
to purchase the balance of the shares purchasable hereunder, and the Holder
shall deliver to Issuer a copy of this Agreement and a letter agreeing that the
Holder will not offer to sell or otherwise dispose of such shares in violation
of applicable law or the provisions of this Agreement.

           (h) Certificates for Common Stock delivered at a closing hereunder
may be endorsed with a restrictive legend that shall read substantially as
follows:

           "THE TRANSFER OF THE SHARES REPRESENTED BY THIS CERTIFICATE IS
           SUBJECT TO CERTAIN PROVISIONS OF AN AGREEMENT BETWEEN THE REGISTERED
           HOLDER HEREOF AND ISSUER AND TO RESALE RESTRICTIONS ARISING UNDER THE
           SECURITIES ACT OF 1933, AS AMENDED. A COPY OF SUCH AGREEMENT IS ON
           FILE AT THE PRINCIPAL OFFICE OF ISSUER AND WILL BE PROVIDED TO THE
           HOLDER HEREOF WITHOUT CHARGE UPON RECEIPT BY ISSUER OF A WRITTEN
           REQUEST THEREFOR."

It is understood and agreed that: (i) the reference to the resale restrictions
of the Securities Act of 1933, as amended (the "Securities Act"), in the above
legend shall be removed by delivery of substitute certificate(s) without such
reference if the Holder shall have delivered to Issuer a copy of a letter from
the staff of the SEC, or an opinion of counsel, in form and substance reasonably
satisfactory to Issuer, to the effect that such legend is not required for
purposes of the Securities Act; (ii) the reference to the provisions to this
Agreement in the above legend shall be removed by delivery of substitute
certificate(s) without such reference if the shares have been sold or
transferred in compliance with the provisions of this Agreement and under
circumstances that do not require the retention of such reference; and (iii) the
legend shall be removed in its entirety if the conditions in the preceding
clauses (i) and (ii) are both satisfied. In addition, such certificates shall
bear any other legend as may be required by law.

           (i) Upon the giving by the Holder to Issuer of the written notice of
exercise of the Option provided for under subsection (e) of this Section 2 and
the tender of the applicable purchase price in immediately available funds, the
Holder shall be deemed to be the holder of record of the shares of Common Stock
issuable upon such exercise, notwithstanding that the stock transfer books of
Issuer shall then be closed or that certificates representing such shares of
Common Stock shall not then be actually delivered to the Holder. Issuer shall
pay all expenses, and any and all United States federal, state and local taxes
and other charges that may be payable in connection with the preparation, issue
and delivery of stock certificates under this Section 2 in the name of the
Holder or its assignee, transferee or designee.

        3. Issuer agrees: (i) that it shall at all times maintain, free from
preemptive rights, sufficient authorized but unissued or treasury shares of
Common Stock so that the Option may be exercised without additional
authorization of Common Stock after giving effect to all other options,
warrants, convertible securities and other rights to purchase Common Stock; (ii)
that it will not, by charter amendment or through reorganization, consolidation,
merger, dissolution or sale of assets, or by any other voluntary act, avoid or
seek to avoid the observance or performance of any of the covenants,
stipulations or conditions to be observed or performed hereunder by Issuer;
(iii) promptly to take all action as may from time to time be required
(including (x) complying with all premerger notification, reporting and waiting
period requirements specified in 15 U.S.C. sec. 18a and regulations promulgated

                                       B-5
<PAGE>   139

thereunder and (y) in the event, under federal or state banking law, prior
approval of or notice to the Federal Reserve Board or any other federal or state
regulatory authority is necessary before the Option may be exercised,
cooperating fully with the Holder in preparing such applications or notices and
providing such information to the Federal Reserve Board or such other federal or
state regulatory authority as they may require) in order to permit the Holder to
exercise the Option and Issuer duly and effectively to issue shares of Common
Stock pursuant hereto; and (iv) promptly to take all action provided herein to
protect the rights of the Holder against dilution.

        4. This Agreement (and the Option granted hereby) are exchangeable,
without expense, at the option of the Holder, upon presentation and surrender of
this Agreement at the principal office of Issuer, for other Agreements providing
for Options of different denominations entitling the holder thereof to purchase,
on the same terms and subject to the same conditions as are set forth herein, in
the aggregate the same number of shares of Common Stock purchasable hereunder.
The terms "Agreement" and "Option" as used herein include any Stock Option
Agreements and related Options for which this Agreement (and the Option granted
hereby) may be exchanged. Upon receipt by Issuer of evidence reasonably
satisfactory to it of the loss, theft, destruction or mutilation of this
Agreement, and (in the case of loss, theft or destruction) of reasonably
satisfactory indemnification, and upon surrender and cancellation of this
Agreement, if mutilated, Issuer will execute and deliver a new Agreement of like
tenor and date. Any such new Agreement executed and delivered shall constitute
an additional contractual obligation on the part of Issuer, whether or not the
Agreement so lost, stolen, destroyed or mutilated shall at any time be
enforceable by anyone.

        5. In addition to the adjustment in the number of shares of Common Stock
that are purchasable upon exercise of the Option pursuant to Section 1 of this
Agreement, the number of shares of Common Stock purchasable upon the exercise of
the Option and the Option Price shall be subject to adjustment from time to time
as provided in this Section 5. In the event of any change in, or distributions
in respect of, the Common Stock by reason of stock dividends, split-ups,
mergers, recapitalizations, combinations, subdivisions, conversions, exchanges
of shares, distributions on or in respect of the Common Stock that would be
prohibited under the terms of the Merger Agreement, or the like, the type and
number of shares of Common Stock purchasable upon exercise hereof and the Option
Price shall be appropriately adjusted in such manner as shall fully preserve the
economic benefits provided hereunder and proper provision shall be made in any
agreement governing any such transaction to provide for such proper adjustment
and the full satisfaction of the Issuer's obligations hereunder.

