WASHINGTON MUTUAL INC
S-4, 1997-03-13
SAVINGS INSTITUTIONS, NOT FEDERALLY CHARTERED
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<PAGE>   1
 
     AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON MARCH 13, 1997
 
                                                    REGISTRATION NO. 333-
================================================================================
 
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                            ------------------------
 
                                    FORM S-4
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                            ------------------------
 
                            WASHINGTON MUTUAL, INC.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
<TABLE>
<S>                               <C>                               <C>
            WASHINGTON                           6035                           91-1653725
 (STATE OR OTHER JURISDICTION OF     (PRIMARY STANDARD INDUSTRIAL   (IRS EMPLOYER IDENTIFICATION NO.)
  INCORPORATION OR ORGANIZATION)     CLASSIFICATION CODE NUMBER)
</TABLE>
 
                               1201 THIRD AVENUE
                           SEATTLE, WASHINGTON 98101
                                 (206) 461-2000
  (ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE NUMBER, INCLUDING AREA CODE, OF
                   REGISTRANT'S PRINCIPAL EXECUTIVE OFFICES)
                            ------------------------
 
                                MARC R. KITTNER
                  SENIOR VICE PRESIDENT AND CORPORATE COUNSEL
                            WASHINGTON MUTUAL, INC.
                               1201 THIRD AVENUE
                           SEATTLE, WASHINGTON 98101
                                 (206) 461-2000
 (NAME, ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE NUMBER, INCLUDING AREA CODE,
                             OF AGENT FOR SERVICE)
                            ------------------------
 
                                   COPIES TO:
 
<TABLE>
<S>                               <C>                               <C>
          FAY L. CHAPMAN                   CHARLES I. COGUT                 PETER ALLAN ATKINS
         DAVID R. WILSON                     LEE MEYERSON                   FRED B. WHITE, III
    FOSTER PEPPER & SHEFELMAN         SIMPSON THACHER & BARTLETT     SKADDEN, ARPS, SLATE, MEAGHER &
        1111 THIRD AVENUE                425 LEXINGTON AVENUE                    FLOM LLP
    SEATTLE, WASHINGTON 98101          NEW YORK, NEW YORK 10017              919 THIRD AVENUE
          (206) 447-4400                    (212) 455-2000               NEW YORK, NEW YORK 10022
                                                                              (212) 735-3000
</TABLE>
 
        APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC:
 As soon as practicable after the effective date of this Registration Statement
 and the satisfaction or waiver of all other conditions to the Merger described
                    in the Joint Proxy Statement/Prospectus.
 
    If the securities being registered on this form are being offered in
connection with the formation of a holding company and there is compliance with
General Instruction G, check the following box.  [ ]
 
                        CALCULATION OF REGISTRATION FEE
- --------------------------------------------------------------------------------
 
<TABLE>
<S>                                        <C>           <C>               <C>               <C>
- ----------------------------------------------------------------------------------------------------------
                                                                           PROPOSED MAXIMUM
          TITLE OF EACH CLASS OF                         PROPOSED MAXIMUM      AGGREGATE       AMOUNT OF
             SECURITIES TO BE              AMOUNT TO BE   OFFERING PRICE       OFFERING      REGISTRATION
                REGISTERED                 REGISTERED(2)     PER SHARE           PRICE          FEE(3)
- ----------------------------------------------------------------------------------------------------------
Common stock, no par value per share(1)...  132,690,700       $47.31        $6,277,597,017    $1,902,302
==========================================================================================================
</TABLE>
 
(1) Also includes associated Rights to purchase shares of the Registrant's
    Common Stock, which Rights are not currently separable from the shares of
    Common Stock and are not currently exercisable.
 
(2) The number of shares to be registered pursuant to this Registration
    Statement is based upon the number of shares of Great Western Financial
    Corporation common stock, par value $1.00 per share ("GWF Common Stock"),
    currently outstanding or reserved for issuance under various plans or
    otherwise expected to be issued upon the consummation of the proposed
    transaction to which this Registration Statement relates multiplied by the
    exchange ratio of 0.9 shares of common stock, no par value per share, of
    Washington Mutual, Inc., for each share of GWF Common Stock.
 
(3) The registration fee was computed pursuant to Rules 457(f) and 457(c) under
    the Securities Act of 1933, as amended, based on the average of the high and
    low sales prices of GWF Common Stock, as reported by the New York Stock
    Exchange on March 7, 1997.
 
    THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL
FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(A) OF
THE SECURITIES ACT OF 1933 OR UNTIL THIS REGISTRATION STATEMENT SHALL BECOME
EFFECTIVE ON SUCH DATE AS THE SECURITIES AND EXCHANGE COMMISSION, ACTING
PURSUANT TO SAID SECTION 8(A), MAY DETERMINE.
================================================================================
<PAGE>   2
 
                         [WASHINGTON MUTUAL, INC. LOGO]
 
                         1201 Third Avenue, Suite 1500
                           Seattle, Washington 98101
 
                                           , 1997
 
Dear Shareholder:
 
     You are cordially invited to attend the Special Meeting of Shareholders of
Washington Mutual, Inc. ("Washington Mutual"), which will be held at the
                                                       , Seattle, Washington, at
          ,         , 1997. I look forward to greeting as many of our
shareholders as possible.
 
     At the special meeting, shareholders of Washington Mutual will be asked to
consider and vote upon a proposal to approve the issuance of shares of
Washington Mutual common stock in connection with a proposed merger (the
"Merger") pursuant to which Great Western Financial Corporation ("Great
Western") will merge with and into New American Capital, Inc., a wholly owned
subsidiary of Washington Mutual ("NACI"), and as a result, the direct and
indirect subsidiaries of Great Western will become subsidiaries of Washington
Mutual. In the Merger, each outstanding share of Great Western common stock will
be converted into the right to receive 0.9 shares of Washington Mutual common
stock, with cash being paid in lieu of fractional shares, and each outstanding
share of Great Western preferred stock will be converted into the right to
receive one share of a new series of Washington Mutual preferred stock, to be
designated as Washington Mutual 8.30% Preferred Stock, Series F (the "Series F
Preferred Stock"). In connection with the Merger, it is expected that Washington
Mutual will issue           shares of common stock and   shares of the Series F
Preferred Stock.
 
     In addition, at the special meeting, holders of Washington Mutual common
stock and holders of each series of Washington Mutual preferred stock will be
asked to vote on a proposal to approve an amendment to Washington Mutual's
Restated Articles of Incorporation (the "Articles") to increase the number of
authorized shares of common stock from 350,000,000 shares to 800,000,000 shares.
Approval of the amendment to the Articles is not necessary to consummate the
Merger.
 
     More complete information about the Merger and the amendment to the
Articles is included in the accompanying Notice of Special Meeting of
Shareholders and the Joint Proxy Statement/Prospectus. YOUR BOARD OF DIRECTORS
BELIEVES THE PROPOSALS ARE IN THE BEST INTERESTS OF WASHINGTON MUTUAL AND ITS
SHAREHOLDERS AND, ACCORDINGLY, RECOMMENDS THAT YOU VOTE "FOR" EACH OF THEM.
 
     Whether or not you attend the special meeting, it is important that your
shares be represented and voted at the special meeting. Therefore, I urge you to
sign, date and promptly return the enclosed proxy in the enclosed postage-paid
envelope. If you decide to attend the special meeting and vote in person, you
will, of course, have that opportunity. If you are planning to attend the
special meeting, we would greatly appreciate it if you would let us know by so
indicating in the appropriate place on your proxy.
 
                                          Sincerely,
                                          /s/ KERRY KILLINGER
                                          Kerry K. Killinger
                                          Chairman, President and Chief
                                          Executive Officer
<PAGE>   3
 
                            WASHINGTON MUTUAL, INC.
 
                   NOTICE OF SPECIAL MEETING OF SHAREHOLDERS
                                           , 1997
 
     The Special Meeting of Shareholders of Washington Mutual, Inc. ("Washington
Mutual"), will be held at the                               , Seattle,
Washington, on          , 1997, at           for the following purposes:
 
          1. To approve the issuance of shares of common stock pursuant to the
     Agreement and Plan for Merger, dated as of March 5, 1997, by and among
     Washington Mutual, Great Western Financial Corporation ("Great Western")
     and New American Capital, Inc., a wholly owned subsidiary of Washington
     Mutual ("NACI"), pursuant to which Great Western will merge with and into
     NACI and, as a result, Great Western will become a wholly-owned subsidiary
     of Washington Mutual;
 
          2. To approve an amendment to Washington Mutual's Restated Articles of
     Incorporation (the "Articles") to increase the number of authorized shares
     of common stock from 350,000,000 shares to 800,000,000 shares.
 
     Both of these proposals are more fully described in the Joint Proxy
Statement/Prospectus, which follows. Only holders of shares of Washington Mutual
common stock and holders of shares of each outstanding series of Washington
Mutual preferred stock of record at the close of business on          , 1997 are
entitled to notice of, and to vote at, this special meeting, and any and all
adjournments thereof.
 
     Holders of Washington Mutual common stock will be asked to vote on both
proposals. Holders of each outstanding series of Washington Mutual preferred
stock will be asked to vote with the holders of Washington Mutual common stock
only on the proposal to amend the Articles to increase the number of authorized
shares of common stock.
 
                                          By Order of the Board of Directors,
 
                                          William L. Lynch
                                          Secretary
 
Seattle, Washington
         , 1997
 
                                   IMPORTANT
Whether or not you expect to attend in person, we urge you to vote on the
proposals, sign, date, and return the enclosed proxy at your earliest
convenience. This will ensure the presence of a quorum at the Special Meeting.
PROMPTLY VOTING, SIGNING, DATING, AND RETURNING THE PROXY WILL SAVE WASHINGTON
MUTUAL THE EXPENSE AND EXTRA WORK OF ADDITIONAL SOLICITATION. An addressed
envelope for which no postage is required if mailed in the United States is
enclosed for that purpose. Sending in your proxy will not prevent you from
voting your stock at the Special Meeting if you desire to do so, as your proxy
is revocable at your option in the manner described in the Proxy Statement.
<PAGE>   4
 
     INFORMATION CONTAINED HEREIN IS SUBJECT TO COMPLETION OR AMENDMENT. A
     REGISTRATION STATEMENT RELATING TO THESE SECURITIES HAS BEEN FILED WITH THE
     SECURITIES AND EXCHANGE COMMISSION. THESE SECURITIES MAY NOT BE SOLD NOR
     MAY OFFERS TO BUY BE ACCEPTED PRIOR TO THE TIME THE REGISTRATION STATEMENT
     BECOMES EFFECTIVE. THIS PROSPECTUS SHALL NOT CONSTITUTE AN OFFER TO SELL OR
     THE SOLICITATION OF AN OFFER TO BUY NOR SHALL THERE BE ANY SALE OF THESE
     SECURITIES IN ANY STATE IN WHICH SUCH OFFER, SOLICITATION OR SALE WOULD BE
     UNLAWFUL PRIOR TO REGISTRATION OR QUALIFICATION UNDER THE SECURITIES LAWS
     OF ANY SUCH STATE.
 
                   SUBJECT TO COMPLETION DATED MARCH 13, 1997
 
PRELIMINARY COPY
 
<TABLE>
     <S>                                             <C>
                 JOINT PROXY STATEMENT OF                             PROSPECTUS OF
               WASHINGTON MUTUAL, INC. AND                       WASHINGTON MUTUAL, INC.
           GREAT WESTERN FINANCIAL CORPORATION
</TABLE>
 
     This Joint Proxy Statement/Prospectus (the "Joint Proxy
Statement/Prospectus") is being furnished to shareholders of Washington Mutual,
Inc., a Washington corporation ("Washington Mutual" or "WMI"), and to
stockholders of Great Western Financial Corporation, a Delaware corporation
("Great Western" or "GWF"), in connection with the solicitation of proxies by
the respective Boards of Directors of such corporations for use at the special
meeting of shareholders of Washington Mutual (including any adjournments,
postponements or reschedulings thereof, the "Washington Mutual Meeting") and the
special meeting of stockholders of Great Western (including any adjournments,
postponements or reschedulings thereof, the "Great Western Meeting," and,
together with the Washington Mutual Meeting, the "Special Meetings") to be held
on             , 1997. At the Great Western Meeting, holders of Great Western
common stock, par value $1.00 per share ("Great Western Common Stock"), will be
asked to consider and vote upon a proposal (the "Merger Proposal") to adopt the
Agreement and Plan of Merger (the "Merger Agreement"), dated as of March 5,
1997, by and among Washington Mutual, New American Capital, Inc., a Delaware
corporation and an indirect wholly owned subsidiary of Washington Mutual
("NACI"), and Great Western, providing for the merger of Great Western with and
into NACI (the "Merger"). At the Washington Mutual Meeting, holders of
Washington Mutual common stock ("Washington Mutual Common Stock") will be asked
to consider and vote upon a proposal to approve the issuance of shares of
Washington Mutual Common Stock in the Merger to the stockholders of Great
Western pursuant to the Merger Agreement. A copy of the Merger Agreement is
attached hereto as Appendix A and is incorporated herein by reference. In
addition, at the Washington Mutual Meeting, holders of Washington Mutual Common
Stock and holders of each outstanding series of Washington Mutual preferred
stock will be asked to vote on a proposal to amend Washington Mutual's Restated
Articles of Incorporation (the "Washington Mutual Articles") to increase the
number of authorized shares of Washington Mutual Common Stock from 350,000,000
shares to 800,000,000 shares. Approval of the amendment to the Washington Mutual
Articles is not a condition to the consummation of the Merger.
 
     This Joint Proxy Statement/Prospectus also constitutes a prospectus of
Washington Mutual with respect to up to 132,690,700 shares of Washington Mutual
Common Stock issuable upon consummation of the Merger to holders of Great
Western Common Stock. This Joint Proxy Statement/Prospectus is also being
furnished to the holders of the Great Western Preferred Stock and Great Western
Depositary Shares (each as defined herein) for informational purposes, but
proxies are not being solicited from such holders and such holders are not
entitled to, and are not being asked to, vote at the Great Western Meeting.
 
     At the effective time of the Merger (the "Effective Time"), (i) each
outstanding share of Great Western Common Stock will be converted into the right
to receive 0.9 shares of Washington Mutual Common Stock (the "Exchange Ratio"),
with cash being paid in lieu of fractional shares, and (ii) each outstanding
share of Great Western 8.30% Cumulative Preferred Stock (the "Great Western
Preferred Stock") will be converted into one share of Washington Mutual 8.30%
Cumulative Preferred Stock, Series F (the "Series F Preferred Stock"). The
terms, preferences, limitations, privileges and rights of the Series F Preferred
Stock will be substantially identical to those of the Great Western Preferred
Stock. As in the case of the Great Western Preferred Stock, each share of Series
F Preferred Stock will be represented by depositary shares (the "New Washington
Mutual Depositary Shares"), each representing a one-tenth interest in a share of
the Series F Preferred Stock.
 
     Based on the closing sales price of the Washington Mutual Common Stock on
the National Market tier of the NASDAQ Stock Market ("NASDAQ") on March 11,
1997, if the Merger had occurred at such time, the Exchange Ratio would have
resulted in an indicated per share value for the Great Western Common Stock of
$49.05. See "Summary -- Comparative Market Prices." Because the Exchange Ratio
is fixed, a change in the market price of the Washington Mutual Common Stock
before the Effective Time would affect the implied market value of the
consideration to be received by holders of Great Western Common Stock ("Great
Western Stockholders") in the Merger in exchange for the Great Western Common
Stock. THERE CAN BE NO ASSURANCE AS TO THE MARKET PRICE PER SHARE OF THE
WASHINGTON MUTUAL COMMON STOCK AT ANY TIME PRIOR TO, AT OR AFTER THE EFFECTIVE
TIME OF THE MERGER. Stockholders are urged to obtain current market quotations.
The Washington Mutual Common Stock is traded on NASDAQ under the symbol "WAMU."
The Great Western Common Stock is listed on the New York Stock Exchange (the
"NYSE") and the Pacific Stock Exchange (the "PSE") under the symbol "GWF."
 
     This Joint Proxy Statement/Prospectus and forms of proxies are first being
mailed to the shareholders of Washington Mutual and the stockholders of Great
Western on or about            , 1997.
                            ------------------------
 
   THE SECURITIES OFFERED HEREBY HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE
 SECURITIES AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION NOR HAS
THE SECURITIES AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION PASSED
  UPON THE ACCURACY OR ADEQUACY OF THIS JOINT PROXY STATEMENT/PROSPECTUS. ANY
             REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.
 
   THE SECURITIES OFFERED HEREBY ARE NOT SAVINGS ACCOUNTS, DEPOSITS OR OTHER
   OBLIGATIONS OF ANY BANK OR SAVINGS ASSOCIATION AND ARE NOT INSURED BY THE
  FEDERAL DEPOSIT INSURANCE CORPORATION, THE BANK INSURANCE FUND, THE SAVINGS
          ASSOCIATION INSURANCE FUND OR ANY OTHER GOVERNMENTAL AGENCY.
 
    The date of this Joint Proxy Statement/Prospectus is             , 1997.
<PAGE>   5
 
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
                                                                                        PAGE
                                                                                        ----
<S>                                                                                     <C>
AVAILABLE INFORMATION.................................................................    2
INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE.......................................    2
SUMMARY...............................................................................    4
  The Special Meetings................................................................    4
  The Parties to the Merger...........................................................    6
  The Merger..........................................................................    7
  Management and Operations of Washington Mutual Following the Merger.................   11
  Description of Washington Mutual Capital Stock......................................   12
  Summary Financial Data of Washington Mutual.........................................   14
  Summary Financial Data of Great Western.............................................   16
  Summary Historical and Pro Forma Combined Financial Data............................   18
  Comparative Per Share Data..........................................................   20
  Comparative Market Prices...........................................................   21
RISK FACTORS..........................................................................   22
THE SPECIAL MEETINGS..................................................................   25
  General.............................................................................   25
  Matters to be Considered at the Special Meetings....................................   25
  Record Date and Voting..............................................................   25
  Proxies and Voting Instructions.....................................................   26
  Quorum; Votes Required..............................................................   27
  Solicitation of Proxies.............................................................   28
THE MERGER............................................................................   29
  General.............................................................................   29
  Background of the Merger............................................................   29
  Reasons for the Merger; Recommendations of the Boards of Directors..................   31
  Opinions of Financial Advisors......................................................   36
  Conversion of Great Western Capital Stock...........................................   51
  Effective Time......................................................................   51
  Representations and Warranties......................................................   52
  Conduct of Business Pending the Merger and Other Agreements.........................   52
  Conditions to the Consummation of the Merger........................................   54
  Regulatory Approvals Required.......................................................   55
  Termination of the Merger Agreement.................................................   56
  Termination Fees....................................................................   57
  Extension, Waiver and Amendment of the Merger Agreement.............................   58
  Interests of Certain Persons in the Merger..........................................   58
  Employee Matters....................................................................   60
  Accounting Treatment................................................................   62
  No Appraisal or Dissenters' Rights..................................................   62
  Exchange of Certificates and Depositary Receipts; Fractional Shares.................   62
  Certain Federal Income Tax Consequences.............................................   64
  Dividend Policy.....................................................................   65
  Resale of Washington Mutual Capital Stock Received by Great Western Common
     Stockholders.....................................................................   66
WASHINGTON MUTUAL.....................................................................   67
  General.............................................................................   67
  Principal Holders of Washington Mutual Common Stock.................................   67
  Principal Holders of Washington Mutual Preferred Stock..............................   68
  Security Ownership of Washington Mutual by Directors and Executive Officers.........   68
</TABLE>
 
                                       (i)
<PAGE>   6
 
<TABLE>
<CAPTION>
                                                                                        PAGE
                                                                                        ----
<S>                                                                                     <C>
GREAT WESTERN.........................................................................   71
  General.............................................................................   71
  Principal Holders of Great Western Common Stock.....................................   71
MANAGEMENT AND OPERATIONS OF WASHINGTON MUTUAL FOLLOWING THE MERGER...................   73
  General.............................................................................   73
  Board of Directors..................................................................   73
  Operations After the Merger.........................................................   73
PRO FORMA COMBINED FINANCIAL INFORMATION (UNAUDITED)..................................   76
LITIGATION............................................................................   85
COMPARISON OF RIGHTS OF WASHINGTON MUTUAL SHAREHOLDERS AND GREAT WESTERN
  STOCKHOLDERS........................................................................   86
  Capital Stock.......................................................................   86
  Board of Directors..................................................................   87
  Monetary Liability of Directors.....................................................   87
  Voting Rights.......................................................................   87
  Interested Shareholders.............................................................   87
  Fair Price Provision................................................................   88
  Removal of Directors and Filling Vacancies on the Board of Directors................   88
  Washington Mutual Rights Plan.......................................................   88
  Great Western Rights Plan...........................................................   89
CERTAIN DIFFERENCES BETWEEN WASHINGTON AND DELAWARE CORPORATE LAWS....................   89
  Amendment of Articles/Certificates of Incorporation.................................   89
  Right to Call Special Meeting of Shareholders.......................................   90
  Indemnification of Officers, Directors and Employees................................   90
  Liability and Indemnification of Officers and Directors.............................   90
  Provisions Affecting Control Share Acquisitions and Business Combinations...........   91
  Mergers, Sales of Assets and Other Transactions.....................................   92
  Action Without a Meeting............................................................   93
  Class Voting........................................................................   93
  Transactions with Officers and Directors............................................   93
  Dissenters' Rights..................................................................   93
  Dividends...........................................................................   94
DESCRIPTION OF WASHINGTON MUTUAL CAPITAL STOCK........................................   95
  Washington Mutual Common Stock......................................................   95
  Washington Mutual Preferred Stock...................................................   95
  Washington Mutual 8.30% Preferred Stock, Series F...................................   96
  New Washington Mutual Depositary Shares.............................................   98
DESCRIPTION OF GREAT WESTERN COMMON STOCK.............................................  101
PROPOSED AMENDMENT TO WASHINGTON MUTUAL ARTICLES OF INCORPORATION -- INCREASE IN
  AUTHORIZED SHARES...................................................................  101
Current Capitalization................................................................  102
Certain Effects of the Proposed Amendment.............................................  102
LEGAL MATTERS.........................................................................  103
EXPERTS...............................................................................  103
STOCKHOLDER PROPOSALS.................................................................  103
APPENDICES
Appendix A   Agreement and Plan of Merger
Appendix B   Opinion of Lehman Brothers Inc.
Appendix C   Opinion of Goldman, Sachs & Co.
Appendix D   Opinion of Merrill Lynch & Co.
</TABLE>
 
                                      (ii)
<PAGE>   7
 
                             AVAILABLE INFORMATION
 
     Washington Mutual and Great Western are both subject to the informational
requirements of the Securities Exchange Act of 1934, as amended (the "Exchange
Act"), and, in accordance therewith, file reports, proxy statements and other
information with the Securities and Exchange Commission (the "Commission"). The
reports, proxy statements and other information filed by Washington Mutual and
Great Western with the Commission may be inspected and copied at the
Commission's public reference room located at 450 Fifth Street, N.W., Room 1024,
Washington D.C. 20549, and at the public reference facilities in the
Commission's regional offices located at: 7 World Trade Center, 13th Floor, New
York, New York 10048; and Citicorp Center, 500 West Madison Street, Suite 1400,
Chicago, IL 60661. Copies of such material may be obtained at prescribed rates
by writing to the Commission, Public Reference Section, 450 Fifth Street, N.W.,
Washington, D.C. 20549. Certain of such reports, proxy statements and other
information are also available from the Commission over the Internet at
http://www.sec.gov. The periodic reports, proxy statements and other information
filed by Washington Mutual with the Commission may also be inspected at the
offices of the National Association of Securities Dealers, Inc., NASDAQ Reports
Section, 1735 K Street, Washington, D.C. 20006. The periodic reports, proxy
statements and other information filed by Great Western with the Commission may
be inspected at the offices of the NYSE, 20 Broad Street, New York, New York
10005 and at the offices of the PSE, 301 Pine Street, San Francisco, California
94104.
 
     This Joint Proxy Statement/Prospectus is included as part of a registration
statement on Form S-4 (together with all amendments and exhibits thereto,
including documents and information incorporated by reference, the "Registration
Statement") filed with the Commission by Washington Mutual, relating to the
registration under the Securities Act of 1933, as amended (the "Securities
Act"), of up to 132,690,700 shares of Washington Mutual Common Stock. This Joint
Proxy Statement/Prospectus does not contain all of the information set forth in
the Registration Statement, certain portions of which have been omitted pursuant
to the rules and regulations of the Commission, to which Registration Statement
reference is hereby made for further information with respect to Washington
Mutual and Great Western and the Washington Mutual Common Stock offered hereby.
Statements contained herein concerning any documents are not necessarily
complete and, in each instance, reference is made to the copies of such
documents filed as exhibits to the Registration Statement. Each such statement
is qualified in its entirety by such reference.
 
                INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE
 
     The following documents filed with the Commission by Washington Mutual
(File No. 0-25188) are incorporated herein by reference: (a) Annual Report on
Form 10-K for the year ended December 31, 1996 (the "1996 Washington Mutual
10-K"); (b) Washington Mutual's Current Report on Form 8-K dated March 6, 1997;
and (c) the description of Washington Mutual capital stock contained in Item 5
of Washington Mutual's Current Report on Form 8-K dated November 29, 1994.
 
     The following documents filed with the Commission by Great Western (File
No. 1-4075) are incorporated herein by reference: (a) Annual Report on Form 10-K
for the year ended December 31, 1996 (the "1996 Great Western 10-K"); (b) the
description of the Great Western Rights (as defined herein) contained in Item 1
of the Great Western Registration Statement on Form 8-A dated June 30, 1995, as
amended by the Form 8-A/A dated January 31, 1997; (c) the Great Western
Revocation of Consent Statement on Schedule 14A dated March 4, 1997, as
supplemented on March 6, 1997 (the "Consent Revocation Statement"); and (d)
Current Reports on Form 8-K, dated January 22, 1997, January 27, 1997 and
February 20, 1997.
 
     All documents filed by either Washington Mutual or Great Western pursuant
to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act subsequent to the date
hereof and prior to the date of the Special Meetings shall be deemed to be
incorporated herein by reference and to be a part hereof from the date of such
filing. Any statement contained herein or in a document incorporated or deemed
to be incorporated herein by reference shall be deemed to be modified or
superseded for purposes hereof to the extent that a statement contained herein
or in any other subsequently filed document which also is, or is deemed to be,
incorporated herein by
 
                                        2
<PAGE>   8
 
reference modifies or supersedes such statement. Any such statement so modified
or superseded shall not be deemed to constitute a part hereof, except as so
modified or superseded.
 
     THIS JOINT PROXY STATEMENT/PROSPECTUS INCORPORATES DOCUMENTS BY REFERENCE
WHICH ARE NOT PRESENTED HEREIN OR DELIVERED HEREWITH. SUCH DOCUMENTS (OTHER THAN
EXHIBITS TO SUCH DOCUMENTS UNLESS SUCH EXHIBITS ARE SPECIFICALLY INCORPORATED
THEREIN BY REFERENCE) RELATING TO WASHINGTON MUTUAL ARE AVAILABLE WITHOUT CHARGE
UPON REQUEST TO: WASHINGTON MUTUAL, INC., 1201 THIRD AVENUE, SEATTLE, WASHINGTON
98101, ATTENTION: INVESTOR RELATIONS OR BY CALLING D.F. KING & CO. (800)
755-7250, AND SUCH DOCUMENTS (OTHER THAN EXHIBITS TO SUCH DOCUMENTS UNLESS SUCH
EXHIBITS ARE SPECIFICALLY INCORPORATED THEREIN BY REFERENCE) RELATING TO GREAT
WESTERN ARE AVAILABLE WITHOUT CHARGE UPON REQUEST TO: GREAT WESTERN FINANCIAL
CORPORATION, 9200 OAKDALE AVENUE, CHATSWORTH, CALIFORNIA 91311, ATTENTION:
INVESTOR RELATIONS OR BY CALLING GEORGESON & COMPANY, INC. (800) 223-2064; BANKS
AND BROKERS CALL (212) 440-9800. IN ORDER TO ENSURE TIMELY DELIVERY OF THE
DOCUMENTS, REQUESTS SHOULD BE MADE BY             , 1997.
 
                                        3
<PAGE>   9
 
                                    SUMMARY
 
     The information below is qualified in its entirety by the more detailed
information appearing elsewhere in this Joint Proxy Statement/Prospectus,
including the documents incorporated by reference in this Joint Proxy
Statement/Prospectus. As used in this Joint Proxy Statement/Prospectus, the term
"Washington Mutual" refers to Washington Mutual and, unless the context
otherwise requires, its subsidiaries, and the term "Great Western" refers to
Great Western and, unless the context otherwise requires, its subsidiaries. The
term "Combined Company" is sometimes used herein to refer to Washington Mutual
following consummation of the Merger. All references to the Great Western Common
Stock in this Joint Proxy Statement/Prospectus include the associated Great
Western Rights issued pursuant to the Great Western Rights Plan (as defined
herein) and all references to the Washington Mutual Common Stock include the
associated Washington Mutual Rights (as defined herein) issued pursuant to the
Washington Mutual Rights Plan (as defined herein).
 
     Forward-looking statements are contained in this Joint Proxy
Statement/Prospectus and in documents incorporated by reference herein regarding
Washington Mutual, Great Western and the Combined Company. Actual results may
vary materially from the forward-looking statements contained in such documents
for reasons which include the factors set forth herein under "Risk Factors" and
in Washington Mutual's Current Report on Form 8-K dated March 6, 1997 which is
incorporated by reference herein.
 
THE SPECIAL MEETINGS
 
  THE WASHINGTON MUTUAL MEETING
 
     Time, Date and Place. The Washington Mutual Meeting will be held at   ,
local time, on             , 1997, at             ,                     ,
Seattle, Washington. See "The Special Meetings -- General."
 
     Matters to be Considered. Shareholders of Washington Mutual will be asked
to consider and vote upon proposals to (i) approve the issuance of shares
("Merger Shares") of Washington Mutual Common Stock to Great Western
Stockholders pursuant to the Merger Agreement (the "Share Issuance Proposal"),
(ii) to amend the Washington Mutual Articles to increase the number of
authorized shares of Washington Mutual Common Stock from 350,000,000 shares to
800,000,000 shares and (iii) to transact such other business as may properly
come before the Washington Mutual Meeting. The approval of the amendment to the
Washington Mutual Articles is not a condition to the consummation of the Merger.
See "The Special Meetings -- Matters to be Considered at the Special Meetings."
 
     Record Date; Shares Entitled to Vote; Quorum. The Board of Directors of
Washington Mutual ("Washington Mutual Board") has fixed the close of business on
            , 1997 as the record date (the "Washington Mutual Record Date") for
the determination of the holders of Washington Mutual Common Stock ("Washington
Mutual Shareholders") and holders of Washington Mutual Preferred Stock entitled
to receive notice of and to vote at the Washington Mutual Meeting.
 
     As of the Washington Mutual Record Date, there were           shares of
Washington Mutual Common Stock entitled to vote at the Washington Mutual
Meeting,           shares of 9.12% Noncumulative Perpetual Preferred Stock,
Series C ("Series C Preferred") entitled to vote at the Washington Mutual
Meeting and           shares of 7.60% Noncumulative Perpetual Preferred Stock,
Series E entitled to vote at the Washington Mutual Meeting ("Series E Preferred"
and together with the Series C Preferred, the "Washington Mutual Preferred
Stock"). Each share of Washington Mutual Common Stock is entitled to one vote on
each of the matters properly presented at the Washington Mutual Meeting. Each
share of Series C Preferred and Series E Preferred is entitled to one vote only
on the proposal to amend the Washington Mutual Articles. For the vote on the
Share Issuance Proposal, the presence, in person or by proxy, of the holders of
a majority of the outstanding shares of Washington Mutual Common Stock will
constitute a quorum. For the vote on the proposal to amend the Washington Mutual
Articles, the presence, in person or by proxy, of the holders of a majority of
(i) the outstanding shares of Washington Mutual Common Stock (for the separate
vote of holders of Washington Mutual Common Stock as a class) and (ii) the
aggregate of the outstanding shares of Washington Mutual Common Stock and
Washington Mutual Preferred Stock (for the vote of holders of Washington Mutual
Common Stock and Washington Mutual Preferred Stock as a single class) will
 
                                        4
<PAGE>   10
 
constitute a quorum, respectively. See "The Special Meetings -- Record Date and
Voting" and " -- Quorum; Votes Required."
 
     Votes Required. Under NASDAQ rules, the Share Issuance Proposal will
require the affirmative vote of a majority of the shares of Washington Mutual
Common Stock voting on such proposal. Approval of the amendment to the
Washington Mutual Articles will require the affirmative votes of the holders of
(i) two-thirds of the shares of Washington Mutual Common Stock and Washington
Mutual Preferred Stock entitled to vote at the Washington Mutual Meeting voting
together as a single class and (ii) two-thirds of the shares of Washington
Mutual Common Stock entitled to vote at the Washington Mutual Meeting voting as
a single class. Accordingly, assuming a quorum is present, a failure to submit a
proxy (or to vote in person at the Washington Mutual Meeting), an abstention by
a Washington Mutual Shareholder or a broker non-vote, which is an indication by
a broker that it does not have discretionary authority to vote on a particular
matter, will have no effect on the Share Issuance Proposal, but will have the
same effect as a "NO" vote with respect to the vote on the proposal to amend the
Washington Mutual Articles. For shares of Washington Mutual Common Stock or
Washington Mutual Preferred Stock held in street name by a broker, the failure
of a shareholder of Washington Mutual to give such broker voting instructions
with regard to any proposal on which such shareholder is entitled to vote will
result in a broker non-vote and will have the effects described in the preceding
sentence. See "The Special Meetings -- Record Date and Voting" and " -- Quorum;
Votes Required."
 
     THE WASHINGTON MUTUAL BOARD HAS UNANIMOUSLY DETERMINED THAT THE TERMS OF
THE MERGER ARE FAIR AND IN THE BEST INTERESTS OF WASHINGTON MUTUAL AND ITS
SHAREHOLDERS AND, ACCORDINGLY, RECOMMENDS THAT YOU VOTE "FOR" THE SHARE ISSUANCE
PROPOSAL. IN ADDITION, THE WASHINGTON MUTUAL BOARD HAS UNANIMOUSLY APPROVED THE
PROPOSAL TO AMEND THE WASHINGTON MUTUAL ARTICLES.
 
     For a discussion of the factors considered by the Washington Mutual Board
in reaching its decision to approve and adopt the Merger Agreement and the Share
Issuance Proposal see "The Merger -- Background of the Merger" and "-- Reasons
for the Merger; Recommendations of the Boards of Directors."
 
     Security Ownership of Management and Others. As of the Washington Mutual
Record Date, directors and executive officers of Washington Mutual and their
affiliates (excluding any shares owned by or through Acadia Partners, L.P. and
affiliates thereof) beneficially owned and were entitled to vote [3,772,886]
shares of Washington Mutual Common Stock and [3,025] shares of Washington Mutual
Preferred Stock, which represented approximately [2.99%] of the shares of
Washington Mutual Common Stock and less than 1% of Washington Mutual Preferred
Stock, respectively, outstanding on such date. In addition, as of the Washington
Mutual Record Date, Mr. Robert M. Bass and Acadia Partners, L.P. beneficially
owned and were entitled to vote [11,379,576] shares and [6,218,004] shares,
respectively, of Washington Mutual Common Stock, which represented approximately
[9.01%] and [4.93%], respectively, of the shares of Washington Mutual Common
Stock outstanding on such date. Mr. Bass, Acadia Partners, L.P. and each
Washington Mutual director and executive officer has indicated a present
intention to vote, or cause to be voted, the Washington Mutual Common Stock so
owned for approval of the Share Issuance Proposal and the amendment of the
Washington Mutual Articles. See "The Special Meetings -- Quorum; Votes
Required."
 
  THE GREAT WESTERN MEETING
 
     Time, Date and Place. The Great Western Meeting will be held at           ,
local time, on             , 1997, at Great Western's Employee Center, 19809
Prairie Street, Chatsworth, California 91311. See "The Special
Meetings -- General."
 
     Matters to be Considered. Stockholders of Great Western will be asked to
consider and vote upon a proposal to approve the Merger Agreement and the
transactions contemplated thereby and to transact such other business as may
properly come before the Great Western Meeting. See "The Special Meetings --
Matters to be Considered at the Special Meetings."
 
     Record Date; Shares Entitled to Vote; Quorum. The Board of Directors of
Great Western ("Great Western Board") has fixed the close of business on
            , 1997 as the record date (the "Great Western Record Date") for the
determination of the Great Western Stockholders entitled to receive notice of
and to
 
                                        5
<PAGE>   11
 
vote at the Great Western Meeting. Holders of Great Western Preferred Stock are
not entitled to vote at the Great Western Meeting.
 
     As of the Great Western Record Date, there were           issued and
outstanding shares of Great Western Common Stock. Each share of Great Western
Common Stock is entitled to one vote on each of the matters properly presented
at the Great Western Meeting. The presence, in person or by proxy, of the
holders of a majority of the issued and outstanding shares of Great Western
Common Stock will constitute a quorum. See "The Special Meetings -- Record Date
and Voting" and " -- Quorum; Votes Required."
 
     Votes Required. Pursuant to Delaware law, assuming a quorum is present, the
affirmative vote of the holders of a majority of the shares of Great Western
Common Stock entitled to vote at the Great Western Meeting is required to
approve the Merger Agreement and the transactions contemplated thereby.
Accordingly, a failure to submit a proxy (or to vote in person at the Great
Western Meeting), an abstention by a Great Western Stockholder or a broker
non-vote, which is an indication by a broker that it does not have discretionary
authority to vote on a particular matter, will have the same effect as a "NO"
vote with respect to the vote on the Merger Agreement and the transactions
contemplated thereby. For shares of Great Western Common Stock held in street
name by a broker, the failure of a Great Western Stockholder to give such broker
voting instructions with regard to the Merger will result in a broker non-vote
and will have the same effect as a "NO" vote with respect to such proposal.
Holders of Great Western Preferred Stock are not entitled to and are not being
asked to vote on approval and adoption of the Merger Agreement and the
transactions contemplated thereby or any other matters that may be considered at
the Great Western Meeting. See "The Special Meetings -- Record Date and Voting"
and " -- Quorum; Votes Required."
 
     THE GREAT WESTERN BOARD HAS UNANIMOUSLY DETERMINED THAT THE TERMS OF THE
MERGER ARE FAIR AND IN THE BEST INTERESTS OF GREAT WESTERN AND ITS STOCKHOLDERS
AND, ACCORDINGLY, RECOMMENDS THAT YOU VOTE "FOR" THE MERGER.
 
     For a discussion of the factors considered by the Great Western Board in
reaching its decision to approve and adopt the Merger Agreement, see "The
Merger -- Background of the Merger" and "-- Reasons for the Merger;
Recommendation of the Boards of Directors."
 
     Security Ownership of Management and Others.  As of the Great Western
Record Date, directors and executive officers of Great Western and their
affiliates beneficially owned and were entitled to vote           shares of
Great Western Common Stock, which represented approximately   % of the shares of
Great Western Common Stock outstanding on such date. Each Great Western director
and executive officer has indicated his or her present intention to vote, or
cause to be voted, the Great Western Common Stock so owned by him or her for
approval of the Merger Proposal. As of the Great Western Record Date, various
subsidiaries of Great Western, as fiduciaries, custodians or agents, had sole or
shared voting power with respect to           shares of Great Western Common
Stock, which represented approximately   % of the shares of Great Western Common
Stock outstanding on the Great Western Record Date. See "The Special
Meetings -- Quorum; Votes Required."
 
THE PARTIES TO THE MERGER
 
  WASHINGTON MUTUAL
 
     Washington Mutual is a regional financial services company committed to
serving consumers and small to mid-sized businesses throughout the Western
United States. Through its subsidiaries, Washington Mutual engages in the
following activities:
 
     -  MORTGAGE LENDING AND CONSUMER BANKING ACTIVITIES. Through its principal
        subsidiaries, Washington Mutual Bank ("WMB"), American Savings Bank,
        F.A. ("ASB"), and Washington Mutual Bank fsb ("WMBfsb"), at December 31,
        1996, Washington Mutual operated 413 consumer financial centers and 96
        loan centers offering a full complement of mortgage lending and consumer
        banking products and services. In 1996, WMB was the leading originator
        of first-lien, single-family residential loans in Washington and Oregon,
        and ASB was the second largest such originator in California.
 
                                        6
<PAGE>   12
 
     -  COMMERCIAL BANKING ACTIVITIES. Through the commercial banking division
        of WMB, at December 31, 1996, Washington Mutual operated 48 full-service
        business branches offering a range of commercial banking products and
        services to small and mid-sized businesses. WMB commenced its commercial
        banking activities through the acquisition of Enterprise Bank of
        Bellevue, Washington ("Enterprise") in 1995 and Western Bank of Coos
        Bay, Oregon ("Western") in 1996.
 
     -  INSURANCE ACTIVITIES. Through WM Life Insurance Company ("WM Life") and
        ASB Insurance Services Inc. ("ASB Insurance"), Washington Mutual
        underwrites and sells annuities and sells a range of life insurance
        contracts, and selected property and casualty insurance policies.
 
     -  SECURITIES ACTIVITIES. Through ASB Financial Services, Inc. ("ASB
        Financial"), Murphey Favre, Inc. ("Murphey Favre") and Composite
        Research & Management Co. ("Composite Research"), Washington Mutual
        offers full service securities brokerage and acts as the investment
        advisor to and the distributor of mutual funds.
 
     Washington Mutual operates in Washington, California, Oregon, Utah, Idaho,
Montana, Arizona, Colorado and Nevada. At December 31, 1996, Washington Mutual
had consolidated assets of $44.6 billion, deposits of $24.1 billion and
stockholders' equity of $2.4 billion. Based on deposits, Washington Mutual was
at that date the second largest banking organization in Washington and the 28th
largest in the United States.
 
     Washington Mutual has its principal executive offices at 1201 Third Avenue,
Seattle, Washington 98101, telephone number (206) 461-2000.
 
  GREAT WESTERN
 
     Great Western is a savings and loan holding company organized in 1955 under
the laws of the state of Delaware. The principal assets of Great Western are the
capital stock of Great Western Bank, a Federal Savings Bank ("GW Bank"), and
Aristar, Inc. ("Aristar"). GW Bank is a federally chartered stock savings bank
which has 416 branches in California and Florida. Real estate lending operations
are conducted directly by GW Bank and by direct subsidiaries through more than
200 offices in 27 states with concentrations in California, Florida, Texas and
Washington. Aristar conducts consumer finance operations through 502 offices in
23 states, most of which operate principally under the names of Blazer Financial
Services or City Finance Company, provides direct installment loans and related
credit insurance services, and purchases retail installment contracts. Great
Western and its subsidiaries also engage in related service businesses,
including investment company advisory and administrative activities, insurance
operations and real estate development.
 
     At December 31, 1996, Great Western had total assets of $42.9 billion,
deposits of $28.6 billion and stockholders' equity of $2.6 billion. Based on
deposits, Great Western was at that date the fourth largest banking organization
in California and the 24th largest in the United States.
 
     Great Western has its principal executive offices at 9200 Oakdale Avenue,
Chatsworth, California 91311, telephone number (818) 775-3111.
 
THE MERGER
 
  EXCHANGE RATIO
 
     At the Effective Time, (i) each outstanding share of Great Western Common
Stock will be converted into the right to receive 0.9 shares of Washington
Mutual Common Stock, with cash being paid in lieu of fractional shares, and (ii)
each outstanding share of Great Western Preferred Stock will be converted into
the right to receive one share of Series F Preferred Stock. The terms,
preferences, limitations, privileges and rights of the Series F Preferred Stock
will be substantially identical to those of the Great Western Preferred Stock.
On March 11, 1997, the closing sales price of Washington Mutual Common Stock on
NASDAQ was $54.38 per share. If the Merger had occurred at such time, the
Exchange Ratio would have resulted in an indicated per share value for the Great
Western Common Stock of $49.05. Because the Exchange Ratio is fixed, a change in
the market price of Washington Mutual Common Stock before the Effective Time
would affect the implied market value of the consideration to be received by
Great Western Stockholders in the Merger. There can be no assurance as to the
market price of Washington Mutual Common Stock at any time before, at or
 
                                        7
<PAGE>   13
 
after the Effective Time. Stockholders are urged to obtain current market
quotations. See "The Merger -- Conversion of Great Western Capital Stock."
 
     At the Effective Time, each option to purchase shares of Great Western
Common Stock (each a "Great Western Common Stock Option") issued by Great
Western pursuant to any of its employee or director stock option programs (each
a "Great Western Common Stock Plan") that is outstanding and unexercised
immediately prior to the Effective Time will be converted automatically into an
option to purchase shares of Washington Mutual Common Stock (each a "Washington
Mutual Stock Option"). The number of shares of Washington Mutual Common Stock
subject to a Washington Mutual Stock Option will be equal to the product of the
number of shares of Great Western Common Stock underlying the Great Western
Common Stock Option multiplied by the Exchange Ratio and rounded down to the
nearest share, and the exercise price per share of Washington Mutual Common
Stock subject to a Washington Mutual Stock Option will be equal to the exercise
price per share of Great Western Common Stock underlying the Great Western
Common Stock Option divided by the Exchange Ratio and rounded up to the nearest
cent. See "The Merger -- Conversion of Great Western Capital Stock."
 
  REASONS FOR THE MERGER; RECOMMENDATIONS OF THE BOARDS OF DIRECTORS
 
     The Boards of Directors of Washington Mutual and Great Western believe that
the Merger represents a unique opportunity to create one of the premier consumer
banking franchises on the West Coast. As a result of the Merger, the Combined
Company would rank as the third largest banking organization in the western
United States and the twelfth largest in the United States, with over 1,500
retail and business banking, consumer lending and mortgage lending offices
located in 36 states and serving an estimated 4.1 million households. The
Combined Company would have a strong deposit market share in Washington, Oregon,
Utah and the key consumer banking state of California, as well as a strong
market presence in parts of Florida. The Combined Company also would rank as one
of the largest originators and servicers of residential mortgage loans in the
United States, giving it the economies of scale and efficiencies to compete
effectively in the rapidly consolidating financial services industry.
 
     In addition, management of Washington Mutual has identified potential cost
savings, estimated at $340 million annually (pre-tax) by 1999, and opportunities
for possible significant revenue enhancements from the Merger. See "Management
and Operations of Washington Mutual Following the Merger -- Operations After the
Merger."
 
     EACH OF THE WASHINGTON MUTUAL BOARD AND THE GREAT WESTERN BOARD BELIEVES
THAT THE TERMS OF THE MERGER ARE FAIR TO, AND IN THE BEST INTERESTS OF, THEIR
RESPECTIVE SHAREHOLDERS. THE WASHINGTON MUTUAL BOARD AND THE GREAT WESTERN BOARD
HAVE EACH, BY UNANIMOUS VOTE OF ALL DIRECTORS PRESENT, APPROVED THE MERGER
AGREEMENT AND THE TRANSACTIONS CONTEMPLATED THEREBY AND RECOMMEND THAT THEIR
RESPECTIVE SHAREHOLDERS APPROVE AND ADOPT THE SHARE ISSUANCE PROPOSAL (IN THE
CASE OF WASHINGTON MUTUAL SHAREHOLDERS) AND THE MERGER PROPOSAL (IN THE CASE OF
GREAT WESTERN STOCKHOLDERS).
 
     IN ADDITION, THE BOARD OF DIRECTORS OF WASHINGTON MUTUAL HAS, BY UNANIMOUS
VOTE OF ALL DIRECTORS PRESENT, APPROVED THE PROPOSED AMENDMENT TO THE WASHINGTON
MUTUAL ARTICLES AND RECOMMENDS THAT THE WASHINGTON MUTUAL SHAREHOLDERS AND THE
HOLDERS OF WASHINGTON MUTUAL PREFERRED STOCK VOTE TO APPROVE SUCH AMENDMENT.
 
     See "The Merger -- Reasons for the Merger; Recommendations of the Boards of
Directors."
 
  OPINIONS OF FINANCIAL ADVISORS
 
     Lehman Brothers Inc. ("Lehman Brothers"), which is serving as financial
advisor to the Washington Mutual Board, has delivered its written opinion, dated
March 5, 1997 (the "Lehman Brothers Opinion") to the Washington Mutual Board,
that the Exchange Ratio is fair, from a financial point of view, to Washington
Mutual. See "The Merger -- Opinions of Financial Advisors." THE FULL TEXT OF THE
LEHMAN BROTHERS OPINION, WHICH SETS FORTH THE ASSUMPTIONS MADE, MATTERS
CONSIDERED AND LIMITS ON ITS REVIEW, IS ATTACHED HERETO AS APPENDIX B AND IS
INCORPORATED BY REFERENCE IN THIS JOINT PROXY STATEMENT/PROSPECTUS.
 
                                        8
<PAGE>   14
 
     Washington Mutual has agreed to pay fees to Lehman Brothers for its
services in connection with the Merger, which fees were payable, in part, at the
time of signing of the Merger Agreement and a substantial portion of which is
contingent upon consummation of the Merger.
 
     Goldman, Sachs & Co. ("Goldman Sachs") and Merrill Lynch & Co. ("Merrill
Lynch"), which are serving as financial advisors to Great Western, have
delivered their written opinions, each dated as of March 5, 1997, to the Great
Western Board to the effect that, as of such date, and based upon and subject to
various qualifications and assumptions described therein, the Exchange Ratio (i)
in the case of Goldman Sachs, is fair to Great Western Stockholders and (ii) in
the case of Merrill Lynch, is fair to the shareholders of Great Western from a
financial point of view. See "The Merger -- Opinions of Financial Advisors." THE
FULL TEXTS OF THE GOLDMAN SACHS OPINION (THE "GOLDMAN SACHS OPINION") AND THE
MERRILL LYNCH OPINION (THE "MERRILL LYNCH OPINION"), EACH OF WHICH SETS FORTH
THE ASSUMPTIONS MADE, MATTERS CONSIDERED AND LIMITS ON ITS REVIEW, ARE ATTACHED
HERETO AS APPENDICES C AND D, RESPECTIVELY, AND ARE INCORPORATED BY REFERENCE IN
THIS JOINT PROXY STATEMENT/PROSPECTUS. GREAT WESTERN STOCKHOLDERS ARE URGED TO
READ SUCH OPINIONS IN THEIR ENTIRETY. SEE "THE MERGER -- OPINIONS OF FINANCIAL
ADVISORS."
 