        6. Upon the occurrence of a Subsequent Triggering Event that occurs
prior to an Exercise Termination Event, Issuer shall, at the request of Grantee
delivered within six months of such Subsequent Triggering Event (whether on its
own behalf or on behalf of any subsequent holder of this Option (or part
thereof) or any of the shares of Common Stock issued pursuant hereto), promptly
prepare, file and keep current a registration statement under the Securities Act
covering this Option and any shares issued and issuable pursuant to this Option
and shall use its reasonable best efforts to cause such registration statement
to become effective and remain current in order to permit the sale or other
disposition of this Option and any shares of Common Stock issued upon total or
partial exercise of this Option ("Option Shares") in accordance with any plan of
disposition requested by Grantee. Issuer will use its reasonable best efforts to
cause such registration statement first to become effective and then to remain
effective for such period not in excess of 180 days from the day such
registration statement first becomes effective or such shorter time as may be
reasonably necessary to effect such sales or other dispositions. Grantee shall
have the right to demand two such registrations. The foregoing notwithstanding,
if, at the time of any request by Grantee for registration of the Option or
Option Shares as provided above, Issuer is in registration with respect to an
underwritten public offering of shares of Common Stock, and if in the good faith
judgment of the managing underwriter or managing

                                       B-6
<PAGE>   140

underwriters, or, if none, the sole underwriter or underwriters, of such
offering the inclusion of the Holder's Option or Option Shares would interfere
with the successful marketing of the shares of Common Stock offered by Issuer,
the number of Option Shares otherwise to be covered in the registration
statement contemplated hereby may be reduced; and provided, however, that after
any such required reduction the number of Option Shares to be included in such
offering for the account of the Holder or Holders shall constitute at least 25%
of the total number of shares to be sold by the Holder or Holders and Issuer in
the aggregate; and provided, further, however, that if such reduction occurs,
then the Issuer shall file a registration statement for the balance as promptly
as practicable and no reduction shall thereafter occur. Each such Holder shall
provide all information reasonably requested by Issuer for inclusion in any
registration statement to be filed hereunder. If requested by any such Holder in
connection with such registration, Issuer shall become a party to any
underwriting agreement relating to the sale of such shares, but only to the
extent of obligating itself in respect of representations, warranties,
indemnities and other agreements customarily included in secondary offering
underwriting agreements for the Issuer. Upon receiving any request under this
Section 6 from Grantee, Issuer agrees to send a copy thereof to any other person
known to Issuer to be entitled to registration rights under this Section 6, in
each case by promptly mailing the same, postage prepaid, to the address of
record of the persons entitled to receive such copies. Notwithstanding anything
to the contrary contained herein, in no event shall Issuer be obligated to
effect more than two registrations pursuant to this Section 6 by reason of the
fact that there shall be more than one Holder as a result of any assignment or
division of this Agreement.

        7. The periods for exercise of certain rights under Sections 2, 6, 10
and 12 shall be extended: (i) to the extent necessary to obtain all regulatory
approvals for the exercise of such rights, and for the expiration of all
statutory waiting periods; and (ii) to the extent necessary to avoid liability
under Section 16(b) of the Exchange Act by reason of such exercise.

        8. Issuer hereby represents and warrants to Grantee as follows:

           (a) Issuer has full corporate power and authority to execute and
deliver this Agreement and to consummate the transactions contemplated hereby.
The execution and delivery of this Agreement and the consummation of the
transactions contemplated hereby have been duly and validly authorized by the
Board of Directors of Issuer and no other corporate proceedings on the part of
Issuer are necessary to authorize this Agreement or to consummate the
transactions so contemplated. This Agreement has been duly and validly executed
and delivered by Issuer.

           (b) Issuer has taken all necessary corporate action to authorize and
reserve and to permit it to issue, and at all times from the date hereof through
the termination of this Agreement in accordance with its terms will have
reserved for issuance upon the exercise of the Option, that number of shares of
Common Stock equal to the maximum number of shares of Common Stock at any time
and from time to time issuable hereunder, and all such shares, upon issuance
pursuant hereto, will be duly authorized, validly issued, fully paid,
nonassessable, and will be delivered free and clear of all claims, liens,
encumbrance and security interests and not subject to any preemptive rights.

        9. Grantee hereby represents and warrants to Issuer that:

           (a) Grantee has all requisite corporate power and authority to enter
into this Agreement and, subject to any approvals or consents referred to
herein, to consummate the transactions contemplated hereby. The execution and
delivery of this Agreement and the consummation of the transactions contemplated
hereby have been duly authorized by all necessary corporate action on the part
of Grantee. This Agreement has been duly executed and delivered by Grantee.

                                       B-7
<PAGE>   141

           (b) The Option is not being, and any shares of Common Stock or other
securities acquired by Grantee upon exercise of the Option will not be, acquired
with a view to the public distribution thereof and will not be transferred or
otherwise disposed of except in a transaction registered or exempt from
registration under the Securities Act.

        10. Neither of the parties hereto may assign any of its rights or
obligations under this Agreement or the Option created hereunder to any other
person, without the express written consent of the other party, except that in
the event a Subsequent Triggering Event shall have occurred prior to an Exercise
Termination Event, Grantee, subject to the express provisions hereof, may assign
in whole or in part its rights and obligations hereunder within six months
following such Subsequent Triggering Event (or such later period as provided in
Section 7); provided, however, that until the date fifteen days following the
date on which the Federal Reserve Board approves an application by Grantee to
acquire the shares of Common Stock subject to the Option (proof of which
approval shall be furnished promptly to Issuer), Grantee may not assign its
rights under the Option except in (i) a widely dispersed public distribution,
(ii) a private placement in which no one party acquires the right to purchase in
excess of 2% of the voting shares of Issuer, (iii) an assignment to a single
party (e.g., a broker or investment banker) for the purpose of conducting a
widely dispersed public distribution on Grantee's behalf, or (iv) any other
manner approved by the Federal Reserve Board.

        11. Each of Grantee and Issuer will use its best efforts to make all
filings with, and to obtain consents of, all third parties and governmental
authorities necessary to the consummation of the transactions contemplated by
this Agreement, including without limitation making application to list the
shares of Common Stock issuable hereunder on the Nasdaq National Market upon
official notice of issuance and applying to the Federal Reserve Board, for
approval to acquire the shares issuable hereunder, but Grantee shall not be
obligated to apply to state banking authorities for approval to acquire the
shares of Common Stock issuable hereunder until such time, if ever, as it deems
appropriate to do so.

        12. (a) Upon the occurrence of a Subsequent Triggering Event that occurs
prior to an Exercise Termination Event, (i) at the request of any Holder,
delivered within thirty days following such occurrence (or such later period as
provided in Section 7) but in any event prior to an Exercise Termination Event,
Issuer shall repurchase the Option from the Holder at a price (the "Option
Repurchase Price") equal to the amount by which (A) the market/offer price (as
defined below) exceeds (B) the Option Price, multiplied by the number of shares
for which this Option may then be exercised, plus, to the extent not previously
reimbursed, Grantee's reasonable out-of-pocket expenses incurred in connection
with the transactions contemplated by, and the enforcement of Grantee's rights
under, the Merger Agreements, including without limitation legal, accounting and
investment banking fees (the "Grantee's Out-of-Pocket Expenses"), and (ii) at
the request of any owner of Option Shares from time to time (the "Owner"),
delivered within thirty days following such occurrence (or such later period as
provided in Section 7), Issuer shall repurchase such number of the Option Shares
from such Owner as the Owner shall designate at a price per share ("Option Share
Repurchase Price") equal to the greater of (A) the market/offer price and (B)
the average option price per share paid by the Owner for the Option Shares so
designated, plus, to the extent not previously reimbursed, Grantee's
Out-of-Pocket Expenses. The term "market/offer price" shall mean the highest of
(w) the price per share of the Common Stock at which a tender offer or exchange
offer therefor has been made, (x) the price per share of the Common Stock to be
paid by any Person, other than Grantee or a subsidiary of Grantee, pursuant to
an agreement with Issuer, (y) the highest closing price for shares of Common
Stock within the six month period immediately preceding the required repurchase
of Options or Option Shares, as the case may be, or (z) in the event of a sale
of all or substantially all of Issuer's assets, the sum of the price paid in
such sale for such assets and the current market value of the remaining assets
of Issuer as

                                       B-8
<PAGE>   142

determined by a nationally recognized investment banking firm selected by a
majority in the interest of the Holders or the Owners, as the case may be, and
reasonably acceptable to Issuer, divided by the number of shares of Common Stock
of Issuer outstanding at the time of such sale. In determining the market/offer
price, the value of consideration other than cash shall be determined by a
nationally recognized investment banking firm selected by a majority in interest
of the Holders or the Owners, as the case may be, and reasonably acceptable to
Issuer.

            (b) Each Holder and Owner, as the case may be, may exercise its
right to require Issuer to repurchase the Option and any Option Shares pursuant
to this Section 12 by surrendering for such purpose to Issuer, at its principal
office, a copy of this Agreement or certificates for Option Shares, as
applicable, accompanied by a written notice or notices stating that such Holder
or Owner elects to require Issuer to repurchase this Option and/or Option Shares
in accordance with the provisions of this Section 12. As promptly as
practicable, and in any event within ten business days after the surrender of
the Option and/or certificates representing Option Shares and the receipt of
such notice or notices relating thereto, Issuer shall deliver or cause to be
delivered to each Holder the Option Repurchase Price and/or to each Owner the
Option Share Repurchase Price therefor or the portion thereof that Issuer is not
then prohibited under applicable law and regulation from so delivering.

            (c) To the extent that Issuer is prohibited under applicable law or
regulation, or as a consequence of administrative policy, or as a result of a
written agreement or other binding obligation with a governmental or regulatory
body or agency, from repurchasing the Option and/or the Option Shares in full,
Issuer shall immediately so notify each Holder and/or each Owner and thereafter
deliver or cause to be delivered, from time to time, to such Holder and/or
Owner, as appropriate, the portion of the Option Repurchase Price and the Option
Share Repurchase Price, respectively, that it is no longer prohibited from
delivering, within ten business days after the date on which Issuer is no longer
so prohibited; provided, however, that if Issuer at any time after delivery of a
notice of repurchase pursuant to paragraph (b) of this Section 12 is prohibited
under applicable law or regulation, or as a consequence of administrative
policy, from delivering to any Holder and/or Owner, as appropriate, the Option
Repurchase Price and the Option Share Repurchase Price, respectively, in part or
in full (and Issuer hereby undertakes to use its best efforts to receive any
required regulatory and legal approvals and to file any required notices as
promptly as practicable in order to accomplish such repurchase), such Holder or
Owner may revoke its notice of repurchase of the Option or the Option Shares
either in whole or to the extent of the prohibition, whereupon Issuer shall
promptly (i) deliver to such Holder and/or Owner, as appropriate, that portion
of the Option Purchase Price or the Option Share Repurchase Price that Issuer is
not prohibited from delivering; and (ii) deliver, as appropriate, either (A) to
such Holder, a new Stock Option Agreement evidencing the right of such Holder to
purchase that number of shares of Common Stock obtained by multiplying the
number of shares of Common Stock for which the surrendered Stock Option
Agreement was exercisable at the time of delivery of the notice of repurchase by
a fraction, the numerator of which is the Option Repurchase Price less the
portion thereof theretofore delivered to the Holder and the denominator of which
is the Option Repurchase Price, or (B) to such Owner, a certificate for the
Option Shares it is then so prohibited from repurchasing.

        13. The parties hereto acknowledge that damages would be an inadequate
remedy for a breach of this Agreement by either party hereto and that the
obligations of the parties hereto shall be enforceable by either party hereto
through injunctive or other equitable relief.

        14. If any term, provision, covenant or restriction contained in this
Agreement is held by a court or a federal or state regulatory agency of
competent jurisdiction to be invalid, void or unenforceable, the remainder of
the terms, provisions and covenants and restrictions contained in this Agreement
shall remain in full force and effect, and shall in no way be affected, impaired
or invalidated.

                                       B-9
<PAGE>   143

If for any reason such court or regulatory agency determines that the Holder is
not permitted to acquire the full number of shares of Common Stock provided in
Section 1(a) hereof (as adjusted pursuant to Section 1(b) or 5 hereof), it is
the express intention of Issuer to allow the Holder to acquire such lesser
number of shares as may be permissible, without any amendment or modification
hereof.

        15. All notices, requests, claims, demands and other communications
hereunder shall be deemed to have been duly given when delivered in person, by
cable, telegram, telecopy or telex, or by registered or certified mail (postage
prepaid, return receipt requested) at the respective addresses of the parties
set forth in the Reorganization Agreement.

        16. This Agreement shall be governed by and construed in accordance with
the laws of the State of New York, regardless of the laws that might otherwise
govern under applicable principles of conflicts of laws thereof.

        17. This Agreement may be executed in two or more counterparts, each of
which shall be deemed to be an original, but all of which shall constitute one
and the same agreement.

        18. Except as otherwise expressly provided herein, each of the parties
hereto shall bear and pay all costs and expenses incurred by it or on its behalf
in connection with the transactions contemplated hereunder, including fees and
expenses of its own financial consultants, investment bankers, accountants and
counsel.

        19. Except as otherwise expressly provided herein or in the Merger
Agreements, this Agreement contains the entire agreement between the parties
with respect to the transactions contemplated hereunder and supersedes all prior
arrangements or understandings with respect thereof, written or oral. The terms
and conditions of this Agreement shall inure to the benefit of and be binding
upon the parties hereto and their respective successors and permitted assigns.
Nothing in this Agreement, expressed or implied, is intended to confer upon any
party, other than the parties hereto, and their respective successors and
permitted assigns, any rights, remedies, obligations or liabilities under or by
reason of this Agreement, except as expressly provided herein.

        20. Capitalized terms used in this Agreement and not defined herein
shall have the meanings assigned thereto in the Merger Agreement.

     IN WITNESS WHEREOF, each of the parties has caused this Agreement to be
executed on its behalf by its officers thereunto duly authorized, all as of the
date first above written.