     Great Western has agreed to pay fees to Goldman Sachs and Merrill Lynch for
their services in connection with the Merger, which fees were payable, in part,
upon execution of the Merger Agreement and a substantial portion of which is
contingent upon consummation of the Merger. See "The Merger -- Opinions of
Financial Advisors."
 
  CONDITIONS TO THE MERGER; REGULATORY APPROVALS
 
     The obligations of Washington Mutual and Great Western to consummate the
Merger are subject to various conditions, including, among others, obtaining
requisite stockholder approvals; obtaining the requisite regulatory approvals,
as described below; the effectiveness of the Registration Statement of which
this Joint Proxy Statement/Prospectus is a part; approval for listing on NASDAQ
of the shares of Washington Mutual Common Stock and Series F Preferred Stock to
be issued in the Merger, subject to official notice of issuance; receipt of
opinions of counsel at the closing of the Merger in respect of certain federal
income tax consequences of the Merger; and receipt of accountants' letters to
the effect that the Merger qualifies for "pooling-of-interests" accounting
treatment.
 
     The Merger is conditioned on obtaining all required regulatory approvals
(the "Requisite Regulatory Approvals"). The principal Requisite Regulatory
Approval is approval of the Office of Thrift Supervision (the "OTS") under the
Home Owners' Loan Act and the Federal Deposit Insurance Act. As described under
"The Merger -- Regulatory Approvals", Washington Mutual intends to file an
application seeking this OTS approval promptly. Washington Mutual expects that
it will be able to obtain the OTS approval on a timely basis and without the
imposition of any condition that would have a material adverse effect on the
Combined Company. See "The Merger -- Conditions to the Consummation of the
Merger" and "-- Regulatory Approvals Required."
 
  TERMINATION OF THE MERGER AGREEMENT
 
     The Merger Agreement may be terminated by mutual consent of the Washington
Mutual Board and the Great Western Board. The Merger Agreement may also be
terminated by either the Washington Mutual Board or the Great Western Board (i)
if a governmental authority issues a final denial of an application with respect
to any of the Requisite Regulatory Approvals or issues a final order prohibiting
the consummation of the Merger, (ii) if the Merger does not occur on or before
March 31, 1998, (iii) in certain events involving a material breach by the other
party of any of its representations, warranties, covenants or agreements in the
Merger Agreement, (iv) if the requisite approval of either the Washington Mutual
Shareholders or the Great Western Stockholders is not obtained at their
respective Special Meetings, or (v) if the board of directors of the other party
withdraws, modifies or changes its approval or recommendation of the Merger
Agreement. The Merger Agreement may also be terminated (i) by the Washington
Mutual Board if a tender offer or exchange offer for 25% or more of the
outstanding shares of Great Western Common Stock is commenced (other than by
Washington Mutual), and the Great Western Board recommends that the Great
Western Stockholders
 
                                        9
<PAGE>   15
 
tender their shares in such tender or exchange offer or otherwise fails to
recommend that Great Western Stockholders reject such tender offer or exchange
offer within ten business days after the commencement thereof, or (ii) by the
Great Western Board if a tender offer or exchange offer for 25% or more of the
outstanding shares of Washington Mutual Common Stock is commenced, and the
Washington Mutual Board recommends that the Washington Mutual Shareholders
tender their shares in such tender or exchange offer or otherwise fails to
recommend that Washington Mutual Shareholders reject such tender offer or
exchange offer within ten business days after the commencement thereof. See "The
Merger -- Termination of the Merger Agreement."
 
     Pursuant to the Merger Agreement, Great Western has agreed to pay a $75
million fee (plus reimbursement for documented reasonable out-of-pocket expenses
up to $20 million) to Washington Mutual if (a) Washington Mutual terminates the
Merger Agreement because the Great Western Board withdraws, modifies or changes
in a manner adverse to Washington Mutual its approval or recommendation of the
Merger, (b) Washington Mutual terminates the Merger Agreement because the Great
Western Board either recommends a third party tender or exchange offer for 25%
or more of the outstanding shares of Common Stock or fails to recommend that
Great Western Stockholders reject such tender or exchange offer, (c) either
Washington Mutual or Great Western terminates the Merger Agreement because the
Great Western Stockholders fail to approve the Merger Agreement, but only if at
the time of such failure, an alternative proposal to acquire Great Western has
been publicly disclosed (or any person shall have publicly disclosed an
intention (whether or not conditional) to make such an alternative proposal), or
(d) Washington Mutual terminates the Merger Agreement as a result of the willful
breach by Great Western of any material representation, warranty, covenant or
other agreement in the Merger Agreement, but only if at or prior to the time of
termination, an alternative proposal to acquire Great Western has been made
known to Great Western or has been publicly disclosed, whether or not such
alternative proposal is rejected by Great Western or withdrawn prior to the time
of termination. An additional $100 million fee is payable by Great Western to
Washington Mutual if, within 18 months after termination of the Merger Agreement
under the circumstances described above, Great Western enters into a definitive
agreement with respect to or consummates an alternative proposal for an
acquisition of Great Western by a third party.
 
     On February 18, 1997, H.F. Ahmanson & Company ("Ahmanson") publicly
announced its proposal for a merger of Great Western and Ahmanson pursuant to
which each share of Great Western Common Stock would be converted into 1.05
shares of Ahmanson common stock (the "Ahmanson Proposal"). The Ahmanson
Proposal, if not unconditionally withdrawn prior to the mailing to Great Western
Stockholders of this Joint Proxy Statement/Prospectus, would constitute an
alternative proposal for purposes of clause (c) of the preceding paragraph. For
purposes of clause (d) above, the Ahmanson Proposal made prior to the date of
the Merger Agreement is not deemed to be an alternative proposal; however, any
alternative proposal made by Ahmanson after the date of the Merger Agreement, or
any amendment or modification made after that date to the Ahmanson Proposal,
would constitute such an alternative proposal. See "The Merger -- Background of
the Merger."
 
     The termination fees described above, which Washington Mutual and Great
Western believe are customary and typical for transactions such as the proposed
Merger, are intended, among other things, to increase the likelihood that the
Merger will be consummated on the terms set forth in the Merger Agreement and,
if the Merger is not consummated under certain circumstances involving an
acquisition or potential acquisition of Great Western by a third party, to
compensate Washington Mutual for its efforts undertaken, expenses incurred and
business opportunities lost in connection with the proposed Merger. These
agreements may have the effect of discouraging offers by third parties to
acquire Great Western prior to the Merger, even if such persons were prepared to
offer to pay consideration to Great Western Stockholders that has a higher
current market price than the shares of Washington Mutual Common Stock to be
received by the holders of Great Western Common Stock pursuant to the Merger
Agreement. See "The Merger -- Background of the Merger."
 
     Ahmanson has filed suit in the Court of Chancery of the State of Delaware
to enjoin all steps necessary for consummation of the Merger and is challenging
the termination fee described above. See "Litigation."
 
                                       10
<PAGE>   16
 
  CERTAIN FEDERAL INCOME TAX CONSEQUENCES
 
     The Merger is intended to qualify as a reorganization within the meaning of
Section 368(a) of the Internal Revenue Code of 1986, as amended (the "Code).
Accordingly, no gain or loss will be recognized by Great Western Stockholders
upon the receipt of Washington Mutual Common Stock or Series F Preferred Stock
in exchange for Great Western Common Stock or Great Western Preferred Stock,
respectively, except with respect to any cash received in lieu of a fractional
share interest in Washington Mutual Common Stock.
 
     There will be no federal income tax consequences to the shareholders of
Washington Mutual as a result of either voting on the proposals described herein
or consummation of the Merger.
 
     All shareholders should carefully read the discussion of the material
federal income tax consequences of the Merger under "The Merger -- Certain
Federal Income Tax Consequences" and are urged to consult with their own tax
advisors as to the federal, state, local and foreign tax consequences of the
Merger in their particular circumstances.
 
  ACCOUNTING TREATMENT
 
     The Merger is expected to be treated as a pooling-of-interests for
accounting and financial reporting purposes. Accordingly, under generally
accepted accounting principles, the assets and liabilities of Great Western will
be recorded on the books of Washington Mutual at their values on the books of
Great Western at the Effective Time. If completed as proposed, no goodwill will
be created as a result of the Merger. See "The Merger -- Accounting Treatment."
 
  INTERESTS OF CERTAIN PERSONS IN THE MERGER
 
     Certain members of Great Western's management and the Great Western Board
have interests in the Merger in addition to their interests as stockholders of
Great Western generally. These include, among other things, provisions in the
Merger Agreement relating to indemnification, the appointment of four members to
the Washington Mutual Board following the Merger and the acceleration of
benefits under certain employee benefit plans. The Great Western Board was aware
of these interests and considered them, among other matters, in unanimously
approving the Merger Agreement and transactions contemplated thereby. See "The
Merger -- Interests of Certain Persons in the Merger."
 
  NO APPRAISAL OR DISSENTERS' RIGHTS
 
     Under Delaware law, holders of Great Western Common Stock and Great Western
Preferred Stock (including the holders of Great Western Depositary Shares) will
have no appraisal rights in connection with the Merger. Under Washington law,
holders of Washington Mutual Common Stock and Washington Mutual Preferred Stock
will have no dissenters' rights with respect to the Merger Proposal, the Share
Issuance Proposal or the amendment of the Washington Mutual Articles. See "The
Merger -- No Appraisal or Dissenters' Rights."
 
MANAGEMENT AND OPERATIONS OF WASHINGTON MUTUAL FOLLOWING THE MERGER
 
     At the Effective Time, Great Western will merge with and into NACI (which,
as of the Effective Time, will be a direct, wholly owned subsidiary of
Washington Mutual), with NACI as the surviving corporation. NACI will be, at the
Effective Time, the direct parent company of ASB. It is intended that, as soon
as practicable after the Merger, GW Bank and ASB will merge and that the name of
the surviving corporation will be Great Western Bank.
 
     At the Effective Time, four representatives mutually agreeable to
Washington Mutual and Great Western will be added to the existing Washington
Mutual Board to form the Board of Directors of the Combined Company. It is
expected that John F. Maher, the President and Chief Executive Officer of Great
Western, will be one of the four directors chosen to serve on the Board of
Directors of the Combined Company.
 
                                       11
<PAGE>   17
 
     Washington Mutual intends to consolidate the branch systems and loan
offices of ASB and GW Bank in California and the loan offices of WMB and GW Bank
in Washington. It is anticipated that approximately 100 branches and 100 loan
offices will be closed. Washington Mutual also intends to consolidate certain
administrative functions. Initial consolidations will occur in 1998 and it is
anticipated that further back office consolidation and efficiencies will be
achieved in 1999. These consolidations, together with cost reductions which
result from the introduction of Washington Mutual's loan origination system and
an integrated data/communications system throughout the GW Bank branches, are
expected to achieve annual operating cost savings of approximately $208 million
and $340 million (pre-tax) in 1998 and 1999, respectively.
 
     In addition, Washington Mutual believes that the Merger should provide
opportunities for significant revenue enhancements for the Combined Company.
Washington Mutual anticipates increased asset growth through additional
production and retention of residential mortgage and consumer loans as portfolio
loans (based in part on leveraging of the additional capital made available as a
result of the Merger and the introduction of new loan products and systems at GW
Bank). It is estimated that this strategy will increase pretax net interest
income in 1999 by approximately $246 million. In addition, Washington Mutual
estimates additional pre-tax fee income in 1999 of approximately $88 million may
be obtainable primarily as a result of implementing Washington Mutual's pricing
policies and products throughout the GW Bank branch network.
 
     Merger-related expenses of approximately $343.0 million (pretax) are
expected to be recorded by Washington Mutual at the Effective Time. This charge
includes the creation of reserves of $145.0 million for severance and management
payments, $106.0 million for facilities and system conversion related expenses
and $92.0 million for other transaction costs.
 
     Washington Mutual also intends to provide an additional $100.0 million in
loan loss provisions as a charge to earnings at the Effective Time. This
additional loan loss provision is being provided in part because a number of
Washington Mutual credit administration and asset management philosophies and
procedures differ from those of Great Western. See "Management and Operations of
Washington Mutual Following the Merger."
 
     It is anticipated that the Combined Company's dividend payout rates will
more closely match Washington Mutual's historical practice than that of Great
Western. No assurance can be given, however, as to the amount or timing of
future dividends. See "Summary Financial Data of Washington Mutual," "Summary
Financial Data of Great Western" and "The Merger -- Dividend Policy."
 
     The estimates of cost savings, revenue enhancements, Merger-related and
other expenses and future dividend policies described above are forward-looking
statements that, while prepared on the basis of Washington Mutual's best
judgments and currently available information regarding Great Western's business
and the future operating performance of the two companies, are inherently
subject to significant business, economic and competitive uncertainties and
contingencies, many of which are beyond the control of either company, and upon
assumptions with respect to future business decisions that are subject to
change. Accordingly, there can be no assurance that such cost-savings and
revenue enhancements will be realized in the amounts or within the time periods
currently estimated, that such charges for Merger-related expenses will be
sufficient, or that dividend policies will not change in the future. See "Risk
Factors."
 
     See "Management and Operations of Washington Mutual Following the Merger."
 
DESCRIPTION OF WASHINGTON MUTUAL CAPITAL STOCK
 
     Upon consummation of the Merger, holders of Great Western Common Stock will
become holders of Washington Mutual Common Stock. Holders of shares of
Washington Mutual Common Stock are entitled to one vote per share for each share
held. Subject to the rights of holders of shares of the outstanding Washington
Mutual Preferred Stock, holders of shares of Washington Mutual Common Stock have
equal rights to participate in dividends when declared and, in the event of
liquidation, in the net assets of Washington Mutual available for distribution
to shareholders. Washington Mutual may not declare any dividends on the
Washington Mutual Common Stock unless full preferential amounts to which holders
of the Washington
 
                                       12
<PAGE>   18
 
Mutual Preferred Stock are entitled have been paid or declared and set apart for
payment. Washington Mutual is also subject to certain contractual and regulatory
restrictions on the payment of dividends.
 
     Each share of Washington Mutual Common Stock currently has attached thereto
a stock purchase right (a "Washington Mutual Right") issued under the Washington
Mutual Rights Plan (as defined herein).
 
     Upon consummation of the Merger, holders of Great Western Preferred Stock
will become holders of the Series F Preferred Stock, which has substantially
identical terms, limitations, privileges and rights as the Great Western
Preferred Stock.
 
     For additional information concerning the capital stock of Washington
Mutual and certain differences between Washington and Delaware corporate laws,
see "Description of Washington Mutual Capital Stock" and "Certain Differences
Between Washington and Delaware Corporate Laws."
 
                                       13
<PAGE>   19
 
                  SUMMARY FINANCIAL DATA OF WASHINGTON MUTUAL
 
     The following table presents summary financial data for Washington Mutual
and is derived from and should be read in conjunction with the Consolidated
Financial Statements and Notes thereto, which are incorporated herein by
reference from the 1996 Washington Mutual 10-K. The financial information
presented herein has been restated for the mergers with Keystone Holdings, Inc.
and Western Bank in 1996 and with Pioneer Savings Bank in 1993 as if the
respective companies had been combined for all prior periods presented.
 
<TABLE>
<CAPTION>
                                                                         YEAR ENDED DECEMBER 31,
                                                 ------------------------------------------------------------------------
                                                     1996           1995           1994           1993           1992
                                                 ------------   ------------   ------------   ------------   ------------
                                                           (DOLLARS IN THOUSANDS, EXCEPT FOR PER SHARE AMOUNTS)
<S>                                              <C>            <C>            <C>            <C>            <C>
Interest income................................  $  3,149,236   $  2,916,086   $  2,295,413   $  2,198,578   $  2,170,969
Interest expense...............................     1,958,229      1,923,436      1,335,358      1,211,896      1,302,489
                                                 ------------   ------------   ------------   ------------   ------------
Net interest income............................     1,191,007        992,650        960,055        986,682        868,480
Provision for loan losses......................       201,512         74,987        122,009        158,728        158,537
Other income...................................       259,264        208,339        220,794        246,576        174,365
Other expense..................................     1,025,304        700,514        695,517        687,519        561,688
                                                 ------------   ------------   ------------   ------------   ------------
Income before income taxes, extraordinary items
  and cumulative effect of change in tax
  accounting method............................       223,455        425,488        363,323        387,011        322,620
Income taxes...................................        70,420        111,906        109,880         96,034         42,462
Provision for payments in lieu of taxes........        25,187          7,887           (824)        14,075         53,980
Extraordinary items, net of federal income tax
  effect(1)....................................            --             --             --         (8,953)        (4,638)
Cumulative effect of change in tax accounting
  method.......................................            --             --             --         13,365         60,045
Minority interest in earnings of consolidated
  subsidiaries.................................        13,570         15,793         13,992         13,991         14,030
                                                 ------------   ------------   ------------   ------------   ------------
Net income (2).................................  $    114,278   $    289,902   $    240,275   $    267,323   $    267,555
                                                 ============   ============   ============   ============   ============
Net income attributable to common stock........  $     95,859   $    271,318   $    221,691   $    253,765   $    262,680
                                                 ============   ============   ============   ============   ============
Net income per common share (2)(3):
  Primary......................................  $       0.85   $       2.47   $       2.09   $       2.42   $       2.82
  Fully diluted................................          0.85           2.42           2.06           2.36           2.71
Average number of shares used to calculate net
  income per common share (4):
  Primary......................................   112,858,781    109,944,477    106,245,127    104,691,406     97,706,842
  Fully diluted................................   113,138,724    115,363,724    111,664,374    110,753,774    103,496,289
Cash dividends declared:
  Common.......................................  $    124,968   $     57,997   $     67,835   $     48,936   $    118,531
  Preferred....................................        18,418         18,584         18,584         13,559          4,875
Cash dividends declared per common share
  (3)(5).......................................          0.90           0.77           0.70           0.50           0.33
</TABLE>
 
<TABLE>
<CAPTION>
                                                                               DECEMBER 31,
                                                 ------------------------------------------------------------------------
                                                     1996           1995           1994           1993           1992
                                                 ------------   ------------   ------------   ------------   ------------
                                                                          (DOLLARS IN THOUSANDS)
<S>                                              <C>            <C>            <C>            <C>            <C>
Assets.........................................  $ 44,551,925   $ 42,026,622   $ 37,481,296   $ 33,614,912   $ 27,678,923
Loans..........................................    30,330,776     24,192,840     25,472,092     21,063,698     16,666,525
Trading, investment and mortgage-backed
  securities...................................    11,973,268     15,352,683      8,738,763      7,416,638      4,640,399
Deposits.......................................    24,080,141     24,462,960     23,344,006     23,516,317     20,729,204
Borrowings (includes annuities)................    17,683,988     14,579,635     11,946,567      7,366,624      5,134,480
Stockholders' equity...........................     2,397,888      2,541,704      1,854,836      1,765,560      1,467,835
</TABLE>
 
<TABLE>
<CAPTION>
                                                                         YEAR ENDED DECEMBER 31,
                                                 ------------------------------------------------------------------------
             OTHER FINANCIAL DATA:                   1996           1995           1994           1993           1992
- -----------------------------------------------  ------------   ------------   ------------   ------------   ------------
<S>                                              <C>            <C>            <C>            <C>            <C>
Net interest margin............................          2.89%          2.62%          2.90%          3.31%          3.36%
Operating efficiency ratio (2)(6)..............         70.70          58.33          58.90          55.75          53.86
Return on average assets (2)...................          0.27           0.73           0.69           0.84           1.29
Return on stockholders' equity (2).............          4.59          13.44          12.66          15.95          21.05
Dividend payout ratio (7)......................         29.01          25.74          24.50          15.98          15.43
Ratios of combined earnings to fixed charges:
  Including interest on deposits...............          1.11x          1.22x          1.27x          1.32x          1.25x
  Excluding interest on deposits...............          1.25x          1.54x          1.75x          2.13x          2.02x
</TABLE>
 
                                       14
<PAGE>   20
 
<TABLE>
<CAPTION>
                                                                               DECEMBER 31,
                                                 ------------------------------------------------------------------------
                                                     1996           1995           1994           1993           1992
                                                 ------------   ------------   ------------   ------------   ------------
<S>                                              <C>            <C>            <C>            <C>            <C>
Stockholders' equity as a percentage of total
  assets:
  Total stockholders' equity...................          5.38%          6.05%          4.95%          5.25%          5.30%
  Common stockholders' equity..................          5.12           5.77           4.63           4.90           4.87
  Tangible stockholders' equity................          5.10           5.69           4.46           4.64           5.28
  Tangible common stockholders' equity.........          4.87           5.40           4.14           4.28           4.83
Nonperforming assets as a percentage of total
  assets.......................................          0.74           0.81           1.12           1.55           2.03
Reserve for loan losses as a percentage of:
  Nonperforming loans..........................        160.52         110.04          87.22          72.74          54.58
  Nonperforming assets.........................        110.29          69.42          58.52          46.91          31.98
</TABLE>
 
- ---------------
(1) Extraordinary items include the call of subordinated capital notes,
    resulting in pretax losses of $2.2 million and $3.1 million during 1993 and
    1992, and penalties for prepayment of FHLB advances, resulting in pretax
    losses of $10.8 million and $3.6 million during 1993 and 1992.
 
(2) Earnings for 1996 were reduced $294.6 million by an after-tax charge of
    $209.8 million for transaction-related expense resulting from Washington
    Mutual's merger with Keystone Holdings, Inc. ("Keystone Holdings") and
    acquisition of American Savings Bank, and by an after-tax charge of $84.8
    million representing Washington Mutual's portion of the one-time assessment
    paid by savings institutions and banks nationally to recapitalize the
    Savings Association Insurance Fund ("SAIF"). The following table presents
    selected financial data for 1996 as reported and without the above mentioned
    charges:
 
<TABLE>
<CAPTION>
                                                                                                                 WITHOUT
                                                                                                             SAIF ASSESSMENT
                                                                                                                   AND
                                                                                                           TRANSACTION-RELATED
                                                                                           AS REPORTED          EXPENSES
                                                                                           -----------     -------------------
                                                                                              (DOLLARS IN THOUSANDS EXCEPT
                                                                                                 FOR PER SHARE AMOUNTS)
        <S>                                                                                <C>             <C>
        Net income.......................................................................   $ 114,278           $ 408,845
        Net income per fully diluted common share........................................        0.85                3.37
        Operating efficiency ratio.......................................................       70.70%              51.20%
        Return on average assets.........................................................        0.27                0.95
        Return on stockholders' equity...................................................        4.59               16.41
</TABLE>
 
(3) Net income per common share, cash dividends paid per common share and number
    of common shares outstanding for 1992 have been adjusted for the third
    quarter 1993 50% stock dividend.
 
(4) As part of the business combination with Keystone Holdings, 8,000,000 shares
    of Washington Mutual Common Stock, with an assigned value of $42.75 per
    share, were issued to an escrow for the benefit of the shareholders of
    Keystone Holdings and the FSLIC Resolution Fund (the "FRF") and their
    transferees. The Combined Company will use the treasury stock method to
    determine the effect of the shares upon the Combined Company's financial
    statements. At December 31, 1996, the dilutive effect of the 8,000,000
    shares of Washington Mutual Common Stock on primary and fully diluted
    earnings per share was minimal.
 
(5) Does not include dividends paid by companies acquired by Washington Mutual.
 
(6) The operating efficiency ratio measures other expense as a percentage of
    operating income (net interest income plus other income). No adjustments
    have been made to the calculation for any nonrecurring or one-time charges
    or assessments.
 
(7) Dividend payout ratio for each period is based on Washington Mutual's net
    income prior to business combinations occurring subsequent to such period.
 
                                       15
<PAGE>   21
 
                    SUMMARY FINANCIAL DATA OF GREAT WESTERN
 
     The following table presents summary financial data for Great Western and
is derived from and should be read in conjunction with the Consolidated
Financial Statements and Notes thereto, which are incorporated herein by
reference from the 1996 Great Western 10-K.
 
<TABLE>
<CAPTION>
                                                                               YEAR ENDED DECEMBER 31,
                                                     ----------------------------------------------------------------------------
                                                         1996            1995            1994            1993            1992
                                                     ------------    ------------    ------------    ------------    ------------
                                                                 (DOLLARS IN THOUSANDS, EXCEPT FOR PER SHARE AMOUNTS)
<S>                                                  <C>             <C>             <C>             <C>             <C>
Interest income...................................   $  3,233,931    $  3,238,711    $  2,629,718    $  2,680,784    $  3,091,093
Interest expense..................................      1,855,914       1,936,582       1,307,448       1,297,930       1,668,731
                                                     ------------    ------------    ------------    ------------    ------------
Net interest income...............................      1,378,017       1,302,129       1,322,270       1,382,854       1,422,362
Provision for loan losses.........................        208,971         187,700         207,200         463,000         420,000
Other income......................................        331,825         327,668         367,897         327,855         282,131
Other expense.....................................      1,314,249       1,019,975       1,076,433       1,155,662       1,188,981
                                                     ------------    ------------    ------------    ------------    ------------
Income before income taxes and cumulative effect
  of change in tax accounting method..............        186,622         422,122         406,534          92,047          95,512
Income taxes......................................         70,800         161,100         155,300          30,000          41,600
Cumulative effect of change in tax accounting
  method..........................................             --              --              --              --          61,000
Cumulative effect of change in postretirement
  benefits cost accounting method.................             --              --              --              --         (29,906)
                                                     ------------    ------------    ------------    ------------    ------------
Net income(1).....................................   $    115,822    $    261,022    $    251,234    $     62,047    $     85,006
                                                     ============    ============    ============    ============    ============
Net income attributable to common stock...........   $     95,527    $    236,007    $    226,219    $     37,032    $     69,463
                                                     ============    ============    ============    ============    ============
Net income per common share(1):
  Primary.........................................   $       0.69    $       1.72    $       1.69    $       0.28    $       0.53
  Fully diluted...................................           0.69            1.71            1.69            0.28            0.53
Average number of shares used to calculate net
  income per common share:
  Primary.........................................    138,505,046     137,111,074     133,769,724     132,007,559     130,735,867
  Fully diluted...................................    139,250,206     137,951,442     133,769,724     138,853,346     137,282,125
Cash dividends paid:
  Common..........................................   $    133,045    $    124,673    $    122,524    $    120,877    $    118,720
  Preferred.......................................         20,295          25,015          25,015          25,015          15,543
Cash dividends paid per common share..............           0.98            0.92            0.92            0.92            0.91
</TABLE>
 
<TABLE>
<CAPTION>
                                                                                     DECEMBER 31,
                                                     ----------------------------------------------------------------------------
                                                         1996            1995            1994            1993            1992
                                                     ------------    ------------    ------------    ------------    ------------
                                                                                (DOLLARS IN THOUSANDS)
<S>                                                  <C>             <C>             <C>             <C>             <C>
Assets............................................   $ 42,874,572    $ 44,586,764    $ 42,218,257    $ 38,348,360    $ 38,439,186
Loans.............................................     30,823,192      29,887,349      28,378,368      30,661,403      30,584,604
Trading, investment and mortgage-backed
  securities......................................      9,067,834      10,895,900      10,186,702       4,060,470       3,791,963
Deposits..........................................     28,586,773      29,234,928      28,700,947      31,531,563      30,908,665
Borrowings........................................     10,501,813      11,345,634      10,120,660       3,479,341       4,151,052
Great Western-obligated mandatorily redeemable
  preferred securities of Great Western's
  subsidiary trust, holding solely $103,092,800
  aggregate principal amount of 8.25% subordinated
  deferrable interest notes, due 2025, of Great
  Western.........................................        100,000         100,000              --              --              --
Stockholders' equity..............................      2,595,200       2,822,476       2,483,786       2,423,401       2,449,734
</TABLE>
 
<TABLE>
<CAPTION>
                                                                               YEAR ENDED DECEMBER 31,
                                                     ----------------------------------------------------------------------------
OTHER FINANCIAL DATA:                                    1996            1995            1994            1993            1992
                                                     ------------    ------------    ------------    ------------    ------------
<S>                                                  <C>             <C>             <C>             <C>             <C>
Net interest margin...............................           3.33%           3.13%           3.60%           3.89%           3.97%
Operating efficiency ratio(1)(2)..................          76.86           62.58           63.69           67.55           69.76
Return on average assets(1).......................           0.27            0.59            0.65            0.16            0.22
Return on stockholders' equity(1).................           4.23           10.03           10.35            2.53            3.50
Dividend payout ratio.............................         142.03           53.80           54.44          328.57          171.70
Ratios of combined earnings to fixed charges:
  Including interest on deposits..................           1.10x           1.21x           1.30x           1.07x           1.05x
  Excluding interest on deposits..................           1.26x           1.56x           2.05x           1.23x           1.26x
</TABLE>
 
                                       16
<PAGE>   22
 
<TABLE>
<CAPTION>
                                                                                     DECEMBER 31,
                                                     ----------------------------------------------------------------------------
                                                         1996            1995            1994            1993            1992
                                                     ------------    ------------    ------------    ------------    ------------
<S>                                                  <C>             <C>             <C>             <C>             <C>
Stockholders' equity as a percentage of total
  assets:
  Total stockholders' equity......................           6.05%           6.33%           5.88%           6.32%           6.37%
  Common stockholders' equity.....................           5.67            5.96            5.49            5.89            5.94
  Tangible stockholders' equity...................           5.42            5.65            5.06            5.25            5.58
  Tangible common stockholders' equity............           5.03            5.27            4.67            4.82            5.15
Nonperforming assets as a percentage of total
  assets..........................................           1.10            1.48            1.71            2.40            4.81
Reserve for loan losses as a percentage of:.......
  Nonperforming loans.............................          89.12           74.58           77.51           80.19           50.57
  Nonperforming assets............................          66.49           54.98           60.76           54.67           24.05
</TABLE>
 
- ---------------
(1) Earnings for 1996 were reduced $194.8 million by an after-tax charge of
    $79.6 million for nonrecurring charges, including a $68.3 million pretax
    restructuring charge primarily to reengineer Great Western's loan
    origination operations and consolidate Great Western's corporate
    headquarters and a $50.0 million pretax provision for losses on the bulk
    sale of nonperforming loans and real estate, and by an after-tax charge of
    $115.2 million representing Great Western's portion of the one-time
    assessment paid by savings institutions and banks nationally to recapitalize
    the SAIF. The following table presents selected financial data for 1996 as
    reported and without the above mentioned charges:
 
<TABLE>
<CAPTION>
                                                                                                               WITHOUT
                                                                                                           SAIF ASSESSMENT
                                                                                                                 AND
                                                                                                         TRANSACTION-RELATED
                                                                                        AS REPORTED           EXPENSES
                                                                                        -----------      -------------------
                                                                                           (DOLLARS IN THOUSANDS, EXCEPT
                                                                                               FOR PER SHARE AMOUNTS)
         <S>                                                                            <C>              <C>
         Net income..................................................................    $ 115,822            $ 310,651
         Net income per fully diluted common share...................................         0.69                 2.09
         Operating efficiency ratio..................................................        76.86%               60.91%
         Return on average assets....................................................         0.27                 0.71
         Return on average equity....................................................         4.23                11.16
</TABLE>
 
(2) The operating efficiency ratio measures other expense as a percentage of
    operating income (net interest income plus other income). No adjustments
    have been made to the calculations for any nonrecurring or one-time charges
    or assessments.
 
                                       17
<PAGE>   23
 
            SUMMARY HISTORICAL AND PRO FORMA COMBINED FINANCIAL DATA
 
     The following table sets forth certain selected historical financial data
for Washington Mutual and Great Western and selected pro forma combined
financial data. The pro forma amounts included in the table below give effect to
the Merger as if it had been consummated on January 1, 1994 for income statement
information and December 31, 1996 for balance sheet information. Pro forma
adjustments made to arrive at the pro forma combined amounts are based on the
pooling-of-interests method of accounting.
 
     This information should be read in conjunction with and is qualified in its
entirety by reference to the Consolidated Financial Statements and notes thereto
from the 1996 Washington Mutual 10-K and the 1996 Great Western 10-K included in
the documents described under "Incorporation of Certain Documents by Reference,"
and the pro forma combined financial statements and accompanying discussion and
notes set forth under "Pro Forma Combined Financial Information." The pro forma
amounts in the table below are presented for informational purposes and are not
necessarily indicative of the financial position or the results of operations of
the Combined Company that actually would have occurred had the Merger been
consummated as of the dates or for the periods presented. The pro forma amounts
are also not necessarily indicative of the future financial position or future
results of operations of the Combined Company. See "Management and Operations of
Washington Mutual Following the Merger -- Operations After the Merger."
 
<TABLE>
<CAPTION>
                                                                YEAR ENDED DECEMBER 31,
                                                       ------------------------------------------
                  WASHINGTON MUTUAL                       1996            1995            1994
- -----------------------------------------------------  -----------     -----------     ----------
                                                                 (DOLLARS IN THOUSANDS)
<S>                                                    <C>             <C>             <C>
Net interest income..................................  $ 1,191,007     $   992,650     $  960,055
Provision for loan losses............................      201,512          74,987        122,009
Other income (expense), net..........................     (766,040)       (492,175)      (474,723)
Income taxes.........................................       95,607         119,793        109,056
Minority interest in income of consolidated
  subsidiaries.......................................       13,570          15,793         13,992
                                                        ----------      ----------     ----------
Net income(1)........................................  $   114,278     $   289,902     $  240,275
                                                        ==========      ==========     ==========
Net income attributable to common stock..............  $    95,859     $   271,318     $  221,691
                                                        ==========      ==========     ==========
</TABLE>
 
<TABLE>
<CAPTION>
                                                                YEAR ENDED DECEMBER 31,
                                                       ------------------------------------------
                    GREAT WESTERN                         1996            1995            1994
- -----------------------------------------------------  -----------     -----------     ----------
                                                                 (DOLLARS IN THOUSANDS)
<S>                                                    <C>             <C>             <C>
Net interest income..................................  $ 1,378,017     $ 1,302,129     $1,322,270
Provision for loan losses............................      208,971         187,700        207,200
Other income (expense), net..........................     (982,424)       (692,307)      (708,536)
Income taxes.........................................       70,800         161,100        155,300
                                                        ----------      ----------     ----------
Net income(1)........................................  $   115,822     $   261,022     $  251,234
                                                        ==========      ==========     ==========
Net income attributable to common stock..............  $    95,527     $   236,007     $  226,219
                                                        ==========      ==========     ==========
</TABLE>
 
                                       18
<PAGE>   24
 
<TABLE>
<CAPTION>
                                                                          YEAR ENDED DECEMBER 31,
                                                                -------------------------------------------
             PRO FORMA INCLUDING GREAT WESTERN(2)                  1996            1995            1994
- --------------------------------------------------------------  -----------     -----------     -----------
                                                                          (DOLLARS IN THOUSANDS)
<S>                                                             <C>             <C>             <C>
Net interest income...........................................  $ 2,569,024     $ 2,294,779     $ 2,282,325
Provision for loan losses.....................................      410,483         262,687         329,209
Other income (expense), net(3)................................   (1,748,464)     (1,184,482)     (1,183,259)
Income taxes..................................................      166,407         280,893         264,356
Minority interest in income of consolidated subsidiaries......       13,570          15,793          13,992
                                                                 ----------      ----------      ----------
Net income(1).................................................  $   230,100     $   550,924     $   491,509
                                                                 ==========      ==========      ==========
Net income attributable to common stock.......................  $   191,386     $   507,325     $   447,910
                                                                 ==========      ==========      ==========
Net income per common share:
  Primary.....................................................  $      0.81     $      2.17     $      1.98
  Fully diluted...............................................         0.80            2.15            1.97
Average number of shares used to calculate net income per
  common share:
  Primary.....................................................  237,513,322     233,344,444     226,637,879
  Fully diluted...............................................  238,463,909     239,520,022     232,057,126
</TABLE>
 
- ---------------
(1) "Net income from continuing operations" and "net income" are equal for the
    three years ended December 31, 1996.
(2) Merger-related expenses and addition to loan loss reserve anticipated to be
    recorded are not included in the Pro Forma Including Great Western summary
    statements of income for the three years ended December 31, 1996.
(3) Includes pretax charge of $312.6 million representing Washington Mutual's
    and Great Western's portion of the one-time assessment paid by savings
    institutions and banks nationally to recapitalize the SAIF.
 
<TABLE>
<CAPTION>
                                                                           DECEMBER 31, 1996
                                                            ------------------------------------------------
                                                                                               PRO FORMA
                                                            WASHINGTON         GREAT           INCLUDING
                                                              MUTUAL          WESTERN       GREAT WESTERN(1)
                                                            -----------     -----------     ----------------
                                                                         (DOLLARS IN THOUSANDS)
<S>                                                         <C>             <C>             <C>
Assets....................................................  $44,551,925     $42,874,572       $ 86,983,497
Loans.....................................................   30,330,776      30,823,192         61,053,968
Deposits..................................................   24,080,141      28,586,773         52,666,914
Borrowings (including annuities)..........................   17,683,988      10,501,813         28,185,801
Stockholders' equity......................................    2,397,888       2,595,200          4,675,088
Loans serviced for others.................................  $22,998,667     $18,396,586       $ 41,395,253
Loans originated during 1996..............................   13,647,456       8,490,240         22,137,696
Loans sold during 1996....................................    2,057,517       1,478,008          3,535,525
Nonperforming assets......................................      329,523         471,801            801,324
Reserve for loan losses...................................      363,442         313,699            777,141
Stockholders' equity as a percentage of total assets:
  Total stockholders' equity..............................         5.38%           6.05%              5.37%
  Common stockholders' equity.............................         5.12            5.67               5.05
  Tangible stockholders' equity...........................         5.10            5.42               4.92
  Tangible common stockholders' equity....................         4.87            5.03               4.59
Nonperforming assets as a percentage of total assets......         0.74            1.10               0.92
Reserve for loan losses as a percentage of:
  Nonperforming loans.....................................       160.52           89.12             134.36
  Nonperforming assets....................................       110.29           66.49              96.98
</TABLE>
 
- ---------------
(1) Merger-related expenses and addition to loan loss reserve anticipated to be
    recorded are included in the Pro Forma Including Great Western financial
    data. Merger-related expenses and addition to loan loss reserve expected to
    be recorded by Washington Mutual are summarized in the following table
    (dollars in thousands): See "Notes to Pro Forma Combined Consolidated
    Statement of Financial Position."
 
<TABLE>
        <S>                                                                          <C>
        Additional loan loss reserves(*)...........................................  $ 100,000
        Severance and management payments..........................................    145,000
        Facilities and equipment...................................................    106,000
        Other expenses.............................................................     92,000
                                                                                     ---------
          Total expenses...........................................................    443,000
        Tax benefit................................................................   (125,000)
                                                                                     ---------
          Net expenses.............................................................  $ 318,000
                                                                                     ==========
</TABLE>
 
        (*)See "Management and Operations of Washington Mutual Following the
           Merger -- Operations After the Merger" for a discussion of the
           increase in the loan loss provision and the Merger-related expenses.
 
                                       19
<PAGE>   25
 
                           COMPARATIVE PER SHARE DATA
 
     The following table shows certain per share data of Washington Mutual
Common Stock and Great Western Common Stock on an historical basis, pro forma
and pro forma equivalent basis reflecting the Merger. The table should be read
in conjunction with the financial information appearing in this Joint Proxy
Statement/Prospectus and the documents incorporated by reference herein. The per
share pro forma and pro forma equivalent data in the following table are
presented for comparative purposes only and are not necessarily indicative of
the combined financial position or results of operations in the future or what
the combined financial position or results of operations would have been had the
Merger been consummated during the period or as of the date for which this pro
forma table is presented.
 
<TABLE>
<CAPTION>
                                                           FOR THE YEAR ENDED DECEMBER
                                                                       31,
                                                           ----------------------------
                                                            1996       1995       1994
                                                           ------     ------     ------
        <S>                                                <C>        <C>        <C>
        WASHINGTON MUTUAL COMMON STOCK
        Net income per fully diluted share(1):
          Historical.....................................  $ 0.85     $ 2.42     $ 2.06
          Pro forma combined.............................    0.80       2.15       1.97
        Cash dividends paid per share:
          Historical.....................................  $ 0.90     $ 0.77     $ 0.70
          Pro forma combined(2)..........................    0.90       0.77       0.70
        Book value per share at period end(3):
          Historical.....................................  $19.30     $20.70     $15.33
          Pro forma combined.............................   18.13      20.58      16.77
        GREAT WESTERN COMMON STOCK
        Net income per fully diluted share:
          Historical.....................................  $ 0.69     $ 1.71     $ 1.69
          Pro forma equivalent(4)........................    0.72       1.94       1.77
        Cash dividends paid per share:
          Historical.....................................  $ 0.98     $ 0.92     $ 0.92
          Pro forma equivalent(4)........................    0.81       0.69       0.63
        Book value per share at period-end:
          Historical.....................................  $17.63     $18.42     $16.30
          Pro forma equivalent(4)........................   16.32      18.52      15.09
</TABLE>
 
- ---------------
(1) As part of the business combination with Keystone Holdings, 8,000,000 shares
    of Washington Mutual Common Stock, with an assigned value of $42.75 per
    share, were issued to an escrow for the benefit of the shareholders of
    Keystone Holdings and the FRF and their transferees. The Combined Company
    will use the treasury stock method to determine the effect of the shares
    upon the Combined Company's financial statements. At December 31, 1996, the
    dilutive effect of the 8,000,000 shares of Washington Mutual Common Stock on
    primary and fully diluted earnings per share was minimal.
 
(2) Pro forma cash dividends per common share represent historical cash
    dividends per share paid by Washington Mutual.
 
(3) Does not include 8,000,0000 shares of common stock issued to an escrow for
    the benefit of the shareholders of Keystone Holdings and the FRF and their
    transferees.
 
(4) The Great Western pro forma equivalent per share amounts are calculated by
    multiplying the Washington Mutual pro forma combined per share amounts by
    the Exchange Ratio of 0.9.
 
                                       20
<PAGE>   26
 
                           COMPARATIVE MARKET PRICES
 
     The table below sets forth, for the periods indicated, historical high and
low closing sales price information for Washington Mutual Common Stock and Great
Western Common Stock. Washington Mutual Common Stock trades on NASDAQ under the
symbol "WAMU." Great Western Common Stock trades on the NYSE and PSE under the
symbol "GWF."
 
<TABLE>
<CAPTION>
                                                          WASHINGTON
                                                            MUTUAL         GREAT WESTERN
                                                         COMMON STOCK      COMMON STOCK
                                                        ---------------   ---------------
                                                         HIGH     LOW      HIGH     LOW
                                                        ------   ------   ------   ------
        <S>                                             <C>      <C>      <C>      <C>
        1995
        ----------------------------------------------
        First Quarter.................................  $20.56   $16.88   $18.88   $16.00
        Second Quarter................................   24.25    20.25    22.50    18.88
        Third Quarter.................................   26.50    22.75    23.75    20.25
        Fourth Quarter................................   29.13    25.00    27.13    22.63
        1996
        ----------------------------------------------
        First Quarter.................................  $32.00   $27.75   $26.13   $22.50
        Second Quarter................................   30.13    26.50    24.50    21.75
        Third Quarter.................................   38.13    28.75    26.75    21.13
        Fourth Quarter................................   45.50    37.00    31.13    27.00
        1997
        ----------------------------------------------
        First Quarter
        (through March 11, 1997)......................  $58.88   $42.75   $48.63   $28.75
</TABLE>
 
     The following table sets forth the closing sale price per share of
Washington Mutual Common Stock on NASDAQ, the closing sale price per share of
Great Western Common Stock on the NYSE, and the equivalent per share price for
the Great Western Common Stock (which is the closing sale price of Washington
Mutual Common Stock multiplied by the Exchange Ratio) as of (i) February 14,
1997 (the last full trading day before the public announcement of the Ahmanson
Proposal), (ii) March 5, 1997 (the last full trading day before the public
announcement of the execution and delivery of the Merger Agreement) and (iii)
March 11, 1997 (the last full trading day for which it was practicable to obtain
such information prior to the filing of this Joint Proxy Statement/Prospectus):
 
<TABLE>
<CAPTION>
                                                    WASHINGTON                          EQUIVALENT
                                                      MUTUAL          GREAT WESTERN     PER SHARE
                                                   COMMON STOCK       COMMON STOCK        PRICE
                                                 ----------------     -------------     ----------
    <S>                                          <C>                  <C>               <C>
    February 14................................       $55.19             $ 34.25          $49.67
    March 5....................................        53.25               45.00           47.93
    March 11...................................        54.50               48.63           49.05
</TABLE>
 
     Stockholders are urged to obtain current market quotations for Washington
Mutual Common Stock and Great Western Common Stock. Because the Exchange Ratio
is fixed, a change in the market price of Washington Mutual Common Stock before
the Merger would affect the market value of the consideration to be received by
Great Western Stockholders in the Merger. There can be no assurance as to the
market price of the Washington Mutual Common Stock at any time before the
Effective Time or as to the market price of the Merger Shares at any time
thereafter. See "The Merger -- Conversion of Great Western Capital Stock."
 
                                       21
<PAGE>   27
 
                                  RISK FACTORS
 
     This Joint Proxy Statement/Prospectus contains forward-looking statements
and information regarding the operation of the Combined Company following the
Merger. Such forward-looking information includes statements concerning the
operational benefits and opportunities for increased revenues, cost savings and
Merger-related expenses and restructuring charges, among others. The paragraphs
below discuss factors that may cause such forward-looking statements to differ
from actual results and that may cause the operating results of the Combined
Company to differ materially from the past results of Washington Mutual and
Great Western as individual companies. In addition to the other information set
forth in this Joint Proxy Statement/Prospectus, Washington Mutual Shareholders,
holders of Washington Mutual Preferred Stock and Great Western Stockholders
should consider the following before voting on the proposals herein.
 
     Forward-Looking Statements May Not Prove Accurate. When used or
incorporated by reference in this Joint Proxy Statement/Prospectus, the words
"anticipate," "estimate," "expect," "project" and similar expressions are
intended to identify forward-looking statements. Such statements are subject to
certain risks, uncertainties and assumptions including those set forth below.
Should one or more of these risks or uncertainties materialize, or should
underlying assumptions prove incorrect, actual results may vary materially from
those anticipated, estimated, expected or projected. Several key factors that
have a direct bearing on Washington Mutual's ability to attain its goals are
discussed below.
 
     Expected Benefits of Combined Business May Not Be Achieved. Washington
Mutual anticipates that substantial benefits will occur as a result of the
Merger as described under "The Merger -- Reasons for the Merger; Recommendations
of the Boards of Directors" and "Management and Operations of Washington Mutual
Following the Merger." Whether the anticipated benefits of the Merger are
ultimately achieved, however, will depend on a number of factors, including the
ability of the Combined Company to achieve operational and administrative cost
savings at projected levels within projected time frames, general economies of
scale and, generally, the ability of the Combined Company to capitalize on its
combined asset base and strategic position. There can be no assurance that the
expected benefits of the Merger relative to the combined business will be
achieved or that such benefits will be achieved within the time periods
expected.
 
     Operational Issues; Management. In December 1996, through a merger with
Keystone Holdings, Washington Mutual acquired ASB, which at that time was an
institution of comparable size to Washington Mutual. As a result of the
acquisition of ASB, Washington Mutual acquired substantial operations in
California, where it had not operated prior to the acquisition of ASB, and
became one of the largest banking organizations and mortgage originators in
California. Upon consummation of the Merger, it is anticipated that GW Bank will
be merged into ASB. While Washington Mutual believes that the integration of
ASB's operations into Washington Mutual is proceeding as anticipated, the
integration of Great Western, ASB and Washington Mutual may pose difficulties
that could adversely affect the results of operations of the Combined Company.
In addition, the merger with Great Western will bring 120 branch locations in
Florida with $7.1 billion in deposits, 160 retail mortgage offices and 42
wholesale offices in 27 states, areas where Washington Mutual has no operating
experience.
 
     Washington Mutual's business plan for the Combined Company assumes that the
Combined Company will be able to increase net interest income by originating and
retaining a greater volume of loans than either Washington Mutual or Great
Western would on a stand-alone basis. Part of the business plan for the Combined
Company anticipates that GW Bank may purchase loans from other banking
subsidiaries of the Combined Company to the extent its own loan organization
does not generate a sufficient volume of loans. To the extent that the Combined
Company is not able to generate a sufficient volume of new loans or retain such
loans in its portfolio at the levels or of the types assumed in the business
plan and forward-looking statements, the estimates of future net income
contained therein and described in this Joint Proxy Statement/Prospectus may
differ materially from actual results.
 
     No assurance can be given that the cost savings which are anticipated
through the consolidation of retail branch and loan offices of ASB and GW Bank
and of administrative functions of the Combined Company will be achieved or will
occur in the time periods anticipated. In addition, when retail branches are
consolidated or closed, financial institutions often lose customers and deposits
as a result. While Washington Mutual has not
 
                                       22
<PAGE>   28
 
experienced significant customer or deposit loss after previous business
combinations, to the extent that the Combined Company loses customers or
deposits significantly in excess of that anticipated, the operations of the
Combined Company could be materially adversely affected, particularly in the
short term. The forward-looking statements assume that the deposit base of both
the Company and GW Bank will remain substantially intact during the period
presented in the forward-looking statements. To the extent that the change in
ownership of Great Western, the consolidation of branches of GW Bank and ASB or
other factors result in a significant temporary or long-term loss of deposits,
actual results of operations may vary materially from the forward-looking
information presented.
 
     The forward-looking statements assume an increase in fee income from the
Combined Company's consumer banking operations. The sources of these fee
increases include introduction of a debit card, a new pricing policy for
checking account services in California, revised policies for checking account
services in accordance with Washington Mutual's current programs, implementation
of free checking throughout the Great Western system and improved revenues in
financial services subsidiaries. While the initial reception of Washington
Mutual's business initiative in California has been positive, Washington Mutual
has limited experience with the introduction of these business initiatives in
California, where the greatest expansion of consumer banking activities is
expected to occur. Accordingly, there can be no assurance that the Combined
Company's emphasis on consumer banking activities will be successful in the
California market or that any increase in fee income anticipated by the
forward-looking statements will be achieved.
 
     The ability of the Combined Company to operate efficiently, at least in the
short term, will depend in part on the ability to retain key management and
operating personnel. If the Combined Company is not able to retain a substantial
number of such personnel of Great Western, the consolidation of the two
companies may be more time-consuming, difficult and expensive, and may
negatively affect the predicted cost savings.
 