KEYSTONE FINANCIAL, INC.

By /s/ CARL L. CAMPBELL
   -------------------------------------------------
   Carl L. Campbell
   Chairman, President and CEO

M&T BANK CORPORATION

By /s/ GARY S. PAUL
   -------------------------------------------------
   Gary S. Paul
   Senior Vice President

                                      B-10
<PAGE>   144

                                   APPENDIX C

                    OPINION OF KEEFE, BRUYETTE & WOODS, INC.

                                       C-1
<PAGE>   145

                         KEEFE, BRUYETTE & WOODS, INC.
                 SPECIALISTS IN BANKING AND FINANCIAL SERVICES

          TWO WORLD TRADE CENTER    89th FLOOR    NEW YORK, N.Y. 10048

<TABLE>
<S>             <C>
  TOLL FREE      TELEPHONE
1-800-966-1559  212-323-8300
</TABLE>

                                 July 28, 2000

The Board of Directors
Keystone Financial, Inc.
One Keystone Plaza
Front & Market Streets
Harrisburg, PA 17101

Members of the Board:

     You have requested our opinion as investment bankers as to the fairness,
from a financial point of view, to the common stockholders of Keystone
Financial, Inc. ("Keystone") and its stockholders of the consideration to be
paid ("Merger Consideration") in the proposed merger ("the Merger") of Keystone
with and into M&T Bank Corporation ("M&T") pursuant to the Agreement and Plan of
Reorganization ("Agreement") dated as of May 15, 2000 between Keystone and M&T.
It is our understanding that the Merger will be structured as a purchase
accounting transaction under generally accepted accounting principles.

     As is more specifically set forth in the Merger Agreement, upon
consummation of the Merger, each outstanding share of Keystone stock, par value
$2.00 per share ("Keystone Common Stock"), will be entitled to receive, at the
election of the holder thereof as is more fully described in the Merger
Agreement, Merger Consideration either of:

     i. Keystone Common Stock converted into and exchanged for 0.05 (the
     "Exchange Ratio") shares of M&T ("M&T Common Stock"), $5.00 par value per
     share subject to certain adjustments as set forth in the Agreement, or

     ii. $21.50 per Keystone Common Stock share payable in cash

     Keefe, Bruyette & Woods, Inc. ("Keefe Bruyette"), as part of its investment
banking business, is continually engaged in the valuation of bank holding
companies and banks, thrift holding companies and thrifts and their securities
in connection with mergers and acquisitions, underwriting, private placements,
competitive bidding processes, market making as a NASD market maker, and
valuations for various other purposes. As specialists in the securities of
banking companies we have experience in, and knowledge of, the valuation of
banking enterprises. In the ordinary course of our business as a broker-dealer,
we may, from time to time, trade the securities of M&T or Keystone, for our own
account, and for the accounts of our customers and, accordingly, may at any time
hold a long or short position in such securities. To the extent we have any such
positions as of the date of this opinion it has been disclosed to Keystone. KBW
has served as financial advisor to Keystone in the negotiation of the

                                       C-2
<PAGE>   146
KEEFE, BRUYETTE & WOODS, INC.

Agreement and in rendering this fairness opinion and will receive a fee from
Keystone for those services.

     In arriving at our opinion, we have reviewed, analyzed and relied upon
material bearing upon the financial and operating condition of M&T and Keystone
and the Merger.

     In the course of our engagement as financial advisor we have, among other
things:

     i. Reviewed the Agreement;

     ii. Reviewed certain historical financial and other information concerning
     Keystone for the three years ending December 31, 1999, including Keystone's
     Annual Report to Shareholders and Annual Reports on Forms 10-K, and interim
     quarterly reports on Form 10-Q;

     iii. Reviewed certain historical financial and other information concerning
     M&T for the three years ending December 31, 1999, including M&T's Annual
     Report to Stockholders and Annual Reports on Forms 10-K, and interim
     quarterly reports on Form 10-Q;

     iv. Reviewed and studied the historical stock prices and trading volumes of
     the common stock of both Keystone and M&T;

     v. Held discussions with senior management of Keystone and M&T with respect
     to their past and current financial performance, financial condition and
     future prospects;

     vi. Reviewed certain internal financial data, projections and other
     information of Keystone and M&T, including financial projections prepared
     by management;

     vii. Analyzed certain publicly available information of other financial
     institutions that we deemed comparable or otherwise relevant to our
     inquiry, and compared Keystone and M&T from a financial point of view with
     certain of these institutions;

     viii. Reviewed the financial terms of certain recent business combinations
     in the banking industry that we deemed comparable or otherwise relevant to
     our inquiry; and

     ix. Conducted such other financial studies, analyses and investigations and
     reviewed such other information as we deemed appropriate to enable us to
     render our opinion.

     In conducting our review and arriving at our opinion, we have relied upon
the accuracy and completeness of all of the financial and other information
provided to us or publicly available and we have not assumed any responsibility
for independently verifying the accuracy or completeness of any such
information. We have relied upon the management of Keystone as to the
reasonableness and achievability of the financial and operating forecasts and
projections (and the assumptions and bases therefor) provided to us, and we have
assumed that such forecasts and projections reflect the best currently available
estimates and judgments of such managements. We are not experts in the
independent verification of the adequacy of allowances for loan and lease losses
and we have assumed that the current and projected aggregate reserves for loan
and lease losses for Keystone and M&T are adequate to cover such losses. We did
not make or obtain any independent evaluations or appraisals of any assets or
liabilities of Keystone, M&T, or any of their respective subsidiaries nor did we
verify any of Keystone's or M&T's books or records or review any individual loan
or credit files.

     We have considered such financial and other factors as we have deemed
appropriate under the circumstances, including, among others, the following: (i)
the historical and financial position and results of operations of Keystone and
M&T; (ii) the assets and liabilities of Keystone and M&T; and (iii) the

                                       C-3
<PAGE>   147
KEEFE, BRUYETTE & WOODS, INC.

nature and terms of certain other merger transactions involving banks and bank
holding companies. We have also taken into account our assessment of general
economic, market and financial conditions and our experience in other
transactions, as well as our experience in securities valuation and knowledge of
the banking industry generally. Our opinion is necessarily based upon conditions
as they exist and can be evaluated on the date hereof and the information made
available to us through the date hereof.

     Based upon and subject to the foregoing, it is our opinion that, as of the
date hereof, the Merger Consideration is fair, from a financial point of view,
to Keystone and its stockholders.

                                        Very truly yours,

                                        /s/ KEEFE, BRUYETTE & WOODS, INC.