     A major asset of Great Western is its consumer finance company subsidiary,
Aristar. Although Washington Mutual has long offered a full line of consumer
loan products, it has not previously owned a consumer finance company. The
ability of the Combined Company to operate efficiently in this area, at least in
the short term, will be enhanced by its ability to retain existing management
personnel of Aristar. The President of Aristar, however, announced in January
1997 that he would be retiring. If Washington Mutual is not able to retain other
key management personnel of Aristar in future periods, results of operations, of
Aristar could be materially adversely affected, which could materially affect
the earnings of the Combined Company. See "Management and Operations of
Washington Mutual Following the Merger."
 
     Concentration of Operations in California. At December 31, 1996, 56% of
Washington Mutual's real estate loan portfolio and 63% of Great Western's real
estate loan portfolio was secured by real estate in California. Following the
Merger, approximately 59% of the Combined Company's real estate loan portfolio
will consist of loans secured by California real estate. In addition, at
December 31, 1996, approximately 66% of the Combined Company's retail deposits
were on deposit at branches in California. As a result, the financial condition
and results of operations of the Combined Company will be subject to general
economic conditions, and particularly the conditions in the single-family and
multi-family residential markets, in California and, to a lesser extent,
Washington, Oregon, Utah and Florida. If economic conditions generally, or in
California in particular, worsen or if the market for residential real estate
declines, the Combined Company may suffer decreased net income or losses
associated with higher default rates and decreased collateral values on its
existing portfolio, and may not be able to originate the volume or type of
single-family or multi-family residential mortgage loans or achieve the level of
deposits and mutual fund assets currently anticipated.
 
     The forward-looking statements regarding the Combined Company's results of
operations assume that the California economy and real estate market will
stabilize or improve. A worsening of current economic conditions or a
significant decline in real estate values in California could cause actual
results to vary materially from the forward-looking statements.
 
     Interest Rate Risk. Each of Washington Mutual and Great Western realizes
its income principally from the differential between the interest earned on
loans, investments and other interest-earning assets, and the interest paid on
deposits, borrowings and other interest-bearing liabilities. Net interest
spreads are affected by the difference between the repricing characteristics of
interest-earning assets and deposits and other liabilities. Loan volumes and
yields, as well as the volume of, and rates on, investments, deposits and
borrowings, are
 
                                       23
<PAGE>   29
 
affected by market interest rates. Significant fluctuations in interest rates
and spreads may adversely affect net income.
 
     Competition. Washington Mutual and Great Western both face significant
competition both in attracting and retaining deposits and in making loans in all
of their respective markets. The most direct competition has historically come
from other thrift institutions, credit unions and commercial banks doing
business in their primary market areas of California, Washington, Oregon and
Florida. As with all banking organizations, however, both Washington Mutual and
Great Western have experienced increasing competition from nonbanking sources,
including mutual funds, corporate and government debt securities and other
investment alternatives. Competition for loans comes principally from other
thrift institutions, commercial banks, mortgage banking companies, consumer
finance companies, credit unions, insurance companies and other institutional
lenders. Some of these competitors have significantly greater financial
resources, larger market share and greater name recognition than either
Washington Mutual or Great Western. There can be no assurance that competition
from such sources will not increase in the future and adversely affect
Washington Mutual's ability to achieve its financial goals following the Merger.
 
                                       24
<PAGE>   30
 
                              THE SPECIAL MEETINGS
GENERAL
 
     This Joint Proxy Statement/Prospectus is being furnished to Washington
Mutual Shareholders in connection with the solicitation of proxies by the
Washington Mutual Board for use at the Washington Mutual Meeting to be held at
     local time on                , 1997, at the                          ,
                         , Seattle, Washington for the purposes set forth
herein. This Joint Proxy Statement/Prospectus is also being furnished to Great
Western Stockholders in connection with the solicitation of proxies by the Great
Western Board for use at the Great Western Meeting to be held at      local time
on                , 1997, at Great Western's Employee Center, 19809 Prairie
Street, Chatsworth, California 91311, for the purposes set forth herein.
 
MATTERS TO BE CONSIDERED AT THE SPECIAL MEETINGS
 
     At the Washington Mutual Meeting, Washington Mutual Shareholders will be
asked to consider and vote upon (i) the issuance of Merger Shares to Great
Western Stockholders pursuant to the Merger Agreement, and (ii) a proposal to
amend the Washington Mutual Articles to increase the number of authorized shares
of Washington Mutual Common Stock from 350,000,000 shares to 800,000,000 shares.
The approval of the amendment to the Washington Mutual Articles is not a
condition to the consummation of the Merger. See "The Merger" and "Proposed
Amendment to Washington Mutual Articles of Incorporation -- Increase in
Authorized Shares."
 
     THE WASHINGTON MUTUAL BOARD HAS, BY UNANIMOUS VOTE OF ALL DIRECTORS
PRESENT, APPROVED THE PROPOSALS AND HAS DETERMINED THAT THEY ARE IN THE BEST
INTERESTS OF WASHINGTON MUTUAL AND ITS SHAREHOLDERS AND, ACCORDINGLY, RECOMMENDS
THAT YOU VOTE "FOR" EACH OF THEM.
 
     At the Great Western Meeting, Great Western Stockholders will be asked to
consider and vote upon a proposal to adopt the Merger Agreement and approve the
Merger, pursuant to which Great Western will be merged with and into NACI with
NACI as the surviving corporation. Upon consummation of the Merger, (i) each
outstanding share of Great Western Common Stock will be converted into the right
to receive 0.9 shares of Washington Mutual Common Stock, with cash being paid in
lieu of fractional shares; and (ii) each outstanding share of Great Western
Preferred Stock will be converted into one share of Series F Preferred Stock.
The terms, preferences, limitations, privileges and rights of the Series F
Preferred Stock will be substantially identical to those of the Great Western
Preferred Stock. As in the case of the Great Western Preferred Stock, each share
of Series F Preferred Stock will be represented by New Washington Mutual
Depositary Shares, each representing a one-tenth interest in a share of the
Series F Preferred Stock.
 
     THE GREAT WESTERN BOARD UNANIMOUSLY APPROVED THE MERGER AGREEMENT AND HAS
DETERMINED THAT THE TERMS OF THE MERGER ARE FAIR AND THE MERGER IS IN THE BEST
INTERESTS OF GREAT WESTERN AND ITS STOCKHOLDERS AND, ACCORDINGLY, RECOMMENDS
THAT YOU VOTE "FOR" THE MERGER PROPOSAL.
 
RECORD DATE AND VOTING
 
     At the close of business on the Washington Mutual Record Date, there were
approximately      holders of record of the           shares of Washington
Mutual Common Stock entitled to vote at the Washington Mutual Meeting. Each
share of Washington Mutual Common Stock is entitled to one vote in each of the
matters properly presented at the Washington Mutual Meeting. At the close of
business on the Washington Mutual Record Date there were approximately
holders of record of the           shares of Series C Preferred outstanding and
approximately      holders of record of the           shares of Series E
Preferred outstanding. Each outstanding share of Preferred Stock is entitled to
one vote on the proposal to amend the Washington Mutual Articles. Only
shareholders of record at the close of business on the Washington Mutual Record
Date will be entitled to notice of and to vote at the Washington Mutual Meeting.
 
     At the close of business on the Great Western Record Date, there were
approximately      holders of record of the           shares of Great Western
Common Stock outstanding. Each share of Great Western
 
                                       25
<PAGE>   31
 
Common Stock is entitled to one vote on the Merger Proposal and on any other
matters properly presented at the Great Western Meeting. Only Great Western
Stockholders of record at the close of business on the Great Western Record Date
will be entitled to notice of and, to vote, at the Great Western Meeting.
 
PROXIES AND VOTING INSTRUCTIONS
 
     Washington Mutual. All shares of Washington Mutual Common Stock and
Washington Mutual Preferred Stock represented by proxies that are properly
completed, dated and executed will be voted at the Washington Mutual Meeting in
accordance with the instructions given thereon by the Washington Mutual
Shareholders. If a properly executed proxy is received without voting
instructions, the shares of Washington Mutual Common Stock and Washington Mutual
Preferred Stock represented by such proxy will be voted "FOR" approval of all
matters on which such shares are entitled to vote at the Washington Mutual
Meeting. However, brokers do not have discretionary authority to vote shares
held in street name on either of the two proposals. Therefore, the failure of
beneficial owners of such shares to give voting instructions to such broker will
result in a broker non-vote, and will have the same effect as a "NO" vote on the
proposal to amend the Washington Mutual Articles, but broker non-votes will be
disregarded or will have no effect on the outcome of the vote on the Share
Issuance Proposal.
 
     As of the date of this Joint Proxy Statement/Prospectus, the Washington
Mutual Board is not aware of any business to be acted upon at the Washington
Mutual Meeting other than as described herein. If, however, any other matters
properly come before the Washington Mutual Meeting, the proxy also confers
discretionary authority on the persons named as proxies to vote upon such
matters. The persons named as proxies by a stockholder may, in their discretion,
propose and vote for one or more adjournments of the Washington Mutual Meeting
to permit further solicitation of proxies in favor of the Share Issuance
Proposal or the proposal to amend the Washington Mutual Articles or to permit
dissemination of information regarding material developments relating to the
Merger or otherwise germane to the Washington Mutual Meeting; provided, however,
that no proxy that is voted against the Share Issuance Proposal or the amendment
to the Washington Mutual Articles will be voted in favor of any adjournment for
the purpose of soliciting proxies. A Washington Mutual Shareholder giving a
proxy has the power to revoke it at any time before it is voted. The proxy may
be revoked by written notice to the Secretary of Washington Mutual received at
Washington Mutual's offices at 1201 Third Avenue, Suite 1500, Seattle,
Washington 98101, before                , 1997, by submitting a duly executed
proxy bearing a later date, or by written notice delivered at the Washington
Mutual Meeting to the Secretary of Washington Mutual prior to the commencement
of the Washington Mutual Meeting. Attendance at the Washington Mutual Meeting
will not, in and of itself, constitute revocation of a previously granted proxy.
 
     Great Western. All shares of Great Western Common Stock represented by
proxies that are properly completed, dated and executed will be voted at the
Great Western Meeting in accordance with the instructions given thereon by the
Great Western Stockholder. If a properly executed proxy is received without
voting instructions, the shares of Great Western Common Stock represented by
such proxy will be voted "FOR" approval of all matters on which such shares are
entitled to vote at the Great Western Meeting. However, brokers do not have
discretionary authority to vote shares held in street name on the Merger
Proposal. Therefore, the failure of beneficial owners of such shares to give
voting instructions to such broker will result in a broker non-vote, and will
have the same effect as a "NO" vote on the Merger Proposal.
 
     As of the date of this Joint Proxy Statement/Prospectus, the Great Western
Board is not aware of any business to be acted upon at the Great Western Meeting
other than as described herein. If, however, any other matters properly come
before the Great Western Meeting, the proxy also confers discretionary authority
on the persons named as proxies to vote upon such matters. The persons named as
proxies by a stockholder may, in their discretion, propose and vote for one or
more adjournments of the Great Western Meeting to permit further solicitation of
proxies in favor of the proposal to approve the Merger Agreement and the
transactions contemplated thereby or to permit dissemination of information
regarding material developments relating to the Merger or otherwise germane to
the Great Western Meeting; provided, however, that no proxy that is voted
against the proposal to approve the Merger Agreement will be voted in favor of
any adjournment for the purpose of soliciting proxies. A Great Western
Stockholder giving a proxy has the power to revoke it at any
 
                                       26
<PAGE>   32
 
time before it is voted. The proxy may be revoked by written notice to the
Secretary of Great Western received at Great Western's offices at 9200 Oakdale
Avenue, Chatsworth, California 91311, before                , 1997, by
submitting a duly executed proxy bearing a later date, or by written notice
delivered in person at the Great Western Meeting to the Secretary of Great
Western prior to the commencement of the Great Western Meeting. Attendance at
the Great Western Meeting will not, in and of itself, constitute revocation of a
previously granted proxy.
 
QUORUM; VOTES REQUIRED
 
     Washington Mutual. For the vote on the Share Issuance Proposal, the
presence, in person or represented by proxy, of the holders of a majority of the
Washington Mutual Common Stock issued and outstanding and entitled to vote at
the Washington Mutual Meeting will constitute a quorum. For the votes on the
proposal to amend the Washington Mutual Articles, the presence, in person or
represented by proxy, of the holders of a majority of (i) the Washington Mutual
Common Stock issued and outstanding and entitled to vote at the Washington
Mutual Meeting (for the separate class vote of the holders of Washington Mutual
Common Stock) and (ii) the aggregate shares of Washington Mutual Common Stock
and Preferred Stock issued and outstanding and entitled to vote at the
Washington Mutual Meeting (for the vote of the holders of Washington Mutual
Common Stock and Washington Mutual Preferred Stock as a class) will constitute a
quorum, respectively.
 
     Under the NASDAQ rules, assuming a quorum is present, the issuance of the
Merger Shares will require the affirmative vote of the holders of a majority of
the shares of Washington Mutual Common Stock voting on the issuance of the
Merger Shares. As described in "The Merger -- Conditions to the Consummation of
the Merger," such shareholder approval is a condition to consummation of the
Merger. In determining whether the proposal to approve the issuance of the
Merger Shares has received the requisite number of affirmative votes,
abstentions and broker non-votes, if any, will be disregarded and will have no
effect on the outcome of the vote concerning the Share Issuance Proposal.
 
     Approval of the proposed amendment to the Washington Mutual Articles
requires the affirmative vote of the holders of at least (i) two-thirds of the
combined shares of Washington Mutual Common Stock and Washington Mutual
Preferred Stock entitled to vote at the Washington Mutual Meeting voting
together as a class and (ii) two-thirds of the shares of Washington Mutual
Common Stock entitled to vote at the Washington Mutual Meeting voting as a
class. In determining whether the proposed amendment to the Washington Mutual
Articles has received the requisite number of affirmative votes, abstentions and
broker non-votes will be counted and will have the same effect as a vote against
each such proposal. Approval of the amendment to the Washington Mutual Articles
is not a condition to consummation of the Merger.
 
     As of the Washington Mutual Record Date, directors and executive officers
of Washington Mutual and their affiliates (excluding any shares owned by or
through Acadia Partners, L.P. and affiliates thereof) beneficially owned and
were entitled to vote [3,772,886] shares of Washington Mutual Common Stock and
[3,025] shares of Washington Mutual Preferred Stock, which represented
approximately [2.99%] of the shares of Washington Mutual Common Stock and less
than 1% of Washington Mutual Preferred Stock, respectively, outstanding on such
date. In addition, as of the Washington Mutual Record Date, Robert M. Bass and
Acadia Partners, L.P. beneficially owned and were entitled to vote [11,379,576]
shares and [6,218,004] shares, respectively, of Washington Mutual Common Stock,
which represented approximately [9.01%] and [4.93%], respectively, of the shares
of Washington Mutual Common Stock outstanding on such date. Mr. Bass, Acadia
Partners L.P. and each Washington Mutual director and executive officer has
indicated a present intention to vote, or cause to be voted, the Washington
Mutual Common Stock so owned "FOR" approval of the Share Issuance Proposal and
the amendment of the Washington Mutual Articles. As of the Washington Mutual
Record Date, Washington Mutual did not own any shares of Great Western Common
Stock and its directors and executive officers beneficially owned in the
aggregate        shares of Great Western Common Stock.
 
     Great Western. For the vote on the proposal to approve the Merger Agreement
and the transactions contemplated thereby, the presence, in person or
represented by proxy, of the holders of a majority of the
 
                                       27
<PAGE>   33
 
Great Western Common Stock issued and outstanding and entitled to vote at the
Great Western Meeting will constitute a quorum.
 
     Under Delaware law and the Great Western Restated Certificate of
Incorporation (the "Great Western Certificate") and the Bylaws of Great Western
(the "Great Western Bylaws"), and assuming a quorum is present, approval of the
Merger requires the affirmative vote of the holders of a majority of the shares
of Great Western Common Stock entitled to vote at the Great Western Meeting.
 
     As of the Great Western Record Date, directors and executive officers of
Great Western and their affiliates beneficially owned and were entitled to vote
               shares of Great Western Common Stock, which represented less than
1% of the shares of Great Western Common Stock outstanding on such date. Each
Great Western director and executive officer has indicated a present intention
to vote, or cause to be voted, the Great Western Common Stock so owned "FOR"
approval of the Merger Proposal. As of the Great Western Record Date, Great
Western did not own any shares of Washington Mutual Common Stock or Washington
Mutual Preferred Stock and its directors and executive officers beneficially
owned in the aggregate                shares of Washington Mutual Common Stock
and                shares of Washington Mutual Preferred Stock.
 
SOLICITATION OF PROXIES
 
     Each of Washington Mutual and Great Western will bear the cost of the
solicitation of proxies from its own stockholders, except that Washington Mutual
and Great Western will share equally the cost of printing this Joint Proxy
Statement/Prospectus. In addition to solicitation by mail, the directors,
officers and employees of Washington Mutual and Great Western and their
subsidiaries may, without being additionally compensated, solicit proxies from
stockholders of their respective companies by telephone, telegram, facsimile or
in person. Arrangements will also be made with brokerage houses and other
custodians, nominees and fiduciaries for the forwarding of solicitation material
to the beneficial owners of stock held of record by such persons, and Washington
Mutual and Great Western will reimburse such custodians, nominees and
fiduciaries for their reasonable out-of-pocket expenses in connection therewith.
 
     Washington Mutual has retained D.F. King & Co. ("D.F. King") to assist
Washington Mutual in connection with its communications with its shareholders
with respect to, and to provide other services to Washington Mutual in
connection with, the Washington Mutual Meeting. D.F. King will receive
$          for its services and reimbursement of out-of-pocket expenses in
connection therewith. Washington Mutual has agreed to indemnify D.F. King
against certain liabilities arising out of or in connection with its engagement.
 
     Great Western has retained Georgeson & Company, Inc. ("Georgeson"), to
assist Great Western in connection with its communications with its stockholders
with respect to, and to provide other services to Great Western in connection
with, the Merger and the Ahmanson Proposal. Georgeson will receive $
for its services and reimbursement of out-of-pocket expenses in connection
therewith. Great Western has agreed to indemnify Georgeson against certain
liabilities arising out of or in connection with its engagement.
 
       STOCKHOLDERS ARE REQUESTED TO COMPLETE, DATE AND SIGN THE ACCOMPANYING
       PROXY AND RETURN IT PROMPTLY IN THE ENCLOSED POSTAGE-PREPAID ENVELOPE.
 
     STOCKHOLDERS SHOULD NOT SEND STOCK CERTIFICATES WITH THEIR PROXY CARDS. IF
THE MERGER IS CONSUMMATED, STOCKHOLDERS OF GREAT WESTERN WILL RECEIVE
INSTRUCTIONS REGARDING THE PROPER PROCEDURES FOR THE EXCHANGE OF THEIR STOCK
CERTIFICATES. SEE "THE MERGER -- CONVERSION OF GREAT WESTERN CAPITAL STOCK."
 
                                       28
<PAGE>   34
 
                                   THE MERGER
 
GENERAL
 
     The Boards of Directors of Washington Mutual and Great Western, by
unanimous vote of all directors present, have approved the Merger Agreement,
which provides for the Merger, at the Effective Time, of Great Western with and
into NACI, with NACI as the surviving corporation. This section of the Joint
Proxy Statement/Prospectus describes certain aspects of the proposed Merger,
including the principal terms of the Merger Agreement. A copy of the Merger
Agreement is attached to this Joint Proxy Statement/Prospectus as Appendix A and
is incorporated herein by reference in its entirety. The description set forth
below of the terms of the Merger Agreement is qualified in its entirety by
reference thereto. All stockholders of Washington Mutual and Great Western are
urged to read the Merger Agreement in its entirety.
 
     At the Effective Time, (i) each outstanding share of Great Western Common
Stock will be converted into the right to receive 0.9 shares of Washington
Mutual Common Stock, with cash being paid in lieu of fractional shares, and (ii)
each outstanding share of Great Western Preferred Stock will be converted into
one share of Series F Preferred Stock. The terms, preferences, limitations,
privileges and rights of the Series F Preferred Stock will be substantially
identical to those of the Great Western Preferred Stock. At the Effective Time,
the separate corporate existence of Great Western will terminate. The Washington
Mutual Articles and Washington Mutual's Bylaws (the "Washington Mutual Bylaws"),
as in effect at the Effective Time, will be the articles of incorporation and
by-laws, respectively, of the Combined Company.
 
BACKGROUND OF THE MERGER
 
     On the evening of February 17, 1997, Charles R. Rinehart, Chairman of the
Board and Chief Executive Officer of Ahmanson, telephoned John F. Maher,
President and Chief Executive Officer of Great Western, with a request to meet
that evening to discuss a merger of Ahmanson and Great Western. Mr. Maher
declined to meet and informed Mr. Rinehart that such a meeting could take place
only after Mr. Maher discussed the matter with the Great Western Board and Great
Western's management and legal and financial advisors. The conversation between
Mr. Maher and Mr. Rinehart was the first regarding a potential merger of the two
companies since October 1995, when Mr. Maher informed Mr. Rinehart that a Great
Western and Ahmanson combination did not advance the strategic objectives of
Great Western or the interests of its stockholders and that, therefore, Great
Western was not interested in pursuing a business combination with Ahmanson.
Following his February 17, 1997 telephone call, Mr. Rinehart delivered a letter
to Mr. Maher outlining a proposed transaction (the "Ahmanson Proposal") whereby
Great Western would be merged with and into Ahmanson in a tax-free transaction
to be accounted for as a purchase. Under the terms of the Ahmanson Proposal,
each share of Great Western Common Stock would have been exchanged for 1.05
shares of Ahmanson common stock.
 
     On the morning of February 18, Ahmanson issued a press release describing
the Ahmanson Proposal and held an analyst conference call to discuss its views
as to the merits of such proposal. Also that morning, Ahmanson filed with the
Commission solicitation materials relating to the commencement by Ahmanson of a
consent solicitation in favor of an amendment to Great Western's by-laws and a
non-binding shareholder resolution and to a proposed solicitation by Ahmanson of
proxies for use at Great Western's upcoming annual stockholders meeting in favor
of additional by-law amendments and the election of three Ahmanson-nominated
directors to the Great Western Board. (Additional information concerning
Ahmanson's consent solicitation and Great Western's response thereto is
contained in the Consent Revocation Statement. See "Incorporation of Certain
Documents by Reference.")
 
     On the same day, Kerry K. Killinger, Chairman, President and Chief
Executive Officer of Washington Mutual, called Mr. Maher and indicated that he
was following developments at Great Western and would be open to discussions
with Mr. Maher if the Great Western Board determined that discussions were
appropriate. Later that day, the Washington Mutual Board met for its regularly
scheduled meeting. At that meeting, Mr. Killinger discussed the Ahmanson
Proposal with the directors. After the Washington Mutual Board meeting, Mr.
Killinger had additional discussions with certain members of the Washington
Mutual Board. The chief executive officer of a large super-regional bank (the
"Other Interested Party") also called Mr. Maher that day to express similar
interest. Mr. Maher informed both parties that the management of
 
                                       29
<PAGE>   35
 
Great Western would need time to consult with the Great Western Board and its
advisors in order to assess the situation.
 
     On the evening of February 18, the Great Western Board held a telephonic
board meeting during which Mr. Maher discussed the Ahmanson Proposal as well as
the other actions taken by Ahmanson. Mr. Maher informed the Great Western Board
of the two indications of interest that he had received that day.
Representatives of Goldman Sachs and Merrill Lynch, Great Western's financial
advisors, and of Skadden, Arps, Slate, Meagher & Flom LLP, Great Western's
special counsel, participated in the call.
 
     Later that week, Mr. Maher separately responded to both Mr. Killinger and
the chief executive officer of the Other Interested Party. Mr. Maher stated
that, as a condition to further discussions with Great Western, each party would
be required to enter reciprocal confidentiality/standstill agreements. Mr. Maher
also asked Washington Mutual and the Other Interested Party to submit
preliminary due diligence request lists. Mr. Maher indicated that he would be
meeting with the Great Western Board on the following Monday and, depending on
the outcome of those discussions, there might be an opportunity for the
interested parties to visit Great Western and conduct due diligence later in
that week.
 
     On February 20, Mr. Killinger discussed developments with certain members
of the Washington Mutual Board. On February 21, Washington Mutual and Great
Western entered into a reciprocal confidentiality/standstill agreement and
thereafter the parties exchanged confidential information regarding the
businesses and operations of the two companies and their respective
subsidiaries. Also on February 21, Great Western and the Other Interested Party
each entered into a reciprocal confidentiality/standstill agreement.
 
     Over the course of the week of February 17, Great Western's management and
its financial advisors received inquiries from a few other potentially
interested parties. Although these parties expressed interest in discussing
possible transactions with Great Western, ranging from business combinations to
the acquisition of only certain of Great Western's business lines or operations,
no confidentiality agreements were signed with any of such parties, and no
formal indications of interest were ever received.
 
     On February 24, the Great Western Board met with its advisors to consider
and analyze (i) the Ahmanson Proposal, (ii) continuing to operate as a
stand-alone entity, (iii) seeking a strategic partnership with either a larger
or similar-sized bank or thrift holding company with a similar strategic focus
and (iv) other possible alternative strategies for enhancing shareholder value.
 
     Mr. Maher called Mr. Killinger after the meeting of the Great Western Board
and invited Washington Mutual to undertake a due diligence investigation of
Great Western and to present a proposal for discussion on March 3. On that same
day, Mr. Maher extended the same offer to the chief executive officer of the
Other Interested Party.
 
     During the week of February 24, Great Western's financial advisers made
inquiries, on behalf of Great Western, of other potential strategic partners,
although no formal proposals were made as a result of such inquiries.
 
     On February 25, the Other Interested Party commenced its due diligence
investigation of Great Western. This investigation lasted for two days.
 
     On February 26, Mr. Killinger traveled to California, where he met with Mr.
Maher and discussed Great Western's operating progress, operating philosophies
and objectives and the potential strategic benefits of a combination between the
two companies. That same day, Washington Mutual began its on-site due diligence
investigation of Great Western.
 
     From February 26 through March 1, members of Washington Mutual's officers'
executive committee, other members of management, a due diligence team composed
of representatives of different operational areas of Washington Mutual and
Washington Mutual's advisors continued their intensive, on-site due diligence
investigation of Great Western.
 
     On February 27, Great Western's legal advisors delivered a form of merger
agreement to Washington Mutual and to the Other Interested Party and to each of
their respective legal advisors.
 
                                       30
<PAGE>   36
 
     On March 3, Mr. Killinger and Mr. Craig E. Tall, Washington Mutual's
Executive Vice President of Corporate Development, as well as certain of
Washington Mutual's legal and financial advisors, traveled to Great Western's
executive offices in Chatsworth, California. There they met with Messrs. James
F. Montgomery, Chairman of the Board; John F. Maher; Carl F. Geuther, Vice
Chairman and Chief Financial Officer; A. William Schenck, Vice Chairman; J.
Lance Erikson, Executive Vice President and General Counsel; other members of
the Great Western management team; and various advisors to Great Western. The
meeting consisted primarily of a presentation by Mr. Killinger of the background
and current status of Washington Mutual, a preliminary transaction proposal and
exchange ratio, and a discussion of the possible benefits of a merger of
Washington Mutual and Great Western.
 
     That same day, the Other Interested Party made a similar presentation to
the Great Western directors and executive officers listed above and indicated a
preliminary exchange ratio. However, Great Western and the Other Interested
Party did not pursue further discussions with respect to a definitive proposal.
 
     Prior to and during the week of March 3, other members of Great Western's
senior management team and representatives of its advisors conducted on-site and
off-site due diligence reviews of Washington Mutual and the Other Interested
Party.
 
     On March 4, legal advisors of Great Western and Washington Mutual met for
preliminary discussions of issues raised by Washington Mutual's initial response
to the draft Merger Agreement proposed by Great Western. Later that day,
representatives of Goldman Sachs and Merrill Lynch telephoned Mr. Killinger and
Mr. Tall and advised them that Great Western was interested in Washington
Mutual's preliminary transaction proposal, but that the proposed exchange ratio
was insufficient. Following that call, Mr. Killinger and Mr. Tall discussed the
status of the negotiations with certain members of the Washington Mutual Board
and, with their concurrence, Mr. Killinger proposed, subject to approval by the
Washington Mutual Board and resolution of all outstanding issues, to increase
the exchange ratio to 0.9 shares of Washington Mutual Common Stock for each
share of Great Western Common Stock. Washington Mutual's and Great Western's
respective legal advisors met the next day to negotiate the Merger Agreement.
 
     At the meetings of the Great Western Board held on March 4 and March 5, the
Great Western Board reviewed, with the assistance of Great Western's management,
legal and financial advisors and a financial services industry consultant, among
other things, a summary of management's due diligence findings concerning
Washington Mutual, presentations by management and Goldman Sachs and Merrill
Lynch concerning the Washington Mutual proposal and the Ahmanson Proposal, the
terms of the definitive Merger Agreement and both Goldman Sachs' and Merrill
Lynch's fairness opinions concerning the Exchange Ratio. Based upon that review,
and after consideration of other factors, the Great Western Board unanimously
approved and authorized the execution of the Merger Agreement on the evening of
March 5. See "-- Reasons for the Merger; Recommendations of the Boards of
Directors -- Great Western."
 
     The Washington Mutual Board met on March 5 in person and telephonically to
consider management's proposal for a merger with Great Western. With the
assistance of Washington Mutual's legal and financial advisors, the Washington
Mutual Board reviewed, among other things, management's due diligence findings
concerning Great Western, presentations by management and Lehman Brothers
concerning the merger proposal, the terms of the Merger Agreement and Lehman
Brothers' fairness opinion concerning the Exchange Ratio. Based upon that
review, the Washington Mutual Board approved, by unanimous vote of all directors
present, and authorized the execution of the Merger Agreement on the evening of
March 5. The Merger Agreement was executed and delivered by the parties shortly
thereafter. See "-- Reasons for the Merger; Recommendations of the Boards of
Directors -- Washington Mutual."
 
     On March 6, the proposed Merger was publicly announced.
 
REASONS FOR THE MERGER; RECOMMENDATIONS OF THE BOARDS OF DIRECTORS
 
  WASHINGTON MUTUAL.  The Washington Mutual Board believes that the Merger will
create a premier regional financial services company with the financial and
managerial resources to compete effectively in the
 
                                       31
<PAGE>   37
 
rapidly changing market for banking and financial services. The Combined Company
will be the third largest bank on the West Coast, based on pro forma total
assets and total deposits as of December 31, 1996.
 
     The Washington Mutual Board determined that the Merger represents a unique
strategic fit between two financially sound institutions with similar business
strategies and complementary product capabilities. The Washington Mutual Board
believes that the Combined Company will be a stronger financial services company
than either is individually, with a market leadership position in residential
mortgage origination and with a stronger, more competitive position from which
to expand its consumer banking franchise and commercial banking activities.
 
     In reaching its conclusions, the Washington Mutual Board considered, among
other things: (i) information concerning the financial performance and
condition, business operations, capital levels, asset quality and prospects of
each of Washington Mutual and Great Western and their projected future results
and prospects as separate entities and on a combined basis; (ii) current
industry, economic and market conditions and trends, including the likelihood of
continuing consolidation and increasing competition in the banking and financial
services industries (and corresponding decrease in the number of suitable merger
partners for Washington Mutual), the growing importance of financial resources
and market position and economies of scale to a banking institution's ability to
compete successfully in this changing environment; (iii) the structure of the
transaction; (iv) the possibility of achieving significant cost savings,
operating efficiencies, revenue enhancements and synergies as a result of the
Merger; (v) the terms of the Merger Agreement; (vi) the opinion of its financial
advisor described below as to the fairness from a financial point of view of the
Exchange Ratio (which was determined through arm's-length negotiations between
Washington Mutual and Great Western); (vii) the likelihood of obtaining required
regulatory approvals; (viii) the changing regulatory environment for banking and
financial services; and (ix) the impact of the Merger on the depositors,
employees, customers and communities served by Washington Mutual. In reaching
its decision to approve the Merger Agreement and recommend the Merger to
shareholders, the Washington Mutual Board did not assign any relative or
specific weights to the various factors considered, and individual directors may
have given differing weights to different factors.
 
     The Washington Mutual Board believes that the Merger will further key
elements of its strategic plan by: (i) further strengthening Washington Mutual's
consumer banking franchise throughout the West; (ii) diversifying its business
mix by deploying capital to higher margin business lines, such as consumer
finance activities; (iii) improving margins of its core businesses; and (iv)
obtaining cost savings and efficiencies through consolidation of operations and
facilities. In particular, the following benefits were considered by the
Washington Mutual Board:
 
          (i) The Merger will significantly increase Washington Mutual's share
     of the consumer banking market in California, thereby building on the base
     created by its recently completed acquisition of ASB. ASB already has a
     state-wide presence in California, with over 200 branches and loan offices
     concentrated in the Los Angeles and San Francisco areas. The merger with
     Great Western will add over 500 branches and loan offices (before
     consolidations) and increase its customer base to more than 4.1 million
     households. As a result of the Merger, Washington Mutual will become the
     third largest depository institution in California (based on deposits as of
     December 31, 1996);
 
          (ii) The Merger will accelerate Washington Mutual's diversification of
     its product line to include higher margin business lines, such as consumer
     finance. Great Western has a strong consumer finance presence, with 502
     offices in 23 states; and
 
          (iii) The consolidation of certain head office functions, back office
     operations and retail branch and loan offices, together with cost savings
     from reduced aggregate marketing expenses and implementation of an
     integrated technology platform, is expected to produce annual savings of
     operating costs currently estimated by management at $208 million and $340
     million (pre-tax) in 1998 and 1999, respectively. In addition, the Combined
     Company will be one of the largest originators and servicers of residential
 
                                       32
<PAGE>   38
 
     mortgage loans in the United States (ranking second in California and sixth
     in the United States in residential loan originations based on combined
     1996 volume, and ranking seventh in the United States in residential loan
     servicing based on the combined servicing portfolio at year-end 1996). The
     Washington Mutual Board believes that the Merger will significantly enhance
     Washington Mutual's ability to achieve the economies of scale and
     efficiencies that are critical to compete effectively in these business
     lines.
 
     In addition, although the Merger will increase slightly the percentage of
Washington Mutual's assets located in California, it will also expand the
geographic range of Washington Mutual's operations to include regions in the
United States in which Washington Mutual did not previously have any presence,
including Florida, as well as the Southeast and the Northeast United States. In
future years the geographical diversification of the Combined Company resulting
from the Merger may reduce the risk of a significant adverse impact resulting
from an economic downturn in any single market area.
 
     The benefits described above are forward-looking statements, and actual
results may vary materially from such statements. See "Risk Factors," for
factors that may cause such variation.
 
  GREAT WESTERN.  In reaching its determination to approve and adopt the Merger
Agreement, the Great Western Board considered the following factors:
 
          (i) the Great Western Board's familiarity with and review of Great
     Western's business, operations, financial condition and earnings on both an
     historical and a prospective basis, including Great Western's current
     strategic initiatives to, among other things, become more like a retail
     consumer bank;
 
          (ii) the Great Western Board's review, based in part on presentations
     by its financial advisors and Great Western management (which presentations
     took into account Washington Mutual's March 3 presentation (see
     "-- Background of the Merger")) and by a financial services industry
     consultant, of (a) the strategy, business, operations, earnings and
     financial condition of Washington Mutual on both an historical and a
     prospective basis and (b) the historical stock price performance of the
     Washington Mutual Common Stock. In this regard, the Great Western Board
     noted that (I) Great Western and Washington Mutual possess compatible and
     complementary corporate cultures and, in recent years, have implemented
     similar strategies for enhancing profitability through the reduction of
     cost of funds and the development of new sources of revenue, (II)
     Washington Mutual has significant market presence in California,
     Washington, Oregon, Utah and, to a lesser extent, certain other Western
     states and that, as a result, the Combined Company not only would be able
     to achieve the same market position in California (ranked third in
     deposits) that a merger with Ahmanson would bring, but would also have more
     geographically diverse assets and operations and be less vulnerable to
     regional economic fluctuations and regional real estate market downturns
     and (III) in contrast to a combination with Ahmanson, the Combined Company
     would have (A) a stronger capital position to take advantage of future
     growth opportunities, (B) greater potential for cross-marketing of new
     products and services, and (C) a stronger credit position. The Great
     Western Board also noted that the stockholders of Great Western, as owners
     of approximately 50% of the Combined Company, would have the ability to
     realize the benefits of this strategic business combination;
 
          (iii) the Great Western Board's review, based in part on presentations
     by its financial advisors, a financial services industry consultant and
     Great Western management, of (a) the strategy, business, operations,
     earnings and financial condition of Ahmanson on both a historical and a
     prospective basis and (b) the historical stock price performance of the
     Ahmanson Common Stock. In this regard, the Great Western Board noted that
     over the course of the past five years, Ahmanson has experienced relatively
     flat growth in earning assets and that loans and deposits have decreased.
     The Great Western Board also noted that Ahmanson has pursued different
     strategies than Great Western and that a merger with Ahmanson would hinder
     many of the initiatives implemented by Great Western over the past few
     years. In particular, the Great Western Board noted that Ahmanson (I) has
     historically had a narrower business strategy with fewer product lines and
     revenue growth opportunities and has emphasized, and continues to
     emphasize, stock repurchases and other financial strategies rather than
     core business growth as a key means of increasing earnings per share and
     shareholder value, (II) has, through a systematic program of
 
                                       33
<PAGE>   39
 
     branch acquisitions and divestitures, concentrated its operations in
     California, which concentration is inconsistent with Great Western's desire
     to achieve greater geographic diversification and stands in contrast to the
     strong Western United States franchise that a merger with Washington Mutual
     would bring and (III) has a higher risk profile with a greater exposure to
     multifamily loans and commercial real estate;
 
          (iv) the Great Western Board noted that, based on the closing market
     prices of the Washington Mutual Common Stock and Ahmanson common stock on
     March 4, 1997, the implied value of the Exchange Ratio was $47.87 as
     compared to the implied per share value of the Ahmanson Proposal of $43.44.
     The Great Western Board also compared the implied per share value for the
     two offers on a historical longer-term basis and noted that, since July,
     1996, the implied value of the Exchange Ratio has always been greater than
     the implied value of the Ahmanson Proposal;
 
          (v) the Great Western Board reviewed commonly-used financial
     benchmarks that demonstrated that Washington Mutual had a higher level of
     asset quality, higher reserve coverage ratio, higher capital ratios, a
     better efficiency ratio (excluding amortization of intangibles and
     non-recurring items), a higher net interest margin and a greater rate of
     growth in earning assets, loans and deposits. The Great Western Board noted
     that Washington Mutual had increased its dividend over the past six
     consecutive quarters and, over a longer term, for every year since 1990. In
     contrast, the Great Western Board noted that Ahmanson had not increased its
     dividend since 1987;
 
          (vi) the financial presentation of its financial advisors (including
     presentations of pro forma financial information with respect to both the
     Merger and a merger of Great Western and Ahmanson and the implied value of
     the Exchange Ratio and the exchange ratio proposed by Ahmanson over certain
     historical periods) and (a) the written opinion of Goldman Sachs rendered
     on March 5, 1997 that, as of the date of such opinion, the Exchange Ratio
     was fair to the stockholders of Great Western and (b) the written opinion
     of Merrill Lynch rendered on March 5, 1997 that, as of the date of such
     opinion, the Exchange Ratio was fair to the stockholders of Great Western
     from a financial point of view. Copies of such opinions, setting forth the
     assumptions made, matters considered and review undertaken, are set forth
     as Appendices C and D, respectively. The full text of each such opinion is
     incorporated herein by reference and the foregoing descriptions thereof are
     qualified in their entirety by such reference. Great Western stockholders
     are urged to read these opinions carefully in their entirety (see "Opinions
     of Financial Advisors -- Opinions of Great Western Financial Advisors");
 
          (vii) the Great Western Board compared reported earnings per share and
     cash earnings per share on a pro forma per share equivalent basis which,
     with the exception of cash earnings per share for 1997, indicated that
     higher per share values on an equivalent basis could be realized by the
     Combined Company compared to a combination of Ahmanson and Great Western
     (see "Opinions of Financial Advisors -- Opinions of Great Western Financial
     Advisors");
 
          (viii) the anticipated cost savings and operating efficiencies
     available to Great Western and Washington Mutual as a combined institution
     following the Merger, the potential for revenue enhancements at the
     combined institution and the likelihood of achieving these cost savings,
     operating efficiencies and revenue enhancements relative to the likelihood
     that they could be achieved in a merger with Ahmanson;
 
          (ix) the anticipated cost savings and operating efficiencies available
     to Great Western and Ahmanson as a combined institution following a
     combination of the two institutions and the potential for revenue
     enhancements at the combined institution. In this regard, the Great Western
     Board considered that Ahmanson utilizes an information system which is
     incompatible with Great Western's, which in turn could increase the
     difficulty of implementing the technology conversion required in such a
     merger on a timely basis and which would require significant expenditures.
     In contrast, Great Western and Washington Mutual share common information
     systems which should greatly facilitate the integration of the two
     companies' operations and the achievement of cost savings and operating
     efficiencies at a minimal cost and on a timely basis;
 
                                       34
<PAGE>   40
 
          (x) the significant experience of the senior management of Washington
     Mutual and its proven record of achieving cost savings, operating
     efficiencies and revenue enhancements in connection with the integration of
     acquired companies. In particular, the Great Western Board noted that
     Washington Mutual's current management team has successfully integrated
     numerous significant acquisitions since 1990 and that Washington Mutual had
     consummated more than 20 acquisitions over a longer period, including both
     in-market and out-of-market acquisitions of banks and thrifts of varying
     size. In contrast, Ahmanson's current management team, many members of
     which have been hired by Ahmanson within the past year, has limited its
     focus to the acquisitions and divestitures of branches;
 
          (xi) the Great Western Board's concern, based upon presentations by
     its financial advisors and Great Western management, that, as a result of
     substantial share repurchases (during fiscal 1995 and 1996, Ahmanson is
     estimated to have repurchased 14.5% of its total outstanding shares as of
     December 31, 1994), Ahmanson's tangible common equity as a percentage of
     tangible assets was among the lowest of any publicly traded thrift. The
     Great Western Board expressed concern that Ahmanson's capital position,
     when combined with its loan loss reserve coverage, its exposure to
     multifamily loans and commercial real estate and its concentration of
     California-based assets, made Ahmanson particularly vulnerable to economic
     downturns and attendant decreases in credit quality;
 
          (xii) the Great Western Board's concerns that because the transaction
     contemplated by Ahmanson would be accounted for as a purchase rather than
     as a pooling of interests, (a) the combined institution would carry on its
     books a substantial amount of goodwill which would rank amongst the highest
     in the financial services industry, which goodwill would have to be
     amortized and, as a result, would reduce reported earnings per share, and
     lead to a substantial difference between reported earnings per share and
     cash earnings per share and (b) a risk existed that the value of the
     Ahmanson common stock received by Great Western's stockholders in a merger
     with Ahmanson would decline if the market did not value Ahmanson with an
     emphasis on cash earnings rather than on reported earnings. In contrast,
     neither of these concerns were raised by the Merger, which will be
     accounted for as a pooling of interests;
 
          (xiii) the Great Western Board's belief regarding the impact of the
     Merger on Great Western's employees relative to their response to a
     transaction with Ahmanson, and the positive effect such impact could have
     on the business, financial condition and results of operations of the
     Combined Company and, conversely, the possible negative effect of such
     impact in a combination of Ahmanson and Great Western;
 
          (xiv) the impact of the Merger on Great Western's other
     non-stockholder constituencies relative to the impact of a transaction with
     Ahmanson, and the positive effect such impact could have on the business,
     financial condition and results of operations of the Combined Company;
 
          (xv) the Great Western Board's review, based in part on presentations
     by its financial advisors, of alternatives to the Merger and the Ahmanson
     Proposal, the range of possible values to Great Western's stockholders
     obtainable through implementation of such alternatives and the timing and
     likelihood of actually receiving such values;
 
          (xvi) the following additional factors which contributed to the Great
     Western Board's conclusion that the Merger is in the best interests of
     Great Western and its stockholders:
 
             (A) the results of the due diligence investigations regarding
        Washington Mutual;
 
             (B) the Great Western Board's assessment, with the assistance of
        counsel, concerning the likelihood that Washington Mutual would obtain
        all required regulatory approvals for the Merger;
 
             (C) the expectation that the Merger will generally be a tax-free
        transaction to Great Western and its stockholders; and
 
             (D) the terms of the Merger Agreement, and certain other
        information regarding the Merger, including the terms and structure of
        the Merger and the proposed arrangements with respect to the board of
        the Combined Company following the Merger. With respect to the
        termination fee provided for in the Merger Agreement, the Great Western
        Board actively directed negotiations with
 
                                       35
<PAGE>   41
 
        a view to substantially reducing the fee and expense reimbursement
        provisions from those initially proposed by Washington Mutual in
        response to Great Western's draft Merger Agreement (which contained no
        termination fee or expense reimbursement). After being advised that
        Washington Mutual's final position was a condition to its merger
        proposal, the Great Western Board ultimately concluded that such
        provisions were necessary in order to secure a transaction that the
        Great Western Board believed to be superior to that proposed by
        Ahmanson. The Great Western Board also considered that Washington Mutual
        had informed Great Western that, in order to pursue a merger with Great
        Western, Washington Mutual would be foregoing significant business
        opportunities. The Great Western Board also noted that, although
        originally included in the proposal by Washington Mutual, Washington
        Mutual had dropped its request for reciprocal stock option agreements in
        connection with the Merger Agreement after negotiations with Great
        Western.
 
     The foregoing discussion of the information and factors considered by the
Great Western Board is not intended to be exhaustive. In reaching its
determination to approve and recommend the Merger, the Great Western Board did
not assign any relative or specific weights to the foregoing factors, and
individual directors may have given differing weights to different factors.
Throughout its deliberations, the Great Western Board received the advice of its
financial advisors and representatives of Skadden, Arps, Slate, Meagher & Flom
LLP, the firm retained to serve as special counsel to Great Western, and Latham
& Watkins, special counsel to the outside directors of Great Western.
 
     EACH OF THE WASHINGTON MUTUAL BOARD AND THE GREAT WESTERN BOARD BELIEVES
THAT THE TERMS OF THE MERGER ARE FAIR TO, AND IN THE BEST INTERESTS OF, THEIR
RESPECTIVE SHAREHOLDERS. THE WASHINGTON MUTUAL BOARD AND THE GREAT WESTERN BOARD
HAVE EACH, BY UNANIMOUS VOTE OF ALL DIRECTORS PRESENT, APPROVED THE MERGER
AGREEMENT AND THE TRANSACTIONS CONTEMPLATED THEREBY AND RECOMMEND THAT THEIR
RESPECTIVE SHAREHOLDERS APPROVE AND ADOPT THE SHARE ISSUANCE PROPOSAL, IN THE
CASE OF WASHINGTON MUTUAL, AND THE MERGER AGREEMENT, IN THE CASE OF GREAT
WESTERN.
 
OPINIONS OF FINANCIAL ADVISORS
 
     OPINION OF LEHMAN BROTHERS INC. Washington Mutual has retained Lehman
Brothers to act as its financial advisor in connection with the Merger. Lehman
Brothers has rendered its written opinion to the Washington Mutual Board, dated
March 5, 1997, to the effect that, based upon and subject to the factors and
assumptions set forth in such opinion, and as of the date of such opinion, the
Exchange Ratio to be offered by Washington Mutual to the stockholders of Great
Western in the Merger was fair to Washington Mutual from a financial point of
view. The full text of the Lehman Brothers' opinion, which sets forth
assumptions made, procedures followed, matters considered and limits on the
review undertaken by Lehman Brothers, is attached hereto as Appendix B. The
summary set forth in this Joint Proxy Statement/Prospectus of the opinion of
Lehman Brothers is qualified in its entirety by reference to the full text of
the Lehman Brothers' opinion attached hereto.
 
     No limitations were imposed by Washington Mutual on the scope of Lehman
Brothers' investigation or the procedures to be followed by Lehman Brothers in
rendering its opinion. Lehman Brothers was not requested to and did not make any
recommendation to the Board of Directors of Washington Mutual as to the form or
amount of consideration to be offered by Washington Mutual to the stockholders
of Great Western in the Merger, which was determined through arm's-length
negotiations between the parties. In arriving at its opinion, Lehman Brothers
did not ascribe a specific range of value to Washington Mutual or Great Western,
but rather made its determination as to the fairness, from a financial point of
view, of the consideration to be offered by Washington Mutual to the
stockholders of Great Western in the Merger on the basis of the financial and
comparative analyses described below. Lehman Brothers' opinion is for the use
and benefit of the Board of Directors of Washington Mutual and was rendered to
the Board in connection with its consideration of the Merger. Lehman Brothers'
opinion is not intended to be and does not constitute a recommendation to any
stockholder of Washington Mutual as to how such stockholder should vote with
respect to the Merger. Lehman Brothers was not requested to opine as to, and its
opinion does not address, Washington Mutual's underlying business decision to
proceed with or effect the Merger.
 
                                       36
<PAGE>   42
 
     In arriving at its opinion, Lehman Brothers reviewed and analyzed: (1) the
Merger Agreement and the specific terms of the Merger, (2) such publicly
available information concerning Washington Mutual and Great Western that it
believed to be relevant to its analysis including, without limitation, the Forms
10-K for the year ended December 31, 1995 and preliminary draft copies of Forms
10-K for the year ended December 31, 1996, quarterly reports on Form 10-Q for
the periods ended March 31, June 30 and September 30, 1996 and recent press
releases for Washington Mutual and Great Western, (3) financial and operating
information with respect to the businesses, operations and prospects of
Washington Mutual and Great Western furnished to it by Washington Mutual and
Great Western, (4) a trading history of Washington Mutual Common Stock and Great
Western Common Stock and a comparison of that trading history with those of
other companies that it deemed relevant, (5) a comparison of the historical
financial results and present financial condition of Washington Mutual and Great
Western with those of other companies that it deemed relevant, and (6) a
comparison of the financial terms of the Merger with the financial terms of
certain other recent transactions that it deemed relevant. In addition, Lehman
Brothers had discussions with the managements of Washington Mutual and Great
Western concerning their respective businesses, operations, assets, liabilities,
financial conditions and prospects, and the potential cost savings, operating
synergies, revenue enhancements and strategic benefits expected to result from a
combination of the businesses of Washington Mutual and Great Western, and
undertook such other studies, analyses and investigations as it deemed
appropriate.
 
     In arriving at its opinion, Lehman Brothers assumed and relied upon the
accuracy and completeness of the financial and other information used by it
without assuming any responsibility for independent verification of such
information and further relied upon the assurances of the managements of
Washington Mutual and Great Western that they were not aware of any facts or
circumstances that would make such information inaccurate or misleading. With
respect to the financial projections of Washington Mutual and Great Western,
upon advice of Washington Mutual, Lehman Brothers assumed that such projections
were reasonably prepared on a basis reflecting the best currently available
estimates and judgments of the respective managements of Washington Mutual and
of Great Western, as to the future financial performance of Washington Mutual
and Great Western including, without limitation, with respect to projected cost
savings, operating synergies and revenue enhancements expected to result from a
combination of the businesses of Washington Mutual and Great Western and that
Washington Mutual and Great Western would perform, and that the Combined Company
will perform, substantially in accordance with such projections. Upon advice of
Washington Mutual and its legal and accounting advisors, Lehman Brothers assumed
that the Merger will qualify for pooling accounting treatment and as a
reorganization within the meaning of Section 368(a) of the Code and therefore as
a tax-free transaction. In arriving at its opinion, Lehman Brothers did not
conduct a physical inspection of the properties and facilities of Washington
Mutual or Great Western and did not make or obtain any evaluations or appraisals
of the assets or liabilities of Washington Mutual or Great Western. In addition,
Lehman Brothers noted that it is not expert in the evaluation of loan portfolios
or allowances for loan and real estate owned losses and, upon advice of
Washington Mutual, it assumed that the allowances for loan and real estate owned
losses provided to it by Washington Mutual and used by it in its analysis and in
arriving at its opinion were in the aggregate adequate to cover all such losses.
Lehman Brothers' opinion necessarily was based upon market, economic and other
conditions as they existed on, and could be evaluated as of, the date of its
letter.
 
     The following is a summary of the analyses Lehman Brothers performed in
arriving at its opinion dated March 5, 1997 as to the fairness, from a financial
point of view, to Washington Mutual of the Exchange Ratio. In connection with
the preparation and delivery of its opinion to the Board of Directors of
Washington Mutual, Lehman Brothers performed a variety of financial and
comparative analyses, as described below. The preparation of a fairness opinion
involves various determinations as to the most appropriate and relevant methods
of financial and comparative analysis and the application of those methods to
the particular circumstances and, therefore, such an opinion is not readily
susceptible to summary description. Furthermore, in arriving at its opinion,
Lehman Brothers did not attribute any particular weight to any analysis or
factor considered by it, but rather made qualitative judgments as to the
significance and relevance of each analysis and factor. Accordingly, Lehman
Brothers believes that its analyses must be considered as a whole and that
considering any portion of such analyses and factors, without considering all
analyses and factors, could create
 
                                       37
<PAGE>   43
 
a misleading or incomplete view of the process underlying its opinion. In its
analyses, Lehman Brothers made numerous assumptions with respect to industry
performance, general business and economic conditions and other matters, many of
which are beyond the control of Washington Mutual. Any estimates contained in
these analyses were not necessarily indicative of actual values or predictive of
future results or values, which may be significantly more or less favorable than
as set forth therein. In addition, analyses relating to the value of businesses
did not purport to be appraisals or to reflect the prices at which businesses
may actually be sold.
 
     Purchase Price Analysis.  Based upon the Exchange Ratio, the closing price
of Washington Mutual's Common Stock on March 4, 1997 of $53.19 represented a
value to be received by holders of Great Western Common Stock of $47.87 per
share. Based on this implied transaction value per share, Lehman Brothers
calculated the price-to-market, price-to-book, price-to-tangible book,
price-to-adjusted tangible book (wherein tangible book value was adjusted to
reflect a tangible common equity to tangible assets ratio of 5.00%) and price to
earnings multiples, and the implied deposit premium paid, as adjusted (defined
as the transaction value, adjusted to exclude a range of implied values of
Aristar, minus the tangible book value, divided by total deposits), in the
Merger. The implied transaction value per share yielded a premium to market
price multiple of 40% over the closing price of Great Western Common Stock of
$34.25 on February 14, 1997, the last trading day prior to the announcement of
the Ahmanson Proposal. This analysis also yielded a price-to-book value multiple
of 2.72x, a price-to-tangible book value multiple of 3.08x, a price-to-adjusted
tangible book value multiple of 3.09x, a price to 1996 earnings multiple of
21.0x (based on Great Western's earnings, before non recurring items, for the
twelve months ended December 31, 1996), a price to estimated 1997 earnings
multiple of 17.6x, and a price to estimated 1998 earnings multiple of 15.4x
(based on estimates of Great Western's 1997 and 1998 earnings published by First
Call as of March 4, 1997) and an implied deposit premium, as adjusted, in the
range of 13.4% to 14.1%. First Call is a data service that monitors and
publishes a compilation of earnings estimates produced by selected research
analysts regarding companies of interest to institutional investors.
 
     Comparable Transaction Analysis.  Using publicly available information,
Lehman Brothers reviewed certain terms and financial characteristics, including
historical price-to-earnings ratios, the price-to-book ratio, the
price-to-tangible book ratio, the price-to-adjusted tangible book ratio and the
deposit premium paid at the time of transaction announcement, of eight savings
institution merger or acquisition transactions (the "Comparable Thrift
Transactions Group") with values greater than $250 million publicly announced
since January 1, 1996 which Lehman Brothers deemed to be comparable to the
present transaction. The Comparable Thrift Transactions Group considered by
Lehman Brothers in its analysis consisted of the following transactions
(identified by acquiror/acquiree): Union Planters/Leader Financial, Washington
Mutual/Keystone Holdings, MacAndrews & Forbes/Cal Fed, HSBC Holdings/First FS&LA
of Rochester, ABN-AMRO/Standard Federal, Mercantile/Roosevelt Financial, CCB
Financial/American Federal and Summit/Collective. The median values for these
transactions for the price to latest twelve months earnings ratio, price-to-book
ratio, price-to-tangible book ratio and price-to-adjusted tangible book ratio
were 14.5x, 1.99x, 2.23x and 2.47x, respectively. The range of values for these
parameters were from 12.6x to 19.4x, 1.55x to 3.06x, 1.55x to 3.31x and 1.34x to
4.33x, respectively. These compared to transaction multiples of 21.0x, 2.72x,
3.08x and 3.09x for Washington Mutual/Great Western based on the closing price
of Washington Mutual Common Stock on March 4, 1997. The range of deposit
premiums paid in these transactions was 3.9% to 26.6%, with a median value of
14.0% compared to an implied deposit premium, as adjusted, in the range of 13.4%
to 14.1% for Washington Mutual/Great Western based on the closing price of
Washington Mutual Common Stock on March 4, 1997. Two transactions within the
Comparable Thrift Transactions Group were publicly announced since January 1,
1997: CCB Financial/American Federal and Summit/Collective. The mean values for
these transactions for the price to latest twelve months earnings ratio,
price-to-book ratio, price-to-tangible book ratio and price-to-adjusted tangible
book ratio were 18.9x, 2.68x, 2.94x and 3.67x, respectively. These compared to
transaction multiples of 21.0x, 2.72x, 3.08x and 3.09x for Washington
Mutual/Great Western based on the closing price of Washington Mutual Common
Stock on March 4, 1997. The mean value for the deposit premium paid in these
transactions was 21.1%, compared to an implied deposit premium, as adjusted, in
the range of 13.4% to 14.1% for Washington Mutual/Great Western based on the
closing price of Washington Mutual Common Stock on March 4, 1997.
 
                                       38
<PAGE>   44
 
     Using publicly available information, Lehman Brothers also reviewed certain
terms and financial characteristics, including historical price-to-earnings
ratios, the price-to-book ratio, the price-to-tangible book ratio and the
price-to-adjusted tangible book ratio and the deposit premium paid at the time
of transaction announcement, of six banking company merger or acquisition
transactions (the "Comparable Bank Transactions Group") with values greater than
$750 million publicly announced since January 1, 1996 which Lehman Brothers
deemed to be relevant to the present transaction. The Comparable Bank
Transactions Group considered by Lehman Brothers in its analysis consisted of
the following transactions (identified by acquiror/ acquiree): Wells Fargo/First
Interstate, NationsBank/Boatmen's Bancshares, Crestar Financial/Citizens
Bancorporation, Mercantile Bancorp/Mark Twain Bancshares, Southern
National/United Carolina Bancshares and Allied Irish Bank/Dauphin Deposit
Corporation. The median values for these transactions for the price to latest
twelve months earnings ratio, price-to-book ratio, price to tangible book ratio
and price-to-adjusted tangible book were 18.9x, 2.76x, 2.91x and 3.57x,
respectively. These compared to transaction multiples of 21.0x, 2.72x, 3.08x and
3.09x for Washington Mutual/Great Western based on the closing price of
Washington Mutual Common Stock on March 4, 1997. The median value for the
deposit premium paid in these transactions was 20.0%, compared to an implied
deposit premium, as adjusted, in the range of 13.4% to 14.1% for Washington
Mutual/Great Western based on the closing price of Washington Mutual Common
Stock on March 4, 1997.
 
     Because the reasons for and circumstances surrounding each of the
transactions analyzed were so diverse and because of the inherent differences in
the businesses, operations, financial conditions and prospects of Washington
Mutual, Great Western and the companies included in the Comparable Thrift
Transactions Group and the Comparable Bank Transactions Group, Lehman Brothers
believed that a purely quantitative comparable transaction analysis would not be
particularly meaningful in the context of the Merger. Lehman Brothers believed
that the appropriate use of a comparable transaction analysis in this instance
would involve qualitative judgments concerning the differences between the
characteristics of these transactions and the Merger which would affect the
acquisition values of the acquired companies and Great Western.
 
     Comparable Company Analysis.  Using publicly available information, Lehman
Brothers compared the financial performance and stock market valuation of Great
Western with the following selected savings institutions (the "Comparable Thrift
Group") deemed relevant by Lehman Brothers: Astoria Financial Corporation, Bank
United Corp., Commercial Federal Corporation, Charter One Financial, Dime
Bancorp, Inc., Downey Financial Corp., First Financial Corp., Golden West
Financial, GreenPoint Financial Corp., People's Bank, MHC., Peoples Heritage
Financial Group, Sovereign Bancorp, Inc., TCF Financial Corp. and Washington
Federal Inc. Indications of such financial performance and stock market
valuation included profitability (return on average assets and return on average
equity for the latest twelve month period ended December 31, 1996, adjusted for
non-recurring items, of 0.73% and 11.6%, respectively, for Great Western and
medians of 0.98% and 15.4%, respectively, for the Comparable Thrift Group); the
ratio of tangible equity to tangible assets (5.42% for Great Western and a
median of 6.50% for the Comparable Thrift Group); the ratio of non-performing
assets to loans and foreclosed real estate (1.75% for Great Western and a median
of 1.47% for the Comparable Thrift Group); the ratio of price to estimated 1997
earnings (12.6x for Great Western and a median of 12.5x for the Comparable
Thrift Group); the ratio of price-to-book (1.94x for Great Western and a median
of 1.93x for the Comparable Thrift Group) and the ratio of
price-to-tangible-book (2.20x for Great Western and a median of 2.24x for the
Comparable Thrift Group). These ratios for the Comparable Thrift Group are based
on public financial statements as of December 31, 1996, closing stock market
prices on March 4, 1997 and earnings per share are based on the most recent
median estimates for 1997 and 1998 earnings published by the Institutional
Broker Estimate System ("IBES"). IBES is a data service that monitors and
publishes compilations of earnings estimates produced by selected research
analysts regarding companies of interest to institutional investors. These
ratios for Great Western are based on public financial statements as of December
31, 1996, First Call 1997 and 1998 earnings per share estimates as of March 4,
1997 and the closing price for Great Western Common Stock of $34.25 as of close
of business on February 14, 1997, the last trading day prior to the announcement
of the Ahmanson Proposal.
 
     Because of the inherent differences in the businesses, operations,
financial conditions and prospects of Washington Mutual, Great Western and the
companies included in the Comparable Thrift Group, Lehman
 
                                       39
<PAGE>   45
 
Brothers believed that a purely quantitative comparable company analysis would
not be particularly meaningful in the context of the Merger. Lehman Brothers
believed that the appropriate use of a comparable company analysis in this
instance would involve qualitative judgments concerning the differences between
Great Western and the companies included in the Comparable Thrift Group which
would affect the trading values of the comparable companies and Great Western.
 
     Discounted Cash Flow Analysis.  Lehman Brothers discounted three years of
estimated cash flows of Great Western and an estimated terminal value of Great
Western Common Stock, assuming a dividend rate sufficient to maintain a tangible
common equity to tangible assets ratio of 5.00% and using a range of discount
rates from 12% to 16%. Lehman Brothers derived an estimate of a range of
terminal values by applying multiples ranging from 11 times to 13 times
estimated year-end 1999 net income. These rates and values were chosen to
reflect different assumptions regarding the required rates of return of holders
or prospective buyers of Great Western Common Stock. In connection with this
analysis, Washington Mutual management provided Lehman Brothers with net income
projections. This analysis, and its underlying assumptions, yielded a range of
values for Great Western Common Stock from approximately $50.00 to $60.00 per
share, as compared to a per share transaction value of $47.87, based on the
closing price of Washington Mutual Common Stock on March 4, 1997.
 
     Pro Forma Merger Analysis.  Lehman Brothers analyzed the impact of the
Merger on Washington Mutual's estimated earnings per share based on the most
recent estimates for the 1997 and 1998 earnings of Washington Mutual and Great
Western published by First Call and assumed growth rates of 12.0% and 10.5% from
1998 to 1999 for Washington Mutual and Great Western, respectively. In
connection with this analysis, management of each of Washington Mutual and Great
Western provided Lehman Brothers with projections for cost savings and fee
income and net interest income revenue enhancements from the Merger, which
projections were incorporated in Lehman Brothers' analyses. Based on such First
Call estimates, assumed growth rates and management projections of cost savings
and revenue enhancements, Lehman Brothers concluded that the Merger would result
in dilution of 9% to Washington Mutual's earnings per share in 1997 and
accretion of 5% and 11% to Washington Mutual's earnings per share for 1998 and
1999, respectively.
 
     Contribution Analysis.  Lehman Brothers analyzed the respective
contributions of Great Western and Washington Mutual to the Combined Company's
pro forma balance sheet as of December 31, 1996 and pro forma historic net
income for 1996, without giving effect to any cost savings or revenue
enhancements resulting from the Merger. This analysis showed that Great Western
would have contributed 49% of total assets, 50% of total loans (gross), 52% of
total equity, 52% of common equity and 50% of tangible common equity on a pro
forma basis as of December 31, 1996 and that Great Western's contribution to the
Combined Company's pre-tax net income, adjusted for non-recurring items, and net
income, adjusted for non-recurring items, would have been 46% and 44%,
respectively. This analysis also showed that, based on First Call earnings
estimates for 1997 and 1998, without giving effect to any cost savings or
revenue enhancements resulting from the Merger, Great Western's contribution to
the Combined Company's net income, would be 46% and 44% for 1997 and 1998,
respectively. Based upon the Exchange Ratio, Great Western shareholders would
own an estimated 52% of the Combined Company upon completion of the Merger.
 
     Lehman Brothers is an internationally recognized investment banking firm.
Lehman Brothers, as part of its investment banking business, is continuously
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 corporate and other purposes. The Board of Washington Mutual
retained Lehman Brothers based upon Lehman Brothers' experience and expertise
and its familiarity with Washington Mutual. Lehman Brothers is acting as
financial advisor to Washington Mutual in connection with the Merger. Pursuant
to a letter agreement dated March 5, 1997, between Washington Mutual and Lehman
Brothers, Washington Mutual has agreed to pay Lehman Brothers a fee of $20
million for its services in connection with the Merger, so long as the Merger
occurs before March 1, 1999. The letter agreement with Lehman Brothers also
provides that Washington Mutual will reimburse Lehman Brothers for its
out-of-pocket expenses and indemnify Lehman Brothers and certain related persons
and entities against certain liabilities, including liabilities under securities
laws, incurred in connection with its services thereunder. In the past, Lehman
Brothers and its affiliates have provided financial
 
                                       40
<PAGE>   46
 
advisory and other services to both Washington Mutual (including underwriting of
public offerings of Washington Mutual's securities and acting as financial
advisor to Keystone Holdings in its sale to Washington Mutual) and Great Western
(including underwriting of public offerings of Great Western and its
subsidiaries' securities and advising GW Bank in its sale of Great Western
Financial Services to Aristar) and have received customary fees for the
rendering of these services. In the ordinary course of their business, Lehman
Brothers and its affiliates actively trade the debt and equity securities of
Washington Mutual and Great Western for their own account and for the accounts
of their customers and, accordingly, may at any time hold a long or short
position in such securities.
 
     OPINIONS OF GREAT WESTERN FINANCIAL ADVISORS. Great Western Board retained
Goldman Sachs and Merrill Lynch (the "Great Western Financial Advisors") in
connection with its consideration of the potential alternatives faced by Great
Western. The Great Western Financial Advisors were retained based upon their
qualifications, expertise and reputation, as well as upon their prior investment
banking relationships with Great Western.
 
     OPINION OF GOLDMAN, SACHS & CO. At the March 5, 1997 meeting of the Great
Western Board, Goldman Sachs rendered its written opinion that, as of such date,
and based upon and subject to various qualifications and assumptions described
therein, the Exchange Ratio is fair to holders of Great Western Common Stock.
 
     THE FULL TEXT OF THE GOLDMAN SACHS OPINION, DATED MARCH 5, 1997, WHICH SETS
FORTH ASSUMPTIONS MADE, MATTERS CONSIDERED AND LIMITS ON THE SCOPE OF REVIEW
UNDERTAKEN, IS ATTACHED AS APPENDIX C TO THIS JOINT PROXY STATEMENT/PROSPECTUS.
STOCKHOLDERS OF GREAT WESTERN ARE URGED TO READ THIS OPINION IN ITS ENTIRETY. NO
LIMITATIONS WERE IMPOSED BY THE GREAT WESTERN BOARD UPON GOLDMAN SACHS WITH
RESPECT TO THE INVESTIGATIONS MADE OR PROCEDURES FOLLOWED BY IT IN RENDERING ITS
OPINION. THE GOLDMAN SACHS OPINION, WHICH IS ADDRESSED TO THE GREAT WESTERN
BOARD, IS DIRECTED ONLY TO THE FAIRNESS OF THE EXCHANGE RATIO AND DOES NOT
CONSTITUTE A RECOMMENDATION TO ANY GREAT WESTERN STOCKHOLDER AS TO HOW SUCH
STOCKHOLDER SHOULD VOTE AT THE GREAT WESTERN MEETING. THE SUMMARY OF THE GOLDMAN
SACHS OPINION SET FORTH IN THIS JOINT PROXY STATEMENT/PROSPECTUS IS QUALIFIED IN
ITS ENTIRETY BY REFERENCE TO THE FULL TEXT OF SUCH OPINION.
 
     In connection with its opinion, Goldman Sachs reviewed, among other things,
the Merger Agreement; Annual Reports to stockholders and Annual Reports on Form
10-K of Great Western for the five years ended December 31, 1995; Annual Reports
to stockholders and Annual Reports on Form 10-K of Washington Mutual for the two
years ended December 31, 1995; Annual Reports to stockholders and Annual Reports
to the Federal Deposit Insurance Corporation on Form F-2 of Washington Mutual
Savings Bank, predecessor to Washington Mutual, for the three years ended
December 31, 1993; certain interim reports to stockholders and Quarterly Reports
on Form 10-Q of Great Western and Washington Mutual; certain other
communications from Great Western and Washington Mutual to their respective
stockholders; and certain internal financial analyses and forecasts for Great
Western and Washington Mutual prepared by their respective managements,
including analyses and forecasts of certain cost savings, operating
efficiencies, revenue effects and financial synergies. Goldman Sachs also held
discussions with members of the senior managements of Great Western and
Washington Mutual regarding the past and current business operations, financial
condition and future prospects of their respective companies and each senior
managements' assessment of the future prospects of the combined company. In
addition, Goldman Sachs reviewed the reported price and trading activity for
Great Western Common Stock and Washington Mutual Common Stock, compared certain
financial and stock market information for Great Western and Washington Mutual
with similar information for certain other companies the securities of which are
publicly traded, reviewed the financial terms of certain recent business
combinations in the savings and loan industry specifically and in other
industries generally and performed such other studies and analyses as Goldman
Sachs considered appropriate.
 
     Goldman Sachs relied without independent verification upon the accuracy and
completeness of all of the financial and other information reviewed by it for
purposes of its opinion. In that regard, Goldman Sachs assumed, with Great
Western's consent, that the financial forecasts, including, without limitation,
analysis of certain cost savings, operating efficiencies, revenue effects and
financial synergies and projections regarding under-performing and
non-performing assets and net charge-offs have been reasonably prepared on a
basis reflecting the best currently available judgments and estimates of Great
Western and Washington Mutual and
 
                                       41
<PAGE>   47
 
that such forecasts will be realized in the amounts and at the times
contemplated thereby. Goldman Sachs is not an expert in the evaluation of loan
and lease portfolios for purposes of assessing the adequacy of the allowances
for losses with respect thereto and assumed, with Great Western's consent, that
such allowances for each of Great Western and Washington Mutual are in the
aggregate adequate to cover all such losses. In addition, Goldman Sachs did not
review individual credit files nor did it make an independent evaluation or
appraisal of the assets and liabilities of Great Western or Washington Mutual or
any of their subsidiaries and Goldman Sachs was not furnished with any such
evaluation or appraisal. Goldman Sachs assumed, with Great Western's consent,
that the Merger will be accounted for as a pooling of interests under generally
accepted accounting principles. Goldman Sachs' opinion was based on economic,
market and other conditions as in effect on, and the information available to it
as of, the date of its opinion. Goldman Sachs did not express any opinion as to
the price or range of prices at which Washington Mutual Common Stock might trade
subsequent to the Merger.
 
     Goldman Sachs, as part of its investment banking business, is continually
engaged in the valuation of 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. Goldman Sachs is
familiar with Great Western having provided certain investment banking services
to Great Western from time to time, including having acted as managing
underwriter of its $300 million issue of capital securities in January 1997, and
having acted as its financial advisor in connection with, and participated in
certain of the negotiations leading to, the Merger Agreement. Goldman Sachs also
has provided certain investment banking services to Washington Mutual from time
to time and may provide investment banking services to Washington Mutual in the
future. In addition, Goldman Sachs is a full service securities firm and in the
course of its trading activities it may from time to time effect transactions,
for its own account or the account of customers, and hold positions in
securities or options on securities of Great Western and Washington Mutual.
 
     Opinion of Merrill Lynch. On March 5, 1997, Merrill Lynch rendered its
written opinion that, as of such date, and based upon and subject to various
qualifications and assumptions described therein, the Exchange Ratio is fair to
the shareholders of Great Western from a financial point of view.
 
     A COPY OF THE MERRILL LYNCH OPINION, DATED MARCH 5, 1997, WHICH SETS FORTH
THE ASSUMPTIONS MADE, MATTERS CONSIDERED AND LIMITATIONS ON THE SCOPE OF REVIEW
UNDERTAKEN BY MERRILL LYNCH, IS ATTACHED AS APPENDIX D TO THIS JOINT PROXY
STATEMENT/PROSPECTUS. MERRILL LYNCH ADDRESSED ITS OPINION TO THE GREAT WESTERN
BOARD AND SUCH OPINION IS DIRECTED ONLY TO THE FAIRNESS OF THE EXCHANGE RATIO
FROM A FINANCIAL POINT OF VIEW AND DOES NOT CONSTITUTE A RECOMMENDATION TO ANY
GREAT WESTERN STOCKHOLDER AS TO HOW SUCH STOCKHOLDER SHOULD VOTE AT THE GREAT
WESTERN MEETING. THE SUMMARY OF THE MERRILL LYNCH OPINION SET FORTH IN THIS
JOINT PROXY STATEMENT/PROSPECTUS IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO
THE FULL TEXT OF THE MERRILL LYNCH OPINION.
 
     In arriving at its opinion, Merrill Lynch, among other things: (i) reviewed
Great Western's Annual Reports on Form 10-K and related audited financial
information for the five fiscal years ended December 31, 1995, a draft of Great
Western's Annual Report on Form 10-K for the period ended December 31, 1996, and
Great Western's Quarterly Reports on Form 10-Q and the related unaudited
financial information for the quarterly periods ending March 31, 1996, June 30,
1996 and September 30, 1996; (ii) reviewed Washington Mutual's Annual Reports on
Form 10-K, a draft of Washington Mutual's Annual Report on Form 10-K for the
period ended December 31, 1996, and related audited financial information for
the five fiscal years ended December 31, 1995 and Washington Mutual's Quarterly
Reports on Form 10-Q and the related unaudited financial information for the
quarterly periods ending March 31, 1996, June 30, 1996 and September 30, 1996;
(iii) reviewed certain limited financial information, including financial
forecasts, relating to the respective businesses, earnings, assets, liabilities
and prospects of Great Western and Washington Mutual furnished to Merrill Lynch
by senior management of Great Western and Washington Mutual; (iv) conducted
certain discussions with members of senior management of Great Western and
Washington Mutual concerning the respective financial condition, businesses,
earnings, assets, liabilities, operations, regulatory condition, financial
forecasts, contingencies and prospects, of Great Western and Washington Mutual
and their respective view as to the future financial performance of Great
Western, Washington Mutual and the combined entity, as the
 
                                       42
<PAGE>   48
 
case may be, following the Merger; (v) reviewed the historical market prices and
trading activity for the Great Western Common Stock and the Washington Mutual
Common Stock and compared them with that of certain publicly traded companies
which Merrill Lynch deemed to be relevant; (vi) compared the respective results
of operations of Great Western and Washington Mutual with those of certain
publicly traded companies which Merrill Lynch deemed to be relevant; (vii)
compared the proposed financial terms of the Merger contemplated by the Merger
Agreement with the financial terms of certain other mergers and acquisitions
which Merrill Lynch deemed to be relevant; (viii) reviewed the amount and timing
of the projected cost savings, related expenses and revenue enhancements
expected to result from the Merger (the "Expected Synergies"), as presented by
the senior management of Washington Mutual; (ix) considered, based upon
information provided by the senior management of Great Western and Washington
Mutual, the pro forma impact of the transaction on the earnings and book value
per share, consolidated capitalization and certain balance sheet and
profitability ratios of Washington Mutual; (x) reviewed a draft of the Merger
Agreement and related agreements; and (xi) reviewed such other financial studies
and analyses and performed such other investigations and took into account such
other matters as Merrill Lynch deemed appropriate.
 
     In preparing its opinion, with Great Western's consent, Merrill Lynch
assumed and relied on the accuracy and completeness of all information supplied
or otherwise made available to Merrill Lynch by Great Western and Washington
Mutual, including that contemplated in the numbered items above, and did not
assume responsibility for independently verifying such information or undertaken
an independent evaluation or appraisal of the assets or liabilities, contingent
or otherwise, of Great Western or Washington Mutual or any of their
subsidiaries, nor was Merrill Lynch furnished any such evaluation or appraisal.
Merrill Lynch is not an expert in the evaluation of allowances for loan losses
and, with Great Western's consent, Merrill Lynch did not make an independent
evaluation of the adequacy of the allowance for loan losses of Great Western or
Washington Mutual, nor did Merrill Lynch review any individual credit files
relating to Washington Mutual or Great Western and, with Great Western's
consent, Merrill Lynch assumed that the aggregate allowance for loan losses for
each of Washington Mutual and Great Western is adequate to cover such losses and
will be adequate on a pro forma basis for the combined entity. In addition,
Merrill Lynch did not conduct any physical inspection of the properties or
facilities of Great Western or Washington Mutual. With Great Western's consent,
Merrill Lynch assumed and relied upon the senior management of Great Western and
Washington Mutual as to the reasonableness and achievability of the financial
forecasts (and the assumptions and bases therefor) provided to, and discussed
with, Merrill Lynch. In that regard, Merrill Lynch assumed and relied with Great
Western's consent that such forecasts, including, without limitation, financial
forecasts, evaluations of contingencies, Expected Synergies and projections
regarding underperforming and non-performing assets, net chargeoffs, adequacy of
reserves, and future economic conditions reflect the best currently available
estimates, allocations and judgments of the senior management of Great Western
and Washington Mutual as to the future financial performance of Great Western,
Washington Mutual or the combined entity, as the case may be. Merrill Lynch's
opinion is predicated on the Merger receiving the tax and accounting treatment
contemplated in the Merger Agreement. Merrill Lynch's opinion is necessarily
based on economic, market and other conditions as in effect on, and the
information made available to Merrill Lynch as of March 5, 1997. Merrill Lynch's
opinion has been rendered without regard to the necessity for, or level of, any
restrictions, obligations, undertakings or divestitures which may be imposed or
required in the course of obtaining regulatory approval for the Merger. Merrill
Lynch did not express any opinion as to the price or range of prices at which
Washington Mutual Common Stock might trade subsequent to the Merger.
 
     Merrill Lynch was retained by the Great Western Board as an independent
contractor to act as financial advisor to Great Western with respect to the
Merger and will receive a fee for its services. Merrill Lynch, in the past, has
provided financial advisory and financing services to Great Western and
Washington Mutual and received customary fees for the rendering of such
services, including acting as lead underwriter for a 14.6 million share
secondary public offering of Washington Mutual Common Stock in January 1997. In
addition, in the ordinary course of Merrill Lynch's securities business, Merrill
Lynch may actively trade debt and/or equity securities of Great Western and
Washington Mutual and their respective affiliates for Merrill Lynch's own
account and the accounts of Merrill Lynch customers, and Merrill Lynch therefore
may from time to time hold a long or short position in such securities. In
addition, certain affiliates of Merrill Lynch act as investment advisors to
publicly held mutual funds which owned, as of March 4, 1997, approximately 5.1
 
                                       43
<PAGE>   49
 
million shares of Great Western Common Stock and approximately 0.5 million
shares of Washington Mutual Common Stock.
 
     Presentation by Great Western Financial Advisors The following summarizes
financial and comparative analyses presented by the Great Western Financial
Advisors to the Great Western Board at its meeting on March 4, 1997, which
analyses were also among those considered by the Great Western Financial
Advisors in rendering their opinions. This summary does not purport to be a
complete description of the analyses underlying the opinions of either of the
Great Western Financial Advisors.
 
     Summary Comparison of Potential Merger Alternatives.  The Great Western
Financial Advisors presented a comparison of the Ahmanson Proposal with the
proposal by Washington Mutual to merge with Great Western in a transaction under
which Great Western Common Stock would be exchanged for 0.9 share of Washington
Mutual Common Stock pursuant to the Exchange Ratio (the "Washington Mutual
Proposal"). The implied values of the Ahmanson Proposal and the Washington
Mutual Proposal were $43.44 and $47.87, respectively. The implied values were
determined by multiplying the applicable exchange ratio by the closing prices of
Ahmanson Common Stock and Washington Mutual Common Stock, respectively, on March
4, 1997. The implied values therefore necessarily were dependent upon the
respective closing prices of Ahmanson Common Stock and Washington Mutual Common
Stock at a specific time.
 
     In addition to reviewing the implied values resulting from the Ahmanson
Proposal and the Washington Mutual Proposal, the analyses presented implied
values expressed as various multiples of certain historical and projected
earnings per share ("EPS") of Great Western, as well as multiples of various
measures of Great Western's book value. The Great Western Financial Advisors
also compared certain of those multiples with the multiples of certain
comparable thrift and bank acquisitions. The comparable thrift acquisitions
("Comparable Thrift Acquisitions") consisted of ten selected thrift acquisitions
since January 1, 1995 with a value of greater than $500 million. They were:
Mercantile Bancorp/Roosevelt Financial; ABN-AMRO Holding/Standard Federal Bank;
HSBC Holding plc/First FSLA-Rochester; MacAndrews & Forbes/California Federal
Bancorp; Washington Mutual/Keystone Holdings; Union Planters Corp./Leader
Financial Group; Republic of New York/Brooklyn Bancorp; NationsBank Corp./CSF
Holdings; Charter One Financial/FirstFed Michigan; and First Union Corp./Coral
Gables Fedcorp. The comparable bank acquisitions ("Comparable Bank
Acquisitions") consisted of nine selected bank acquisitions since January 1,
1995 with a value of greater than $3 billion. These acquisitions were:
NationsBank Corp./Boatmen's Bancshares; Wells Fargo/First Interstate; Fleet
Financial Group/National Westminster; CoreStates Financial/Meridian Bancorp;
Chemical Bank/Chase Manhattan Corp.; First Chicago Corp./NBD Bancorp, Inc.; PNC
Bank Corp./Midlantic Corp.; First Union Corp./First Fidelity Bancorp; and Fleet
Financial Group/Shawmut National.
 
     The Ahmanson Proposal and the Washington Mutual Proposal reflected
multiples of (i) 20.79 times and 22.90 times, respectively, the year ended
December 31, 1996 Great Western EPS (excluding a one time SAIF assessment in the
third quarter and certain other non-recurring charges in the fourth quarter),
compared to a median of 12.94 times and 12.44 times, respectively, for the
Comparable Thrift Acquisitions and Comparable Bank Acquisitions; (ii) 15.97
times and 17.60 times, respectively, 1997 Great Western EPS based on First Call
estimates (the "First Call Estimates") and 16.09 times and 17.73 times,
respectively, Great Western 1997 EPS based on forecasts prepared by Great
Western management (the "Great Western Management Forecast") (excluding an
anticipated gain of $32 million or $0.14 per share for the potential sale of
Great Western's investment management business); (iii) 14.06 times and 15.49
times, respectively, Great Western 1998 EPS based on the First Call Estimates
and 12.82 times and 14.12 times, respectively, Great Western 1998 EPS based on
the Great Western Management Forecast; (iv) 2.54 times and 2.80 times,
respectively, fully-diluted book value per share of Great Western at December
31, 1996, compared to a median of 1.66 times and 1.90 times, respectively, for
the Comparable Thrift Acquisitions and Comparable Bank Acquisitions; (v) 2.87
times and 3.18 times, respectively, fully-diluted tangible book value per share
of Great Western at December 31, 1996, compared to a median of 1.67 times and
2.30 times, respectively, for the Comparable Thrift Acquisitions and Comparable
Bank Acquisitions. The Ahmanson Proposal and the Washington Mutual Proposal
represented an implied deposit premium (aggregate implied values less tangible
book value divided by total deposits) of 14.05% and 16.32%, respectively,
compared to a median of 6.56% and 12.34%,
 
                                       44
<PAGE>   50
 
respectively, for the Comparable Thrift Acquisitions and Comparable Bank
Acquisitions. In addition, the implied values reflected premiums over the
closing price of Great Western Common Stock on February 14, 1997 (the last
trading day prior to the announcement of the Ahmanson Proposal) of 26.84% for
the Ahmanson Proposal and 39.76% for the Washington Mutual Proposal, compared to
a median of 27% and 24%, respectively, for the Comparable Thrift Acquisitions
and Comparable Bank Acquisitions. First Call is a service which provides a
compilation of securities analysts' earnings forecasts.
 
     The Great Western Financial Advisors also graphed in chart form the implied
values of the Ahmanson Proposal and the Washington Mutual Proposal based on
daily closing prices for the period from (a) February 14, 1997 through March 3,
1997 and (b) February 14, 1996 through March 3, 1997. In addition, the Great
Western Financial Advisors compared in tabular form the implied values of the
Ahmanson Proposal and the Washington Mutual Proposal for six selected periods
based on the average of the daily closing prices during these periods. The
implied values for the Ahmanson Proposal and the Washington Mutual Proposal
were, respectively: (i) $44.11 and $49.86 for the period from February 14, 1997
to March 3, 1997; (ii) $42.41 and $49.30 for the preceding one month period;
(iii) $37.75 and $43.42 for the preceding three month period; (iv) $34.18 and
$39.45 for the preceding six month period; (v) $30.20 and $33.51 for the
preceding one year period; and (vi) $24.71 and $24.55 for the preceding three
year period.
 
     Pro Forma Financial Analysis.  The Great Western Financial Advisors
analyzed the projected pro forma combined financial impact of the Ahmanson
Proposal and the Washington Mutual Proposal from the perspectives of Ahmanson in
the case of the Ahmanson Proposal, Washington Mutual in the case of the
Washington Mutual Proposal and Great Western for both the Ahmanson Proposal and
the Washington Mutual Proposal on a per share equivalent basis compared to
projected Great Western stand-alone data. The analysis considered the pro forma
effects of the transaction on a variety of financial measures, including, among
others, EPS calculated in accordance with generally accepted accounting
principles ("GAAP"), return on average common equity ("GAAP ROACE"), cash
earnings per share (defined as GAAP EPS before goodwill amortization ("Cash
EPS")), cash return on average common equity (defined as GAAP net income before
goodwill amortization divided by average tangible common equity ("Cash ROACE")),
goodwill as a percentage of total equity, goodwill amortization as a percentage
of net income, pro forma dividends per share (based upon Ahmanson's and
Washington Mutual's indicated dividends) and tangible book value per share. This
analysis was based on the assumptions that (i) the pro forma combined company
would realize the synergies as projected and within the time period specified by
Ahmanson ($400 million by 1999) and by Washington Mutual ($569 million by 1999),
respectively, and (ii) Ahmanson's publicly disclosed plan to repurchase an
aggregate of approximately $2 billion of its common stock by 1999. Pro forma
data for Ahmanson was based on publicly available information and the First Call
Estimates. Pro forma data for Washington Mutual was based on publicly available
information and Washington Mutual management estimates supplied to Great
Western. Pro forma data for Great Western was based on publicly available
information, the Great Western Management Forecast and the First Call Estimates
(the "Great Western First Call Estimates").
 
     Pro Forma Per Share Analysis from Ahmanson's Perspective.  Among other
things, the analysis compared the pro forma accretion/dilution in Ahmanson EPS
under the Ahmanson Proposal for 1997, 1998 and 1999 as follows: for Ahmanson
GAAP EPS's: (i) in 1997, dilutive by 3.9% based on the Great Western Management
Forecast and by 3.6% based on the Great Western First Call Estimates; (ii) in
1998, accretive by 3.0% based on the Great Western Management Forecast and
dilutive by 1.8% based on the Great Western First Call Estimates; and (iii) in
1999, accretive by 11.8% based on the Great Western Management Forecast and by
6.8% based on the First Call Estimates. The analysis indicated that 1999 GAAP
ROACE would be 12.5% based on the Great Western Management Forecast. For
Ahmanson Cash EPS, the analysis indicated that the Ahmanson Proposal would be
accretive by: (i) in 1997, 6.2% based on the Great Western Management Forecast
and 6.4% based on the Great Western First Call Estimates; (ii) in 1998, 20.1%
based on the Great Western Management Forecast and 15.4% based on the Great
Western First Call Estimates; and (iii) in 1999, 27.8% based on the Great
Western Management Forecast and 23.1% based on the Great Western First Call
Estimates. The analysis indicated that 1999 Cash ROACE would be 32.0% based on
the Great Western Management Forecast. The December 31, 1997 goodwill to total
equity ratio was estimated to
 
                                       45
<PAGE>   51
 
be 55.2% and the 1998 goodwill amortization to net income ratio was estimated to
be 22.8%. Tangible book value per share of Ahmanson Common Stock was estimated
to decrease by 17.6%.
 
     Pro Forma Per Share Analysis from Washington Mutual's Perspective.  Among
other things, the analysis compared the pro forma accretion/dilution in
Washington Mutual EPS (in relation to Washington Mutual's First Call Estimates)
under the Washington Mutual Proposal for 1997, 1998 and 1999 as follows: For
Washington Mutual GAAP EPS: (i) in 1997, dilutive by 12.1% based on the Great
Western Management Forecast and by 11.7% based on the Great Western First Call
Estimates; (ii) in 1998, accretive by 13.0% based on the Great Western
Management Forecast and by 9.5% based on the Great Western First Call Estimates;
and (iii) in 1999, accretive by 22.3% based on the Great Western Management
Forecast and by 18.9% based on the Great Western First Call Estimates. The
analysis indicated that 1999 GAAP ROACE would be 24.6% based on the Great
Western Management Forecast. For Washington Mutual Cash EPS, the analysis
indicated that the Merger would be (i) in 1997, dilutive by 9.2% based on the
Great Western Management Forecast and by 8.8% based on the Great Western First
Call Estimates; (ii) in 1998, accretive by 15.1% based on the Great Western
Management Forecast and by 11.3% based on the Great Western First Call
Estimates; and (iii) in 1999, accretive by 23.9% based on the Great Western
Management Forecast and by 21.5% based on the Great Western First Call
Estimates. The analysis indicated that 1999 Cash ROACE would be 26.4% based on
the Great Western Management Forecast. The December 31, 1997 goodwill to total
equity ratio was estimated to be 6.7% and the 1998 goodwill amortization to net
income ratio was estimated to be 3.5%. Tangible book value per share of
Washington Mutual Common Stock was estimated to decline by 11.3%.
 
     Pro Forma Per Share Analysis from Great Western's Perspective.  Among other
things, the analysis compared the accretion in EPS under the Ahmanson Proposal
and the Washington Mutual Proposal for 1997, 1998 and 1999. The analysis
indicated that the proposed combination would be accretive on a per share
equivalent basis compared to stand-alone Great Western GAAP EPS by: (i) in 1997,
10.6% based on the Great Western Management Forecast and 9.7% based on the Great
Western First Call Estimates under the Ahmanson Proposal, compared to 13.1%
based on the Great Western Management Forecast and 12.4% based on the Great
Western First Call Estimates under the Washington Mutual Proposal; (ii) in 1998,
9.8% based on the Great Western Management Forecast and 14.7% based on the Great
Western First Call Estimates under the Ahmanson Proposal, compared to 38.1%
based on the Great Western Management Forecast and 46.6% based on the Great
Western First Call Estimates under the Washington Mutual Proposal; and (iii) in
1999, 22.2% based on the Great Western Management Forecast and 28.1% based on
the Great Western First Call Estimates under the Ahmanson Proposal, compared to
55.3% based on the Great Western Management Forecast and 65.7% based on the
Great Western First Call Estimates under the Washington Mutual Proposal. The
same analysis was performed for Great Western Cash EPS. The analysis indicated
that the proposed combinations would be accretive on a per share equivalent
basis compared to stand-alone Great Western Cash EPS by: (i) in 1997, 17.3%
based on the Great Western Management Forecast and 16.5% based on the Great
Western First Call Estimates under the Ahmanson Proposal, compared to 8.5% based
on the Great Western Management Forecast and 8.0% based on the Great Western
First Call Estimates under the Washington Mutual Proposal; (ii) in 1998, 24.7%
based on the Great Western Management Forecast and 30.6% based on the Great
Western First Call Estimates under the Ahmanson Proposal, compared to 32.7%
based on the Great Western Management Forecast and 39.5% based on the Great
Western First Call Estimates under the Washington Mutual Proposal; and (iii) in
1999, 36.5% based on the Great Western Management Forecast and 43.2% based on
the Great Western First Call Estimates under the Ahmanson Proposal, compared to
48.9% based on the Great Western Management Forecast and 59.2% based on the
Great Western First Call Estimates under the Washington Mutual Proposal. Implied
annual dividend per share of Great Western Common Stock was estimated to be
$0.92 under the Ahmanson Proposal, representing a 7.6% decline under the
Ahmanson Proposal, compared to $0.90 under the Washington Mutual Proposal,
representing a 10.0% decline. The ratio of tangible common equity to tangible
assets was estimated to be 3.75% under the Ahmanson Proposal, representing a
decline of 1.30%, compared to 4.72% under the Washington Mutual Proposal,
representing a decline of 0.32%. Tangible book value per share was estimated to
decline by 9.6% under the Ahmanson Proposal, compared to an estimated decline of
0.8% under the Washington Mutual
 
                                       46
<PAGE>   52
 
Proposal. Under the Ahmanson Proposal, existing stockholders of Great Western
would own 57% of the combined company, compared to 52% under the Washington
Mutual Proposal.
 
     Sensitivity to Capital Ratios.  The Great Western Financial Advisors
analyzed the Ahmanson Proposal under two capitalization scenarios. The Great
Western data for both scenarios were based on the Great Western Management
Forecast. In the first scenario, the ratio of tangible common equity to tangible
assets was 3.85% for Ahmanson (the "Base Case"). The second scenario assumed
that Ahmanson's repurchases of Ahmanson Common Stock were reduced to achieve and
maintain a 5% tangible common equity to tangible assets ratio for Ahmanson (the
"5% Case"). From Ahmanson's perspective, the proposed combination produced pro
forma: (i) 1999 GAAP EPS accretion of 11.8% in the Base Case and 6.7% in the 5%
Case; (ii) 1999 GAAP ROACE of 12.52% in the Base Case and 11.41% in the 5% Case;
(iii) 1999 Cash EPS accretion of 27.8% in the Base Case and 21.1% in the 5%
Case; and (iv) 1999 Cash ROACE of 31.98% in the Base Case and 25.31% in the 5%
Case. From Great Western's equivalent per share perspective: (i) 1999 GAAP EPS
under the Ahmanson Proposal would accrete by 22.2% in the Base Case and 16.6% in
the 5% Case; and (ii) 1999 Cash EPS would accrete by 36.5% in the Base Case and
29.3% in the 5% Case.
 
     Sensitivity to Synergies.  The Great Western Financial Advisors analyzed
the effects of achieving different levels of synergies on the impact of the
Ahmanson Proposal and the Washington Mutual Proposal. In this analysis, the
Great Western Financial Advisors reviewed projected pro forma combined data for
1999 assuming that Ahmanson and Washington Mutual would achieve 50%, 75% and
100%, respectively, of the amount of synergies projected by Ahmanson and
Washington Mutual, respectively. The Great Western data for the analysis was
based on the Great Western Management Forecast. From Ahmanson's perspective: (i)
1999 GAAP EPS would be diluted by 1.5% if 50% of the projected synergies were
realized and would accrete by 5.2% if 75% of the projected synergies were
realized and by 11.8% if 100% of the projected synergies were realized; (ii)
1999 GAAP ROACE would be 11.10% if 50% of the projected synergies were realized,
11.81% if 75% of the projected synergies were realized and 12.52% if 100% of the
projected synergies were realized; (iii) 1999 Cash EPS would accrete by 14.73%
if 50% of the projected synergies were realized, 21.31% if 75% of the projected
synergies were realized and 27.8% if 100% of projected synergies were realized;
and (iv) 1999 Cash ROACE would be 28.47% if 50% of the projected synergies were
realized, 30.23% if 75% of the projected synergies were realized and 31.98% if
100% of the projected synergies were realized. From Washington Mutual's
perspective: (i) 1999 GAAP EPS would accrete by 8.7% if 50% of the projected
synergies were realized, 15.5% if 75% of the projected synergies were realized
and 22.3% if 100% of the projected synergies were realized; and (ii) 1999 GAAP
ROACE would be 22.40% if 50% of the projected synergies were realized; 23.53% if
75% of the projected synergies were realized and 24.64% if 100% of the projected
synergies were realized.
 
     From Great Western's per share perspective: (i) 1999 GAAP EPS would accrete
by 7.7% if 50% of the projected synergies were realized, 15.0% if 75% of the
projected synergies were realized and 22.2% if 100% of the projected synergies
were realized under the Ahmanson Proposal, compared to 38.0% if 50% of the
projected synergies were realized, 46.7% if 75% of the projected synergies were
realized and 55.3% if 100% projected synergies were realized under the
Washington Mutual Proposal; and (ii) 1999 Cash EPS would accrete by 22.5% if 50%
of the projected synergies were realized, 29.5% if 75% of the projected
synergies were realized, and 36.5% if 100% of the projected synergies were
realized under the Ahmanson Proposal.
 
     Selected Company Analysis.  Based on publicly available information and the
First Call Estimates, the Great Western Financial Advisors reviewed and compared
actual and estimated selected financial, operating, and stock market information
and financial ratios of Great Western, Ahmanson and Washington Mutual and a
group of seven thrift organizations consisting of Golden West, Greenpoint
Financial, Charter One, Dime Bancorp, TCF Financial, Glendale Federal and Bank
United (collectively the "Thrift Composite Companies"). With certain exceptions,
the financial data was at or for the year ended December 31, 1996; where
applicable, market data was at March 3, 1997 (except for the stock prices of
Great Western Common Stock and Ahmanson Common Stock, which were as of February
14, 1997) and estimates were based on First Call Estimates. For Ahmanson and
certain of the Thrift Composite Companies, the market data was adjusted to
eliminate the estimated market value of goodwill litigation claims based upon
trading data for California Federal Bank Contingent Litigation Recovery
Participation Interests.
 
                                       47
<PAGE>   53
 
     The Great Western Financial Advisors noted that, among other things, Great
Western, Ahmanson and Washington Mutual had: (i) 1997 ratios of price to GAAP
EPS ("GAAP P/E") of 12.6 times, 12.3 times and 13.5 times, respectively,
compared to a median of 11.5 times for the Thrift Composite Companies; (ii) 1998
GAAP P/E of 11.1 times, 10.5 times and 11.3 times, respectively, compared to a
median of 10.3 times for the Thrift Composite Companies; (iii) 1997 ratios of
price to CASH EPS ("CASH P/E") of 11.4 times, 11.5 times, and 12.8 times,
respectively, compared to a median of 11.4 times for the Thrift Composite
Companies; and (iv) 1998 Cash P/E of 10.2 times, 10.0 times and 10.8 times,
respectively, compared to a median of 10.3 times for the Thrift Composite
Companies. The price to book value per share ratio was 1.9 times for both Great
Western and Ahmanson and 2.9 times for Washington Mutual, compared to a median
of 1.7 times for the Thrift Composite Companies. The price to tangible book
value per share ratio was 2.2 times for both Great Western and Ahmanson and 3.0
times for Washington Mutual, compared to a median of 1.7 times for the Thrift
Composite Companies.
 
     The Great Western Financial Advisors analyzed and compared the capital
structure of Great Western, Ahmanson, Washington Mutual and the Thrift Composite
Companies. Among other things, Great Western, Ahmanson and Washington Mutual
had: (i) ratios of total capital (including capital securities, preferred and
common stock) to total assets of 6.99%, 5.18% and 5.38%, respectively, compared
to a median of 6.37% for the Thrift Composite Companies; (ii) ratios of tangible
common equity to tangible assets of 5.03%, 3.31% and 4.83%, respectively,
compared to a median of 6.22% for the Thrift Composite Companies; and (iv)
estimated share repurchase percentages (estimated shares repurchased during the
past two calendar years divided by shares outstanding at December 1994 (adjusted
to reflect any major stock acquisitions)) of 5.1%, 14.5% and 0.0%, respectively,
for Great Western, Ahmanson and Washington Mutual, compared to a median of 2.8%
for the Thrift Composite Companies.
 