                                       C-4
<PAGE>   148

                                   APPENDIX D

         OPINION OF MERRILL, LYNCH, PIERCE, FENNER & SMITH INCORPORATED

                                       D-1
<PAGE>   149

[MERRILL LYNCH LETTERHEAD]

                                                                   July 28, 2000

Board of Directors
M&T Bank Corporation
One M&T Plaza
P.O. Box 223
Buffalo, NY 14240-0223

Members of the Board:

     We understand that M&T Bank Corporation (along with its subsidiaries, "M&T
Bank") and Keystone Financial, Inc. (along with its subsidiaries, "Keystone")
have entered into an Agreement and Plan of Reorganization and related Agreement
and Plan of Merger, dated as of May 16, 2000 (the "Merger Agreement"), pursuant
to which, among other things, Keystone will be merged with and into a subsidiary
of M&T Bank (the "Merger"). In the Merger, each outstanding share of Keystone
common stock, par value $2.00 per share (the "Keystone Shares"), other than
specified Keystone Shares, will be converted into the right to receive, at the
option of the holder thereof (and subject to certain proration limitations set
forth in the Merger Agreement), either (i) that number of shares of the common
stock, par value $5.00 per share, of M&T Bank (the "M&T Bank Shares") equal to
the Exchange Ratio (as defined in the Merger Agreement), with such shares of
stock being defined in the Merger Agreement as the "Stock Consideration", or
(ii) cash equal to the Cash Consideration (as defined in the Merger Agreement).
The Stock Consideration and the Cash Consideration are defined collectively in
the Merger Agreement as the Merger Consideration.

     You have asked us whether, in our opinion, the Merger Consideration is fair
to M&T Bank from a financial point of view.

     In arriving at the opinion set forth below, we have, among other things:

     (1) Reviewed certain publicly available business and financial information
     relating to M&T Bank and Keystone that we deemed to be relevant;

     (2) Reviewed certain information, including financial forecasts, relating
     to the respective businesses, earnings, assets, liabilities and prospects
     of M&T Bank and Keystone furnished to us by senior management of M&T Bank
     and Keystone, as well as the amount and timing of the cost savings, revenue
     enhancements and related expenses expected to result from the Merger (the
     "Expected Synergies") furnished to us by senior management of M&T Bank and
     Keystone;

     (3) Conducted discussions with members of senior management and
     representatives of M&T Bank and Keystone concerning the matters described
     in (1) and (2) above, as well as their respective businesses and prospects
     before and after giving effect to the Merger and the Expected Synergies;

     (4) Reviewed the market prices and valuation multiples for the M&T Bank
     Shares and the Keystone Shares and compared them with those of certain
     publicly traded companies that we deemed to be relevant;

                                       D-2
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[MERRILL LYNCH LOGO]

     (5) Reviewed the respective publicly reported financial condition and
     results of operations of M&T Bank and Keystone and compared them with those
     of certain publicly traded companies that we deemed to be relevant;

     (6) Compared the proposed financial terms of the Merger with the financial
     terms of certain other transactions that we deemed to be relevant;

     (7) Participated in certain discussions among representatives of M&T Bank
     and Keystone and their financial and legal advisors with respect to the
     Merger;

     (8) Reviewed the potential pro forma impact of the Merger on M&T Bank;

     (9) Reviewed the Merger Agreement; and

     (10) Reviewed such other financial studies and analyses and took into
     account such other matters as we deemed necessary, including our assessment
     of general economic, market and monetary conditions.

     In preparing our opinion, we have assumed and relied on the accuracy and
completeness of all information supplied or otherwise made available to us,
discussed with or reviewed by or for us, or publicly available, and we have not
assumed any responsibility for independently verifying such information or
undertaken an independent evaluation or appraisal of the assets or liabilities
of M&T Bank or Keystone or been furnished with any such evaluation or appraisal.
We are not experts in the evaluation of allowances for loan losses, and we have
neither made an independent evaluation of the adequacy of the allowance for loan
losses of M&T Bank or Keystone, nor have we reviewed any individual credit files
of M&T Bank or Keystone or been requested to conduct such a review, and, as a
result, we have assumed that the respective allowance for loan losses for M&T
Bank and Keystone is adequate to cover such losses and will be adequate on a pro
forma basis for the combined entity. In addition, we have not assumed any
obligation to conduct, nor have we conducted, any physical inspection of the
properties or facilities of M&T Bank or Keystone. With respect to the financial
and operating information, including without limitation financial forecasts,
valuations of contingencies and projections regarding under-performing and
non-performing assets, net charge-offs, adequacy of reserves, future economic
conditions and information on the Expected Synergies, furnished to or discussed
with us by M&T Bank or Keystone, we have assumed that they have been reasonably
prepared and reflect the best currently available estimates and judgments of the
senior management of M&T Bank and Keystone as to the future financial and
operating performance of M&T Bank, Keystone or the combined entity, as the case
may be, and the Expected Synergies. We have further assumed that the Merger will
be accounted for as a purchase under generally accepted accounting principles
and that it will qualify as a tax-free reorganization for U.S. federal income
tax purposes.

     Our opinion is necessarily based upon market, economic and other conditions
as in effect, and on the information made available to us as of, the date
hereof. For the purposes of rendering this opinion, we have assumed that the
Merger will be consummated substantially in accordance with the terms set forth
in the Merger Agreement, including in all respects material to our analysis,
that the representations and warranties of each party in the Agreement and in
all related documents and instruments (collectively, the "Documents") that are
referred to therein are true and correct, that each party to the Documents will
perform all of the covenants and agreements required to be performed by such
party under such Documents, and that all conditions to the consummation of the
Merger will be satisfied without waiver thereof. We have also assumed that in
the course of obtaining the necessary regulatory or other consents or approvals
(contractual or otherwise) for the Merger, no restrictions, including any

                                       D-3
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[MERRILL LYNCH LOGO]

divestiture requirements, termination or other payments or amendment or
modifications, will be imposed that will have a material adverse effect on the
future results of operations or financial condition of M&T Bank, Keystone or the
combined entity, as the case may be, or the contemplated benefits of the Merger,
including the Expected Synergies.

     We have been retained by the Board of Directors of M&T Bank to render a
fairness opinion to M&T Bank in connection with the Merger and will receive a
fee from M&T Bank for our services, a significant portion of which is contingent
upon the consummation of the Merger. In addition, M&T Bank has agreed to
indemnify us for certain liabilities arising out of our engagement. In the
ordinary course of our business, we also may actively trade the M&T Bank Shares
and other securities of M&T Bank and its affiliates and the Keystone Shares and
other securities of Keystone and its affiliates for our own account and for the
accounts of our customers, and, accordingly, may at any time hold long or short
positions in such securities.