     The Great Western Financial Advisors reviewed measures of asset quality for
Great Western, Ahmanson, Washington Mutual and the Thrift Composite Companies.
Great Western, Ahmanson and Washington Mutual had: (i) ratios of non-performing
assets to net loans plus other-real-estate-owned of 1.77%, 3.33%, and 1.46%,
respectively, compared to a median of 1.79% for the Thrift Composite Companies;
(ii) ratios of loan loss reserves to nonperforming loans of 74%, 50% and 107%,
respectively, compared to a median of 48% for the Thrift Composite Companies;
and (iii) ratios of loan loss provisions to average loans of 0.68%, 0.46%, and
0.75%, respectively, compared to 0.29% for the Thrift Composite Companies.
 
     The Great Western Financial Advisors examined certain profitability ratios
of Great Western, Ahmanson, Washington Mutual and the Thrift Composite
Companies. Great Western, Ahmanson and Washington Mutual had: (i) a return on
average assets (excluding extraordinary items and significant non-recurring
items) of 0.65%, 0.58%, and 0.65%, respectively, compared to a median of 1.10%,
for the Thrift Composite Companies; (ii) return on average common equity
(excluding extraordinary items and significant non-recurring items) of 10.6%,
11.1% and 12.2%, respectively, compared to a median of 17.7% for the Thrift
Composite Companies; (iii) ratios of non-interest income to revenues (excluding
significant non-recurring items) of 18%, 15% and 16%, respectively, compared to
a median of 15% for the Thrift Composite Companies; (iv) efficiency ratios
(defined as non-interest expenses divided by net interest income plus
non-interest income, but excluding amortization of intangibles and significant
non-recurring income and non-significant items) of 59%, 61% and 51%,
respectively, compared to a median of 54% for the Thrift Composite Companies;
and (iv) net interest margins of 3.33%, 2.63% and 2.89%, respectively, compared
to a median of 2.53% for the Thrift Composite Companies.
 
     Discounted Dividend Analysis.  Using a discounted dividend analysis, the
Great Western Financial Advisors estimated the net present value per share of
Washington Mutual Common Stock. Using discount rates ranging from 13% to 15% and
terminal value multiples of 11.0 times to 13.0 earnings, the Great Western
Financial Advisors calculated that the net present value per share of Washington
Mutual Common Stock ranged from $45.28 per share to $55.47 per share. This
analysis was based on a number of assumptions, including the First Call
Estimates for 1997 and 1998 Washington Mutual EPS, earnings growth of 9% per
year from 1998 to 2002, growth of 5% per year from 1997 to 2001, maintaining a
constant tangible common equity to tangible assets ratio of 5%, and a terminal
value for year 2001 determined by applying a multiple to year 2002 forecasted
earnings. The Great Western Financial Advisors also conducted a sensitivity
analysis using
 
                                       48
<PAGE>   54
 
earnings growth rates of 7% to 11% and capital ratios of 4% to 6% (and assuming
a 14.0% discount rate and a 12.0 times terminal multiple). This analysis showed
that the net present value per share of Washington Mutual Common Stock ranged
from $44.03 per share to $56.45 per share. In addition, the Great Western
Financial Advisors estimated the net present value per share of Washington
Mutual Common Stock using Washington Mutual's management estimates, but
otherwise using the same assumptions as set forth above. Based on these
assumptions, the Great Western Financial Advisors calculated that the net
present value per share of Washington Mutual Common Stock ranged from $53.10 per
share to $65.11 per share. The Great Western Financial Advisors also conducted a
sensitivity analysis using earnings growth rates of 7% to 11% and capital ratios
of 4% to 6% (and assuming a 14.0% discount rate and a 12.0 times terminal
multiple). The analysis showed that the net present value per share of
Washington Mutual Common Stock ranged from $53.14 per share to $64.67 per share.
 
     The Great Western Financial Advisors also calculated the net present value
per share of Ahmanson Common Stock. Using discount rates ranging from 13% to 15%
and terminal value multiples of 11.0 times to 13.0 times, the Great Western
Financial Advisors calculated that the net present value per share of Ahmanson
Common Stock ranged from $32.29 per share to $40.22 per share. This analysis was
based on a number of assumptions, including the First Call Estimates for 1997
and 1998 Ahmanson EPS, earnings growth of 10% per year from 1998 to 2002, asset
growth of 0% per year from 1997 to 2001, maintaining a constant tangible common
equity to tangible assets ratio of 5%, excluding the estimated market value of
the Ahmanson goodwill litigation claim, and a terminal value for year 2001
determined by applying a multiple to year 2002 forecasted earnings. The Great
Western Financial Advisors also conducted a sensitivity analysis using earnings
growth rates of 8% to 12% and capital ratios of 4% to 6% (and assuming a 14.0%
discount rate and a 12.0 times terminal multiple); the analysis showed that the
net present value per share of Ahmanson Common Stock ranged from $30.57 per
share to $41.72 per share.
 
     Historical Stock Price Performance.  The Great Western Financial Advisors
charted the weekly closing prices of Ahmanson Common Stock and Washington Mutual
Common Stock for the period from February 27, 1987 to February 28, 1997. The
Great Western Financial Advisors also compared the historical total returns of
Ahmanson Common Stock and Washington Mutual Common Stock to the historical total
returns for the S&P 500 Index, the S&P Bank Index and the S&P Thrift Index. The
analysis indicated a compounded annual total return (defined as stock price
appreciation plus reinvestment of dividends) to shareholders of: (i) for the
period from January 1, 1997 to March 3, 1997, 31% for the Ahmanson Common Stock
and 22% for Washington Mutual Common Stock, compared to 8% for the S&P 500
Index, 16% for the S&P Bank Index, and 32% for the S&P Thrift Index; (ii) for
the one year period ended December 31, 1996, 27% for the Ahmanson Common Stock
and 54% for the Washington Mutual Common Stock, compared to 23% for the S&P 500
Index, 42% for the S&P Bank Index, and 20% for the S&P Thrift Index; (iii) for
the three year period ended December 31, 1996, 23% for the Ahmanson Common Stock
and 26% for the Washington Mutual Common Stock, compared to 20% for the S&P 500
Index, 29% for the S&P Bank Index, and 20% for the S&P Thrift Index; (iv) for
the five year period ended December 31, 1996, 18% for the Ahmanson Common Stock
and 27% for Washington Mutual Common Stock, compared to 15% for the S&P 500
Index, 26% for the S&P Bank Index, and 14% for the S&P Thrift Index; (v) for the
ten year period ended December 31, 1996, 9% for the Ahmanson Common Stock and
24% for Washington Mutual Common Stock, compared to 15% for the S&P 500 Index
(the S&P Bank Index and the S&P Thrift Index are not available for these
periods).
 
     The preparation of a fairness opinion is a complex process and is not
necessarily susceptible to partial analysis or summary description. The Great
Western Financial Advisors believe that their analyses must be considered as a
whole and that selecting portions of their analyses, without considering the
analyses taken as a whole, would create an incomplete or misleading view of the
process underlying the analyses set forth in their respective opinions. In
addition, the Great Western Financial Advisors considered the results of all
such analyses and did not assign relative weights to any of the analyses, so
that the ranges of valuations resulting from any particular analysis described
above should not be taken to be the Great Western Financial Advisors' view of
the actual value of Great Western.
 
                                       49
<PAGE>   55
 
     In performing their analyses, the Great Western Financial Advisors made
numerous assumptions with respect to industry performance, general business,
economic and regulatory conditions and other matters, many of which are beyond
the control of Great Western. The analyses performed by the Great Western
Financial Advisors are not necessarily indicative of actual values, trading
values or actual future results that might be achieved, all of which may be
significantly more or less favorable than suggested by such analyses. No public
company utilized as a comparison is identical to Great Western and none of the
Comparable Thrift Acquisitions or other business combinations utilized as a
comparison is identical to the transactions contemplated by the Merger
Agreement. Accordingly, an analysis of publicly traded comparable companies and
comparable business combinations resulting from the transactions is not
mathematical; rather it involves complex considerations and judgments concerning
differences in financial and operating characteristics of the comparable
companies or the company or transaction to which they are being compared. In
connection with their analyses, the Great Western Financial Advisors made, and
were provided estimates and forecasts by the respective management of Great
Western and Washington Mutual, numerous assumptions with respect to industry
performance, general business and economic conditions and other matters, many of
which are beyond the control of Great Western and Washington Mutual. Analyses
based upon forecasts of future results are not necessarily indicative of actual
future results, which may be significantly more or less favorable than suggested
by such analyses. Because such analyses are inherently subject to uncertainty,
being based upon numerous factors or events beyond the control of Great Western,
Washington Mutual or the Great Western Financial Advisors, neither Great
Western, Washington Mutual nor the Great Western Financial Advisors assume
responsibility if future results or actual values are materially different from
these forecasts or assumptions. Such analyses were prepared solely as part of
the Great Western Financial Advisors' analyses of the fairness of the Exchange
Ratio and were provided to the Great Western Board. The analyses do not purport
to be appraisals or to reflect the prices at which a company might be sold. In
addition, as described above, the opinions of the Great Western Financial
Advisors were one of many factors taken into consideration by the Great Western
Board in making its determination to approve the Merger. Consequently, the
analyses described above should not be viewed as determinative of the Great
Western Board's or Great Western management's opinion with respect to the value
of Great Western or a combination of either Great Western and Ahmanson or Great
Western and Washington Mutual or whether the Great Western Board or Great
Western management would have been willing to agree to a different exchange
ratio. The Great Western Board placed no limits on the scope of the analysis
performed, or opinions expressed, by the Great Western Financial Advisors.
 
     Pursuant to the terms of the engagement letters dated February 25, 1997 and
February 18, 1997 Great Western agreed to pay each of the Great Western
Financial Advisors (i) a retainer of $1 million, (ii) a fee of $8.8 million upon
execution of the Merger Agreement, and (iii) a fee of 0.25% of the aggregate
value of the consideration to be paid pursuant to the Merger upon consummation
of the Merger against which the fees set forth in clauses in (i) and (ii) of
this sentence will be credited. Great Western also agreed to reimburse each of
the Great Western Financial Advisors for its reasonable out-of-pocket expenses,
including all reasonable fees and disbursements of its attorneys, and to
indemnify each of the Great Western Financial Advisors and certain related
persons against certain liabilities, including certain liabilities under federal
securities law, arising out of its engagement. In connection with the Great
Western Financial Advisors' engagement as financial advisors to Great Western,
Great Western anticipates that certain employees of each of the Great Western
Financial Advisors may communicate in person, by telephone or otherwise with a
limited number of institutions, brokers or other persons who are Great Western
Stockholders for the purpose of assisting in the solicitation of proxies in
favor of the Merger Agreement. The Great Western Financial Advisors will not
receive any fee for or in connection with such solicitation activities by their
respective employees apart from the fees each of them is otherwise entitled to
receive as described above.
 
CONVERSION OF GREAT WESTERN CAPITAL STOCK
 
     Conversion of Great Western Common Stock. At the Effective Time, each
outstanding share of Great Western Common Stock, other than shares held in Great
Western's treasury or directly or indirectly by Washington Mutual or its
subsidiaries or by Great Western or its subsidiaries, will automatically be
converted
 
                                       50
<PAGE>   56
 
into the right to receive 0.9 shares of Washington Mutual Common Stock, with
cash being paid in lieu of fractional shares.
 
     Conversion of Great Western 8.30% Preferred Stock. At the Effective Time,
each outstanding share of Great Western Preferred Stock will be converted into
the right to receive one share of Series F Preferred Stock. The terms of the
Series F Preferred Stock will be substantially identical to the terms of the
Great Western Preferred Stock. At the Effective Time, Washington Mutual will
assume the obligations of Great Western under the Deposit Agreement, dated as of
September 10, 1992 (the "Preferred Stock Deposit Agreement"), between Great
Western and Harris Trust Co. of California as depositary (the "Preferred Stock
Depositary"). Washington Mutual will instruct the Preferred Stock Depositary to
treat the shares of Series F Preferred Stock received by it in exchange for
shares of Great Western Preferred Stock as newly deposited securities under the
Preferred Stock Deposit Agreement. In accordance with the terms of the Preferred
Stock Deposit Agreement, receipts evidencing Great Western Depositary Shares
("Great Western Depositary Receipts") then outstanding would thereafter
represent shares of Series F Preferred Stock. Washington Mutual would request
that the Preferred Stock Depositary call for surrender all outstanding Great
Western Depositary Receipts to be exchanged for receipts evidencing New
Washington Mutual Depositary Shares ("New Washington Mutual Depositary
Receipts"). See "Description of Washington Mutual Capital Stock."
 
     Each outstanding share of Great Western Capital Stock held in Great
Western's treasury or directly or indirectly by Washington Mutual or its
subsidiaries or Great Western or its subsidiaries would, with certain limited
exceptions, be canceled at the Effective Time and would cease to exist, and no
securities of Washington Mutual or other consideration would be delivered in
exchange therefor. All shares of Washington Mutual Common Stock that are owned
by Great Western or its subsidiaries, if any, would become treasury stock of
Washington Mutual.
 
     Conversion of Common Stock Options. At the Effective Time, each Great
Western Common Stock Option issued by Great Western pursuant to any Great
Western Common Stock Plan that is outstanding and unexercised immediately prior
to the Effective Time would be converted automatically into one Washington
Mutual Stock Option with (i) the number of shares of Washington Mutual Common
Stock subject to the Washington Mutual Stock Option being equal to the product
of the number of shares of Great Western Common Stock subject to the Great
Western Common Stock Option multiplied by the Exchange Ratio and rounded down to
the nearest share and (ii) the exercise price per share of Washington Mutual
Common Stock subject to the Washington Mutual Stock Option being equal to the
exercise price per share of Great Western Common Stock under the Great Western
Common Stock Option divided by the Exchange Ratio and rounded up to the nearest
cent. The conversion would be intended to be effected in a manner such that any
Great Western Common Stock Options that are "incentive stock options" within the
meaning of Section 422 of the Code shall remain so. Pursuant to the terms of the
Great Western Common Stock Plans, consummation of the Merger will constitute a
change in control of Great Western, resulting in accelerated vesting of
outstanding Great Western Common Stock Options. See "-- Interests of Certain
Persons in the Merger."
 
EFFECTIVE TIME
 
     The Effective Time will be the date and time when the Merger becomes
effective, as set forth in a Certificate of Merger, which, shall be filed with
the Secretary of State of the State of Delaware. The filing of the Certificate
of Merger will occur at 10:00 a.m. on a date to be specified by the parties,
which will be the tenth business day of a month that is at least two days after
the satisfaction or waiver (subject to applicable law) of the conditions to
consummation of the Merger set forth in the Merger Agreement (excluding
conditions which by their terms cannot be satisfied until the date of closing)
unless another date and time is agreed to by Washington Mutual and Great
Western. The Merger Agreement may be terminated by either party if, among other
reasons, the Merger shall not have been consummated on or before March 31, 1998.
See "-- Conditions to the Consummation of the Merger" and "-- Termination of the
Merger Agreement" below.
 
                                       51
<PAGE>   57
 
REPRESENTATIONS AND WARRANTIES
 
     In the Merger Agreement each of Washington Mutual and Great Western makes
representations and warranties to the other regarding, among other things, (i)
its corporate organization and existence; (ii) its capitalization; (iii) its
corporate power and authority to enter into, and its due authorization,
execution and delivery of, the Merger Agreement; (iv) that neither the Merger
Agreement nor the contemplated transactions violate its charter and bylaws,
applicable law and certain material agreements; (v) required governmental and
third party approvals; (vi) timely filing of required regulatory reports; (vii)
its financial statements and filings with the Commission; (viii) its investment
banking arrangements; (ix) the absence of certain materially adverse changes in
its business since September 30, 1996; (x) the absence of certain material legal
proceedings; (xi) the filing and accuracy of its tax returns; (xii) documents
filed with the Commission and the accuracy of the information contained therein;
(xiii) its compliance with applicable law; (xiv) the absence of undisclosed
agreements between it and regulatory agencies; (xv) the absence of undisclosed
liabilities; (xvi) that the Merger Agreement and the transactions contemplated
thereby do not result in the grant of any rights to any person under such
party's respective Rights Agreement; (xvii) accuracy of certain information;
(xviii) environmental liabilities; (xix) pooling of interests accounting
treatment; (xx) receipt of a fairness opinion from its financial advisor; (xxi)
intellectual property matters; and (xxii) compliance with the Community
Reinvestment Act.
 
     In addition, Great Western has made certain other representations and
warranties to Washington Mutual regarding, among other things (i) employees,
employee benefit plans and related matters and (ii) the absence of certain
defaults under material contracts.
 
CONDUCT OF BUSINESS PENDING THE MERGER AND OTHER AGREEMENTS
 
     Pursuant to the Merger Agreement, prior to the Effective Time, Washington
Mutual and Great Western have each agreed to, and to cause their respective
subsidiaries to, (i) conduct its business in the usual, regular and ordinary
course consistent with past practice, (ii) use its reasonable best efforts to
maintain and preserve intact its business organization, employees and
advantageous business relationships and retain the services of its officers and
key employees and (iii) refrain from taking any action that would reasonably be
expected to adversely affect or delay the ability of either Washington Mutual or
Great Western to obtain any Requisite Regulatory Approvals or to consummate the
transactions contemplated by the Merger Agreement.
 
     In addition, except as expressly contemplated or permitted by the Merger
Agreement or specified in a schedule thereto or required by applicable law, each
of Great Western and Washington Mutual has agreed that it and its subsidiaries
will not, without the prior written consent of the other party, among other
things: (i) adjust, split, combine or reclassify any capital stock, declare or
pay dividends (except, subject to certain restrictions, cash dividends on common
stock not greater than the dividend paid during the fiscal quarter preceding the
date of the Merger Agreement, and, in the case of Washington Mutual only, as
such rates may be increased consistent with past practice, and regular dividends
on Great Western's and Washington Mutual's preferred stock); set any record or
payment dates for the payment of any dividends or distributions on its capital
stock except in the ordinary and usual course of business consistent with past
practice; or make any other distribution on, or directly or indirectly redeem,
purchase or otherwise acquire, any shares of its capital stock or any securities
or obligations convertible into or exchangeable for any shares of its capital
stock or issue any additional shares of capital stock except pursuant to certain
exceptions set forth in the Merger Agreement; (ii) sell, transfer, mortgage or
encumber or otherwise dispose of any of its properties or assets or cancel,
release or assign any indebtedness to any person except in the ordinary course
of business consistent with past practice or pursuant to certain exceptions set
forth in the Merger Agreement; (iii) except for transactions in the ordinary
course of business, consistent with past practice, make any material acquisition
of or investment either by purchase of stock or securities, merger or
consolidation, contributions to capital, property transfers or purchases of any
property or assets of any other party (other than a wholly owned subsidiary)
except that, subject to clause (iii) of the preceding paragraph, Washington
Mutual may enter into an agreement or agreements for, and may consummate,
business combinations provided that the aggregate amount of assets of such
acquired companies does not exceed $5,000,000,000 unless such acquisition would
require Washington Mutual to register as a bank holding company; (iv) in the
case of Great Western only,
 
                                       52
<PAGE>   58
 
enter into, renew or terminate any contract or agreement, other than loans made
in the ordinary course of business, that calls for aggregate annual payments of
$500,000 and which either is not terminable at will on 60 days or less notice
without payment of a penalty or has a term of less than one year; or make any
material change in any of its leases or contracts other than certain renewals of
contracts and leases for a term of one year or less without material adverse
changes to their terms; (v) in the case of Great Western only, other than
general salary increases consistent with past practice, increase in any material
respect the compensation or fringe benefits of any of its employees or enter
into or modify any employee benefit plans or employment agreements; (vi) in the
case of Great Western only, make capital expenditures in excess of specified
amounts other than expenditures necessary to maintain existing assets in good
repair; (vii) in the case of Great Western only, open, relocate or close any
branch or loan production office or make any application therefor; (viii) in the
case of Great Western only, make or acquire loans or issue commitments for any
loans except in the ordinary course of business consistent with past practice or
issue or agree to issue any letters of credit or otherwise guarantee the
obligation of other persons except in the ordinary course of business in order
to facilitate the sale of REO; (ix) subject to certain exceptions, engage or
participate in any material transaction or incur or sustain any material
obligations not in the ordinary course of business; (x) in the case of Great
Western only, foreclose on or otherwise acquire any real property other than
1-to-4 family residential properties in the ordinary course of business; (xi) in
the case of Great Western only, sell, transfer or otherwise convey or agree to
sell Sierra Investment Management Corporation; (xii) settle any material
litigation involving money damages except in the ordinary course of business
consistent with past practice; (xiii) take any action that would prevent or
impede the Merger from qualifying (A) as a reorganization within the meaning of
Section 368(a) of the Code or (B) for pooling of interests accounting treatment;
(xiv) amend its certificate of incorporation or bylaws or its Rights Agreement
in a manner that would materially and adversely affect either party's ability to
consummate the Merger; provided, that prior to the Great Western Meeting, Great
Western will not amend the Great Western Rights Plan, without Washington
Mutual's prior written consent; (xv) in the case of Great Western only, except
in the ordinary course of business consistent with past practice or following
prior consultation with Washington Mutual, materially change its investment
securities portfolio policy or the manner in which the portfolio is classified
or reported; (xvi) take any action intended or reasonably expected to result in
any of its representations or warranties being or becoming untrue in any
material respect, or any Closing condition not being satisfied or in a violation
of any provision of the Merger Agreement; (xvii) subject to certain exceptions,
make any changes in its accounting methods; (xviii) in the case of Great Western
only, engage in the business of making or make any VA guaranteed or FHA insured
mortgage loans; or (xix) in the case of Great Western only, enter into any
contract or agreements or amendments or supplements thereto pertaining to any
further development of specialized software.
 
     In the Merger Agreement, each party has agreed not to, and not to authorize
or permit any of its officers, directors, employees or agents (collectively,
"Representatives") to, directly or indirectly, solicit, initiate or encourage
any inquiries relating to or that may reasonably be expected to lead to, or the
making of any proposal which constitutes, a "Takeover Proposal" (as defined
below), recommend or endorse any Takeover Proposal, or participate in any
discussions or negotiations regarding 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. However, at any
time prior to the time its shareholders shall have voted to approve the Merger
Agreement, Washington Mutual or Great Western (each, a "party") may, and may
authorize and permit its Representatives to, provide third parties with
nonpublic information, otherwise facilitate any effort or attempt by any third
party to make or implement a Takeover Proposal, recommend or endorse any
Takeover Proposal with or by any third party, and participate in discussions and
negotiations with any third party relating to any Takeover Proposal, if such
party's Board of Directors, after having consulted with and considered the
advice of its financial advisors and outside counsel, has determined in good
faith that the failure to do so would create a reasonable possibility of a
breach of the fiduciary duties of such party's Board of Directors. Each of
Washington Mutual and Great Western shall (i) advise the other orally (within
one day) and in writing of the receipt of any such inquiry or proposal and (ii)
unless its Board of Directors, after consulting with, and considering the advice
of, its outside counsel has determined in good faith that such action would
create a reasonable possibility of a breach of the fiduciary duties of such
Board of Directors, inform the other party
 
                                       53
<PAGE>   59
 
orally and in writing as promptly as practicable of the material terms and
conditions of any such inquiries or proposals (including the identity of the
party making such inquiry or proposal), and shall keep the other party informed
of the status thereof. Great Western may not furnish any nonpublic information
to any third party except pursuant to the terms of a confidentiality agreement
containing terms substantially identical to the terms contained in the
confidentiality agreement between Great Western and Washington Mutual. "Takeover
Proposal" means, with respect to any person, any tender or exchange offer,
proposal for a merger, consolidation or other business combination involving
Great Western or Washington Mutual or any of their respective subsidiaries or
any proposal or offer to acquire in any manner a substantial equity interest in,
or a substantial portion of the assets of, Great Western or Washington Mutual or
any of their respective subsidiaries, other than the transactions contemplated
or permitted by the Merger Agreement; provided, however, that any proposal or
offer involving the acquisition by Washington Mutual of any equity interest in
or assets of any person, whether by tender or exchange offer, merger,
consolidation, or otherwise, or the disposition by Washington Mutual of assets,
deposits or subsidiaries, which is permitted by the Merger Agreement shall not
constitute a Takeover Proposal.
 
     Washington Mutual and Great Western have also agreed to use their
reasonable best efforts to promptly prepare and file all necessary
documentation, to effect all applications, notices, petitions and filings, and
to obtain and to cooperate in obtaining permits, consents, approvals and
authorizations of all third parties and governmental entities necessary or
advisable to consummate the transactions contemplated by the Merger Agreement
and to comply with the terms and conditions of all such permits, consents,
approvals and authorizations. Washington Mutual and Great Western have, subject
to the restrictions set forth in the Merger Agreement, each agreed, upon
request, to furnish to the other party all information concerning themselves and
their subsidiaries, directors, officers and shareholders and such other matters
as may be necessary in furtherance of the Merger. Washington Mutual and Great
Western have also agreed, subject to the terms and conditions of the Merger
Agreement, to use their best efforts to take, or cause to be taken, all actions
necessary, proper or advisable to comply promptly with all legal requirements
which may be imposed on such party or its subsidiaries and to consummate the
Merger. Washington Mutual has further agreed to use its best efforts to cause
the shares of Washington Mutual Common Stock and the Washington Mutual
Depositary Shares to be issued in the Merger to be approved for listing on
NASDAQ, subject to official notice of issuance.
 
     Washington Mutual also will be obligated to indemnify the officers and
directors of Great Western and its subsidiaries for any liabilities incurred in
connection with any matters existing or occurring at or prior to the Effective
Time and to provide directors and officers liability insurance with respect to
such matters for six years. See "-- Interests of Certain Persons in the Merger."
 
CONDITIONS TO THE CONSUMMATION OF THE MERGER
 
     Each of the party's obligation to effect the Merger is subject, among other
things, to satisfaction, at or prior to the Effective Time of the following
conditions: (i) the Merger Agreement shall have been approved and adopted by the
requisite affirmative votes of the stockholders of Great Western and the
issuance of the Merger Shares shall have been approved by the requisite
affirmative vote of the shareholders of Washington Mutual; (ii) the shares of
Washington Mutual Common Stock and the Washington Mutual Depositary Shares to be
issued in the Merger shall have been authorized for listing on NASDAQ, subject
to official notice of issuance; (iii) all regulatory approvals required to
consummate the transactions contemplated by the Merger Agreement shall have been
obtained and shall remain in full force and effect and all statutory waiting
periods in respect thereof shall have expired (all such approvals and the
expiration of all such waiting periods being referred to herein as the
"Requisite Regulatory Approvals"); (iv) the Registration Statement shall have
become effective under the Securities Act, no stop order suspending the
effectiveness of the Registration Statement shall have been issued and no
proceedings for that purpose shall have been initiated or threatened by the
Commission; (v) no order, injunction or decree issued by any court or agency of
competent jurisdiction or other legal restraint or prohibition preventing the
consummation of the Merger or any of the transactions contemplated by the Merger
Agreement shall be in effect and no statute, rule, regulation, order, injunction
or decree shall have been enacted, entered or promulgated which prohibits,
restricts or makes illegal consumma-
 
                                       54
<PAGE>   60
 
tion of the Merger; and (vi) each of Washington Mutual and Great Western shall
each have received a letter from its independent public accountants that the
Merger will qualify for pooling of interests accounting treatment.
 
     Washington Mutual's obligation to effect the Merger is also subject to,
among other things, the satisfaction or waiver by Washington Mutual at or prior
to the Effective Time of, among others, the following conditions: (i) the
representations and warranties of Great Western set forth in the Merger
Agreement (including, without limitation, the representation that since
September 30, 1996, no event has occurred which has had or would reasonably be
expected to have, individually or in the aggregate, a "Material Adverse Effect"
(as such term is defined in the Merger Agreement) on Great Western) shall be
true and correct in all respects as of the date of the Merger Agreement and
(except to the extent such representations and warranties speak as of an earlier
date) as of the Effective Time as though made on and as of the Effective Time;
provided, however, that for purposes of determining the satisfaction of the
condition described in this clause (i), such representations and warranties
(other than certain representations regarding capitalization and related
matters) shall be deemed to be true and correct in all respects unless the
failure or failures of such representations and warranties to be so true and
correct, individually or in the aggregate, results or would reasonably be
expected to result in a Material Adverse Effect on Great Western and its
subsidiaries taken as a whole; (ii) Great Western shall have performed in all
material respects all obligations required to be performed by it under the
Merger Agreement at or prior to the Effective Time; (iii) the Great Western
Rights (as defined herein) issued pursuant to the Great Western Rights Plan (as
defined here) shall not have become nonredeemable, exercisable, distributed or
triggered pursuant to the terms of such plan; (v) receipt of an opinion of
Foster Pepper & Shefelman, addressed to Washington Mutual, substantially to the
effect that the Merger will qualify as a "reorganization" under Section 368(a)
of the Code.
 
     Great Western's obligation to effect the Merger is also subject to, among
other things, the satisfaction or waiver by Great Western at or prior to the
Effective Time of, among others, the following conditions: (i) the
representations and warranties of Washington Mutual set forth in the Merger
Agreement (including, without limitation, the representation that since
September 30, 1996, no event has occurred which has had or would reasonably be
expected to have, individually or in the aggregate, a Material Adverse Effect on
Washington Mutual) shall be true and correct in all respects as of the date of
the Merger Agreement and (except to the extent such representations and
warranties speak as of an earlier date) as of the Effective Time as though made
on and as of the Effective Time, and provided, however, that, for purposes of
the provision described in this clause (i), such representations and warranties
shall be deemed to be true and correct in all respects unless the failure or
failures of such representations and warranties to be so true and correct,
individually or in the aggregate, results or would reasonably be expected to
result in a Material Adverse Effect on Washington Mutual and its subsidiaries
taken as a whole; (ii) Washington Mutual shall have performed in all material
respects all obligations required to be performed by it under the Merger
Agreement at or prior to the Effective Time; (iii) the Washington Mutual Rights
(as defined herein) issued pursuant to the Washington Mutual Rights Plan (as
defined herein) shall not have become nonredeemable, exercisable, distributed or
triggered pursuant to the terms of such plan; and (iv) receipt of an opinion of
Skadden, Arps, Slate, Meagher & Flom, LLP, addressed to Great Western,
substantially to the effect that the Merger will qualify as "reorganization"
under Section 368(a) of the Code.
 
REGULATORY APPROVALS REQUIRED
 
     Under the Merger Agreement, the obligations of both Washington Mutual and
Great Western to consummate the Merger are conditioned upon the receipt of all
Requisite Regulatory Approvals. See "The Merger -- Conditions to Consummation of
the Merger." Each of Washington Mutual and Great Western has agreed to use its
reasonable best efforts to obtain the Requisite Regulatory Approvals.
 
     The Merger and the Bank Merger are subject to the approval of the OTS under
the HOLA and the Federal Deposit Insurance Act, respectively, and related OTS
regulations. These approvals would require consideration by the OTS of various
factors, including assessments of the competitive effect of the contemplated
transactions, the managerial and financial resources and future prospects of the
resulting institutions and the effect of the contemplated transactions on the
convenience and needs of the communities
 
                                       55
<PAGE>   61
 
to be served. The Community Reinvestment Act of 1977, as amended ("CRA") also
requires that the OTS, in deciding whether to approve the Merger and the Bank
Merger, assess the records of performance of GW Bank and the bank subsidiaries
of Washington Mutual in meeting the credit needs of the communities they serve,
including low and moderate income neighborhoods. As part of the review process,
it is not unusual for the OTS to receive protests and other adverse comments
from community groups and others. Each of GW Bank, WMB, ASB and WMBfsb currently
has an "outstanding" CRA rating from its primary regulator. The regulations of
the OTS require publication of notice of, and an opportunity for public comment
with respect to, the applications filed in connection with the Merger and the
Bank Merger and authorize the OTS to hold a public hearing or meeting in
connection therewith if the OTS determines it to be appropriate. Any such
hearing, meeting or comments provided by third parties could prolong the period
during which the Merger and Bank Merger are subject to review by the OTS. The
Merger and Bank Merger may not be consummated for a period of 15 to 30 days
following OTS approval (the precise length of the period to be determined by the
OTS with the concurrence of the Attorney General of the United States), during
which time the United States Department of Justice could challenge the Merger
and Bank Merger on antitrust grounds. The commencement of an antitrust action
would stay the effectiveness of any approval granted by the OTS unless a court
specifically ordered otherwise.
 
     The Merger may also be subject to approvals of, or notices to, various
state agencies (each a "State Agency"), including state banking regulators in
Utah and Colorado, several state insurance departments, and other state agencies
such as those that regulate consumer finance.
 
     Washington Mutual will promptly submit applications and notices seeking the
requisite OTS and other State Agency approvals. There can be no assurance that
these approvals will be granted, and if granted there can be no assurance as to
the dates of such approvals or as to what conditions, if any, may be imposed. In
addition, the U.S. Department of Justice must examine whether there are
significant anti-competitive effects of the Merger and Bank Merger. There can be
no assurance that the U.S. Department of Justice or the Attorney General of the
state of California or any other state will not challenge the Merger or, if
challenged, what the result of such a challenge would be.
 
     Washington Mutual and Great Western are not aware of any other significant
governmental approvals that are required for consummation of the Merger except
as described above. Should any other approval or action be required, it is
presently contemplated that such approval would be sought. There can be no
assurance whether or when any such approval, if required, could be obtained.
 
TERMINATION OF THE MERGER AGREEMENT
 
     The Merger Agreement may be terminated by mutual agreement of the Great
Western Board and the Washington Mutual Board. The Merger Agreement may also be
terminated by either the Great Western Board or the Washington Mutual Board (a)
if any governmental authority which must grant a Requisite Regulatory Approval
has denied approval of the Merger and such approval has become final and
nonappealable or has issued a final nonappealable order enjoining or otherwise
prohibiting the consummation of the transactions contemplated by the Merger
Agreement; (b) if the Merger shall not have been consummated on or before March
31, 1998, unless the failure of the Closing (as defined in the Merger Agreement)
to occur by such date shall be due to the failure of the party seeking to
terminate the Merger Agreement to perform or observe the covenants and
agreements of such party set forth therein; (c) provided that the terminating
party is not then in material breach of the Merger Agreement, if the other party
shall have breached any of the covenants or agreements made by such other party
or any of the representations or warranties made by such other party, and in
either case, such breach is not cured within 30 days following written notice to
the breaching party, or which breach cannot be cured prior to the Closing (as
defined in the Merger Agreement) and such breach would entitle the non-breaching
party not to consummate the transactions contemplated by the Merger Agreement;
(d) if any approval of the shareholders of Washington Mutual or Great Western
contemplated by the Merger Agreement shall not have been obtained by reason of
the failure to obtain the required vote at the relevant Special Meeting; (e) if
the board of directors of the other party shall have withdrawn, modified or
changed in a manner adverse to the terminating party its approval or
recommendation of the Merger Agreement and the transactions contemplated
thereby; (f) by (i) the Washington Mutual
 
                                       56
<PAGE>   62
 
Board if a tender offer or exchange offer for 25% or more of the outstanding
shares of Great Western Common Stock is commenced (other than by Washington
Mutual or a Subsidiary), and the Great Western Board recommends that the Great
Western Stockholders tender their shares in such tender or exchange offer or
otherwise fails to recommend that such stockholders reject such tender offer or
exchange offer within ten business days after the commencement thereof; or (ii)
the Great Western Board if a tender offer or exchange offer for 25% or more of
the outstanding shares of Washington Mutual Common Stock is commenced and the
Washington Mutual Board recommends that the stockholders of Parent tender their
shares in such tender or exchange offer or otherwise fails to recommend that
such stockholders reject such tender or exchange offer within ten business days
after the commencement thereof (which, in the case of an exchange offer, shall
be the effective date of the registration statement relating to such offers).
 
TERMINATION FEES
 
     Pursuant to the Merger Agreement, Great Western has agreed to pay a $75
million fee (plus reimbursement for documented reasonable out-of-pocket expenses
up to $20 million) to Washington Mutual if (a) Washington Mutual terminates the
Merger Agreement because the Great Western Board withdraws, modifies or changes
in a manner adverse to Washington Mutual its approval or recommendation of the
Merger, (b) Washington Mutual terminates the Merger Agreement because the Great
Western Board either recommends a third party tender or exchange offer for 25%
or more of the outstanding shares of Common Stock or fails to recommend that
stockholders reject such tender or exchange offer, (c) either Washington Mutual
or Great Western terminates the Merger Agreement because the Great Western
stockholders fail to approve the Merger Agreement, but only if at the time of
such failure, an alternative proposal to acquire Great Western has been publicly
disclosed (or any person shall have publicly disclosed an intention (whether or
not conditional) to make an alternative takeover proposal; for this purpose, the
Ahmanson Proposal, if not unconditionally withdrawn prior to the mailing to
Great Western stockholders of this Joint Proxy Statement/Prospectus, would be
such an alternative proposal), or (d) Washington Mutual terminates the Merger
Agreement as a result of the willful breach by Great Western of any material
representation, warranty, covenant or other agreement in the Merger Agreement,
but only if at or prior to the time of termination, an alternative takeover
proposal to acquire Great Western has been made known to Great Western or has
been publicly disclosed, whether or not such alternative proposal is rejected by
Great Western or withdrawn prior to the time of termination. For purposes of
clause (d) above, the Ahmanson Proposal made prior to the date of the Merger
Agreement is not deemed to be such an alternative takeover proposal; however,
any alternative takeover proposal made by Ahmanson after the date of the Merger
Agreement, or any amendment or modification made after that date to the Ahmanson
Proposal would constitute such an alternative proposal. An additional $100
million fee is payable by Great Western to Washington Mutual if, within 18
months after termination of the Merger Agreement under the circumstances
described above, Great Western enters into a definitive agreement with respect
to or consummates an alternative proposal for an acquisition of Great Western by
a third party.
 
     The termination fees described above, which Washington Mutual and Great
Western believe are customary and typical for transactions such as the proposed
Merger, are intended, among other things, to increase the likelihood that the
Merger will be consummated on the terms set forth in the Merger Agreement and,
if the Merger is not consummated under certain circumstances involving an
acquisition or potential acquisition of Great Western by a third party, to
compensate Washington Mutual for its efforts undertaken, expenses incurred and
business opportunities lost in connection with the proposed Merger. These
agreements may have the effect of discouraging offers by third parties to
acquire Great Western prior to the Merger, even if such persons were prepared to
offer to pay consideration to Great Western Stockholders that has a higher
current market price than the shares of Washington Mutual Common Stock to be
received by the holders of Great Western Common Stock pursuant to the Merger
Agreement. Ahmanson has filed suit in the Court of Chancery of the State of
Delaware to enjoin all steps necessary for consummation of the Merger and is
challenging the termination fee described above. See "Litigation" and "The
Merger -- Background of the Merger."
 
                                       57
<PAGE>   63
 
EXTENSION, WAIVER AND AMENDMENT OF THE MERGER AGREEMENT
 
     At any time prior to the Effective Time, Great Western and Washington
Mutual, by action taken or authorized by their respective boards of directors,
may, to the extent legally allowed, (i) extend the time for the performance of
any of the obligations or other acts of the other parties, (ii) waive any
inaccuracies in the representations and warranties contained in the Merger
Agreement and (iii) waive compliance with any of the agreements or conditions
contained in the Merger Agreement. Subject to compliance with applicable law,
the Merger Agreement may be amended at any time by an agreement among the
parties, approved or authorized by their respective boards of directors; except
that after any approval of the transactions contemplated by the Merger Agreement
by the Great Western Stockholders, there may not be, without further approval of
such stockholders, any amendment to the Merger Agreement that reduces the amount
or changes the form of the consideration to be delivered to the Great Western
Stockholders thereunder.
 
INTERESTS OF CERTAIN PERSONS IN THE MERGER
 
     Certain members of Great Western's management and the Great Western Board,
respectively, may be deemed to have certain interests in the Merger that are in
addition to their interests as stockholders of Great Western, generally. The
Great Western Board was aware of these interests and considered them, among
other matters, in approving the Merger Agreement and the transactions
contemplated thereby.
 
     Board of Directors.  Pursuant to the terms of the Merger Agreement, members
of the Washington Mutual Board will continue to serve on the Washington Mutual
Board and, at the Effective Time, Washington Mutual will take all action
necessary to appoint four representatives of Great Western, mutually agreeable
to Washington Mutual and Great Western, to the Washington Mutual Board. See
"Management and Operations of Washington Mutual Following the Merger."
 
     Indemnification; Directors' and Officers' Insurance.  The Merger Agreement
requires that Washington Mutual and Great Western, to the extent set forth in
the following paragraph, cooperate and use their best efforts to defend and
respond to any threatened or actual claim, action, suit, proceeding or
investigation, whether civil, criminal or administrative, whether asserted or
arising before or after the Effective Time (each a "Claim"), against each
present and former director, officer and employee of Great Western and its
subsidiaries (each an "Indemnified Party"), arising in whole or in part out of
(i) his or her actions as such a director, officer, employee, or serving on
behalf of such a person, or (ii) the Merger Agreement or any actions in
connection therewith.
 
     The Merger Agreement also requires Washington Mutual after the Effective
Time to indemnify and hold harmless, as and to the fullest extent permitted by
the corporate governance documents of Great Western and its Subsidiaries, the
indemnification letters between Great Western and each of its directors and
executive officers (the "Indemnification Letters") and by law, each Indemnified
Party against any losses, claims, damages, liabilities, costs, expenses
(including reasonable attorneys' fees and 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 an undertaking from
such Indemnified Party to repay such advanced expenses if it is finally and
unappealably determined that such Indemnified Party was not entitled to
indemnification hereunder), 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 Time), the Indemnified Parties may retain counsel reasonably
satisfactory to them after consultation with Washington Mutual except as
provided in the Merger Agreement.
 
     These indemnification obligations of Washington Mutual will continue in
full force for at least six years after the Effective Time and will apply to any
Claim asserted or made within such period (including, without limitation, Claims
arising out of or pertaining to the transactions contemplated by the Merger
Agreement).
 
     The Merger Agreement requires that Washington Mutual use its best efforts
to cause the persons serving as officers and directors of Great Western
immediately prior to the Effective Time to be covered for a period of six years
from the Effective Time by the directors' and officers' liability insurance
policy maintained by Great
 
                                       58
<PAGE>   64
 
Western (provided that Washington Mutual may substitute therefor policies of at
least the same coverage and amounts containing terms and conditions which are
not less advantageous to such directors and officers of Great Western than the
terms and conditions of such existing policy) with respect to acts or omissions
occurring prior to the Effective Time which were committed by such officers and
directors in their capacity as such.
 
     Employment Agreements.  Great Western has entered into employment
agreements (the "EMC Agreements") with the members of its Executive Management
Committee which provide, among other things, for severance payments upon certain
terminations of employment prior to, or during the two year period (three years,
in the case of Mr. Maher's agreement) following, a change in control of Great
Western. In order to qualify for the severance benefits described below,
termination of employment must be (i) by Great Western or a successor employer
other than for "cause" (as such term is defined in the EMC Agreements) or (ii)
by the executive because of a material breach of the EMC Agreement by Great
Western or a successor employer which is not cured within fifteen days after
receipt of notice thereof. The EMC Agreements provide that, following a
qualifying termination, the executive is entitled to receive (a) a lump sum
payment equal to the product of (1) the sum of (A) the executive's annual base
salary plus (B) the executive's target bonus under Great Western's Annual
Incentive Plan for Executive Officers (the "Executive Officer Incentive Plan")
in respect of the year in which such termination occurs (or the year in which
the change in control occurs, whichever is greater) and (2) the number three,
and (b) a pro-rata target bonus under the Executive Officer Incentive Plan in
respect of the year in which such termination occurs, provided, that if the
termination occurs during the same year in which the change in control occurs,
the amount described in this clause (b) will be offset by any payments received
under the Executive Officer Incentive Plan in connection with the change in
control. In addition, the executive would be entitled to continuation of
welfare-type benefits for three years following such termination. Mr. Maher's
EMC Agreement provides that he may elect to terminate his employment, without a
material breach by Great Western or a successor employer, and receive the
benefits described above during the period commencing no earlier than eighteen
months following a change in control of Great Western and ending no later than
the second anniversary of such change in control; provided, that the
eighteen-month minimum period shall not apply if, at any time during the first
year following such change in control, more than 50% of the non-employee members
of the Great Western Board as of the date immediately preceding the change in
control are no longer members of the Great Western Board; and provided further,
that, if Mr. Maher elects to so terminate his EMC Agreement, cash benefits which
would become payable will be reduced by 25%. If any payments received by an
executive under his or her EMC Agreement or any other benefit plan, agreement or
arrangement in which such executive participates would be subject to an excise
tax ("Excise Tax") under Section 4999 of the Code, he or she will be entitled to
receive any additional amount necessary to make such executive whole with
respect to such Excise Tax. If the value of the aggregate payments which are
contingent upon a change in control of Great Western ("parachute payments") is
less than specified Code limits that currently approximate three times the
average of an executive's compensation for the prior five years (the "Section
280G Limit") for any reason (including that some or all of such entitlement does
not constitute a parachute payment), the executive is entitled to receive the
Section 280G Limit. Consummation of the Merger will constitute a change in
control of Great Western for purposes of the EMC Agreements.
 
     Consulting Agreement.  Great Western has entered into a consulting
agreement (the "Consulting Agreement") with Mr. Montgomery that has a term which
expires December 31, 2000 and which provides, among other things, that Mr.
Montgomery will serve as Chairman of the Board of Great Western for a term
ending no earlier than December 31, 1997. If, during the term of the Consulting
Agreement, Great Western or its successor materially breaches the Consulting
Agreement and fails to cure such breach within fifteen days of notice thereof,
Mr. Montgomery is entitled to terminate the Consulting Agreement and receive his
annual consulting fees until the expiration of the term. In no event will
payments to Mr. Montgomery which
are contingent upon a change of control of Great Western ("parachute payments")
exceed the Section 280G Limit. Notwithstanding the foregoing, if the value of
such aggregate entitlement constituting parachute payments is less than the
Section 280G Limit for any reason (including that some or all of such
entitlement does not constitute a parachute payment), Mr. Montgomery is entitled
to receive the Section 280G Limit.
 
                                       59
<PAGE>   65
 
     Supplemental Retirement Plans.  Great Western's Supplemental Executive
Retirement Plan (the "SERP") provides that if, prior to, or within 24 months
following, a change in control of Great Western, an executive officer's
employment is terminated under circumstances which would entitle such officer to
receive the severance benefits payable under his or her EMC Agreement, such
officer will be entitled to receive retirement benefits that are not actuarially
reduced for early retirement. Great Western's Retirement Restoration Plan
provides for the vesting of benefits payable thereunder if a participant incurs
a qualifying termination of employment prior to, or within 24 months following,
a change in control of Great Western. Consummation of the Merger will constitute
a change in control of Great Western for purposes of these plans.
 
     Deferred Compensation Plans.  Great Western's deferred compensation plans
provide for full vesting (where applicable) of employer matching contributions
upon a change in control of Great Western or if an employee participant incurs a
termination of employment under circumstances that would entitle such employee
participant to receive severance benefits under his or her EMC Agreement (if
such participant is an executive officer) or, if the employee is not an
executive officer, under the Special Severance Plan (as defined below) (whether
or not a participant in such Plan). In addition, a participant may, prior to a
change in control, elect to receive the full amount of his or her account
balances in a lump sum within 45 days following such change in control, and may,
during the 2-year period following a change in control, elect to receive 95% of
his or her account balances in a lump sum. Consummation of the Merger will
constitute a change in control of Great Western for purposes of these plans.
 
     Great Western Equity-Based Incentive Awards.  The provisions of the Merger
Agreement relating to the conversion of Great Western Stock Options outstanding
under Great Western Stock Plans into stock options for Washington Mutual Common
Stock are described under the "The Merger -- Conversion of Great Western Capital
Stock." Pursuant to the terms of the Great Western Stock Plans, upon
consummation of the Merger, each Great Western Common Stock Option held by
employees and directors will become immediately exercisable, all shares of
restricted stock will immediately vest free of restrictions and all other awards
granted thereunder will become fully vested and exercisable.
 
     Great Western Cash-Based Incentive Awards.  Great Western maintains
separate cash-based incentive plans for the benefit of its executive officers
and its subsidiaries' senior officers, respectively. Each of these plans
provides that, within five days following a change in control of Great Western,
a participant will receive a pro-rata portion of such participant's target bonus
for the year in which such change in control occurs. The consummation of the
Merger will constitute a change in control of Great Western for purposes of
these cash-based incentive plans. These amounts are in addition to any severance
benefits which may be paid to executive officers under the EMC Agreements, to
participants in the Special Severance Plan and to certain participants under the
Severance Plan (each as defined below); however, the amounts payable upon a
change in control of Great Western under the Executive Officer Incentive Plan
and the Special Severance Plan will offset any pro-rata bonus which may become
payable under the EMC Agreements and the Special Severance Plan as a part of
severance benefits, if such pro-rata bonus becomes payable during the year in
which a change in control occurs.
 
     Umbrella Trusts.  Great Western maintains two "rabbi trusts" (the "Trusts")
for the purposes of funding benefits payable under the following Great Western
benefit plans and agreements: the EMC Agreements; the Great Western deferred
compensation plans; the SERP; the Retirement Restoration Plan; the consulting
agreement between Great Western and Mr. James F. Montgomery, the Chairman and
former Chief Executive Officer of Great Western; supplemental retirement benefit
for Mr. Firmin A. Gryp, a director of Great Western; and Great Western's
retirement plan for directors. Each of the Trusts provides for full funding
thereof upon the occurrence of certain events which would anticipate a change in
control of Great Western. The delivery of the Ahmanson Proposal on February 17,
1997, constitutes such an event, and the Trusts will be so funded.
 
EMPLOYEE MATTERS
 
     Employee Benefit Plans.  The Merger Agreement provides that for a period of
at least one year from and after the Effective Time, Washington Mutual will
provide to employees of Great Western immediately prior to
 
                                       60
<PAGE>   66
 
the Effective Time ("Great Western Employees") compensation and benefits on
terms no less favorable in the aggregate than those provided to similarly
situated employees of Washington Mutual. For purposes of all employee benefit
plans of Washington Mutual or its subsidiaries in which Great Western Employees
participate from and after the Effective Time (including all policies and
employee fringe benefit programs, including vacation policies, of Washington
Mutual or its subsidiaries but excluding Washington Mutual's Service Award Plan)
and under which an employee's benefit depends, in whole or in part, on length of
service, credit will be given to Great Western Employees for service previously
credited with the Great Western or its subsidiaries prior to the Effective Time
to the extent that such crediting of service does not result in duplication of
benefits, provided that Washington Mutual will determine each Great Western
Employee's length of service in a manner consistent with Washington Mutual's
customary practice with respect to its employees. Washington Mutual will also
cause each employee benefit plan in which Great Western Employees participate
from and after the Effective Time to waive (i) any preexisting condition
restriction which was waived under the terms of any analogous Great Western
employee benefit plan immediately prior to the Effective Time or (ii) any
waiting period limitation which would otherwise be applicable to a Great Western
Employee on or after the Effective Time to the extent such Great Western
Employee had satisfied any similar waiting period limitation under an analogous
Great Western employee benefit plan prior to the Effective Time. For a period of
three (3) years, in the case of those beneficiaries who are entitled to
participate in such Program pursuant to employment agreements, or two (2) years,
in the case of those beneficiaries who are otherwise entitled to participate in
such Program, commencing on the Effective Time, Washington Mutual has agreed
that it will continue to maintain Great Western's Executive Medical Program, on
terms no less favorable that those in effect as of March 5, 1997, for the
benefit of those Great Western Employees who are as of the date of the Merger
Agreement eligible to participate in such Program.
 
     Pursuant to the Merger Agreement, Washington Mutual has agreed to honor in
accordance with their terms all of Great Western's employee benefit plans
("Great Western Plans"), provided that Washington Mutual will be entitled to
terminate such plans, agreements and arrangements in accordance with their terms
and applicable law. In addition, Washington Mutual and Great Western have agreed
that consummation of the Merger will constitute a "Change in Control" for
purposes of Great Western's employee benefit plans that contain change in
control provisions and have agreed to honor such change in control provisions,
including, but not limited to, the accelerated vesting and/or payment of
equity-based awards under Great Western's employee benefit plans. Great Western
has agreed to make no further mortgage loans to employees under the Great
Western employee home loan program; to amend the Great Western retiree medical
plans so that no additional retirees shall become entitled to continuing medical
insurance benefits thereunder; and to amend Great Western's 401(k) plan prior to
Closing so that participant loans are no longer available.
 
     Severance Plans.  Great Western has adopted for the benefit of its senior
vice presidents (and officers of equivalent rank) and first vice presidents (and
officers of equivalent rank) a severance plan (the "Special Severance Plan")
which provides for certain benefits to be paid and provided in the event of a
qualifying termination of employment prior to, or during the two-year period
following, a change in control of Great Western. In order to qualify for the
severance benefits described below, termination of employment must be (i) by
Great Western or a successor employer other than for "cause" or (ii) by the
executive for "good reason" (as each such term is defined in the Special
Severance Plan). The Special Severance Plan provides that, following a
qualifying termination, a participant is entitled to receive (a) a lump sum
payment equal to two times (for senior vice presidents and officers of
equivalent rank) or one and one-half times (for first vice presidents and
officers of equivalent rank) the sum of (1) such executive's annual base salary
and (2) such executive's target bonus under Great Western's annual incentive
program for the year in which the termination of employment occurs (or the year
in which the change in control occurs, whichever is higher), and (b) a pro-rata
bonus for the year during which the termination of employment occurs, provided,
that if the termination occurs during the same year in which the change in
control occurs, the amount described in this clause (b) will be offset by any
payments received under Great Western's annual incentive program in connection
with the change in control. In addition, the executive will be entitled to the
continuation of welfare-type benefits for 24 months (in the case of senior vice
presidents and officers of equivalent rank) or 18 months (in the case of first
vice presidents and officers of equivalent rank). The Special Severance Plan
provides that no payment will be made to a participant that would be
nondeductible by reason of Section 280G
 
                                       61
<PAGE>   67
 
of the Code. Consummation of the Merger will constitute a change in control of
Great Western for purposes of the Special Severance Plan.
 
     Great Western has also adopted a broad-based severance plan (the "Severance
Plan") for the benefit of eligible Great Western Employees who are not offered a
comparable position by an acquiring company or whose employment is terminated
within twelve months of a change in control of Great Western. Eligible employees
may receive the following benefits and payments: 60 days' non-working notice
pay; one month's salary for every full year of service, payable at such
employee's election in a lump sum or pursuant to Great Western's payroll
policies (subject to a four-month minimum and sixteen-month maximum);
continuation of group insurance coverage for a period corresponding to the
aggregate number of months of non-working notice pay and severance pay (but not
if severance is paid in a lump sum); additional contribution credits under Great
Western's retirement plan and credit for additional service for purposes of
calculating benefits thereunder; extension of mortgage loans under Great
Western's employee home loan program so long as the employee resides in the
residence; and certain other benefits.
 
ACCOUNTING TREATMENT
 
     The Merger is intended to be treated as a pooling of interests for
accounting purposes. Accordingly, under generally accepted accounting
principles, the assets and liabilities of Great Western will be recorded on the
books of Washington Mutual at their values on the books of Great Western at the
time of consummation of the Merger. If completed as proposed, no goodwill will
be created as a result of the Merger.
 
     Pursuant to the Merger Agreement, each of Great Western and Washington
Mutual are required to use its reasonable best efforts to deliver from each
party who may be deemed to be an "affiliate" of such party (collectively, the
"Affiliates") for the purposes of SEC Accounting Series Release No. 130 as
amended by Release No. 135 ("ASR 135"), to the other party an Affiliate Letter,
pursuant to which, among other things, each Affiliate agrees, with certain
limited exceptions, not to sell or otherwise dispose of any interest in the
Great Western Capital Stock, Washington Mutual Common Stock or Series F
Preferred Stock during the period commencing 30 days preceding the Effective
Date until such time as consolidated financial results covering at least 30 days
of post-Merger combined operations of Washington Mutual and Great Western have
been published.
 
NO APPRAISAL OR DISSENTERS' RIGHTS
 
     Great Western. Great Western Stockholders do not have any appraisal rights
under Delaware law in connection with the Merger Agreement or the consummation
of the transactions contemplated thereby.
 
     Washington Mutual. Washington Mutual Shareholders do not have dissenters'
rights under Washington law in connection with the Merger, the Share Issuance or
the amendment of the Washington Mutual Articles.
 
EXCHANGE OF CERTIFICATES AND DEPOSITARY RECEIPTS; FRACTIONAL SHARES
 
     Great Western. At or prior to the Effective Time, Washington Mutual will
deposit, or cause to be deposited, with an exchange agent (the "Exchange
Agent"), for the benefit of the holders of certificates of Great Western Capital
Stock, certificates representing the shares of Washington Mutual Common Stock
and Series F Preferred Stock (and cash in lieu of fractional shares of
Washington Mutual Common Stock, if applicable).
 
     As soon as is practicable after the Effective Time, and in no event later
than ten business days thereafter, the Exchange Agent will mail a form of
transmittal letter to the holders of certificates representing shares of Great
Western Common Stock. The form of transmittal letter will contain instructions
with respect to the surrender of such certificates in exchange for shares of
Washington Mutual Common Stock (and cash in lieu of fractional shares of
Washington Mutual Common Stock, if applicable).
 
     The Preferred Stock Depositary is the only holder of record of shares of
the Great Western Preferred Stock, which is represented by the Great Western
Depositary Shares. The Exchange Agent will effect the exchange of certificates
representing the Great Western Preferred Stock for certificates representing the
new
 
                                       62
<PAGE>   68
 
Series F Preferred Stock in connection with the Merger. All holders of record of
Great Western Depositary Shares evidenced by Great Western Depositary Receipts
are instructed to follow the exchange procedures outlined immediately below.
 
     Promptly after the Effective Time, the Preferred Stock Depositary will mail
to each holder of record of Great Western Depositary Shares a notice advising
the holder of the effectiveness of the Merger accompanied by a transmittal form
(the "Depositary Receipt Transmittal Form"). The Depositary Receipt Transmittal
Form will contain instructions with respect to the surrender of Great Western
Depositary Receipts evidencing the Great Western Depositary Shares and will
specify that delivery will be effected, and risk of loss and title to such Great
Western Depositary Receipts will pass, only upon delivery of the Great Western
Depositary Receipts to the Preferred Stock Depositary. Upon surrender in
accordance with the instructions contained in the Depositary Receipt Transmittal
Form to the Preferred Stock Depositary of Great Western Depositary Receipts
evidencing the Great Western Depositary Shares, the holder thereof will be
entitled to receive in exchange therefor New Washington Mutual Depositary
Receipts evidencing the appropriate number of corresponding New Washington
Mutual Depositary Shares.
 
     No dividends or other distributions declared with respect to Washington
Mutual Common Stock or Series F Preferred Stock (including the related New
Washington Mutual Depositary) with a record date after the Effective Time will
be paid to the holder of any certificate representing shares of Great Western
Capital Stock or Great Western Depositary Receipts until such certificate or
receipt have been surrendered for exchange. Holders of certificates representing
shares of Great Western Common Stock or Great Western 8.30% Preferred Stock (or
Great Western Depositary Receipts representing Great Western Depositary Shares)
will be paid the amount of dividends or other distributions with a record date
after the Effective Time after surrender of such certificates, without any
interest thereon.
 
     No fractional shares of Washington Mutual Common Stock will be issued to
any holder of Great Western Common Stock upon consummation of the Merger. In
lieu of each fractional share that will otherwise be issued, Washington Mutual
will pay cash in an amount equal to such fraction multiplied by the average of
the closing sale prices of Washington Mutual Common Stock on NASDAQ for the five
trading days immediately preceding the date on which the Effective Time occurs.
No interest will be paid or accrued on the cash in lieu of fractional shares
payable to holders of such certificates. No such holder will be entitled to
dividends, voting rights or any other rights as a shareholder in respect of any
fractional share of Washington Mutual Common Stock that such holder otherwise
would have been entitled to receive.
 
     None of Washington Mutual, NACI, Great Western, the Exchange Agent, the
Preferred Stock Depositary or any other person would be liable to any former
holder of Great Western Capital Stock or a Great Western Depositary Receipt for
any amount properly delivered to a public official pursuant to applicable
abandoned property, escheat or similar laws.
 
     If a certificate representing Great Western Common Stock or a Great Western
Depositary Receipt has been lost, stolen or destroyed, the Exchange Agent, in
the case of Great Western Common Stock, or the Preferred Stock Depositary, in
the case of a Great Western Depositary Receipt, will issue the consideration
properly payable in accordance with the Merger Agreement upon receipt of
appropriate evidence as to such loss, theft or destruction, appropriate evidence
as to the ownership of such certificate or receipt by the claimant, and
appropriate and customary indemnification.
 
     For a description of the differences between the rights of the holders of
Washington Mutual Common Stock and Great Western Common Stock, see "Comparison
of Rights of Holders of Great Western Common Stock and Washington Mutual Common
Stock." For a description of the Washington Mutual Capital Stock, including the
Series F Preferred Stock and the New Washington Mutual Depositary Shares, see
"Description of Washington Mutual Capital Stock."
 
     Shares of Washington Mutual Common Stock and Preferred Stock issued and
outstanding immediately prior to the Effective Time would remain issued and
outstanding and be unaffected by the Merger, and holders of such stock would not
be required to exchange the certificates representing such stock or take any
other action by reason of the consummation of the Merger.
 
                                       63
<PAGE>   69
 
CERTAIN FEDERAL INCOME TAX CONSEQUENCES
 
     THE FOLLOWING IS A SUMMARY OF THE MATERIAL FEDERAL INCOME TAX CONSEQUENCES
OF THE MERGER TO THE SHAREHOLDERS OF WASHINGTON MUTUAL AND THE STOCKHOLDERS OF
GREAT WESTERN. THIS SUMMARY DOES NOT ADDRESS ALL THE TAX CONSEQUENCES OF THE
MERGER. EACH SHAREHOLDER'S INDIVIDUAL CIRCUMSTANCES MAY AFFECT THE TAX
CONSEQUENCES OF THE MERGER TO SUCH SHAREHOLDER. THIS SUMMARY MAY NOT APPLY TO
CERTAIN CLASSES OF TAXPAYERS, INCLUDING, WITHOUT LIMITATION, INSURANCE
COMPANIES, TAX-EXEMPT ORGANIZATIONS, FINANCIAL INSTITUTIONS, DEALERS IN
SECURITIES, PERSONS WHO ACQUIRED OR ACQUIRE SHARES OF GREAT WESTERN STOCK
PURSUANT TO THE EXERCISE OF DIRECTOR OR EMPLOYEE STOCK OPTIONS OR RIGHTS OR
OTHERWISE AS COMPENSATION AND PERSONS WHO HOLD SHARES OF GREAT WESTERN STOCK IN
A HEDGING TRANSACTION OR AS PART OF A STRADDLE OR CONVERSION TRANSACTION. IN
ADDITION, NO INFORMATION IS PROVIDED HEREIN WITH RESPECT TO THE TAX CONSEQUENCES
OF THE MERGER TO SHAREHOLDERS UNDER APPLICABLE FOREIGN, STATE OR LOCAL LAWS.
CONSEQUENTLY, EACH SHAREHOLDER IS URGED TO CONSULT SUCH SHAREHOLDER'S OWN TAX
ADVISOR AS TO THE SPECIFIC TAX CONSEQUENCES OF THE MERGER TO THAT SHAREHOLDER.
 
  WASHINGTON MUTUAL SHAREHOLDERS
 
     There will be no federal income tax consequences to the shareholders of
Washington Mutual as a result of either voting on the proposals described herein
or the consummation of the Merger.
 
  GREAT WESTERN STOCKHOLDERS
 
     The Merger is expected to constitute a "reorganization" within the meaning
of Section 368 of the Code. Consummation of the Merger is conditioned upon,
among other things, the receipt by Great Western of an opinion of Skadden, Arps,
Slate, Meagher & Flom LLP and the receipt by Washington Mutual of an opinion of
Foster Pepper & Shefelman, each dated as of the Effective Time, to the effect
that, on the basis of facts, representations and assumptions set forth therein,
the Merger will be treated for federal income tax purposes as a reorganization
within the meaning of Section 368(a) of the Code. The opinions will not,
however, be binding upon the Internal Revenue Service (the "IRS") or the courts.
No ruling from the IRS will be applied for with respect to the federal income
tax consequences of the Merger. There can be no assurance that the IRS will
agree with the conclusions set forth in this Joint Proxy Statement/Prospectus.
 
     Accordingly, such opinions will provide that no gain or loss will be
recognized by holders of Great Western Common Stock or Great Western Preferred
Stock who exchange such stock solely for Washington Mutual Common Stock or
Series F Preferred Stock, respectively, pursuant to the Merger (except with
respect to cash received in lieu of a fractional share interest in Washington
Mutual Common Stock). The aggregate tax basis of the Washington Mutual Common
Stock or Series F Preferred Stock received in the Merger will equal the
aggregate tax basis of the Great Western Common Stock or Great Western Preferred
Stock, as the case may be, surrendered in exchange therefor, reduced by the tax
basis of the Great Western Common Stock allocable to any fractional share of
Washington Mutual Common Stock in lieu of which cash is received. Provided the
Great Western Common Stock or Great Western Preferred Stock so surrendered was
held as a capital asset at the Effective Time, the holding period of the
Washington Mutual Common Stock or Series F Preferred Stock received will include
the holding period of shares of Great Western Common Stock or Great Western
Preferred Stock surrendered in exchange therefor.
 
     Each Great Western Common Stockholder who receives cash in lieu of a
fractional share of Washington Mutual Common Stock will be treated as receiving
a distribution in redemption of such share interest. In general, such
distribution in redemption will be treated as a payment in exchange for such
share interest, subject to the provisions and limitations of Code Section 302
(which in certain circumstances could result in the receipt of cash being
treated as a dividend). If treated as a payment in exchange for such share
interest,
 
                                       64
<PAGE>   70
 
gain or loss will be measured by the difference between the tax basis allocable
to the fractional share and the amount of cash received therefor. Such gain or
loss will be a capital gain or loss if the Great Western Common Stock was held
as a capital asset as of the Effective Time. Such capital gain or loss will be
treated as long-term capital gain or loss if the fractional share interest was
held for more than one year at the Effective Time.
 
  BACKUP WITHHOLDING
 
     The cash payments, if any, due holders of Great Western Common Stock (other
than certain exempt entities and persons) pursuant to the Merger will be subject
to a 31 percent backup withholding tax by the Exchange Agent under federal
income tax law unless certain requirements are met. Generally, the Exchange
Agent will be required to deduct and withhold the tax if (i) the shareholder
fails to furnish a taxpayer identification number ("TIN") to the Exchange Agent
or fails to certify under penalty of perjury that such TIN is correct, (ii) the
IRS notifies the Exchange Agent that the shareholder has failed to report
interest dividends or original issue discount in the past, or (iii) there has
been a failure by the shareholder to certify under penalty of perjury that such
shareholder is not subject to the 31 percent backup withholding tax. Any amounts
withheld by the Exchange Agent in collection of the 31 percent backup
withholding tax will generally be treated as a credit against the federal income
tax liability of the shareholder from whom such tax was withheld. The TIN of an
individual shareholder is the shareholder's Social Security Number.
 
     THE FOREGOING CONSTITUTES ONLY A GENERAL DESCRIPTION OF THE FEDERAL INCOME
TAX CONSEQUENCES OF THE MERGER TO GREAT WESTERN SHAREHOLDERS UNDER CURRENTLY
EXISTING FEDERAL INCOME TAX LAWS, WITHOUT CONSIDERATION OF THE PARTICULAR FACTS
AND CIRCUMSTANCES OF EACH SHAREHOLDER'S SITUATION. EACH GREAT WESTERN
SHAREHOLDER IS URGED TO CONSULT HIS OR HER OWN TAX AND FINANCIAL ADVISOR WITH
REGARD TO THE EFFECT OF THE MERGER ON SUCH SHAREHOLDER'S OWN SITUATION,
INCLUDING ANY ESTATE, GIFT, STATE, LOCAL OR FOREIGN TAX CONSEQUENCES ARISING OUT
OF THE MERGER AND/OR ANY SALE THEREAFTER OF WASHINGTON MUTUAL STOCK RECEIVED IN
THE MERGER.
 
DIVIDEND POLICY
 
  Washington Mutual
 
     Dividends may be paid on the Washington Mutual Common Stock as and when
declared by the Washington Mutual Board out of funds legally available for the
payment of dividends. The factors affecting this determination include
Washington Mutual's long-term interests, current and projected earnings,
adequacy of capitalization, expected asset and deposit growth as well as other
financial conditions, legal, regulatory and contractual restrictions, and tax
considerations.
 
     According to Washington law, Washington Mutual dividends may be paid only
if, after giving effect to the dividend, Washington Mutual will be able to pay
its debts as they become due in the ordinary course of business and Washington
Mutual's total assets will not be less than the sum of its total liabilities
plus the amount that would be needed, if Washington Mutual were to be dissolved
at the time of the dividend, to satisfy the preferential rights of persons whose
right to payment is superior to those receiving the dividend. Washington
Mutual's ability to pay dividends is also dependent on the ability of WMBfsb,
WMB and other subsidiary operations to pay dividends to Washington Mutual.
 
     The two series of outstanding Washington Mutual Preferred Stock rank prior
to the Washington Mutual Common Stock and to all other classes and series of
equity securities of Washington Mutual, other than any classes or series of
equity securities of Washington Mutual ranking on a parity with the Washington
Mutual Preferred Stock.
 
     The rights of holders of Washington Mutual Preferred Stock to receive
dividends is noncumulative. Accordingly, if the Washington Mutual Board fails to
declare a dividend on any dividend payment date, the holders of Washington
Mutual Preferred Stock will have no right to receive a dividend in respect of
the dividend period ending on such dividend payment date and Washington Mutual
will have no obligation to pay
 
                                       65
<PAGE>   71
 
the dividend accrued for such period, whether or not dividends are declared
payable on any future dividend payment dates.
 
     Full dividends on Washington Mutual Preferred Stock must be declared and
paid or set apart for payment for the most recent dividend period ended before
(i) any dividend (other than in Washington Mutual Common Stock) on stock junior
to the Washington Mutual Preferred Stock ("Junior Stock") may be declared or
paid or set aside for payment or other distribution made upon the Washington
Mutual Common Stock or on any other Junior Stock or (ii) Junior Stock is
redeemed (or any moneys are paid to or made available for a sinking fund for the
redemption of any share of any such stock) or any Junior Stock or stock on a
parity with Preferred Stock ("Parity Stock") is purchased or otherwise acquired
by Washington Mutual for any consideration except by conversion into or exchange
for Junior Stock.
 
     The Washington Mutual Board may issue Washington Mutual Preferred Stock
that is entitled to such dividend rights as the Washington Mutual Board may
determine, including priority over Washington Mutual Common Stock in the payment
of dividends.
 
  Great Western
 
     Holders of shares of Great Western Common Stock are entitled to receive
dividends from funds legally available therefor when, as and if declared by the
Great Western Board. Each quarter, the Great Western Board considers the payment
of dividends. The factors affecting this determination include Great Western's
long-term interests, current and projected earnings, adequacy of capitalization,
expected asset and deposit growth, as well as other financial conditions, legal,
regulatory and contractual restrictions, and tax considerations.
 
RESALE OF WASHINGTON MUTUAL CAPITAL STOCK RECEIVED BY GREAT WESTERN COMMON
STOCKHOLDERS
 
     The shares of Washington Mutual Common Stock to be issued to common
stockholders of Great Western upon consummation of the Merger have been
registered under the Securities Act. The shares of Washington Mutual Common
Stock and New Washington Mutual Depositary Shares that would be issued to
stockholders of Great Western upon consummation of the Merger could be traded
freely without restriction by those stockholders who are not deemed to be
"affiliates" of Great Western or Washington Mutual, as that term is defined in
rules promulgated under the Securities Act.
 
     Shares of Washington Mutual Common Stock and New Washington Mutual
Depositary Shares received by those stockholders of Great Western who are deemed
to be "affiliates" of Great Western at the time of the Great Western Meeting may
be resold without registration under the Securities Act only as permitted by
Rule 145 under the Securities Act or as otherwise permitted under the Securities
Act.
 
                                       66
<PAGE>   72
 
                               WASHINGTON MUTUAL
GENERAL
 
     Washington Mutual is a regional financial services company committed to
serving consumers and small to mid-sized businesses throughout the Western
United States. Through its subsidiaries, Washington Mutual engages in the
following activities:
 
     -  MORTGAGE LENDING AND CONSUMER BANKING ACTIVITIES. Through its principal
        subsidiaries, Washington Mutual Bank ("WMB"), American Savings Bank,
        F.A. ("ASB"), and Washington Mutual Bank fsb ("WMBfsb"), at December 31,
        1996, Washington Mutual operated 413 consumer financial centers and 96
        loan centers offering a full complement of mortgage lending and consumer
        banking products and services. In 1996, WMB was the leading originator
        of first-lien, single-family residential loans in Washington and Oregon,
        and ASB was the second largest such originator in California.
 
     -  COMMERCIAL BANKING ACTIVITIES. Through the commercial banking division
        of WMB, at December 31, 1996, Washington Mutual operated 48 full-service
        business branches offering a range of commercial banking products and
        services to small and mid-sized businesses. WMB commenced its commercial
        banking activities through the acquisition of Enterprise Bank of
        Bellevue, Washington in 1995 and Western Bank of Coos Bay, Oregon in
        1996.
 
     -  INSURANCE ACTIVITIES. Through WM Life Insurance Company and ASB
        Insurance Services Inc., Washington Mutual underwrites and sells
        annuities and sells a range of life insurance contracts, and selected
        property and casualty insurance policies.
 
     -  SECURITIES ACTIVITIES. Through ASB Financial Services, Inc., Murphey
        Favre, Inc. and Composite Research and Management Co. ("Composite
        Research"), Washington Mutual offers full service securities brokerage
        and acts as the investment advisor to and the distributor of mutual
        funds.
 
     Washington Mutual operates in Washington, California, Oregon, Utah, Idaho,
Montana, Arizona, Colorado and Nevada. At December 31, 1996, Washington Mutual
had consolidated assets of $44.6 billion, deposits of $24.1 billion and
stockholders' equity of $2.4 billion. Based on deposits, Washington Mutual was
at that date the second largest banking organization in Washington and the 28th
largest in the United States.
 
PRINCIPAL HOLDERS OF WASHINGTON MUTUAL COMMON STOCK
 
     The following table sets forth information regarding beneficial ownership
of Washington Mutual Common Stock by each person known to Washington Mutual to
have owned more than 5% of the outstanding shares of the Washington Mutual
Common Stock on February 24, 1997. The following is based solely on statements
filed with the Commission or other information believed by Washington Mutual to
be reliable. Each of the named shareholders has sole voting and investment power
with respect to the shares shown, except as noted below.
 
<TABLE>
<CAPTION>
                   NAME AND ADDRESS              SHARES OF COMMON STOCK
                  OF BENEFICIAL OWNER              BENEFICIALLY OWNED         PERCENT OF CLASS
        ---------------------------------------  ----------------------       ----------------
        <S>                                      <C>                          <C>
        Robert M. Bass.........................        11,379,576(1)(2)             9.01%
          201 Main Street, Suite 3100
          Fort Worth, Texas 76102
        FMR Corp...............................         6,481,795(3)                5.14%
          82 Devonshire Street
          Boston, Massachusetts 02109
</TABLE>
 
- ---------------
 
(1) Includes 1,901,276 shares held in escrow for the benefit of Keystone
    Holdings Partners, L.P. ("KH Partners") and its transferees pursuant to the
    merger agreement dated July 21, 1996, as amended November 1, 1996, by and
    among Washington Mutual, KH Partners, Keystone Holdings, Inc. and certain of
    its subsidiaries (the "Keystone Merger Agreement"). Pursuant to the Keystone
    Merger Agreement, shares of common stock received by KH Partners and a
    governmental entity were placed in escrow pending the outcome of certain
    litigation between Keystone Holdings, Inc. and the United States
 
                                       67
<PAGE>   73
 
    of America. Pursuant to the escrow, KH Partners and its transferees have the
    sole right to vote the Washington Mutual Common Stock received by KH
    Partners while it is in escrow. KH Partners has distributed such voting
    rights to its partners in accordance with their sharing percentages, and Mr.
    Robert M. Bass ("Mr. Bass"), as a limited partner of KH Partners, may
    therefore be deemed to be the beneficial owner of such 1,901,276 shares as
    to which voting rights have been distributed to him.
 
(2) A Schedule 13D was filed by Mr. Bass; Acadia Partners, L.P. ("Acadia"), a
    Delaware limited partnership; Acadia FW Partners, L.P. ("Acadia FW"), a
    Delaware limited partnership; Acadia MGP, Inc. ("Acadia MGP"), a Texas
    corporation; J. Taylor Crandall ("Mr. Crandall"); Capital Partnership, a
    Texas general partnership ("Capital"); Margaret Lee Bass 1980 Trust, a trust
    existing under the laws of Texas ("MLBT"); Panther City Investment Company,
    a Texas corporation ("Panther City"); W. Robert Cotham ("Mr. Cotham"); KH
    Carl Partners, L.P., a Delaware limited partnership ("KH Carl"); Bernard J.
    Carl ("Mr. Carl"); Rosecliff New American 1988 Partners, L.P., a Delaware
    limited partnership ("Rosecliff"); and Daniel J. Doctoroff ("Mr.
    Doctoroff"). The Schedule 13D indicated that based on overlapping employment
    and investment relationships, Mr. Bass, Acadia, Acadia FW, Acadia MGP, Mr.
    Crandall, Capital, MLBT, Panther City, W. Cotham, KH Carl, Mr. Carl,
    Rosecliff and Mr. Doctoroff may be deemed to constitute a "group" within the
    meaning of section 13(d)(3) of the Exchange Act, although the foregoing
    persons expressly disclaimed that any such "group" exists.
 
     Acadia beneficially owns 6,218,004 shares of Washington Mutual Common Stock
     and based on their relationship to Acadia, each of Acadia FW, Acadia MGP
     and Mr. Crandall, as President and sole stockholder of Acadia MGP, may also
     be deemed the beneficial owner of these 6,218,004 shares. Capital owns
     1,126,946 shares of Washington Mutual Common Stock and based on their
     relationship to Capital, MLBT, Panther City and Mr. Cotham may each also be
     deemed to be the beneficial owner of these 1,126,946 shares. Rosecliff owns
     1,062,535 shares of Washington Mutual Common Stock and Mr. Doctoroff, as
     sole general partner of Rosecliff, also beneficially owns these 1,026,535
     shares. Mr. Carl beneficially owns 2,298,162 shares of Washington Mutual
     Common Stock, of which 555,514 shares are owned by KH Carl.
 
(3) Includes 5,928,815 shares owned by Fidelity Management & Research Company, a
    wholly-owned subsidiary of FMR Corp.
 
PRINCIPAL HOLDERS OF WASHINGTON MUTUAL PREFERRED STOCK
 
     Washington Mutual knows of no person who owns more than 5% of the
outstanding shares of either the Series C Preferred or the Series E Preferred,
as of February 24, 1997.
 
SECURITY OWNERSHIP OF WASHINGTON MUTUAL BY DIRECTORS AND EXECUTIVE OFFICERS
 
     The following table and accompanying footnotes provides a summary of the
beneficial ownership of the Washington Mutual Common Stock, Series C Preferred
and Series E Preferred as of February 24, 1997, by (i) directors, (ii)
Washington Mutual's Chief Executive Officer, (iii) the highest compensated
executive officers other than the Chief Executive Officer and (iv) the directors
and executive officers as a group. The following summary is based on information
furnished by the respective directors and officers. Each of the
 
                                       68
<PAGE>   74
 
named directors and officers has sole voting and investment power with respect
to the shares shown, except as noted below.
 
<TABLE>
<CAPTION>
                                                                           COMMON STOCK(1)
                                                                           ----------------
                          NAME                    NUMBER OF SHARES(2)      PERCENT OF CLASS
        ----------------------------------------- -------------------      ----------------
        <S>                                       <C>                      <C>
        Douglas P. Beighle.......................          14,520(3)                *
        David Bonderman..........................       1,894,141(4)             1.50%
        Herbert M. Bridge........................          22,456(5)                *
        J. Taylor Crandall.......................       6,549,755(6)             5.19%
        Roger H. Eigsti..........................           7,000                   *
        John W. Ellis............................          28,775(7)                *
        Daniel J. Evans..........................          15,750(8)                *
        Anne V. Farrell..........................           4,000                   *
        William P. Gerberding....................           5,835                   *
        Kerry K. Killinger.......................       1,044,224(9)                *
        Lee D. Lannoye...........................          97,153(10)               *
        Samuel B. McKinney.......................           5,250                   *
        Michael K. Murphy........................           6,750(11)               *
        Deanna W. Oppenheimer....................          86,052(12)               *
        Louis H. Pepper..........................         255,854(13)               *
        William G. Reed, Jr......................          27,375(14)               *
        James H. Stever..........................           9,500(15)               *
        Craig E. Tall............................         266,714(16)               *
        S. Liane Wilson..........................         180,062(17)               *
        All directors and executive officers as a
          group (22 persons).....................      10,880,947(4)(6)(18)       8.62%
</TABLE>
 
- ---------------
* Less than 1%
 
 (1) Other than as set forth below, none of the above named officers and
     directors owned any shares of Series C Preferred or Series E Preferred as
     of February 28, 1997:
 
<TABLE>
<CAPTION>
                      SERIES C PREFERRED                NUMBER OF SHARES     PERCENT OF CLASS
        ----------------------------------------------  ----------------     ----------------
        <S>                                             <C>                  <C>
        Herbert M. Bridge.............................        200 shares       less than 1%
        James H. Stever...............................        500 shares       less than 1%
        All directors and executive officers as a
          group.......................................        700 shares       less than 1%
</TABLE>
 
<TABLE>
<CAPTION>
                      SERIES C PREFERRED                NUMBER OF SHARES     PERCENT OF CLASS
        ----------------------------------------------  ----------------     ----------------
        <S>                                             <C>                  <C>
        Louis H. Pepper...............................      1,525 shares       less than 1%
        Herbert M. Bridge.............................        800 shares       less than 1%
        All directors and executive officers as a
          group.......................................      2,325 shares       less than 1%
</TABLE>
 
 (2) Includes 3,000 shares issuable pursuant to stock options exercisable within
     60 days of February 24, 1997 by each of Messrs. Beighle, Eigsti, Ellis,
     Evans, Gerberding, Murphy, Pepper, Reed and Stever; 2,000 shares issuable
     pursuant to stock options exercisable within 60 days of February 24, 1997
     by each of Dr. McKinney and Mrs. Farrell, and 1,000 shares issuable
     pursuant to stock options exercisable within 60 days of February 24, 1997
     by Mr. Bridge.
 
 (3) Includes 1,350 shares held in a Keogh Plan.
 
 (4) Includes 255,517 shares held in escrow for the benefit of KH Partners and
     its transferees pursuant to the Keystone Merger Agreement. Such shares were
     placed in escrow pending the outcome of certain litigation between Keystone
     Holdings, Inc. and the United States of America. Pursuant to the escrow, KH
     Partners and its transferees have the sole right to vote such Washington
     Mutual Common Stock received by KH Partners while it is in escrow. KH
     Partners has distributed such voting rights to its partners in accordance
     with their sharing percentages, and Mr. Bonderman, as a limited partner of
     KH Partners, may therefore be deemed to be the beneficial owner of such
     shares of the Washington Mutual Common Stock as to which voting rights have
     been distributed to him. Includes also 364,810 shares
 
                                       69
<PAGE>   75
 
     owned by KH Group Management, Inc. ("KH Group"), of which 60,952 shares are
     held in escrow for the benefit of KH Group and its transferees pursuant to
     the Keystone Merger Agreement. (See footnote 1 to the table in "Principal
     Holders of Washington Mutual Common Stock" above). KH Group, as a limited
     partner of KH Partners, may be deemed to be the beneficial owner of such
     shares of the Washington Mutual Common Stock as to which voting rights have
     been distributed to it.
 
 (5) All shares are held jointly with Mr. Bridge's spouse. Mr. Bridge intends to
     retire as a director effective April 15, 1997.
 
 (6) Includes 6,218,004 shares owned by Acadia. Mr. Crandall is the president
     and sole stockholder of Acadia MGP, which is the managing general partner
     of Acadia FW, which is the sole general partner of Acadia, which is the
     direct beneficial owner of these 6,218,004 shares.
 
 (7) Includes 14,275 shares held in a Keogh plan and 1,500 shares held in trust
     for the benefit of Mr. Ellis' grandchildren.
 
 (8) Includes 5,175 shares held jointly with Mr. Evans' spouse and 7,575 shares
     held in a Keogh Plan, which is part of the Evans Family Revocable Trust, of
     which Mr. Evans and his spouse serve as co-trustees.
 
 (9) Includes 463,916 shares issuable pursuant to stock options exercisable
     within 60 days of February 24, 1997 and 43,401 shares subject to
     shareholder approval of Washington Mutual's 1997 Amended and Restated
     Restricted Stock Plan and to divestiture under Washington Mutual's existing
     1994 Restricted Stock Plan (the "Restricted Stock Plan") if Washington
     Mutual fails to achieve certain earnings goals.
 
(10) Includes 32,856 shares issuable pursuant to stock options exercisable
     within 60 days of February 24, 1997 and 9,384 shares subject to shareholder
     approval of Washington Mutual's 1997 Amended and Restated Restricted Stock
     Plan and to divestiture under the Restricted Stock Plan if Washington
     Mutual fails to achieve certain earnings goals.
 
(11) Includes 1,500 shares held jointly with Mr. Murphy's spouse.
 
(12) Includes 29,000 shares issuable pursuant to stock options exercisable
     within 60 days of February 24, 1997 and 14,076 shares subject to
     shareholder approval of Washington Mutual's 1997 Amended and Restated
     Restricted Stock Plan and to divestiture under the Restricted Stock Plan if
     Washington Mutual fails to achieve certain earnings goals.
 
(13) Mr. Pepper is retiring as a director. His term as a director ends upon the
     election of his successor at the Washington Mutual 1997 Annual Meeting of
     Shareholders.
 
(14) All shares are held jointly with Mr. Reed's spouse.
 
(15) Includes 800 shares held in the Stever Family Foundation, for which Mr.
     Stever is the President, and 4,500 shares are held jointly with Mr.
     Stever's spouse.
 
(16) Includes 94,666 shares issuable pursuant to stock options exercisable
     within 60 days of February 24, 1997 and 16,422 shares subject to
     shareholder approval of Washington Mutual's 1997 Amended and Restated
     Restricted Stock Plan and to divestiture under the Restricted Stock Plan if
     Washington Mutual fails to achieve certain earnings goals.
 
(17) Includes 81,833 shares issuable pursuant to stock options exercisable
     within 60 days of February 24, 1997 and 16,422 shares subject to
     shareholder approval of Washington Mutual's 1997 Amended and Restated
     Restricted Stock Plan and to divestiture under the Restricted Stock Plan if
     Washington Mutual fails to achieve certain earnings goals.
 
(18) Includes, in the aggregate, 756,335 shares issuable pursuant to stock
     options exercisable within 60 days of February 24, 1997, and 133,722 shares
     subject to shareholder approval of Washington Mutual's 1997 Amended and
     Restated Restricted Stock Plan and to divestiture under the Restricted
     Stock Plan if Washington Mutual fails to achieve certain earnings goals.
 
                                       70
<PAGE>   76
 
                                 GREAT WESTERN
 
GENERAL
 
     Great Western, with consolidated assets of approximately $42.9 billion at
December 31, 1996, is a savings and loan holding company organized in 1955 under
the laws of the state of Delaware. The principal assets of Great Western are the
capital stock of GW Bank and Aristar. GW Bank is a federally chartered stock
savings bank and conducts most of its retail banking through 416 offices located
in California and Florida. Real estate lending operations are conducted directly
by GW Bank through more than 200 offices in 27 states with concentrations in
California, Florida, Texas and Washington. Directly or through its subsidiaries,
GW Bank also engages in mortgage banking, and other related financial services.
Aristar conducts consumer finance operations through 502 offices in 23 states,
most of which operate principally under the names Blazer Financial Services or
City Finance Company and provide direct installment loans and related credit
insurance services and purchase retail installment contracts.
 
PRINCIPAL HOLDERS OF GREAT WESTERN COMMON STOCK
 
     The following table sets forth the number of shares of each class of equity
securities of Great Western beneficially owned as of February 24, 1997 (with the
exception of shares held in Great Western's Employee Savings Plan, which are
reported as of December 31, 1996) by each director and certain executive
officers and by all directors and executive officers as a group (17 persons).
Beneficial ownership is defined in accordance with the rules of the Commission
and means generally the power to vote or dispose of securities, regardless of
any economic interest.
 
<TABLE>
<CAPTION>
                                                                                         PERCENT OF
                                                                AMOUNT AND NATURE OF     OUTSTANDING
                                                               BENEFICIAL OWNERSHIP OF     COMMON
                   NAME OF BENEFICIAL OWNER                    SHARES OF COMMON STOCK       STOCK
- -------------------------------------------------------------- -----------------------   -----------
<S>                                                            <C>                       <C>
David Alexander...............................................           22,675(2)            (1)
H. Frederick Christie.........................................           26,250(2)            (1)
Charles D. Miller.............................................           30,000(3)            (1)
Stephen E. Frank..............................................           41,250(4)            (1)
John V. Giovenco..............................................           38,750(2)            (1)
Firmin A. Gryp................................................          103,644(2)(5)         (1)
Enrique Hernandez, Jr. .......................................            9,250(4)            (1)
James F. Montgomery...........................................          605,488(6)            (1)
Alberta E. Siegel.............................................           25,000(2)            (1)
Willis B. Wood, Jr. ..........................................           16,750(7)            (1)
John F. Maher.................................................          611,762(8)            (1)
J. Lance Erikson..............................................          119,845(9)            (1)
Carl F. Geuther...............................................          220,350(10)           (1)
Michael M. Pappas.............................................          249,525(11)           (1)
A. William Schenck, III.......................................           68,288(12)           (1)
Jaynie M. Studenmund..........................................           10,600               (1)
Raymond W. Sims...............................................                0
All Directors and Executive Officers as a Group...............        2,199,427(13)          1.58%
</TABLE>
 
- ---------------
 
 (1) Certain directors and executive officers share with their spouses voting
     and investment powers with respect to these shares. The percentage of
     shares beneficially owned by any director or executive officer does not
     exceed one percent of the outstanding shares of Common Stock.
 
 (2) Includes 21,250 shares subject to options granted to this Director under
     Great Western's 1988 Stock Option and Incentive Plan (the "1988 Incentive
     Plan") which are exercisable within 60 days of February 24, 1997.
 
                                       71
<PAGE>   77
 
 (3) Includes 18,750 shares subject to options granted to this Director under
     the 1988 Incentive Plan which are exercisable within 60 days of February
     24, 1997.
 
 (4) Includes 8,750 shares subject to options granted to this Director under the
     1988 Incentive Plan which are exercisable within 60 days of February 24,
     1997.
 
 (5) Includes 112 shares held by the trustee under Great Western's Employee
     Savings Incentive Plan (the "Employee Savings Incentive Plan").
 
 (6) Includes 495,600 shares subject to options exercisable within 60 days of
     February 24, 1997 and 945 shares held by the Trustee under the Employee
     Savings Incentive Plan.
 
 (7) Includes 16,250 shares subject to options granted to this Director under
     the 1988 Incentive Plan which are exercisable within 60 days of February
     24, 1997.
 
 (8) Includes 396,137 shares subject to options granted to this Director under
     the 1988 Incentive Plan which are exercisable within 60 days of February
     24, 1997 and 25 shares held by the Trustee under the Employee Savings
     Incentive Plan.
 
 (9) Includes 99,010 shares subject to options exercisable within 60 days of
     February 24, 1997 and 112 held by the Trustee under the Employee Savings
     Incentive Plan.
 
(10) Includes 179,845 shares subject to options exercisable within 60 days of
     February 24, 1997.
 
(11) Includes 172,500 shares subject to options exercisable within 60 days of
     February 24, 1997.
 
(12) Includes 49,762 shares subject to options exercisable within 60 days of
     February 24, 1997.
 
(13) Includes options to purchase 1,551,604 shares under employee stock options
     which are exercisable on or within 60 days after February 24, 1997 and
     1,194 shares held in trust under the Employee Savings Incentive Plan with
     respect to which such persons have the right to direct the vote.
 
     The following entities are the only stockholders known to Great Western to
be the beneficial owners of more than 5% of Great Western's equity securities.
This information has been obtained from reports filed pursuant to Regulation
13D-G under the Exchange Act and the rules and regulations promulgated
thereunder.
 
<TABLE>
<CAPTION>
                                                                                         PERCENT OF
                                                                AMOUNT AND NATURE OF     OUTSTANDING
                                                               BENEFICIAL OWNERSHIP OF     COMMON
             NAME AND ADDRESS OF BENEFICIAL OWNER              SHARES OF COMMON STOCK       STOCK
- -------------------------------------------------------------- -----------------------   -----------
<S>                                                            <C>                       <C>
Wellington Management Company LLP.............................        8,771,730(1)           6.37%
  75 State Street
  Boston, Massachusetts 02109
Vanguard/Windsor Funds, Inc. .................................        8,236,786(2)           5.98%
  Vanguard Financial Center
  Valley Forge, Pennsylvania 19482
</TABLE>
 
- ---------------
 
 (1) Wellington Management Company ("WMC") has reported that it is an investment
     advisor and, as such, is considered beneficial owner in the aggregate of
     the shares listed in the table. WMC has declared that it has shared power
     to vote 53,902 of the shares and shared dispositive power over all of the
     shares shown in the table. The shares shown in the table for the
     Vanguard/Windsor Funds, Inc. are also included in the total amount reported
     in the table for WMC.
 
(2) Vanguard/Windsor Funds, Inc. ("Vanguard/Windsor") has reported that it is an
    investment company and, as such, is considered the beneficial owner in the
    aggregate of the shares listed in the table. Vanguard/Windsor has declared
    that it has sole power to vote or direct the vote and shared power to
    dispose or to direct the disposition of the shares shown in the table.
 
                                       72
<PAGE>   78
 
                 MANAGEMENT AND OPERATIONS OF WASHINGTON MUTUAL
                              FOLLOWING THE MERGER
 
     The estimates of cost savings, revenue enhancements and Merger-related and
other expenses described below are forward-looking statements that, while
prepared on the basis of Washington Mutual's best judgments and currently
available information regarding Great Western's business and the future
operating performance of the two companies, are inherently subject to
significant business, economic and competitive uncertainties and contingencies,
many of which are beyond the control of either company, and upon assumptions
with respect to future business decisions that are subject to changes.
Accordingly, there can be no assurance that such cost-savings and revenue
enhancements will be realized in the amounts or within the time periods
currently estimated, or that such charges for Merger-related expenses will be as
estimated. See "Risk Factors".
 
GENERAL
 
     The Merger Agreement provides for the merger of Great Western with and into
NACI, with NACI as the surviving corporation. The separate existence of Great
Western will cease upon completion of the Merger and stockholders of Great
Western will become shareholders of Washington Mutual as described herein.
 
BOARD OF DIRECTORS
 
     At the Effective Time, four representatives mutually agreeable to
Washington Mutual and Great Western will be added to the existing Washington
Mutual Board to form the Board of Directors of the Combined Company. It is
expected that at such time John F. Maher, the President and Chief Executive
Officer of Great Western, will be one of the four directors chosen to serve on
the Board of Directors of the Combined Company. Information regarding the
existing Washington Mutual Board is set forth in the 1996 Washington Mutual
10-K, which is incorporated herein by reference. See "Incorporation of Certain
Documents by Reference" and "Available Information."
 
OPERATIONS AFTER THE MERGER
 
     General. Upon consummation of the Merger, it is anticipated that GW Bank
will be merged with and into ASB, a wholly-owned subsidiary of Washington
Mutual, with ASB as the surviving corporation. It is intended that at the
effective date of such merger, ASB will change its name to Great Western Bank.
The Combined Company intends to conduct its banking operations in California and
Florida under the "Great Western Bank" name. Great Western Bank loan offices in
Washington will be combined with existing Washington Mutual offices and operated
under the "Washington Mutual Bank" name.
 
     Operations. The Combined Company intends to utilize the Washington Mutual
marketing, sales, products and systems which it has been installing in the ASB
system and to provide these same products and systems to Great Western. Great
Western's business banking programs will be retained and incorporated throughout
the Combined Company, with a particular emphasis on business checking.
Washington Mutual also intends to consolidate and coordinate the operations,
sales, marketing and product selection of the broker-dealer subsidiaries of WMB,
ASB and GW Bank.
 
     Cost Savings.  Although no assurances can be given that any specific level
of expense savings will be realized or as to the timing thereof, Washington
Mutual currently expects to achieve substantial savings in the Combined
Company's operating expense base, primarily through consolidation of back office
operations, elimination of redundant corporate overhead and staff positions,
consolidation of retail branches and loan offices, reduction of aggregate
marketing expenses and implementation of integrated technology platforms into
Great Western's operations in order to reduce loan origination, servicing and
other operational costs. Although the amounts shown below are expressed as
percentages of Great Western's expense base (as is industry practice),
Washington Mutual expects that cost reductions will come from the operations of
both companies. The following table provides details of the estimated cost
savings by business division and period in which they
 
                                       73
<PAGE>   79
 
are expected to be realized. All calculations are based on Great Western's 1997
budgeted expenses. The divisional cost savings are shown as a percentage of
Great Western's gross divisional operating expenses.
 
<TABLE>
<CAPTION>
                                                  % OF GWF               % OF GWF               % OF GWF
                                         1997     OPERATING     1998     OPERATING     1999     OPERATING
                                        AMOUNT    EXPENSES     AMOUNT    EXPENSES     AMOUNT    EXPENSES
                                        ------    ---------    ------    ---------    ------    ---------
                                                              (DOLLARS IN MILLIONS)
<S>                                     <C>       <C>          <C>       <C>          <C>       <C>
Administration/Finance................   $  8          6%       $ 52         41%       $ 65         51%
Lending...............................     --         --          15         11          69         49
Corporate Operations..................     --         --          56         25          96         43
Retail Banking........................      7          2          77         21          99         27
Subsidiaries..........................     --         --           8          5          11          7
                                        ------                 ------                 ------
     Total Pretax Cost Savings........   $ 15                   $208                   $340
                                        ======                 ======                 ======
Total Pretax Cost Savings as a
  Percentage of:
     Gross estimated operating
       expenses.......................     --          2%         --         21%         --         35%
     Net estimated operating
       expenses(1)....................     --          2          --         23          --         38
</TABLE>
 
- ---------------
 
(1) Net operating expenses are net of $85 million consisting principally of loan
    origination costs which are deferred and amortized over the life of the
    loans and various reimbursable costs.
 
     The cost savings estimated above are based on information provided by Great
Western during Washington Mutual's due diligence investigation, the knowledge
and experience that Washington Mutual has accumulated from its prior
acquisitions and the following significant assumptions: (i) the closing of
approximately 100 branch offices of the Combined Company in California; (ii) the
closing of approximately 100 loan offices of the Combined Company in California,
Washington and other states; (iii) the consolidation of other bank premises and
facilities and the outsourcing of the corporate properties management function;
(iv) the adoption of a common branch operating system for the Combined Company,
with an attendant reduction in per deposit account origination and maintenance
costs; (v) the reduction of aggregate advertising expenditures due to market
overlap between ASB and GW Bank locations and elimination of duplicative staff
functions in marketing and research; (vi) the elimination of duplicative back
office functions, particularly in the accounting, finance and human resources
areas; (vii) a reduction in GW Bank's current cost to originate a loan (which
brings such costs to a level that more closely approximates the industry average
and is still above the comparable cost of such originations at Washington
Mutual); and (viii) a reduction in the cost to service loans, again to a level
that is below the current GW Bank cost but still above the current cost at
Washington Mutual.
 
     Of the estimated annual cost savings of $340 million in 1999 described
above, approximately $50 million is expected to be derived from the
consolidation of retail branches. A substantial portion of the savings are
expected to be derived from the integration of information systems and other
back office operations. Washington Mutual and Great Western use the same systems
for many of their major information processing services (including the Hogan
system for deposit operations and the Alltel system for loan servicing), and
Washington Mutual believes this will significantly facilitate the integration
process between the two companies.
 
     Potential Revenue Enhancements. Washington Mutual anticipates that the
Combined Company will be able to generate increased revenues as a result of the
Merger and related changes to the two companies' existing business plans. The
table below sets forth the estimated pretax amounts of these revenue
enhancements and the time periods in which they will be generated. The amounts
presented are estimates only, based on Washington Mutual's current best judgment
after its initial review of Great Western's operations and business plan and on
the assumptions as to capital ratios and asset growth set forth below.
 