     This opinion is for the sole and exclusive use and benefit of the Board of
Directors of M&T Bank. It is further understood that this opinion will not be
reproduced, summarized, described or referred to or given to any person without
Merrill Lynch's prior written consent. Our opinion does not address the merits
of the underlying decision by M&T Bank to engage in the Merger and does not
constitute a recommendation to any shareholder of M&T Bank as to how such
shareholder should vote on the proposed Merger or any other matter related
thereto, if any vote thereof is required.

     We have not considered, nor are we expressing any opinion herein with
respect to, the prices at which M&T Bank Shares or Keystone Shares will trade
following the announcement of the Merger or the price at which the M&T Bank
Shares will trade following the consummation of the Merger.

     On the basis of and subject to the foregoing, we are of the opinion that,
as of the date hereof, the Merger Consideration is fair to M&T Bank from a
financial point of view.

                                      Very truly yours,

                                      /s/ MERRILL LYNCH, PIERCE, FENNER & SMITH
                                      INCORPORATED
                                      MERRILL LYNCH, PIERCE, FENNER & SMITH
                                                  INCORPORATED

                                       D-4
<PAGE>   152

                                   APPENDIX E

                     SUBCHAPTER D OF PENNSYLVANIA BUSINESS
                                CORPORATION LAW

                                       E-1
<PAGE>   153

SEC. 1571.  APPLICATION AND EFFECT OF SUBCHAPTER.

     (a) General rule. -- Except as otherwise provided in subsection (b), any
shareholder of a business corporation shall have the right to dissent from, and
to obtain payment of the fair value of his shares in the event of, any corporate
action, or to otherwise obtain fair value for his shares, where this subpart
expressly provides that a shareholder shall have the rights and remedies
provided in this subchapter. See:

     Section 1906(c) (relating to dissenters rights upon special treatment).
Section 1930 (relating to dissenters rights).
Section 1931(d) (relating to dissenters rights in share exchanges).
Section 1932(c) (relating to dissenters rights in asset transfers).
Section 1952(d) (relating to dissenters rights in division).
Section 1962(c) (relating to dissenters rights in conversion).
Section 2104(b) (relating to procedure).
Section 2324 (relating to corporation option where a restriction on transfer of
a security is held invalid).
Section 2325(b) (relating to minimum vote requirement).
Section 2704 (relating to dissenters rights upon election).
Section 2907(a) (relating to proceedings to terminate breach of qualifying
conditions).
Section 7104(b) (3) (relating to procedure).

     (b) Exceptions. --

     (1) Except as otherwise provided in paragraph (2), the holders of the
shares of any class or series that, at the record date fixed to determine the
shareholders entitled to notice of and to vote at the meeting at which a plan
specified in any of section 1930, 1931(d), 1932(c) or 1952(d) is to be voted on,
are either:

     (i) listed on a national securities exchange; or

     (ii) held of record by more than 2,000 shareholders;

     have the right to obtain payment of the fair value of any such shares under
this subchapter.

     (2) Paragraph (1) shall not apply to and dissenters rights shall be
available without regard to the exception provided in that paragraph in the case
of:

     (i) Shares converted by a plan if the shares are not converted solely into
     shares of the acquiring, surviving, new or other corporation or solely into
     such shares and money in lieu of fractional shares.

     (ii) Shares of any preferred or special class unless the articles, the plan
     or the terms of the transaction entitle all shareholders of the class to
     vote thereon and require for the adoption of the plan or the effectuation
     of the transaction the affirmative vote of a majority of the votes cast by
     all shareholders of the class.

     (3) Shares entitled to dissenter rights under section 1906(c) (relating to
dissenters rights upon special treatment).

     (c) Grant of optional dissenters rights. -- The bylaws or a resolution of
the board of directors may direct that all or a part of the shareholders shall
have dissenters rights in connection with any corporate action or other
transaction that would otherwise not entitle such shareholders to dissenters
rights.

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<PAGE>   154

     (d) Notice of dissenters rights. -- Unless otherwise provided by statute,
if a proposed corporate action that would give rise to dissenters rights under
this subpart is submitted to a vote at a meeting of shareholders, there shall be
included in or enclosed with the notice of meeting:

     (1) a statement of the proposed action and a statement that the
     shareholders have a right to dissent and obtain payment of the fair value
     of their shares by complying with the terms of this subchapter; and

     (2) a copy of this subchapter.

     (e) Other statutes. -- The procedures of this subchapter shall also be
applicable to any transaction described in any statute other than this part that
makes reference to this subchapter for the purpose of granting dissenters
rights.

     (f) Certain provisions of articles ineffective. -- This subchapter may not
be relaxed by any provision of the articles.

     (g) Cross references. -- See sections 1105 (relating to restriction on
equitable relief), 1904 (relating to de facto transaction doctrine abolished)
and 2512 (relating to dissenters rights procedure).

SEC. 1572.  DEFINITIONS.

     The following words and phrases when used in this subchapter shall have the
following meanings given to them in this section unless the context clearly
indicates otherwise:

     "Corporation." The issuer of the shares held or owned by the dissenter
     before the corporate action or the successor by merger, consolidation,
     division, conversion or otherwise of that issuer. A plan of division may
     designate which of the resulting corporations is the successor corporation
     for the purposes of this subchapter. The successor corporation in a
     division shall have sole responsibility for payments to dissenters and
     other liabilities under this subchapter except as otherwise provided in the
     plan of division.

     "Dissenter." A shareholder or beneficial owner who is entitled to and does
     assert dissenters rights under this subchapter and who has performed every
     act required up to the time involved for the assertion of those rights.

     "Fair value." The fair value of shares immediately before the effectuation
     of the corporate action to which the dissenter objects, taking into account
     all relevant factors, but excluding any appreciation or depreciation in
     anticipation of the corporate action.

     "Interest." Interest from the effective date of the corporate action until
     the date of payment at such rate as is fair and equitable under all of the
     circumstances, taking into account all relevant factors including the
     average rate currently paid by the corporation on its principal bank loans.

SEC. 1573.  RECORD AND BENEFICIAL HOLDERS AND OWNERS.

     (a) Record holders of shares. -- A record holder of shares of a business
corporation may assert dissenters rights as to fewer than all of the shares
registered in his name only if he dissents with respect to all the shares of the
same class or series beneficially owned by any one person and discloses the name
and address of the person or persons on whose behalf he dissents. In that event,
his rights shall be determined as if the shares as to which he has dissented and
his other shares were registered in the names of different shareholders.

     (b) Beneficial owners of shares. -- A beneficial owner of shares of a
business corporation who is not the record holder may assert dissenters rights
with respect to shares on his behalf and shall be

                                       E-3
<PAGE>   155

treated as a dissenting shareholder under the terms of this subchapter if he
submits to the corporation not later than the time of the assertion of
dissenters rights a written consent of the record holder. A beneficial owner may
not dissent with respect to some but less than all shares of the same class or
series owned by the owner, whether or not the shares so owned by him are
registered in his name.

SEC. 1574.  NOTICE OF INTENTION TO DISSENT.

     If the proposed corporate action is submitted to a vote at a meeting of
shareholders of a business corporation, any person who wishes to dissent and
obtain payment of the fair value of his shares must file with the corporation,
prior to the vote, a written notice of intention to demand that he be paid the
fair value for his shares if the proposed action is effectuated, must effect no
change in the beneficial ownership of his shares from the date of such filing
continuously through the effective date of the proposed action and must refrain
from voting his shares in approval of such action. A dissenter who fails in any
respect shall not acquire any right to payment of the fair value of his shares
under this subchapter. Neither a proxy nor a vote against the proposed corporate
action shall constitute the written notice required by this section.

SEC. 1575.  NOTICE TO DEMAND PAYMENT.

     (a) General rule. -- If the proposed corporate action is approved by the
required vote at a meeting of shareholders of a business corporation, the
corporation shall mail a further notice to all dissenters who gave due notice of
intention to demand payment of the fair value of their shares and who refrained
from voting in favor of the proposed action. If the proposed corporate action is
to be taken without a vote of shareholders, the corporation shall send to all
shareholders who are entitled to dissent and demand payment of the fair value of
their shares a dissent and demand payment of the fair value of their shares a
notice of the adoption of the plan or other corporate action. In either case,
the notice shall:

     (1) State where and when a demand for payment must be sent and certificates
     for certificated shares must be deposited in order to obtain payment.

     (2) Inform holders of uncertificated shares to what extent transfer of
     shares will be restricted from the time that demand for payment is
     received.

     (3) Supply a form for demanding payment that includes a request for
     certification of the date on which the shareholder, or the person on whose
     behalf the shareholder dissents, acquired beneficial ownership of the
     shares.

     (4) Be accompanied by a copy of this subchapter.

     (b) Time for receipt of demand for payment. -- The time set for receipt of
the demand and deposit of certificated shares shall be not less than 30 days
from the mailing of the notice.

SEC. 1576.  FAILURE TO COMPLY WITH NOTICE TO DEMAND PAYMENT, ETC.

     (a) Effect of failure of shareholder to act. -- A shareholder who fails to
timely demand payment, or fails (in the case of certificated shares) to timely
deposit certificates, as required by a notice pursuant to section 1575 (relating
to notice to demand payment) shall not have any right under this subchapter to
receive payment of the fair value of his shares.

     (b) Restriction on uncertificated shares. -- If the shares are not
represented by certificates, the business corporation may restrict their
transfer from the time of receipt of demand for payment until

                                       E-4
<PAGE>   156

effectuation of the proposed corporate action or the release of restrictions
under the terms of section 1577(a) (relating to failure to effectuate corporate
action).

     (c) Rights retained by shareholder. -- The dissenter shall retain all other
rights of a shareholder until those rights are modified by effectuation of the
proposed corporate action.

SEC. 1577.  RELEASE OF RESTRICTIONS OR PAYMENT FOR SHARES.

     (a) Failure to effectuate corporate action. -- Within 60 days after the
date set for demanding payment and depositing certificates, if the business
corporation has not effectuated the proposed corporate action, it shall return
any certificates that have been deposited and release uncertificated shares from
any transfer restrictions imposed by reason of the demand for payment.

     (b) Renewal of notice to demand payment. -- When uncertificated shares have
been released from transfer restrictions and deposited certificates have been
returned, the corporation may at any later time send a new notice conforming to
the requirements of section 1575 (relating to notice to demand payment), with
like effect.

     (c) Payment of fair value of shares. -- Promptly after effectuation of the
proposed corporate action, or upon timely receipt of demand for payment if the
corporate has already been effectuated, the corporation shall either remit to
dissenters who have made demand and (if their shares are certificated) have
deposited their certificates the amount that the corporation estimates to be the
fair value of the shares, or give written notice that no remittance under this
section will be made. The remittance or notice shall be accompanied by:

     (1) The closing balance sheet and statement of income of the issuer of the
     shares held or owned by the dissenter for a fiscal year ending not more
     than 16 months before the date of remittance or notice together with the
     latest available interim financial statements.

     (2) A statement of the corporations estimate of the fair value of the
     shares.

     (3) A notice of the right of the dissenter to demand supplemental payment,
     as the case may be, accompanied by a copy of this subchapter.

     (d) Failure to make payment. -- If the corporation does not remit the
amount of its estimate of the fair value of the shares as provided by subsection
(c), it shall return any certificates that have been deposited and release
uncertificated shares from any transfer restrictions imposed by reason of the
demand for payment. The corporation may make a notation on any such certificate
or on the records of the corporation relating to any such uncertificated shares
that such demand has been made. If shares with respect to which notation has
been so made shall be transferred, each new certificate issued therefor or the
records relating to any transferred uncertificated shares shall bear a similar
notation, together with the name of the original dissenting holder or owner of
such shares. A transferee of such shares shall not acquire by such transfer any
rights in the corporation other than those that the original dissenter had after
making demand for payment of their fair value.

SEC. 1578.  ESTIMATE BY DISSENTER OF FAIR VALUE OF SHARES.

     (a) General rule. -- If the business corporation gives notice of its
estimate of the fair value of the shares, without remitting such amount, or
remits payment of its estimate of the fair value of a dissenters shares as
permitted by section 1577(c) (relating to payment of fair value of shares) and
the dissenter believes that the amount stated or remitted is less than the fair
value of his shares, he may send to the corporation his own estimate of the fair
value of the shares, which shall be deemed a demand for payment of the amount or
the deficiency.

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<PAGE>   157

     (b) Effect of failure to file estimate. -- Where the dissenter does not
file his own estimate under subsection (a) within 30 days after the mailing by
the corporation of its remittance or notice, the dissenter shall be entitled to
no more than the amount stated in the notice or remitted to him by the
corporation.

SEC. 1579.  VALUATION PROCEEDINGS GENERALLY.

     (a) General rule. -- Within 60 days after the latest of:

     (1) effectuation of the proposed corporate action;

     (2) timely receipt of any demands for payment under section 1575 (relating
     to notice to demand payment); or

     (3) timely receipt of any estimates pursuant to section 1578 (relating to
     estimate by dissenter of fair value of shares);

     if any demands for payment remain unsettled, the business corporation may
file in court an application for relief requesting that the fair value of the
shares be determined by the court.