<TABLE>
<CAPTION>
    INCREASE IN:                                                            1998     1999
                                    (DOLLARS IN MILLIONS)                   ----     ----
    <S>                                                                     <C>      <C>
    Fee Income (pretax)...................................................  $ 60     $ 88
    Net Interest Income (pretax)..........................................   113      246
                                                                             ---      ---
         Total............................................................  $173     $334
                                                                             ===      ===
</TABLE>
 
                                       74
<PAGE>   80
 
     Fee Income Enhancement. Washington Mutual believes that the Combined
Company will be able to enhance its fee income from retail operations.
Washington Mutual has begun to introduce its Free Checking program into ASB's
system and intends to expand the program into GW Bank following the Merger.
Washington Mutual's historical experience has been that the introduction of Free
Checking substantially increases the number of new checking accounts which
correspondingly increases revenue from sales of related product enhancements,
ATM usage, account related services and debit card use. Washington Mutual also
intends to implement new pricing policies for checking account services
throughout GW Bank and ASB, which policies it believes are in line with
competitive charges in their market areas.
 
     Net Interest Income. Washington Mutual estimates that, as a result of the
Merger, pretax net interest income will increase by approximately $113 million
in 1998 and $246 million in 1999 over the amounts that the two companies
estimate they would have achieved on a stand-alone basis. This estimate is based
on leveraging the additional capital generated by the Merger (consisting of (i)
net retained earnings resulting from the cost savings and fee income increases
described above, after giving effect to the Merger-related expenses and
provision described below, (ii) retention of the capital which Great Western had
intended to utilize in its stock repurchase program, and (iii) capital of Great
Western in excess of approximately a 5% common equity to assets ratio).
Washington Mutual anticipates that this additional capital will be used to
support asset growth.
 
     The incremental asset growth is expected to be based on (i) increased loan
production at Great Western resulting primarily from the introduction of new
loan products from Washington Mutual and the installation of Washington Mutual's
loan origination system throughout the GW Bank network, and (ii) increased loan
retentions, including both higher retention levels at GW Bank and retention of
loan originations anticipated for ASB that would otherwise have been sold under
ASB's existing business plan, due to capital levels of that company. Washington
Mutual offers a wider selection of residential mortgage loan products than GW
Bank, including ARMs tied to indices other than those currently used by GW Bank.
Washington Mutual also offers three major loan product lines that historically
have not been available at GW Bank: secured and unsecured installment loans,
manufactured housing loans, and residential construction loans. In addition,
Washington Mutual believes that its loan origination system will reduce the
processing time of loan originations from that currently experienced by GW Bank.
 
     In making the estimate of increased pretax net interest income described
above, Washington Mutual has assumed incremental asset growth at Great Western
of approximately $3.1 billion in 1997 (from $42.9 billion at December 31, 1996),
$7.4 billion in 1998 and $7.6 billion in 1999. It has further assumed that the
weighted average pretax margin on these assets, net of provision for loan
losses, will be approximately 1.66% in 1998 and approximately 1.72% in 1999.
These margins reflect management's estimates with respect to the expected mix of
loan types in the additional retained loan originations. Although the higher
retention rate assumed in this estimate will result in a decrease in the gains
on sale of loans recognized by Great Western and Washington Mutual, it is
expected to make a positive contribution to net interest income, as described
above.
 
     Merger-Related Expense and Addition to Loan Loss Reserve. Merger-related
expenses of approximately $343.0 million (pretax) and a $100.0 million (pretax)
addition to the loan loss reserve are expected to be recorded by Washington
Mutual at the Effective Time. The merger-related expenses include the creation
of reserves of $145.0 million for severance and management payments, $106.0
million for facilities and system conversion related expenses and $92.0 million
for other expenses.
 
     The additional $100 million in loan loss provisions will be taken as a
charge to earnings at the Effective Date. This additional loan loss provision is
being provided in part because a number of Washington Mutual credit
administration and asset management philosophies and procedures differ from
those of Great Western. The principal difference is that Washington Mutual's
plan of realization of troubled loans differs from Great Western's and therefore
require different levels of loan loss reserves. Washington Mutual intends to
conform Great Western's asset management practices, administration, philosophies
and procedures to its own. Washington Mutual believes that, while there has been
an increase in the price of houses in certain California markets, a decline in
collateral values for some portions of the California real estate market is
continuing to occur. In light of these declines, Washington Mutual believes that
it is appropriate to increase reserves to
 
                                       75
<PAGE>   81
 
reflect its judgment about the potential impact on Great Western's loan
portfolio. Great Western's management does not believe that this judgment
indicates that the existing loan loss reserves of Great Western are not
reasonable.
 
     Management After the Merger. Washington Mutual is undertaking a review of
its management needs following the Merger and intends to retain those personnel
which it believes will contribute to the implementation of its business
strategy.
 
                                       76
<PAGE>   82
 
                    PRO FORMA COMBINED FINANCIAL INFORMATION
                                  (UNAUDITED)
 
     The following pro forma combined unaudited consolidated statement of
financial position as of December 31, 1996 and the pro forma combined unaudited
consolidated statements of income for the three years ended December 31, 1996
are based upon the historical consolidated financial statements of Washington
Mutual and Great Western as previously filed with the Commission under the
Exchange Act, and incorporated by reference in this Joint Proxy
Statement/Prospectus, and should be read in conjunction with those consolidated
financial statements and related notes. These combined unaudited pro forma
condensed financial statements are not necessarily indicative of the operating
results that would have been achieved had the Merger been consummated as of the
beginning of the periods presented and should not be construed as representative
of future operating results. These combined unaudited pro forma condensed
financial statements give effect to the Merger by combining the results of
operations of Washington Mutual and Great Western using the
"pooling-of-interests" method of accounting.
 
                                       77
<PAGE>   83
 
                        PRO FORMA COMBINED CONSOLIDATED
                        STATEMENT OF FINANCIAL POSITION
 
<TABLE>
<CAPTION>
                                                                   DECEMBER 31, 1996
                                      ---------------------------------------------------------------------------
                                                                           PRO FORMA
                                                                         ADJUSTMENTS(1)               PRO FORMA
                                      WASHINGTON       GREAT       --------------------------         INCLUDING
                                        MUTUAL        WESTERN       DEBIT      CREDIT    REF.       GREAT WESTERN
                                      -----------   ------------   --------   --------   ----       -------------
                                                                (DOLLARS IN THOUSANDS)
                                                                      (UNAUDITED)
<S>                                   <C>           <C>            <C>        <C>        <C>        <C>
ASSETS
Cash and cash equivalents............ $   831,063   $    834,292   $          $145,000     1(b)      $ 1,428,355
                                                                                92,000     1(b)
Trading account securities...........       1,647             --                                           1,647
Available-for-sale securities........   9,111,274      7,827,071                                      16,938,345
Held-to-maturity securities..........   2,860,347      1,618,709                                       4,479,056
Loans, net of the allowance for loan
  losses.............................  30,103,386     30,717,320               100,000     1(b)       60,720,706
Loans held for sale..................     227,390        105,872                                         333,262
REO and other real estate............     103,111        159,997                                         263,108
Premises and equipment...............     482,391        552,422               106,000     1(b)          928,813
Goodwill and other intangible
  assets.............................     133,509        285,991                                         419,500
Other assets.........................     697,807        772,898                                       1,470,705
                                      -----------    -----------   --------   --------               -----------
         Total assets................ $44,551,925   $ 42,874,572   $     --   $443,000               $86,983,497
                                      ===========    ===========   ========   ========               ===========
LIABILITIES
Deposits:
  Checking accounts.................. $ 2,979,962   $  4,577,626   $          $                      $ 7,557,588
  Savings and money market
    accounts.........................   6,842,061      6,744,210                                      13,586,271
  Time deposit accounts..............  14,258,118     17,264,937                                      31,523,055
                                      -----------    -----------   --------   --------               -----------
         Total deposits..............  24,080,141     28,586,773         --         --                52,666,914
Annuities............................     878,057             --                                         878,057
Federal funds and commercial paper...   1,052,000      1,101,506                                       2,153,506
Securities sold under agreements to
  repurchase.........................   7,835,453      4,197,666                                      12,033,119
Advances from the FHLB...............   7,241,492      2,769,933                                      10,011,425
Other borrowings.....................     676,986      2,432,708                                       3,109,694
Other liabilities....................     389,908      1,090,786    125,000                1(b)        1,355,694
                                      -----------    -----------   --------   --------               -----------
         Total liabilities...........  42,154,037     40,179,372    125,000         --                82,208,409
Great Western-obligated mandatorily
  redeemable preferred securities of
  Great Western subsidiary trust,
  holding solely $103,092,800
  aggregate principal amount of 8.25%
  subordinated deferrable interest
  notes, due 2025, of Great
  Western............................          --        100,000                                         100,000
STOCKHOLDERS' EQUITY
Preferred stock......................          --        165,000    165,000                1(a)               --
Common stock.........................          --        137,876    137,876                1(a)               --
Capital surplus......................     952,747        680,428               302,876     1(a)        1,936,051
Valuation reserve for
  available-for-sale securities......      41,666         76,959                                         118,625
Retained earnings....................   1,403,475      1,534,937    318,000                1(b)        2,620,412
                                      -----------    -----------   --------   --------               -----------
         Total stockholders'
           equity....................   2,397,888      2,595,200    620,876    302,876                 4,675,088
                                      -----------    -----------   --------   --------               -----------
         Total liabilities and
           stockholders' equity...... $44,551,925   $ 42,874,572   $745,876   $302,876               $86,983,497
                                      ===========    ===========   ========   ========               ===========
Book value per common share(2).......      $19.30         $17.63                                          $18.13
Number of common shares
  outstanding(2)..................... 118,142,285    137,875,955                                     242,230,645
</TABLE>
 
                                       78
<PAGE>   84
 
                    NOTES TO PRO FORMA COMBINED CONSOLIDATED
                        STATEMENT OF FINANCIAL POSITION
 
(1) Statement of Financial Position.  The pro forma adjustments reflected in the
unaudited pro forma combined statement of financial position of Washington
Mutual including Great Western as of December 31, 1996 give effect to the
following adjustments:
 
     (a) Stockholders' equity of Great Western has been adjusted to give effect
         to the exchange of 660,000 shares of Great Western Preferred Stock and
         137,875,955 shares of Great Western Common Stock for 660,000 shares of
         Series F Preferred Stock and 124,088,360 shares of Washington Mutual
         Common Stock. Pro forma adjusting entries are as follows:
 
<TABLE>
<CAPTION>
                                                                  DEBIT        CREDIT
                                                                 --------     --------
                                                                      (DOLLARS IN
                                                                      THOUSANDS)
        <S>                                                      <C>          <C>
        Preferred stock........................................  $165,000
        Common stock...........................................   137,876
        Capital surplus........................................               $302,876
</TABLE>
 
     (b) Merger-related Expenses.  Merger-related expenses and addition to loan
         loss reserve anticipated to be recorded are included in the Pro Forma
         Including Great Western statement of financial position as of December
         31, 1996. Merger-related expenses expected to be recorded by Washington
         Mutual are summarized in the following table (dollars in thousands):
 
<TABLE>
        <S>                                                                <C>
        Additional loan loss reserves(*).................................  $ 100,000
        Severance and management payments................................    145,000
        Facilities and equipment.........................................    106,000
        Other expenses...................................................     92,000
                                                                           ---------
             Total expenses..............................................    443,000
        Tax benefit......................................................   (125,000)
                                                                           ---------
        Net expenses.....................................................  $ 318,000
                                                                           =========
</TABLE>
 
          Pro forma adjusting entries are as follows:
 
<TABLE>
<CAPTION>
                                                                  DEBIT        CREDIT
                                                                 --------     --------
                                                                      (DOLLARS IN
                                                                      THOUSANDS)
        <S>                                                      <C>          <C>
          Retained earnings -- net charges.....................  $318,000
          Other liabilities -- tax benefit.....................   125,000
          Cash -- Severance and management premiums............               $145,000
          Cash -- Other expenses...............................                 92,000
          Loans -- Additional loan loss reserves...............                100,000
          Facilities and equipment.............................                106,000
</TABLE>
 
          * See "Management and Operations of Washington Mutual Following the
            Transaction -- Operations After the Merger -- Merger-related
            Expenses and Addition to Loan Loss Reserve" for a discussion of the
            increase in the loan loss provision and Merger-related expenses.
 
                                       79
<PAGE>   85
 
(2) Per Share Data.  Washington Mutual's book value per common share of $19.30
and pro forma combined book value per common share of $18.13 as of December 31,
1996 were calculated using the following information:
 
<TABLE>
<CAPTION>
                                                        WASHINGTON      PRO FORMA INCLUDING
                                                          MUTUAL           GREAT WESTERN
                                                       ------------     -------------------
                                                       (DOLLARS IN THOUSANDS)
        <S>                                            <C>              <C>
        Stockholders' equity.........................  $  2,397,888        $   4,993,088
        Noncumulative Perpetual Series C
          Preferred Stock............................       (68,813)             (68,813)
        Noncumulative Perpetual Series E
          Preferred Stock............................       (49,250)             (49,250)
        Great Western Preferred Stock................            --             (165,000)
        Merger-related expenses......................            --             (318,000)
                                                       ------------     -------------------
        Total stockholders' equity attributable to
          common shares..............................  $  2,279,825        $   4,392,025
                                                        ===========       ==============
        Number of common shares outstanding(*).......   118,142,285          242,230,645
</TABLE>
 
         (*) Does not include 8,000,000 shares of common stock issued to an
             escrow for the benefit of the shareholders of Keystone Holdings and
             the FRF and their transferees.
 
                                       80
<PAGE>   86
 
                               PRO FORMA COMBINED CONSOLIDATED
 
                                    STATEMENTS OF INCOME
 
<TABLE>
<CAPTION>
                                                            YEAR ENDED DECEMBER 31, 1996
                                               ------------------------------------------------------
                                                                                       PRO FORMA
                                                WASHINGTON          GREAT              INCLUDING
                                                  MUTUAL           WESTERN        GREAT WESTERN(1)(2)
                                               ------------     -------------     -------------------
                                                           (DOLLARS IN THOUSANDS, EXCEPT
                                                               FOR PER SHARE AMOUNTS)
                                                                    (UNAUDITED)
<S>                                            <C>              <C>               <C>
INTEREST INCOME
Loans........................................  $  2,139,513     $   2,481,640        $   4,621,153
Investment and mortgage-backed securities....     1,003,410           704,784            1,708,194
Cash equivalents.............................         6,313            47,507               53,820
                                                 ----------        ----------           ----------
     Total interest income...................     3,149,236         3,233,931            6,383,167
INTEREST EXPENSE
Deposits.....................................     1,060,823         1,179,479            2,240,302
Borrowings...................................       897,406           676,435            1,573,841
                                                 ----------        ----------           ----------
     Total interest expense..................     1,958,229         1,855,914            3,814,143
                                                 ----------        ----------           ----------
       Net interest income...................     1,191,007         1,378,017            2,569,024
Provision for loan losses....................       201,512           208,971              410,483
                                                 ----------        ----------           ----------
       Net interest income after provision...       989,495         1,169,046            2,158,541
OTHER INCOME
Depositor fees...............................       102,597           179,871              282,468
Loan servicing fees..........................        41,303            45,684               86,987
Securities, annuities and other fees.........        53,350            88,850              142,200
Other operating income.......................        36,419             5,127               41,546
Gain on sale of loans........................        19,729            31,950               51,679
Gain (loss) on sale of other assets..........         5,866           (19,657)             (13,791)
                                                 ----------        ----------           ----------
     Total other income......................       259,264           331,825              591,089
OTHER EXPENSE
Salaries and employee benefits...............       336,065           438,604              774,669
Occupancy and equipment......................       124,278           179,617              303,895
Regulatory assessments.......................        43,171            65,100              108,271
SAIF special assessment......................       124,193           188,359              312,552
Data processing fees.........................        40,733            57,292               98,025
Other operating expense......................       159,541           278,536              438,077
Restructure expense..........................            --            68,293               68,293
Transaction-related expense..................       158,121                --              158,121
Amortization of goodwill and other intangible
  assets.....................................        27,672            37,722               65,394
REO operations...............................        11,530               726               12,256
                                                 ----------        ----------           ----------
     Total other expense.....................     1,025,304         1,314,249            2,339,553
                                                 ----------        ----------           ----------
       Income before income taxes and
          minority interest..................       223,455           186,622              410,077
Income taxes.................................        70,420            70,800              141,220
Provision (benefit) for payments in lieu of
  taxes......................................        25,187                --               25,187
                                                 ----------        ----------           ----------
       Income before minority interest.......       127,848           115,822              243,670
Minority interest in income of consolidated
  subsidiaries...............................        13,570                --               13,570
                                                 ----------        ----------           ----------
Net Income(3)................................  $    114,278     $     115,822        $     230,100
                                                 ==========        ==========           ==========
Net Income Attributable to Common Stock......  $     95,859     $      95,527        $     191,386
                                                 ==========        ==========           ==========
Net income per common share(3)(4):
  Primary....................................         $0.85             $0.69                $0.81
  Fully diluted..............................          0.85              0.69                 0.80
Average number of common shares used to
  calculate net income per common share(4):
  Primary....................................   112,858,781       138,505,046          237,513,322
  Fully diluted..............................   113,138,724       139,250,206          238,463,909
</TABLE>
 
                                       81
<PAGE>   87
 
                        PRO FORMA COMBINED CONSOLIDATED
 
                              STATEMENTS OF INCOME
 
<TABLE>
<CAPTION>
                                                            YEAR ENDED DECEMBER 31, 1995
                                               ------------------------------------------------------
                                                                                       PRO FORMA
                                                WASHINGTON          GREAT              INCLUDING
                                                  MUTUAL           WESTERN        GREAT WESTERN(1)(2)
                                               ------------     -------------     -------------------
                                                           (DOLLARS IN THOUSANDS, EXCEPT
                                                               FOR PER SHARE AMOUNTS)
                                                                    (UNAUDITED)
<S>                                            <C>              <C>               <C>
INTEREST INCOME
Loans........................................  $  2,061,801     $   2,387,937        $   4,449,738
New West note receivable.....................        58,841                --               58,841
Investment and mortgage-backed securities....       790,696           806,496            1,597,192
Cash equivalents.............................         4,748            44,278               49,026
                                                 ----------        ----------           ----------
     Total interest income...................     2,916,086         3,238,711            6,154,797
INTEREST EXPENSE
Deposits.....................................     1,134,818         1,217,085            2,351,903
Borrowings...................................       788,618           719,497            1,508,115
                                                 ----------        ----------           ----------
     Total interest expense..................     1,923,436         1,936,582            3,860,018
                                                 ----------        ----------           ----------
       Net interest income...................       992,650         1,302,129            2,294,779
Provision for loan losses....................        74,987           187,700              262,687
                                                 ----------        ----------           ----------
       Net interest income after provision...       917,663         1,114,429            2,032,092
OTHER INCOME
Depositor fees...............................        79,017           154,862              233,879
Loan servicing fees..........................        29,315            55,159               84,474
Securities, annuities and other fees.........        49,679            74,161              123,840
Other operating income.......................        31,035            13,284               44,319
Gain on sale of loans........................         1,717             9,319               11,036
Gain (loss) on sale of other assets..........          (655)           20,883               20,228
Loss on sale of covered assets...............       (37,399)               --              (37,399)
FDIC assistance on covered assets............        55,630                --               55,630
                                                 ----------        ----------           ----------
     Total other income......................       208,339           327,668              536,007
OTHER EXPENSE
Salaries and employee benefits...............       313,304           441,366              754,670
Occupancy and equipment......................       110,981           179,654              290,635
Regulatory assessments.......................        54,909            66,365              121,274
Data processing fees.........................        36,538            60,847               97,385
Other operating expense......................       143,794           225,852              369,646
Transaction-related expense..................         2,000                --                2,000
Amortization of goodwill and other
  intangibles................................        28,306            40,286               68,592
REO operations...............................        10,682             5,605               16,287
                                                 ----------        ----------           ----------
     Total other expense.....................       700,514         1,019,975            1,720,489
                                                 ----------        ----------           ----------
       Income before income taxes and
          minority interest..................       425,488           422,122              847,610
Income taxes.................................       111,906           161,100              273,006
Provision (benefit) for payments in lieu of
  taxes......................................         7,887                --                7,887
                                                 ----------        ----------           ----------
       Income before minority interest.......       305,695           261,022              566,717
Minority interest in income of consolidated
  subsidiaries...............................        15,793                --               15,793
                                                 ----------        ----------           ----------
Net Income(3)................................  $    289,902     $     261,022        $     550,924
                                                 ==========        ==========           ==========
Net Income Attributable to Common Stock......  $    271,318     $     236,007        $     507,325
                                                 ==========        ==========           ==========
Net income per common share(3)(4):
  Primary....................................         $2.47             $1.72                $2.17
  Fully diluted..............................          2.42              1.71                 2.15
Average number of common shares used to
  calculate net income per common share(4):
  Primary....................................   109,944,477       137,111,074          233,344,444
  Fully diluted..............................   115,363,724       137,951,442          239,520,022
</TABLE>
 
                                       82
<PAGE>   88
 
                        PRO FORMA COMBINED CONSOLIDATED
 
                              STATEMENTS OF INCOME
 
<TABLE>
<CAPTION>
                                                             YEAR ENDED DECEMBER 31, 1994
                                                -------------------------------------------------------
                                                                                           PRO FORMA
                                                   WASHINGTON             GREAT         INCLUDING GREAT
                                                     MUTUAL              WESTERN         WESTERN(1)(2)
                                                -----------------     -------------     ---------------
                                                             (DOLLARS IN THOUSANDS, EXCEPT
                                                                FOR PER SHARE AMOUNTS)
                                                                      (UNAUDITED)
<S>                                             <C>                   <C>               <C>
INTEREST INCOME
Loans.........................................    $   1,658,818       $   2,291,884       $ 3,950,702
New West note receivable......................          141,039                  --           141,039
Investment and mortgage-backed securities.....          494,387             304,886           799,273
Cash equivalents..............................            1,169              32,948            34,117
                                                     ----------          ----------        ----------
     Total interest income....................        2,295,413           2,629,718         4,925,131
INTEREST EXPENSE
Deposits......................................          852,666             950,299         1,802,965
Borrowings....................................          482,692             357,149           839,841
                                                     ----------          ----------        ----------
     Total interest expense...................        1,335,358           1,307,448         2,642,806
                                                     ----------          ----------        ----------
       Net interest income....................          960,055           1,322,270         2,282,325
Provision for loan losses.....................          122,009             207,200           329,209
                                                     ----------          ----------        ----------
       Net interest income after provision....          838,046           1,115,070         1,953,116
OTHER INCOME
Depositor fees................................           45,255             140,703           185,958
Loan servicing fees...........................           23,247              50,853            74,100
Securities, annuities and other fees..........           65,248              96,923           162,171
Other operating income........................           39,630               8,164            47,794
Gain on sale of loans.........................           23,488               7,012            30,500
Gain (loss) on sale of other assets...........           23,926              64,242            88,168
                                                     ----------          ----------        ----------
     Total other income.......................          220,794             367,897           588,691
OTHER EXPENSE
Salaries and employee benefits................          315,424             469,115           784,539
Occupancy and equipment.......................          102,403             199,048           301,451
Regulatory assessments........................           54,887              77,451           132,338
Data processing fees..........................           33,862              32,512            66,374
Other operating expense.......................          146,463             207,764           354,227
Amortization of goodwill and other intangible
  assets......................................           29,076              58,689            87,765
REO operations................................           13,402              31,854            45,256
                                                     ----------          ----------        ----------
     Total other expense......................          695,517           1,076,433         1,771,950
                                                     ----------          ----------        ----------
       Income before income taxes and minority
          interest............................          363,323             406,534           769,857
Income taxes..................................          109,880             155,300           265,180
Provision (benefit) for payments in lieu of
  taxes.......................................             (824)                 --              (824)
                                                     ----------          ----------        ----------
       Income before minority interest........          254,267             251,234           505,501
Minority interest in income of consolidated
  subsidiaries................................           13,992                  --            13,992
                                                     ----------          ----------        ----------
Net Income(3).................................    $     240,275       $     251,234       $   491,509
                                                     ==========          ==========        ==========
Net Income Attributable to Common Stock.......    $     221,691       $     226,219       $   447,910
                                                     ==========          ==========        ==========
Net income per common share(3)(4):
  Primary.....................................            $2.09               $1.69             $1.98
  Fully diluted...............................             2.06                1.69              1.97
Average number of common shares used to
  calculate net income per common share(4):
  Primary.....................................      106,245,127         133,769,724       226,637,879
  Fully diluted...............................      111,664,374         133,769,724       232,057,126
</TABLE>
 
                                       83
<PAGE>   89
 
         NOTES TO PRO FORMA COMBINED CONSOLIDATED STATEMENTS OF INCOME
 
     (1) No pro forma adjustments are necessary.
 
     (2) Merger-related Expenses.  Merger-related expenses anticipated to be
recorded are not included in the Pro Forma Including Great Western statements of
income for the three years ended December 31, 1996. Merger-related expenses
expected to be recorded by Washington Mutual are summarized in the following
table (dollars in thousands):
 
<TABLE>
    <S>                                                                        <C>
    Additional loan loss reserves(*).........................................  $ 100,000
    Severance and management payments........................................    145,000
    Facilities and equipment.................................................    106,000
    Other expenses...........................................................     92,000
                                                                               ---------
      Total expenses.........................................................    443,000
    Tax benefit..............................................................   (125,000)
                                                                               ---------
      Net expenses...........................................................  $ 318,000
                                                                               =========
</TABLE>
 
     (*) See "Management and Operations of Washington Mutual After the
         Transaction -- Operations After the Merger -- Merger-related Expenses
         and Addition to Loan Loss Reserve" for a discussion of the increase in
         the loan loss provision and the Merger-related expenses.
 
     (3) "Net income from continuing operations" and "net income" are equal for
the three years ended December 31, 1996.
 
                                       84
<PAGE>   90
 
     (4) Per Share Data.  Fully diluted net income per common share for the
three years ended December 31, 1996 were calculated using the following
information:
 
<TABLE>
<CAPTION>
                                                              YEAR ENDED DECEMBER 31,
                                                   ----------------------------------------------
                                                       1996             1995             1994
                                                   ------------     ------------     ------------
                                                               (DOLLARS IN THOUSANDS)
<S>                                                <C>              <C>              <C>
WASHINGTON MUTUAL
Net income.......................................  $    114,278     $    289,902     $    240,275
Preferred stock dividends:
  Noncumulative Perpetual, Series C..............        (6,276)          (6,384)          (6,384)
  Noncumulative Perpetual, Series E..............        (3,743)          (3,800)          (3,800)
  Noncumulative Convertible Perpetual Preferred
     Stock, Series D(*)..........................        (8,400)              --               --
                                                   ------------     ------------     ------------
Net income available to fully diluted common
  stock..........................................  $     95,859     $    279,718     $    230,091
                                                   ============     ============     ============
Average common shares used to calculate net
  income per common share:
  Primary........................................   112,858,781      109,944,477      106,245,127
  Dilutive effect of stock options and litigation
     shares(**)..................................       279,943               --               --
  Noncumulative Convertible Perpetual Preferred
     Stock, Series D.............................            --        5,419,247        5,419,247
                                                   ------------     ------------     ------------
  Fully diluted..................................   113,138,724      115,363,724      111,664,374
                                                   ============     ============     ============
PRO FORMA INCLUDING GREAT WESTERN
Net income.......................................  $    230,100     $    550,924     $    491,509
Preferred stock dividends:
  Noncumulative Perpetual, Series C..............        (6,276)          (6,384)          (6,384)
  Noncumulative Perpetual, Series E..............        (3,743)          (3,800)          (3,800)
  Noncumulative Convertible Perpetual Preferred
     Stock, Series D(*)..........................        (8,400)              --               --
  Great Western Preferred Stock..................       (20,295)         (25,015)         (25,015)
                                                   ------------     ------------     ------------
Net income available to fully diluted common
  stock..........................................  $    196,386     $    515,725     $    456,310
                                                   ============     ============     ============
Average common shares used to calculate net
  income per common share:
  Primary........................................   237,513,322      233,344,444      226,637,879
  Dilutive effect of stock options and litigation
     shares(**)..................................       950,587          756,331               --
  Noncumulative Convertible Perpetual Preferred
     Stock, Series D.............................            --        5,419,247        5,419,247
                                                   ------------     ------------     ------------
  Fully diluted..................................   238,463,909      239,520,022      232,057,126
                                                   ============     ============     ============
</TABLE>
 
 (*)In 1996, for purposes of calculating fully diluted earnings per share, the
    assumed conversion of the Series D Preferred Stock was anti-dilutive.
 
(**)As part of the business combination with Keystone Holdings, 8,000,000 shares
    of Washington Mutual Common Stock, with a assigned value of $42.75 per
    share, were issued to an escrow for the benefit of the shareholders of
    Keystone Holdings and the FRF and their transferees. The Combined Company
    will use the treasury stock method to determine the effect of the shares
    upon the Combined Company's financial statements. At December 31, 1996, the
    dilutive effect of the 8,000,000 shares of Washington Mutual Common Stock on
    primary and fully diluted earnings per share was minimal.
 
                                       85
<PAGE>   91
 
                                   LITIGATION
 
     On February 18, 1997, Ahmanson filed a Verified Complaint for Declaratory
and Injunctive Relief against Great Western and its directors (the "Ahmanson
Complaint") in the Court of Chancery of the State of Delaware. The Ahmanson
Complaint alleges, among other things, that: (i) the defendants have breached
their fiduciary duties with respect to the Great Western Rights Plan; (ii) the
adoption of any defensive measure by the defendants which has the effect of
impeding, thwarting, frustrating or interfering with the Ahmanson Merger
Proposal would constitute a breach of the defendants' fiduciary duties; and
(iii) the individual directors of Great Western have breached their fiduciary
duties with respect to Section 203 of the DGCL (the "Delaware Business
Combination Statute").
 
     Ahmanson seeks declaratory and injunctive relief as follows: (i) an order
enjoining the defendants from adopting any defensive measure which has the
effect of impeding, thwarting, frustrating or interfering with the Ahmanson
Proposal; (ii) an order compelling the defendants to redeem the rights
associated with the Great Western Rights Plan or to amend the Great Western
Rights Plan so as to make it inapplicable to the Ahmanson Proposal; (iii) an
order enjoining the defendants from taking any action pursuant to the Great
Western Rights Plan that would dilute or interfere with Ahmanson's voting rights
or otherwise discriminate against Ahmanson; (iv) an order compelling the
defendants to approve the Ahmanson Proposal for the purposes of the Delaware
Business Combination Statute; (v) an order enjoining the defendants from taking
any action to enforce or apply the Delaware Business Combination Statute that
would impede, thwart, frustrate or interfere with the Ahmanson Merger Proposal;
and (vi) an order awarding Ahmanson its costs and expenses in the action.
 
     On February 26, 1996, Great Western and the individual defendants filed
their Answer, and Affirmative Defenses to the Ahmanson Complaint and Great
Western filed its Counterclaims to the Ahmanson Complaint. In the Counterclaim,
Great Western stated, among other things, that the proposed By-law amendment
relating to the granting of certain break-up fees and other similar arrangements
without the prior approval of the Great Western Stockholders would impermissibly
limit the Board's power, granted under Delaware law and Great Western's Restated
Certificate of Incorporation, to manage the business and affairs of Great
Western. Great Western also stated that such By-law amendment is inequitable
because it would impair the Board's ability to negotiate an alternative
transaction to the Ahmanson Proposal should the Board choose to do so. Further,
Great Western denied all of the material allegations raised by the Ahmanson
Complaint and asserted affirmative defenses, including that: (i) the Ahmanson
Complaint fails to state a claim on which relief can be granted; and (ii)
Ahmanson is acting in its own self interest at the expense of Great Western and
its stockholders and thus comes to Court with unclean hands.
 
     Great Western seeks declaratory and injunctive relief as to, among other
matters, the following: (i) dismissal of the Ahmanson Complaint with prejudice
and denial of the relief requested by Ahmanson; and (ii) an order declaring the
proposed By-law amendment to be invalid, illegal and inequitable. On February
27, 1997, Vice-Chancellor Jacobs informed Great Western and Ahmanson that he
would rule on the legality and validity of the proposed By-law amendment as soon
as the issue becomes relevant. For a description of the consent solicitation of
Ahmanson and Great Western's response thereto, see the Consent Revocation
Statement incorporated herein by reference. See "Incorporation of Certain
Documents by Reference."
 
     Between February 18, 1997 and February 26, 1997, six complaints (the
"Complaints") were filed against Great Western and its directors in the Court of
Chancery of the State of Delaware by Fred T. Isquith, Harry Lewis, Bernd
Bildstein, Charles Uttenreither, Melvyn Zupnick and Emil Schachter. Each action
was brought on behalf of the plaintiff, individually, and as a purported class
action on behalf of all stockholders of Great Western. The Complaints allege,
among other things, that the defendants are violating their fiduciary duties
owed to the stockholders of Great Western with respect to the Ahmanson Merger
Proposal. The plaintiffs generally seek: (i) an order declaring that the action
may be maintained as a class action; (ii) an order preliminarily and permanently
enjoining the defendants to consider and negotiate with respect to all bona fide
offers or proposals for Great Western or its assets, in the best interests of
Great Western stockholders; and (iii) compensatory damages, the costs and
disbursements of the action and such other and further relief as may be just and
proper. In addition, certain plaintiffs seek judgments ordering Great Western's
directors,
 
                                       86
<PAGE>   92
 
individually, to announce their intention with respect to certain matters
relating to the Ahmanson Proposal. Great Western and its directors deny the
operative allegations of the Complaints; however, answers have not yet been
filed and discovery has not yet commenced.
 
     On March 3, 1997, Ahmanson filed a Complaint against Great Western (the
"Ahmanson Section 220 Complaint") in the Court of Chancery of the State of
Delaware. The Ahmanson Section 220 Complaint alleges, among other things, that:
(i) Ahmanson is entitled, pursuant to Section 220 of the Delaware General
Corporation Law, to inspect and copy certain books and records of Great Western
and (ii) that Great Western has failed to make available for inspection and
copying by Ahmanson a list of the stockholders of Great Western and other
related information. Ahmanson requested that the Court enter an order directing
Great Western to provide Ahmanson with the requested information. On March 6,
1997, Great Western provided Ahmanson with all of the information requested in
the Ahmanson Section 220 Complaint. On March 7, 1997, Great Western mailed a
letter to Ahmanson requesting that Ahmanson dismiss the Ahmanson Section 220
Complaint as moot.
 
     On March 7, 1997, Ahmanson filed a Motion for Leave to File Amended and
Supplemental Complaint against Great Western and its directors (the "Ahmanson
Supplemental Complaint") in the Court of Chancery of the State of Delaware. In
addition to the allegations made in the Ahmanson Complaint, the Ahmanson
Supplemental Complaint further alleges, among other things, that: (i) the
defendants have failed to create a level playing field by discriminatorily
favoring other potential bidders to the exclusion of Ahmanson and by entering
into the Merger Agreement; (ii) the defendants have actively and unlawfully
sought to thwart its stockholders from exercising certain of their rights for
the purpose of entrenchment; (iii) the defendants have failed to find the best
value reasonably available; and (iv) the defendants have irreparably harmed
Ahmanson by depriving it of the unique opportunity to acquire Great Western.
Consequently, Ahmanson seeks additional declaratory and injunctive relief
enjoining Great Western and the individual defendants from, among other things,
discriminating against Ahmanson, delaying Great Western's annual meeting of
stockholders, or taking steps to consummate the Merger or other transactions
with Washington Mutual.
 
     Great Western and its directors intend to vigorously defend the claims in
the Ahmanson Complaint, the Ahmanson Supplemental Complaint and the Complaints.
 
             COMPARISON OF RIGHTS OF WASHINGTON MUTUAL SHAREHOLDERS
                         AND GREAT WESTERN STOCKHOLDERS
 
     Washington Mutual is incorporated under the laws of the State of Washington
and Great Western is incorporated under the laws of the State of Delaware. Upon
consummation of the Merger, the Great Western Stockholders, whose rights as
stockholders are currently governed by the DGCL, the Great Western Certificate
and the Great Western Bylaws will upon the exchange of their Great Western
Common Stock, become holders of shares of Washington Mutual Common Stock and
their rights as such will be governed by the WBCA, the Washington Mutual
Articles, and the Washington Mutual Bylaws. The material differences between the
rights of holders of Great Western Common Stock and Washington Mutual Common
Stock, resulting from the differences in their governing documents and the
application of the DGCL or the WBCA thereto, are summarized below.
 
     The following summary does not purport to be a complete summary and is
qualified in its entirety by reference to the governing corporate documents of
each of Washington Mutual and Great Western and applicable law. For a discussion
of such changes, see below, "Certain Differences between Washington and Delaware
Corporate Laws."
 
CAPITAL STOCK
 
     The Washington Mutual Articles currently authorize 350,000,000 shares of
Washington Mutual Common Stock and 10,000,000 shares of Washington Mutual
Preferred Stock. See "Description of Washington Mutual Common Stock." If the
proposed amendment to the Washington Mutual Articles is approved at the
 
                                       87
<PAGE>   93
 
Washington Mutual Meeting, the number of authorized shares of Washington Mutual
Common Stock will be increased to 800,000,000.
 
     The Great Western Certificate currently authorizes 200,000,000 shares of
Great Western Common Stock and 10,000,000 shares of Great Western Preferred
Stock.
 
BOARD OF DIRECTORS
 
     The Washington Mutual Articles provide that the number of directors
comprising the Washington Mutual Board shall be as stated in the Washington
Mutual Bylaws, provided that the number of directors shall not be less than
five. The Washington Mutual Board can amend the Washington Mutual Bylaws to
change the number of directors without shareholder approval. The Washington
Mutual Bylaws currently provide that the Washington Mutual Board shall consist
of fifteen directors. The Washington Mutual Board is divided into three classes
of as equal a number of directors as possible. The term of office of each
different class is three years, each term expiring in a different year. Upon
consummation of the Merger, the number of directors of the Combined Company will
be increased to nineteen.
 
     The Great Western Certificate provides that the Great Western Board shall
consist of such number of directors as determined in the Great Western Bylaws,
and in the absence of such determination, the number of directors is set at
thirteen. The Great Western Bylaws currently provide that the number of
directors shall be eleven. The Great Western Board is divided into three classes
of as equal a number of directors as possible. The term of office of each
different class is three years, each term expiring in a different year.
 
MONETARY LIABILITY OF DIRECTORS
 
     The Washington Mutual Articles and the Great Western Certificate each
provide for the elimination of personal monetary liability of directors to the
fullest extent permissible under the laws of Washington and Delaware,
respectively. The provision in the Washington Mutual Articles incorporates
future amendments to Washington law with respect to the elimination of such
liability.
 
VOTING RIGHTS
 
     Neither the Washington Mutual Articles nor the Great Western Certificate
provide for cumulative voting in the election of directors. Upon consummation of
the Merger, based on the capitalization of Washington Mutual and Great Western
on             , 1997, Washington Mutual common shareholders and Great Western
common stockholders will hold approximately        shares        and shares of
common stock of the Combined Company, respectively, constituting approximately
     % and      %, respectively, of the Combined Company's voting power.
Consequently, following the Merger, neither Washington Mutual nor Great Western
shareholders will possess the same relative voting power in the Combined Company
as they possessed prior to the Merger.
 
INTERESTED SHAREHOLDERS
 
     The Washington Mutual Articles prohibit, except under certain
circumstances, Washington Mutual (or any subsidiary of Washington Mutual) from
engaging in certain significant business transactions with a "Major Stockholder"
(defined as a person who, without the prior approval of the Washington Mutual
Board, acquires beneficial ownership of five percent or more of the votes held
by the holders of the outstanding shares of Washington Mutual's voting stock).
Prohibited transactions include, among others, any merger with, disposition of
assets to, acquisition by Washington Mutual of the assets of, issuance of
securities of Washington Mutual to, or acquisition by Washington Mutual of
securities of a Major Stockholder, or any reclassification of the voting stock
of Washington Mutual or of any subsidiary beneficially owned by a Major
Stockholder, or any partial or complete liquidation, spin off, split off or
split up of Washington Mutual or any subsidiary. The above prohibitions do not
apply, in general, if the specific transaction is approved by the Washington
Mutual Board prior to the involvement of the Major Stockholder; a vote of at
least eighty percent of the Continuing Directors (defined as those members of
the Washington Mutual Board prior to the involvement of the Major Stockholder);
a vote of ninety-five percent of the outstanding shares of Washington
 
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<PAGE>   94
 
Mutual voting stock other than shares held by the Major Stockholder; or a
supermajority vote of either the Washington Mutual Board or the holders of
voting stock owned other than by any Major Stockholder. The Washington Mutual
Articles also provide that during the time a Major Stockholder exists,
Washington Mutual may voluntarily dissolve only upon the unanimous consent of
the Washington Mutual shareholders or an affirmative vote of at least two-thirds
of the Washington Mutual Board and the holders of at least two-thirds of both
the shares entitled to vote on such a dissolution and of each class of shares
entitled to vote on such a dissolution as a class, if any.
 
     The Great Western Certificate does not contain a similar provision.
 
FAIR PRICE PROVISION
 
     The WBCA contains a provision (the "Fair Price Provision") in Section
23B.17.020 that requires, unless the articles of a corporation provide
otherwise, that a transaction between a corporation, or any subsidiary thereof,
and a shareholder who beneficially owns twenty percent or more of the
outstanding shares of capital stock entitled to vote generally in the election
of directors ("Voting Stock") of such corporation (an "Interested Shareholder"),
or an affiliated person of an Interested Shareholder, must be approved by the
affirmative vote of the holders of not less than two-thirds of the corporation,
excluding the votes of shares owned by or voted under the control of an
Interested Shareholder, unless such a transaction is approved by a majority of
the board of directors of the corporation, excluding directors who are a
director or officer of, or have a material financial interest in, an Interested
Shareholder ("Interested Directors"). Such supermajority vote is also not
required if a majority of directors who are not Interested Directors determines
that the fair market value of the consideration to be received by shareholders
who are not Interested Shareholders is not less than the highest fair market
value of the consideration paid by the Interested Shareholder in acquiring such
shares within the preceding twenty-four months. The Washington Mutual Articles
are silent as to a Fair Price Provision and therefore, Washington Mutual is
governed by the WBCA's Fair Price Provision.
 
     Other than Section 203 of the DGCL (as discussed below), neither the DGCL
nor the Great Western Certificate contain a provision similar to the Fair Price
Provision.
 
REMOVAL OF DIRECTORS AND FILLING VACANCIES ON THE BOARD OF DIRECTORS
 
     The Washington Mutual Articles provide that directors may only be removed
for "good cause" (which is not defined). Under the Washington Mutual Bylaws a
director may be removed by the vote of the holders of a majority of the shares
entitled to vote at an election of the director whose removal is sought. The
Washington Mutual Bylaws also provide that a vacancy on the Washington Mutual
Board arising through resignation, removal or death of an existing director, or
by reason of an authorized increase in the number of directors, may be filled by
the affirmative vote of four-fifths of the remaining directors, though less than
a quorum.
 
     Under Delaware law, a director of a corporation with a classified board may
be removed only for cause, unless the certificate of incorporation specifies
otherwise. Great Western has a classified board of directors and the Great
Western Certificate provides that directors may be removed only for cause. The
Great Western Certificate provides that any vacancy, whether arising through
death, resignation or removal of a director, or through an increase in the
number of directors of any class, shall be filled by a majority vote of the
remaining directors of the class in which the vacancy occurs or by the sole
remaining director of that class if only one such director remains.
 
WASHINGTON MUTUAL RIGHTS PLAN
 
     Washington Mutual has adopted a shareholder rights plan (the "Washington
Mutual Rights Plan") which provides that one right to purchase an additional
share of common stock (the "Washington Mutual Rights") is attached to each
outstanding share of Washington Mutual Common Stock. The Washington Mutual
Rights have certain anti-takeover effects and are intended to discourage
coercive or unfair takeover tactics and to encourage any potential acquirer to
negotiate a price fair to all stockholders. The Washington Mutual Rights may
cause substantial dilution to an acquiring party that attempts to acquire
Washington
 
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<PAGE>   95
 
Mutual on terms not approved by the Washington Mutual Board, but they will not
interfere with any friendly merger or other business combination.
 
     The Washington Mutual Rights are not exercisable until the tenth day after
a party acquires beneficial ownership of 20 percent or more of outstanding
Washington Mutual Common Stock or commences or publicly announces for the first
time a tender offer to do so. Each Washington Mutual Right entitles the holder
to purchase one share of Washington Mutual Common Stock for an exercise price
that is currently $26.67 per share. In the event, among certain other specified
events, that an acquiring party thereafter gains control of 30 percent or more
of the Washington Mutual Common Stock, any Washington Mutual Rights held by that
party will be void and, for the next 60 days, all other holders of rights can
receive that number of shares of Washington Mutual Common Stock having a market
value of two times the exercise price of the Washington Mutual Right. The
Washington Mutual Rights, which expire on October 26, 2000, may be redeemed by
Washington Mutual for $0.0044 per right prior to being exercisable. Until a
Washington Mutual Right is exercised, the holder of that Washington Mutual Right
will have no rights as a shareholder of Washington Mutual, including, without
limitation, the right to vote or to receive dividends.
 
GREAT WESTERN RIGHTS PLAN
 
     On June 27, 1995, the Great Western Board adopted a shareholder rights plan
(the "Great Western Rights Plan") and declared a dividend of one right for each
share of Great Western Common Stock outstanding on July 14, 1996, the expiration
date of the shareholder rights plan adopted by the Great Western Board in June
1986.
 
     Like the Washington Mutual Rights Plan, the Great Western Rights Plan also
has certain anti-takeover effects. In the event that any person or group
acquires beneficial ownership of 15 percent or more of the outstanding shares of
Great Western Common Stock other than pursuant to a "Qualifying Offer," as
defined in the Great Western Rights Plan, each holder of a right, other than a
right beneficially owned by the acquiring person, will thereafter have the right
to receive upon exercise that number of shares of Great Western Common Stock
having a market value of two times the exercise price of the right. In addition,
if at any time following such acquisition of 15 percent or more of the
outstanding Great Western Common Stock, Great Western is acquired in a merger or
other business combination transaction or 50 percent or more of its consolidated
assets or earning power are sold, other than resulting from a Qualifying Offer
and meeting certain fair price criteria, each holder of a right will thereafter
enjoy the right to receive, upon exercise of that right at the prevailing
exercise price of the right, that number of shares of common stock of the
acquiring company which at the time of such transaction will have a market value
of two times the exercise price of the right. As with the Washington Mutual
Rights Plan, the Great Western Rights Plan will not be triggered by a merger or
business combination which is approved in advance by the Great Western Board.
 
                     CERTAIN DIFFERENCES BETWEEN WASHINGTON
                          AND DELAWARE CORPORATE LAWS
 
     The WBCA governs the rights of Washington Mutual shareholders and will
govern the rights of Great Western stockholders who become shareholders of the
Combined Company upon consummation of the Merger. The WBCA and the DGCL differ
in many respects. Certain of the significant differences between the provisions
of the WBCA and the DGCL that could materially affect the rights of Great
Western stockholders are discussed below.
 
AMENDMENT OF ARTICLES/CERTIFICATES OF INCORPORATION
 
     Under the WBCA, with certain exceptions, amendments to a corporation's
articles of incorporation must be recommended to the shareholders by the board
of directors, unless the board of directors determines that because of conflict
of interest or other special circumstances it should make no recommendation and
communicates the basis for its determination to the shareholders with the
amendment. All amendments to the Washington Mutual Articles must be approved by
a majority of all the votes entitled to be cast by any voting group entitled to
vote thereon unless another proportion is specified in the articles of
incorporation, by the board of directors as a condition to its recommendation or
by provisions of the WBCA. The Washington
 
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<PAGE>   96
 
Mutual Articles require an amendment to the articles to receive affirmative vote
of the shareholders representing at least two-thirds of Washington Mutual's
issued capital stock at any regular meeting or special meeting duly called for
that purpose.
 
     Under the DGCL, amendments to a corporation's certificate of incorporation
require the approval of stockholders holding a majority of the outstanding
shares entitled to vote on such amendment and a majority of the outstanding
stock of such class entitled to vote on such amendment as a class, unless a
greater proportion is specified in the certificate of incorporation or by other
provisions of the DGCL. The Great Western Certificate is silent as to any voting
requirement necessary to amend the Great Western Certificate.
 
RIGHT TO CALL SPECIAL MEETING OF SHAREHOLDERS
 
     The WBCA provides that a special meeting of shareholders of a corporation
may be called by its board of directors, by holders of at least 10% of all the
votes entitled to be cast on any issue proposed to be considered at the proposed
special meeting, or by other persons authorized to do so by the articles of
incorporation or bylaws of the corporation. However, the WBCA allows the right
of shareholders to call a special meeting to be limited or denied to the extent
provided in the articles of incorporation. The Washington Mutual Articles
provide that the Washington Mutual Board or any person authorized by the
Washington Mutual Bylaws may call a special meeting. However, authority to call
a special meeting is limited to holders of at least twenty-five percent of all
the votes entitled to be cast on any issue to be considered at the proposed
meeting. The Washington Mutual Bylaws extend authority to call a special meeting
to the chairman of the Washington Mutual Board and to any one director making a
written request to call such a meeting.
 
     Under the DGCL, a special meeting of stockholders may be called by the
board of directors or by any other person authorized to do so in the certificate
of incorporation or the bylaws. Neither the Great Western Certificate nor the
Great Western Bylaws authorize any other person to call a special meeting.
 
INDEMNIFICATION OF OFFICERS, DIRECTORS AND EMPLOYEES
 
     Under the WBCA, if authorized by its articles of incorporation, a bylaw
adopted or ratified by shareholders, or a resolution adopted or ratified, before
or after the event, by the shareholders, a corporation has the power to
indemnify a director, officer or employee made a party to a proceeding, or
advance or reimburse expenses incurred in a proceeding, under any circumstances,
except that no such indemnification shall be allowed for: (a) acts or omissions
of a director, officer or employee finally adjudged to be intentional misconduct
or a knowing violation of the law; (b) conduct of a director, officer or
employee finally adjudged to be an unlawful distribution; or (c) any transaction
with respect to which it was finally adjudged that such director, officer or
employee personally received a benefit in money, property or services to which
the director, officer or employee was not legally entitled. The WBCA's
legislative history suggests that a corporation may indemnify its directors,
officers and employees for amounts paid in settlement of derivative actions,
provided that the director's, officer's or employee's conduct does not fall
within one of the categories set forth above. Generally, the Washington Mutual
Bylaws provide that Washington Mutual shall indemnify its directors, officers
and employees to the fullest extent permitted by the WBCA, including
indemnification of persons seeking to enforce indemnification rights through a
proceeding authorized by the Washington Mutual Board and initiated by such
person.
 