     (b) Mandatory joinder of dissenters. -- All dissenters, wherever residing,
whose demands have not been settled shall be made parties to the proceeding as
in an action against their shares. A copy of the application shall be served on
each dissenter. If a dissenter is a nonresident, the copy may be served on him
in the manner provided or prescribed by or pursuant to 42 Pa. C.S. Ch. 53
(relating to bases of jurisdiction and interstate and international procedure).

     (c) Jurisdiction of the court. -- The jurisdiction of the court shall be
plenary and exclusive. The court may appoint an appraiser to receive evidence
and recommend a decision on the issue of fair value. The appraiser shall have
such power and authority as may be specified in the order of appointment or in
any amendment thereof.

     (d) Measure of recovery. -- Each dissenter who is made a party shall be
entitled to recover the amount by which the fair value of his shares is found to
exceed the amount, if any, previously remitted, plus interest.

     (e) Effect of corporation's failure to file application. -- If the
corporation fails to file an application as provided in subsection (a), any
dissenter who made a demand and who has not already settled his claim against
the corporation may do so in the name of the corporation at any time within 30
days after the expiration of the 60-day period. If a dissenter does not file an
application within the 30-day period, each dissenter entitled to file an
application shall be paid the corporation's estimate of the fair value of the
shares and no more, and may bring an action to recover any amount not previously
remitted.

SEC. 1580.  COSTS AND EXPENSES OF VALUATION PROCEEDINGS.

     (a) General rule. -- The costs and expenses of any proceedings under
section 1579 (relating to valuation proceedings generally), including the
reasonable compensation and expenses of the appraiser appointed by the court,
shall be determined by the court and assessed against the business corporation
except that any part of the costs and expenses may be apportioned and assessed
as the court deems appropriate against all or some of the dissenters who are
parties and whose action in demanding supplemental payment under section 1578
(relating to estimate by dissenter of fair value of shares) the court finds to
be dilatory, obdurate, arbitrary, vexatious or in bad faith.

                                       E-6
<PAGE>   158

     (b) Assessment of counsel fees and expert fees where lack of good faith
appears. -- Fees and expenses of counsel and of experts for the respective
parties may be assessed as the court deems appropriate against the corporation
and in favor of any or all dissenters if the corporation failed to comply
substantially with the requirements of this subchapter and may be assessed
against either the corporation or a dissenter, in favor of any other party, if
the court finds that the party against whom the fees and expenses are assessed
acted in bad faith or in a dilatory, obdurate, arbitrary or vexatious manner in
respect to the rights provided by this subchapter.

     (c) Award of fees for benefits to other dissenter. -- If the court finds
that the services of counsel for any dissenter were of substantial benefit to
other dissenters similarly situated and should not be assessed against the
corporation, it may award to those counsel reasonable fees to be paid out of the
amounts awarded to the dissenters who were benefited.

                                       E-7
<PAGE>   159

                                   APPENDIX F

                      PROPOSED CERTIFICATE OF AMENDMENT TO
                        CERTIFICATE OF INCORPORATION OF
                              M&T BANK CORPORATION

                                       F-1
<PAGE>   160

                                    FORM OF
                        CERTIFICATE OF AMENDMENT OF THE
                        CERTIFICATE OF INCORPORATION OF
                              M&T BANK CORPORATION
               UNDER SECTION 805 OF THE BUSINESS CORPORATION LAW

     The undersigned, being the Chairman of the Board, President and Chief
Executive Officer and the Corporate Secretary of M&T Bank Corporation, do hereby
certify and set forth:

     (1) The name of the corporation is M&T Bank Corporation. The name under
     which the corporation was formed is First Empire State Corporation.

     (2) The certificate of incorporation of M&T Bank Corporation was filed by
     the Department of State on the 6th day of November, 1969. A first restated
     certificate of incorporation was filed by the Department of State on the
     19th day of December, 1969; a second restated certificate of incorporation
     was filed by the Department of State on the 28th day of April, 1986; a
     third restated certificate of incorporation was filed by the Department of
     State on the 20th day of April, 1989; an amendment to the certificate of
     incorporation was filed by the Department of State on the 14th day of
     March, 1991; a fourth restated certificate of incorporation was filed by
     the Department of State on the 8th day of May, 1997; an amendment to the
     certificate of incorporation was filed by the Department of State on the
     29th day of May, 1998; and a fifth restated certificate of incorporation
     was filed by the Department of State on the 3rd day of June, 1998.

     (3) Article FOURTH, Section 1, of the certificate of incorporation of M&T
     Bank Corporation, which sets forth the aggregate number of shares which the
     corporation shall have authority to issue, the division of such shares into
     classes, and the number and par value of shares in each class, is hereby
     amended to read as follows:

        FOURTH: 1. The aggregate number of shares of stock which the Corporation
        shall have authority to issue is one hundred fifty-one million
        (151,000,000) shares, divided into two classes, namely, preferred shares
        and common shares. The number of preferred shares authorized is one
        million (1,000,000) shares of the par value of one dollar ($1.00) per
        share. The number of common shares authorized is one hundred fifty
        million (150,000,000) shares of the par value of fifty cents ($0.50) per
        share.

     This amendment to the certificate of incorporation of M&T Bank Corporation
     provides for a change of shares as follows:

        Issued Shares: This amendment provides for a change of [*] issued common
        shares of the par value of $5.00 per share. Resulting from the change
        are [*] issued common shares of the par value of $0.50 per share. The
        terms of the change are as follows: Each issued common share existing
        immediately prior to the effective time of this amendment (whether
        outstanding or held in treasury) shall be changed by this amendment into
        10 issued common shares.

        Unissued shares: This amendment provides for a change of [*] unissued
        common shares of the par value of $5.00 per share. Resulting from the
        change are [*] unissued common shares of the par value of $0.50. The
        terms of the change are as follows: Each unissued common share existing
        immediately prior to the effective time of this amendment (whether
        outstanding or held in treasury) shall be changed by this amendment into
        10 unissued common shares.

---------------

* To be completed at time of filing of Certificate of Amendment.
                                       F-2
<PAGE>   161

     (4) This amendment to the certificate of incorporation of M&T Bank
     Corporation was authorized, pursuant to section 803(a) of the Business
     Corporation Law, by the vote of the board of directors of the corporation
     followed by the vote of the holders of a majority of all outstanding shares
     entitled to vote thereon at a meeting of the shareholders.

     IN WITNESS WHEREOF, the undersigned have executed, signed and verified this
certificate this      day of                      , 2000.

                                      M&T BANK CORPORATION

                                      By:
                                         ---------------------------------------
                                          Robert G. Wilmers
                                         Chairman of the Board,
                                         President and Chief Executive Officer

                                      By:
                                         ---------------------------------------
                                          Marie King
                                          Corporate Secretary

                                       F-3


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