LIABILITY AND INDEMNIFICATION OF OFFICERS AND DIRECTORS
 
     The DGCL provides that a corporation may limit or eliminate a director's
personal liability for monetary damages to the corporation or its stockholders
for breach of fiduciary duty as a director, except for liability (i) for any
breach of the director's duty of loyalty to such corporation or its
stockholders, (ii) for acts or omissions not in good faith or which involve
intentional misconduct or a knowing violation of law, (iii) for paying a
dividend or approving a stock repurchase in violation of Section 174 of the
DGCL, or (iv) for any transaction from which the director derived an improper
personal benefit.
 
     Under the DGCL, directors and officers as well as other employees and
individuals may be indemnified against expenses (including attorneys fees),
judgments, fines and amounts paid in settlement in connection
 
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<PAGE>   97
 
with specified actions, suits or proceedings, whether civil, criminal,
administrative or investigative (other than an action by or in the right of the
corporation as a derivative action) if they acted in good faith and in a manner
they reasonably believed to be in, or not opposed to, the best interest of the
corporation, and, with respect to criminal action or proceeding, if they had no
reasonable cause to believe their conduct was unlawful. The Great Western Bylaws
provide for the indemnification of its directors, officers and employees to the
fullest extent authorized by the DGCL.
 
PROVISIONS AFFECTING CONTROL SHARE ACQUISITIONS AND BUSINESS COMBINATIONS
 
     The WBCA imposes restrictions on certain transactions between a corporation
and certain significant shareholders. Subject to certain exceptions, pursuant to
the Fair Price Provision, a merger, share exchange, sale of assets other than in
the regular course of business, or dissolution of a corporation involving an
Interested Shareholder owning beneficially 20% or more of the corporation's
voting securities must be approved by the holders of two-thirds of the
corporation's outstanding voting securities, other than those shares held by an
Interested Shareholder. This restriction does not apply if a majority of
Disinterested Directors determine that the fair market value of the
consideration received by as a result of the transaction by shareholders who are
not Interested Shareholders is not less than the highest consideration paid by
the Interested Shareholder for the corporation's shares during the preceding two
years or if the transaction is approved by a majority of directors who are not
affiliated with the Interested Shareholder. Although a Washington corporation
may, in its original articles of incorporation, elect not to be covered by this
provision, Washington Mutual has not done so.
 
     The WBCA also prohibits a "target corporation," with certain exceptions,
from engaging in certain "significant business transactions" with a person or
group of persons who beneficially owns 10% or more of the voting securities of a
target corporation (an "Acquiring Person") for a period of five years after the
acquisition of such securities, unless the transaction or acquisition of shares
is approved by a majority of the members of the target corporation's board of
directors prior to the date of the acquisition. The significant business
transactions include, among other, merger or consolidation with, disposition of
assets to or with, or issuance or redemption of stock to or from, the Acquiring
Person, termination of 5% or more of the employees of the target corporation
employed in Washington State as a result of the Acquiring Person's acquisition
of 10% or more of the shares or allowing the Acquiring Person to receive any
disproportionate benefit as a shareholder. Target corporations include domestic
corporations with their principal executive offices in Washington and either a
majority or over 1,000 of their employees resident in Washington. Washington
Mutual believes it currently meets these standards and is subject to the
statute. A corporation may not "opt out" of this statute.
 
     Section 203 of the DGCL prohibits a Delaware corporation from engaging in a
"business combination" with an "interested stockholder" for three years
following the date that such person becomes an interested stockholder. With
certain exceptions, an interested shareholder is a person or group who or which
owns 15% or more of the corporation's outstanding voting stock (including any
rights to acquire stock pursuant to an option, warrant, agreement, arrangement
or understanding, or upon the exercise of conversion or exchange rights, and
stock with respect to which the person has voting rights only), or is an
affiliate or associate of the corporation and was the owner of 15% or more of
such voting stock at any time within the previous three years.
 
     For purposes of Section 203, the term "business combination" is defined
broadly to include mergers with or caused by the interested stockholder; sales
or other dispositions to the interested shareholder (except proportionately with
the corporation's other stockholders) of assets of the corporation or a
subsidiary equal to ten percent or more of the aggregate market value of the
corporation's consolidated assets or its outstanding stock; the issuance or
transfer by the corporation or a subsidiary of stock of the corporation or such
subsidiary to the interested stockholder (except for certain transfers in a
conversion or exchange or a pro rata distribution or certain other transactions,
none of which increase the interested stockholder's proportionate ownership of
any class or series of the corporation's or such subsidiary's stock); or receipt
by the interested stockholder (except proportionately as a stockholder),
directly or indirectly, of any loans, advances, guarantees, pledges or other
financial benefits provided by or through the corporation or a subsidiary.
 
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<PAGE>   98
 
     The three-year moratorium imposed on business combinations by Section 203
does not apply if: (i) prior to the date at which such stockholder becomes an
interested stockholder the board of directors approves either the business
combination or the transaction which resulted in the person becoming an
interested shareholder; (ii) the interested stockholder owns 85% of the
corporation's voting stock upon consummation of the transaction which made him
or her an interested shareholder (excluding from the 85% calculation shares
owned by directors who are also officers of the target corporation and shares
held by employee stock plans which do not permit employees to decide
confidentially whether to accept a tender or exchange offer); or (iii) on or
after the date such person becomes an interested shareholder, the board approves
the business combination and it is also approved at a shareholder meeting by
66 2/3% of the voting stock not owned by the interested shareholder. Section 203
does not apply if the business combination is proposed prior to the consummation
or abandonment of and subsequent to the earlier of the public announcement or
the notice required under Section 203 of the proposed transaction which (i)
constitutes certain (x) mergers or consolidations, (y) sales or other transfers
of assets having an aggregate market value equal to 50% or more of the aggregate
market value of all of the assets of the corporation determined on a
consolidated basis or the aggregate or the aggregate market value of all the
outstanding stock of the corporation or (z) proposed tender or exchange offers
for 50% or more of the corporation's outstanding voting stock; (ii) is with or
by a person who was either not an interested stockholder during the last three
years or who became an interested stockholder with the approval of the
corporation's board of directors; and (iii) is approved or not opposed by a
majority of the board members elected prior to any person becoming an interested
stockholder during the previous three years (or their chosen successors).
 
     A Delaware corporation may elect not to be governed by Section 203 by a
provision of its original certificate of incorporation or an amendment thereto
or to the bylaws, which amendment must be approved by majority stockholder vote
and may not be further amended by the board of directors. Such an amendment is
not effective until 12 months following its adoption. Great Western has not
opted out of Section 203.
 
MERGERS, SALES OF ASSETS AND OTHER TRANSACTIONS
 
     Under the WBCA, a merger or share exchange of a corporation must be
approved by the affirmative vote of a majority of directors when a quorum is
present, and by each voting group entitled to vote separately on the plan by
two-thirds of all votes entitled to be cast on the plan by that voting group,
unless another proportion is specified in the articles of incorporation. The
Washington Mutual Articles provide for the affirmative vote of shareholders
holding a majority of the outstanding voting shares to approve such a
transaction.
 
     The WBCA also provides that, in general, a corporation may sell, lease,
exchange or otherwise dispose of all, or substantially all, of its property,
other than in the usual and regular course of business or dissolve if the board
of directors recommends the proposed transaction to the shareholders and the
shareholders approve the transaction by two-thirds of all the votes entitled to
be cast in the transaction, unless another proportion is specified in the
articles of incorporation. The Washington Mutual Articles provide for the
affirmative vote of shareholders holding a majority of the outstanding voting
shares to approve such a transaction.
 
     Under the DGCL, a merger, consolidation or sale of all, or substantially
all, of the assets of a corporation must be approved by the board of directors
and by a majority (unless the certificate of incorporation requires a higher
percentage) of outstanding stock of the corporation entitled to vote thereon,
provided that no vote of stockholders of a constituent corporation surviving a
merger is required (unless the corporation provides otherwise in its certificate
of incorporation) if (a) the merger agreement does not amend the surviving
corporation's certificate of incorporation, (b) each share of stock of the
surviving corporation outstanding immediately prior to the merger is to be an
identical outstanding or treasury share of the surviving corporation after the
merger, and (c) the number of shares to be issued by the surviving corporation
in the merger does not exceed twenty percent of the shares outstanding
immediately prior to the merger. The Great Western Certificate does not require
a higher percentage.
 
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<PAGE>   99
 
ACTION WITHOUT A MEETING
 
     Under the WBCA, shareholder action that may be taken at a shareholders'
meeting may be taken without a meeting if written consents describing such
action are signed by all shareholders entitled to vote thereon.
 
     Under the DGCL, unless otherwise provided in the certificate of
incorporation, any action that may be taken at a meeting of stockholders may be
taken without a meeting, without prior notice and without a vote if the holders
of outstanding stock, having not less than the minimum number of votes that
would be necessary to authorize such action, consent in writing. The Great
Western Certificate contains no provision restricting action by written
stockholder consent.
 
CLASS VOTING
 
     Under the WBCA, a corporation's articles of incorporation may authorize one
or more classes of shares that have special, conditional or limited voting
rights, including the right to vote on certain matters as a group. The articles
of incorporation may not limit the rights of holders of a class to vote as a
group with respect to certain amendments to the articles of incorporation and
certain extraordinary transactions that adversely affect the rights of holders
of that class. The Washington Mutual Articles authorize for issuance three
series of preferred stock, no par value. Generally, each series is vested with
class voting rights limited to (i) issuance or authorization of any additional
class of equity stock ranking prior to the series affected and (ii) any
amendment of the Washington Mutual Articles which would adversely affect the
powers, preferences or other rights or privileges of the series.
 
     The DGCL generally does not require class voting, except for amendments to
the certificate of incorporation that change the number of authorized shares or
the par value of shares of a specific class or that adversely affect such class
of shares.
 
TRANSACTIONS WITH OFFICERS OR DIRECTORS
 
     The WBCA sets forth a safe harbor for transactions between a corporation
and one or more of its directors. A conflicting interest transaction may not be
enjoined, set aside or give rise to damages if: (i) it is approved by a majority
of qualified directors (but no fewer than two); (ii) it is approved by the
affirmative vote of the majority of all qualified shares after notice and
disclosure to the shareholders or (iii) at the time of commitment, the
transaction is established to have been fair to the corporation. For purposes of
this provision, a "qualified director" is one who does not have either: (a) a
conflicting interest respecting the transaction or (b) a familial, financial,
professional or employment relationship with a second director who does have a
conflicting interest respecting the transaction, which relationship would, in
the circumstances, reasonably be expected to exert an influence on the first
director's judgment when voting on the transaction. "Qualified shares" are
defined generally as shares other than those beneficially owned, or the voting
of which is controlled, by a director (or an affiliate of the director) who has
a conflicting interest respecting the transaction.
 
     Under Delaware law, certain contracts or transactions in which one or more
of a corporation's directors has an interest are not void or voidable because of
such interest provided that certain conditions, such as obtaining the required
approval and fulfilling the requirements of good faith and full disclosure, are
met. Under Delaware law, either (a) the stockholders or the board of directors
must approve any such contract or transaction after full disclosure of the
material facts or (b) the contract or transaction must have been "fair" as to
the corporation at the time it was approved. If board approval is sought, the
contract or transaction must be approved by a majority of disinterested
directors (even though less than a majority of quorum).
 
DISSENTERS' RIGHTS
 
     Under the WBCA, a shareholder is entitled to dissent from and, upon
perfection of the shareholder's appraisal right, to obtain the fair value of his
or her shares in the event of certain corporate actions, including certain
mergers, share exchanges, sales of substantially all assets of the corporation,
and certain amendments to the corporation's articles of incorporation that
materially and adversely affect shareholder rights.
 
                                       94
<PAGE>   100
 
     Under Delaware law, a shareholder of a corporation participating in certain
major corporate transactions may, under varying circumstances, be entitled to
appraisal rights pursuant to which such shareholder may receive cash in the
amount of the fair market value of his or her shares in lieu of the
consideration he or she would otherwise receive in the transaction. Such
appraisal rights are not available (a) with respect to the sale, lease or
exchange of all or substantially all of the assets of a corporation, (b) with
respect to a merger or consolidation by a corporation the shares of which are
either listed on a national securities exchange or designated as a national
market system security on an interdealer quotation system by the National
Association of Securities Dealers, Inc. or are held of record by more than 2,000
holders if such stockholders receive only shares of the surviving corporation or
shares of any other corporation which are either listed on a national securities
exchange or held of record by more than 2,000 holders, plus cash in lieu of
fractional shares, or (c) to stockholders of a corporation surviving a merger if
no vote of the stockholders of the surviving corporation is required to approve
the merger because the merger agreement does not amend the existing certificate
or incorporation, each share of the surviving corporation outstanding prior to
the merger is an identical outstanding or treasury share after the merger, and
the number of shares to be issued in the merger does not exceed 20% of the
shares of the surviving corporation outstanding immediately prior to the merger
and if certain other conditions are met.
 
DIVIDENDS
 
     Under the WBCA, a corporation may make a distribution in cash or in
property to its shareholders upon the authorization of its board of directors
unless, after giving effect to such distribution, (i) the corporation would not
be able to pay its debts as they become due in the usual course of business or
(ii) the corporation's total assets would be less than the sum of its total
liabilities plus, unless the articles of incorporation permit otherwise, the
amount that would be needed, if the corporation were to be dissolved at the time
of the distribution, to satisfy the preferential rights of shareholders whose
preferential rights are superior to those receiving the distribution.
 
     Delaware law permits a corporation to declare and pay dividends out of
statutory surplus or, if there is no surplus, out of net profits for the fiscal
year in which the dividend is declared and/or for the preceding fiscal year as
long as the amount of capital of the corporation following the declaration and
payment of the dividend is not less than the aggregate amount of the capital
represented by the issued and outstanding stock of all classes having a
preference upon the distribution of assets. In addition, Delaware law generally
provides that a corporation may redeem or repurchase its shares only if such
redemption or repurchase would not impair the capital of the corporation.
 
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<PAGE>   101
 
                 DESCRIPTION OF WASHINGTON MUTUAL CAPITAL STOCK
 
     The Washington Mutual Articles authorize the issuance of up to 350,000,000
shares of Washington Mutual Common Stock and up to 10,000,000 shares of
preferred stock, no par value per share, issuable in one or more series with
such terms and at such times and for such consideration as the Washington Mutual
Board determines. As described later herein, the Washington Mutual Board is
recommending that the Washington Mutual Shareholders approve an amendment to the
Articles to increase the number of authorized shares of Common Stock from
350,000,000 shares to 800,000,000 shares. As of             , 1997, there were
issued and outstanding           shares of Washington Mutual Common Stock,
          shares of Series C Preferred and           shares of Series E
Preferred. In the Merger, Washington Mutual will issue           shares of
Common Stock and           shares of Series F Preferred Stock. See "Proposed
Amendment to Washington Mutual Articles of Incorporation -- Increase in
Authorized Shares."
 
     The following description contains a summary of material features of the
capital stock of Washington Mutual but does not purport to be complete and is
subject in all respects to the applicable provisions of the WBCA and is
qualified on its entirety by reference to the Washington Mutual Articles and the
terms of Washington Mutual Rights Agreement.
 
WASHINGTON MUTUAL COMMON STOCK
 
     Each holder of Washington Mutual Common Stock is entitled to one vote for
each share held on all matters voted upon by shareholders. Shareholders are not
permitted to cumulate their votes for the election of directors.
 
     In the event of liquidation, dissolution or distribution of Washington
Mutual, holders of Washington Mutual Common Stock will be entitled to share
ratably in any remaining assets of Washington Mutual legally available for
distribution to the Shareholders after payment of all liabilities and amounts
owed with respect to Washington Mutual Preferred Stock.
 
     Holders of Washington Mutual Common Stock are not entitled to preemptive
rights with respect to any additional shares that may be issued.
 
     The authorized but unissued and unreserved shares of Washington Mutual
Common Stock will be available for general corporate purposes, including but not
limited to possible issuance in exchange for capital notes, as stock dividends
or stock splits, in future mergers or acquisitions, under a cash dividend
reinvestment plan, for employee benefit plans, or in a future underwritten or
other public offering. Except as described above or as otherwise required to
approve the transactions in which the additional authorized shares of Washington
Mutual Common Stock would be issued, no shareholder approval will be required
for the issuance of these shares.
 
     At                , 1997, options to purchase           shares of
Washington Mutual Common Stock under Washington Mutual's stock option plans had
been granted, but not exercised or terminated, leaving           shares
available for further grants under such plans.
 
WASHINGTON MUTUAL PREFERRED STOCK
 
     Under the Washington Mutual Articles, the Washington Mutual Board is
authorized without further shareholder action to provide for the issuance of up
to 10,000,000 shares of Washington Mutual Preferred Stock in one or more series
with such voting powers, designations, preferences or relative, participating,
optional or other special rights, qualifications, limitations and restrictions,
as shall be set forth in resolutions providing for the issue thereof adopted by
the Washington Mutual Board. As of the date of this Joint Proxy
Statement/Prospectus, the series of Washington Mutual Preferred Stock
outstanding are the Series C Preferred and the Series E Preferred. The
Washington Mutual Preferred Stock is prior to the Washington Mutual Common Stock
as to dividends and liquidation, but does not confer general voting rights.
 
     The Series C Preferred Stock has a liquidation preference of $25.00 per
share plus dividends accrued and unpaid for the then-current dividend period,
and is not convertible into any other Washington Mutual
 
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<PAGE>   102
 
securities. Dividends on the Series C Preferred, if and when declared by the
Washington Mutual Board, are at an annual rate of $2.28 per share, are
noncumulative and payable quarterly. On or after December 31, 1997, Washington
Mutual may at its option redeem the Series C Preferred. The Series C Preferred
Stock is prior to the Washington Mutual Common Stock as to dividends and
liquidation. The Series C Preferred does not confer general voting rights,
except as provided by Washington law, or when any dividends in the Series C
Preferred are not declared and paid for six full quarterly dividend periods. If
such dividends are not declared and paid, holders of Series C Preferred,
together with holders of Washington Mutual Preferred Stock ranking on parity
with the Series C Preferred, voting separately as a class, shall have the right
to elect an additional two directors to the Washington Mutual Board to serve
until the dividends have been declared and paid for four consecutive dividend
periods. The affirmative vote or consent of the holders of at least two-thirds
of the outstanding shares of the Series C Preferred, voting as a separate class,
will be required for any amendment of the Washington Mutual Articles (including
any certificate of designation or any similar document relating to any series of
preferred stock of Washington Mutual) that (a) provides for the authorization or
issuance of any additional class of equity stock ranking prior to the Series C
Preferred as to dividends, liquidations or dissolution or is convertible into an
additional class of equity stock; or (b) amends, repeals, changes or adversely
affects the powers, preferences, privileges or rights of Series C Preferred;
provided, however, that amending the Washington Mutual Articles to increase the
number of authorized shares of Washington Mutual Common Stock or Washington
Mutual Preferred Stock is not within the scope of (b) above.
 
     The Series E Preferred has a liquidation preference of $25.00 per share
plus dividends accrued and unpaid for the then-current dividend period, and is
not convertible into any other Washington Mutual securities. Dividends on the
Series E Preferred, if and when declared by the Washington Mutual Board, are at
an annual rate of $1.90 per share, are noncumulative and payable quarterly. On
or after September 15, 1998, Washington Mutual may at its option redeem the
Series E Preferred. The Series E Preferred is prior to the Common Stock as to
dividends and liquidation. The Series E Preferred does not confer general voting
rights, except as provided by Washington law, or when any dividends in the
Series E Preferred are not declared and paid for six full quarterly dividend
periods. If such dividends are not declared and paid, holders of Series E
Preferred, together with holders of Washington Mutual Preferred ranking on
parity with the Series E Preferred, voting separately as a class, shall have the
right to elect an additional two directors to the Washington Mutual Board to
serve until the dividends have been declared and paid for four consecutive
dividend periods. The affirmative vote or consent of the holders of at least
two-thirds of the outstanding shares of the Series E Preferred, voting as a
separate class, will be required for any amendment of the Washington Mutual
Articles (including any certificate of designation or any similar document
relating to any series of preferred stock of Washington Mutual) that (a)
provides for the authorization or issuance of any additional class of equity
stock ranking prior to the Series E Preferred as to dividends, liquidations or
dissolution or is convertible into an additional class of equity stock; or (b)
amends, repeals, changes or adversely affects the powers, preferences,
privileges or rights of Series E Preferred Stock; provided, however, that
amending the Washington Mutual Articles to increase the number of authorized
shares of Washington Mutual Common Stock or Washington Mutual Preferred Stock is
not within the scope of (b) above.
 
WASHINGTON MUTUAL 8.30% PREFERRED STOCK, SERIES F
 
     The summary of terms of the New Washington Mutual 8.30% Preferred Stock,
Series F, contained herein does not purport to be complete and is subject to,
and qualified in its entirety by, the provisions of the Washington Mutual
Charter, as amended through the Effective Time, and the provisions of the
Preferred Stock Deposit Agreement.
 
     Pursuant to the terms of the Merger Agreement, each share of Great Western
8.30% Preferred Stock would be converted into one share of Series F Preferred
Stock. The Series F Preferred Stock will be substantially identical to the Great
Western 8.30% Preferred Stock.
 
     Rank. The Series F Preferred Stock will rank on a parity as to payment of
dividends and distribution of assets upon dissolution, liquidation or winding up
of Washington Mutual with each other currently outstanding series of Washington
Mutual Preferred Stock. See "Description of Washington Mutual Capital Stock --
Washington Mutual Preferred Stock." The Series F Preferred Stock will rank prior
to the Washington Mutual
 
                                       97
<PAGE>   103
 
Common Stock with respect to the payment of dividends and distribution of assets
upon dissolution, liquidation or winding up of Washington Mutual.
 
     Dividends. Holders of shares of the Series F Preferred Stock will be
entitled to receive, when, as and if declared by the Washington Mutual Board out
of funds of Washington Mutual legally available for payment, cash dividends at
the rate of 8.30% per annum (equivalent to $2.075 per New Washington Mutual
Depositary Share). Dividends on the Series F Preferred Stock will be payable
quarterly on February 1, May 1, August 1 and November 1 of each year, commencing
upon consummation of the Merger, at such annual rate. Each dividend will be
payable to holders of record as they appear on the stock books of Washington
Mutual (or, if applicable, the records of the Preferred Stock Depositary) on
such record dates, not exceeding 45 days preceding the payment dates thereof, as
shall be fixed by the Washington Mutual Board. Dividends will be cumulative from
the date of original issue, whether or not there shall be funds legally
available for the payment thereof. Dividends payable on the Series F Preferred
Stock for any period greater or less than a full dividend period shall be
computed on the basis of a 360-day year consisting of twelve 30-day months.
Dividends payable on the Series F Preferred Stock for each full dividend period
shall be computed by dividing the annual dividend rate by four.
 
     Redemption. Shares of Series F Preferred Stock will not be redeemable prior
to November 1, 1997. The shares of Series F Preferred Stock will be redeemable
at the option of Washington Mutual, in whole or in part, at any time or from
time to time, on or after November 1, 1997, on not less than 30 nor more than 60
days' notice by mail, at a redemption price of $250.00 per share (equivalent to
$25.00 per New Washington Mutual Depositary Share) plus accrued and unpaid
dividends to the redemption date. If less than all of the outstanding shares of
Series F Preferred Stock are redeemed, the shares of the Series F Preferred
Stock will be selected pro rata or by lot or any other method that the
Washington Mutual Board determines to be equitable.
 
     The Series F Preferred Stock will not be subject to any sinking fund or
other obligation of Washington Mutual to redeem or retire the Series F Preferred
Stock.
 
     Liquidation Rights. In the event of any voluntary or involuntary
liquidation, dissolution or winding up of Washington Mutual, the holders of
shares of Series F Preferred Stock are entitled to receive out of assets of
Washington Mutual available for distribution to stockholders, before any
distribution of assets is made to holders of Washington Mutual Common Stock or
of any other shares of stock of Washington Mutual ranking as to such a
distribution junior to the shares of Series F Preferred Stock, liquidating
distributions in the amount of $250.00 per share (equivalent to $25.00 per New
Washington Mutual Depositary Share) plus accrued and unpaid dividends. After
payment of such liquidating distributions, the holders of shares of Series F
Preferred Stock will not be entitled to any further participation in any
distribution of assets by Washington Mutual.
 
     Voting Rights. Except as indicated below or except as expressly required by
applicable law, the holders of the Series F Preferred Stock will not be entitled
to vote for any purpose.
 
     If the equivalent of six quarterly dividends payable on the Series F
Preferred Stock are in arrears, the number of directors of Washington Mutual
will be increased by two and the holders of Series F Preferred Stock, voting
separately as a class together with any other series of Washington Mutual
Preferred Stock ranking on a parity with the Series F Preferred Stock as to
dividends and distributions of assets and which by its terms provides for
similar voting rights (the "Other Washington Mutual Preferred Stock"), will be
entitled to elect two directors to fill such vacancies. Such right to elect two
additional directors shall continue until all dividends in arrears have been
paid or declared and set apart for payment. Each director elected by the holders
of shares of the Series F Preferred Stock and any other class of Washington
Mutual Preferred Stock shall continue to serve as such director for the full
term for which he shall have been elected, notwithstanding that prior to the end
of such term such default shall cease to exist.
 
     So long as any shares of the Series F Preferred Stock remain outstanding,
the consent or the affirmative vote of the holders of at least two-thirds of the
vote entitled to be cast with respect to the then outstanding shares of such
series of the Series F Preferred Stock together with any Other Washington Mutual
Preferred
 
                                       98
<PAGE>   104
 
Stock, voting as one class, either expressed in writing or at a meeting called
for that purpose, will be necessary (i) to permit, effect or validate the
authorization, or any increase in the authorized amount, of any class or series
of shares of Washington Mutual ranking prior to the Series F Preferred Stock as
to dividends, voting or upon distribution of assets and (ii) to repeal, amend or
otherwise change any of the provisions applicable to the Series F Preferred
Stock in any manner which adversely affects the powers, preferences, voting
power or other rights or privileges of the Series F Preferred Stock. In case the
Series F Preferred Stock would be so affected by any such action referred to in
clause (ii) above in a different manner than one or more series of the Other
Washington Mutual Preferred Stock then outstanding, the holders of shares of the
Series F Preferred Stock, together with any series of the Other Washington
Mutual Preferred Stock which will be similarly affected, will be entitled to
vote as a class, and Washington Mutual will not take such action without the
consent or affirmative vote of the holders of at least two-thirds of the total
number of votes entitled to be cast with respect to each such series of the
Series F Preferred Stock and the Other Washington Mutual Preferred Stock then
outstanding.
 
     With respect to any matter as to which the Series F Preferred Stock is
entitled to vote, holders of the Series F Preferred Stock and any Other
Washington Mutual Preferred Stock will be entitled to cast the number of votes
assigned to the outstanding shares of Series F Preferred Stock. As a result of
the provisions described in the preceding paragraph requiring the holders of
shares of the Series F Preferred Stock to vote together as a class with the
holders of shares of one or more series of Other Washington Mutual Preferred
Stock, it is possible that the holders of such shares of Other Washington Mutual
Preferred Stock could approve action that would adversely affect Series F
Preferred Stock, including the creation of a class of capital stock ranking
prior to such series of Series F Preferred Stock as to dividends, voting or
distributions of assets.
 
     Conversion Rights. The Series F Preferred Stock is not convertible into
shares of any other class or series of Washington Mutual Capital Stock.
 
NEW WASHINGTON MUTUAL DEPOSITARY SHARES
 
     At the Effective Time, Washington Mutual will assume the obligations of
Great Western under the Preferred Stock Deposit Agreement and will instruct the
Preferred Stock Depositary to treat the shares of Series F Preferred Stock as
new deposited securities under the Preferred Stock Deposit Agreement. In
accordance with the terms of the Preferred Stock Deposit Agreement, the Great
Western Depositary Shares then outstanding shall thereafter represent the shares
of Series F Preferred Stock. Washington Mutual will request that the Preferred
Stock Depositary call for surrender of all outstanding Great Western Depositary
Receipts to be exchanged for New Washington Mutual Depositary Receipts
specifically describing the Series F Preferred Stock. The New Washington Mutual
Depositary Receipts to be issued in exchange for the Great Western Depositary
Receipts will evidence the New Washington Mutual Depositary Shares.
 
     Each New Washington Mutual Depositary Share will represent a one-tenth
interest in a share of Series F Preferred Stock. Washington Mutual has agreed to
use its best efforts to list the New Washington Mutual Depositary Shares on the
NYSE, subject to official notice of issuance. The New Washington Mutual
Depositary Shares will be freely transferable under the Securities Act.
 
     Subject to the terms of the Preferred Stock Deposit Agreement, each owner
of a New Washington Mutual Depositary Share will be entitled through the
Preferred Stock Depositary, in proportion to the one-tenth interest in a share
of Series F Preferred Stock underlying such New Washington Mutual Depositary
Share, to all rights and preferences of a share of Series F Preferred Stock
(including, voting, redemption and liquidation rights). Because each share of
Series F Preferred Stock entitles the holder thereof to one vote on matters on
which the Series F Preferred Stock is entitled to vote, each related New
Washington Mutual Depositary Share, will, in effect, entitle the holder thereof
to one-tenth of a vote thereon, rather than one full vote. See "--Washington
Mutual 8.30% Preferred Stock, Series F -- Voting Rights."
 
     Pending the preparation of definitive, engraved New Washington Mutual
Depositary Receipts, the Preferred Stock Depositary may, upon the written order
of Washington Mutual, issue temporary New Washington Mutual Depositary Receipts
substantially identical to (and entitling the holders thereof to all the rights
pertaining to) the definitive form. Definitive New Washington Mutual Depositary
Receipts will be
 
                                       99
<PAGE>   105
 
prepared thereafter without unreasonable delay, and temporary New Washington
Mutual Depositary Receipts will be exchangeable for definitive New Washington
Mutual Depositary Receipts at Washington Mutual's expense.
 
     Dividends and Other Distributions. The Preferred Stock Depositary will
distribute all cash dividends or other cash distributions received in respect of
the Series F Preferred Stock to the record holders of New Washington Mutual
Depositary Receipts in proportion, insofar as practicable, to the respective
numbers of New Washington Mutual Depositary Shares evidenced by the New
Washington Mutual Depositary Receipts held by such holders on the relevant
record date. The Preferred Stock Depositary shall distribute only such amount,
however, as can be distributed without attributing to any holder of New
Washington Mutual Depositary Receipts a fraction of one cent, and any balance
not so distributed shall be added to and treated as part of the next sum
received by the Preferred Stock Depositary for distribution to record holders of
New Washington Mutual Depositary Receipts then outstanding.
 
     In the event of a distribution other than in cash, the Preferred Stock
Depositary will distribute such amounts of the securities or property received
by it as are, as nearly as practicable, in proportion to the respective numbers
of New Washington Mutual Depositary Shares evidenced by the New Washington
Mutual Depositary Receipts held by such holders on the relevant record date,
unless the Preferred Security Depositary determines that it is not feasible to
make such distribution, in which case the Preferred Stock Depositary may, with
the approval of Washington Mutual, adopt such method as it deems equitable and
practicable for the purpose of effecting such distribution, including the sale
of such securities or property.
 
     The Preferred Stock Deposit Agreement also contains provisions relating to
the manner in which any subscription or similar rights offered by Washington
Mutual to holders of the Series F Preferred Stock shall be made available to
holders of the related New Washington Mutual Depositary Receipts.
 
     The amounts distributed in all of the foregoing cases will be reduced by
any amounts required to be withheld by Washington Mutual or the Depositary on
account of taxes and governmental charges.
 
     Redemption of New Washington Mutual Depositary Shares. If shares of Series
F Preferred Stock represented by New Washington Mutual Depositary Shares are
redeemed, the New Washington Mutual Depositary Shares will be redeemed from the
proceeds received by the Preferred Stock Depositary resulting from the
redemption, in whole or in part, of the Series F Preferred Stock held by the
Preferred Stock Depositary. The Preferred Stock Depositary shall mail notice of
redemption not less than 30 and not more than 60 days prior to the date fixed
for redemption to the record holders of the New Washington Mutual Depositary
Receipts evidencing the New Washington Mutual Depositary Shares to be so
redeemed at their respective addresses appearing in the Preferred Stock
Depositary's books. The redemption price per New Washington Mutual Depositary
Share will be equal to the applicable fraction of the redemption price per share
payable with respect to such series of the Series F Preferred Stock plus all
money and other property, if any, payable with respect to such New Washington
Mutual Depositary Share, including all amounts payable by Washington Mutual in
respect of any accumulated but unpaid dividends. Whenever Washington Mutual
redeems shares of Series F Preferred Stock held by a Preferred Stock Depositary,
the Preferred Stock Depositary will redeem as of the same redemption date the
number of New Washington Mutual Depositary Shares representing shares of the
Series F Preferred Stock so redeemed. If less than all the New Depositary Shares
are to be redeemed, the New Washington Mutual Depositary Shares to be redeemed
will be selected by lot or pro rata (subject to rounding to avoid fractions of
New Washington Mutual Depositary Shares) as may be determined by the Preferred
Stock Depositary.
 
     After the date fixed for redemption, the New Washington Mutual Depositary
Shares so called for redemption will no longer be deemed to be outstanding and
all rights of the holders of New Washington Mutual Depositary Receipts
evidencing such New Washington Mutual Depositary Shares will cease, except the
right to receive the redemption price payable and any money or other property to
which such holders were entitled upon such redemption upon surrender to the
Preferred Stock Depositary of the New Washington Mutual Depositary Receipts
evidencing such New Washington Mutual Depositary Shares.
 
                                       100
<PAGE>   106
 
     Voting the Series F Preferred Stock. Upon receipt of notice of any meeting
or action to be taken by written consent at or as to which the holders of the
Series F Preferred Stock are entitled to vote or consent, the Preferred Stock
Depositary will mail the information contained in such notice of meeting or
action to the record holders of the New Washington Mutual Depositary Receipts
evidencing the New Washington Mutual Depositary Shares. Each record holder of
such New Washington Mutual Depositary Receipts on the record date (which will be
the same date as the record date for the Series F Preferred Stock) will be
entitled to instruct the Preferred Stock Depositary as to the exercise of the
voting rights or the giving or refusal of consent, as the case may be,
pertaining to the number of shares of the Series F Preferred Stock represented
by the New Washington Mutual Depositary Shares evidenced by such holder's New
Washington Mutual Depositary Receipts. The Preferred Stock Depositary will
endeavor, insofar as practicable, to vote, or give or withhold consent with
respect to, the maximum number of whole shares of the Series F Preferred Stock
represented by all New Washington Mutual Depositary Shares as to which any
particular voting or consent instructions are received, and Washington Mutual
will agree to take all action which may be deemed necessary by the Preferred
Stock Depositary in order to enable the Preferred Stock Depositary to do so. The
Preferred Stock Depositary will abstain from voting, or giving consents with
respect to, shares of the Series F Preferred Stock to the extent it does not
receive specific instructions from the holders of New Washington Mutual Receipts
evidencing New Washington Mutual Depositary Shares.
 
     Amendment and Termination of the Preferred Stock Deposit Agreement. The
form of New Washington Mutual Depositary Receipts evidencing the New Washington
Mutual Depositary Shares and any provision of the Preferred Stock Deposit
Agreement may at any time and from time to time be amended by agreement between
Washington Mutual and the Preferred Stock Depositary in any respect which they
may deem necessary or desirable. However, any amendment which imposes or
increases any fees, taxes or charges upon holders of New Washington Mutual
Depositary Shares or New Washington Mutual Depositary Receipts or which
materially and adversely alters the existing rights of such holders will not be
effective unless such amendment has been approved by the record holders of New
Washington Mutual Depositary Receipts evidencing at least a majority of such New
Washington Mutual Depositary Shares then outstanding. Notwithstanding the
foregoing, no such amendment may impair the right of any holder of New
Washington Mutual Depositary Shares or New Washington Mutual Depositary Receipts
to receive any moneys or other property to which such holder may be entitled
under the terms of such New Washington Mutual Depositary Receipts or the related
Preferred Stock Deposit Agreement at the times and in the manner and amount
provided for therein. The Preferred Stock Deposit Agreement may be terminated by
Washington Mutual or the Preferred Stock Depositary only after (i) all
outstanding New Washington Mutual Depositary Shares relating thereto have been
redeemed and any accumulated and unpaid dividends on the Series F Preferred
Stock, together with all other moneys and property, if any, to which holders of
the related New Washington Mutual Depositary Shares are entitled under the terms
of such New Washington Mutual Depositary Shares or the Preferred Stock Deposit
Agreement, have been paid or distributed as provided in the Preferred Stock
Deposit Agreement or provision therefor has been duly made or (ii) there has
been a final distribution in respect of the Series F Preferred Stock in
connection with any liquidation, dissolution or winding up of Washington Mutual
and such distribution has been distributed to the holders of the New Washington
Mutual Depositary Receipts.
 
     Miscellaneous. The Preferred Stock Depositary will forward to record
holders of New Washington Mutual Depositary Receipts, at their respective
addresses appearing in the Preferred Stock Depositary's books, all reports and
communications from Washington Mutual which are delivered to the Preferred Stock
Depositary and which Washington Mutual is required to furnish to holders of such
New Washington Mutual Depositary Receipts. The Preferred Stock Deposit Agreement
contains provisions relating to adjustments in the fraction of a share of Series
F Preferred Stock represented by New Washington Mutual Depositary Shares in the
event of a change in par or stated value, split-up, combination or other
reclassification of the Series F Preferred Stock or upon any recapitalization,
merger or sale of substantially all of the assets of Washington Mutual.
 
     Neither the Preferred Stock Depositary nor any of its agents nor any
registrar nor Washington Mutual will be (i) liable if it is prevented or delayed
by law or any circumstance beyond its control in performing its
 
                                       101
<PAGE>   107
 
obligations under the Preferred Stock Deposit Agreement, (ii) subject to any
liability under the Preferred Stock Deposit Agreement to holders of New
Washington Mutual Depositary Receipts other than for the relevant party's gross
negligence or willful misconduct, or (iii) obligated to prosecute or defend any
legal proceeding in respect of any New Washington Mutual Depositary Receipts,
New Washington Mutual Depositary Shares or the Series F Preferred Stock unless
satisfactory indemnity is furnished. They may rely upon written advice of
counsel or accountants, or information provided by holders of New Washington
Mutual Depositary Shares or other persons in good faith believed to be competent
and on documents reasonably believed to be genuine.
 
     Charges of the Preferred Stock Depositary. Washington Mutual will pay all
transfer and other taxes and governmental charges arising solely from the
existence of the depositary arrangements. Washington Mutual will pay charges of
the Preferred Stock Depositary in connection with the initial deposit of the
related Washington Mutual Preferred Stock and the initial issuance of the New
Washington Mutual Depositary Receipts evidencing the New Washington Mutual
Depositary Shares, any redemption of the Series F Preferred Stock and any
withdrawals of Series F Preferred Stock by the holders of New Washington Mutual
Depositary Shares. Holders of New Washington Mutual Depositary Shares will pay
other transfer and other taxes and governmental charges and such other charges
as are expressly provided in the Preferred Stock Deposit Agreement to be for
their accounts.
 
     Resignation or Removal of the Preferred Stock Depositary. The Preferred
Stock Depositary may resign at any time by delivering to Washington Mutual
notice of its election to do so, and Washington Mutual may at any time remove
the Preferred Stock Depositary, any such resignation or removal to take effect
upon the appointment of a successor depositary and its acceptance of such
appointment. Such successor depositary must be appointed within 60 days after
delivery of the notice of resignation or removal.
 
                   DESCRIPTION OF GREAT WESTERN COMMON STOCK
 
     The holders of the outstanding shares of Great Western Common Stock have
full voting rights, one vote for each share held of record. Subject to the
rights of holders of preferred stock of Great Western, holders of Great Western
Common Stock are entitled to receive such dividends as may be declared by the
Great Western Board out of funds legally available therefor. Upon liquidation,
dissolution, or winding up of Great Western (but subject to the rights of
holders of preferred stock of Great Western), the assets legally available for
distribution to holders of Great Western Common Stock shall be distributed
ratably among such holders. Holders of Great Western Common Stock have no
preemptive or other subscription or conversion rights, and no liability for
further calls upon shares. The Great Western Common Stock is not subject to
assessment.
 
     The Transfer Agent and Registrar for the Great Western Common Stock is
Harris Trust Company of California.
 
       PROPOSED AMENDMENT TO WASHINGTON MUTUAL ARTICLES OF INCORPORATION
                        -- INCREASE IN AUTHORIZED SHARES
 
     The Washington Mutual Board has adopted a resolution, and is seeking the
approval of the Washington Mutual Shareholders, for an amendment to the
Washington Mutual Articles to increase the authorized shares of Washington
Mutual Common Stock. Article II of Washington Mutual's Articles currently
provides that Washington Mutual has authority to issue 350,000,000 shares of
Common Stock. In addition, a total of 10,000,000 shares of Preferred Stock are
authorized. The Washington Mutual Board has approved and recommends that the
shareholders adopt an amendment to Article II of the Washington Mutual Articles
to increase the number of authorized shares of Washington Mutual Common Stock to
800,000,000. The amendment will not increase or otherwise affect the number of
authorized shares of Preferred stock that may be issued by Washington Mutual.
The proposed amendment to the Washington Mutual Articles would amend and restate
the first sentence of Article II A. to read as follows:
 
        The total number of shares of capital stock which the Company
        has authority to issue is 810,000,000 shares of which
        800,000,000 shares shall be shares of common stock with no
 
                                       102
<PAGE>   108
 
        par value per share and 10,000,000 shares shall be shares of
        preferred stock with no par value per share.
 
     If approved, the amendment to Article II would be effective upon the filing
of articles of amendment to the Washington Mutual Articles with the Washington
Secretary of State, which would occur promptly after the Washington Mutual
Meeting. Approval of this Amendment is not a condition of the Merger.
 
CURRENT CAPITALIZATION
 
     The primary reasons for the proposed increase in the number of authorized
shares are to provide additional available shares for use in future transactions
and to have available shares to give effect to Washington Mutual's Shareholder
Rights Plan. As of the Washington Mutual Record Date, Washington Mutual had a
total of           shares issued and outstanding and an aggregate of
shares reserved for issuance upon the exercise of outstanding stock options and
upon the issuance of additional stock options under Washington Mutual's 1994
Stock Option Plan. Consequently,           shares of Washington Mutual Common
Stock are authorized, unissued and not reserved for issuance ("Available Common
Shares"). In addition, Washington Mutual must have available sufficient shares
for issuance to give effect to the Washington Mutual Rights Plan.
 
     Assuming shareholder approval of the Share Issuance Proposal, Washington
Mutual will issue           shares of the additionally authorized Washington
Mutual Common Stock in connection with the Merger, and will reserve an
additional           shares of Washington Mutual Common Stock for issuance upon
the exercise of Great Western Stock Options converted to Washington Mutual Stock
Options in the Merger. Accordingly, following the Merger,           shares of
Washington Mutual Common Stock will be authorized, unissued and not reserved for
issuance and will also need to have additional shares available to give effect
to the Washington Mutual Rights Plan.
 
     The Washington Mutual Board believes that having additional shares of
Washington Mutual Common Stock authorized and available for issuance at the
Washington Mutual Board's discretion is in the best interest of Washington
Mutual and its shareholders and would provide several long-term advantages to
Washington Mutual and its shareholders. Washington Mutual would have greater
flexibility in considering future actions involving the issuance of stock and in
determining the Company's proper capitalization, such as through stock dividends
or splits and other employee and shareholder distributions. Additional
authorized shares could also be used to raise cash through sales of stock to
public and private investors. The Washington Mutual Board also would have
greater flexibility to authorize the Company to pursue additional acquisitions
that involve the issuance of stock and that the Washington Mutual Board believes
provide the potential for growth and profit.
 
     Under Washington Mutual's Rights Plan, each share of Washington Mutual
Common Stock has attached to it the right to buy an additional share of
Washington Mutual Common Stock upon the occurrence of certain triggering events.
The rights have certain antitakeover effects and are intended to discourage
coercive or unfair takeover tactics and to encourage any potential acquiror to
negotiate a price fair to all shareholders. In order for the Shareholder Rights
Plan to have its intended effect, Washington Mutual must have a sufficient
number of Available Common Shares that the rights can be fully exercised by
Washington Mutual Shareholders. Upon consummation of the Merger, Washington
Mutual estimates that approximately             Available Common Shares will be
required for the Washington Mutual Rights Plan to have its intended effect and
that at that time, Washington Mutual will have only             Available Common
Shares. Accordingly, the Washington Mutual Board is recommending that Washington
Mutual Shareholders approve the increase in the number of authorized shares of
Common Stock, in part to provide the additional shares necessary to give full
effect to the Shareholder Rights Plan.
 
CERTAIN EFFECTS OF THE PROPOSED AMENDMENT
 
     In certain circumstances, an increase in the authorized shares of
Washington Mutual Common Stock could be used to enhance the Washington Mutual
Board's bargaining capability on behalf of Washington Mutual's shareholders in a
takeover situation and could render more difficult or discourage a merger,
tender offer or proxy contest. Similarly, an increase in the authorized shares
of Washington Mutual Common Stock
 
                                       103
<PAGE>   109
 
could have an anti-takeover effect in that such additional shares could be used
to dilute the stock ownership of persons seeking to obtain control of Washington
Mutual. Washington Mutual is not aware of any present efforts to gain control of
Washington Mutual or to organize a proxy contest. If such proposal was
presented, management would make a recommendation based upon the best interests
of Washington Mutual's shareholders.
 
     In the event the proposal to increase the number of authorized shares of
Washington Mutual Common Stock is approved, further shareholder approval of the
issuance of the 450 million additional shares of Washington Mutual Common Stock
will not be sought prior to such issuance unless such issuances relate to a
merger, consolidation or other transaction that otherwise requires shareholder
approval. Upon issuance, such shares will have the same rights as the
outstanding shares of Washington Mutual Common Stock. Holders of Washington
Mutual Common Stock have no preemptive rights.
 
     Other than the             shares to be issued and reserved for issuance
pursuant to the Merger and except as otherwise described in this Joint Proxy
Statement/Prospectus, Washington Mutual has no present plans to issue additional
shares of Washington Mutual Common Stock. The proposed increase in the number of
authorized shares will not change the number of shares currently outstanding or
the rights of the holders of such stock.
 
     THE BOARD OF DIRECTORS, BY UNANIMOUS VOTE OF ALL THE DIRECTORS PRESENT,
APPROVED THE AMENDMENT TO THE WASHINGTON MUTUAL ARTICLES TO INCREASE THE NUMBER
OF AUTHORIZED SHARES OF WASHINGTON MUTUAL COMMON STOCK AND RECOMMENDS THAT
SHAREHOLDERS VOTE "FOR" THE AMENDMENT.
 
                                 LEGAL MATTERS
 
     The validity of the shares of Washington Mutual Common Stock which will be
issued in connection with the Merger and certain legal matters in connection
with the Merger will be passed upon for Washington Mutual by Foster Pepper &
Shefelman, Seattle, Washington.
 
     Certain legal matters in connection with the Merger will be passed upon for
Great Western by Skadden, Arps, Slate, Meagher & Flom LLP.
 
                                    EXPERTS
 
     The consolidated financial statements of Washington Mutual as of December
31, 1996 and 1995, and for each of the years in the three-year period ended
December 31, 1996, have been incorporated by reference herein and in the
Registration Statement in reliance upon the report of Deloitte & Touche LLP,
independent auditors. Insofar as the report of Deloitte & Touche LLP relates to
the amounts included for Keystone Holdings, Inc. and Subsidiaries for 1995 and
1994, it is based solely on the report of KPMG Peat Marwick LLP, independent
auditors, incorporated by reference herein, and upon the authority of such firms
as experts in accounting and auditing.
 
     The consolidated financial statements of Great Western Financial
Corporation incorporated in this Prospectus by reference to the Annual Report on
Form 10-K for the year ended December 31, 1996, have been so incorporated in
reliance on the report of Price Waterhouse LLP, independent accountants, given
on the authority of said firm as experts in auditing and accounting.
 
                             STOCKHOLDER PROPOSALS
 
     Any Washington Mutual shareholder who wishes to submit a proposal for
presentation to the 1997 Annual Meeting of Stockholders must submit the proposal
to Washington Mutual, 1201 Third Avenue, Seattle, Washington 98101, Attention:
Office of the Secretary, not later than               1997, for inclusion, if
appropriate, in Washington Mutual's proxy statement and the form of proxy
relating to the 1997 Annual Meeting.
 
                                       104
<PAGE>   110
 
     In order to have been considered for inclusion in Great Western's proxy
materials for the 1997 Annual Meeting, stockholder proposals must have been
received by Great Western at its headquarters office not later than November 21,
1996 and must have satisfied the conditions established by the SEC for
stockholder proposals to be included in Great Western's proxy materials for that
meeting.
 
                                       105
<PAGE>   111
 
                                                                      APPENDIX A
                                                                  CONFORMED COPY
 
                          AGREEMENT AND PLAN OF MERGER
 
                                  BY AND AMONG
 
                            WASHINGTON MUTUAL, INC.
 
                           NEW AMERICAN CAPITAL, INC.
 
                                      AND
 
                      GREAT WESTERN FINANCIAL CORPORATION
 
                           DATED AS OF MARCH 5, 1997
<PAGE>   112
 
                               TABLE OF CONTENTS
 
                                   ARTICLE I
 
                                   THE MERGER
 
<TABLE>
<CAPTION>
                                                                                         PAGE
                                                                                         ----
<S>    <C>                                                                               <C>
1.1    The Merger......................................................................   A-1
1.2    Effective Time..................................................................   A-1
1.3    Effects of the Merger...........................................................   A-1
1.4    Conversion of Subject Company Common Stock, Subject Company 8.30% Preferred        A-1
       Stock...........................................................................
1.5    Parent Common Stock; Parent Preferred Stock.....................................   A-3
1.6    Merger Sub Common Stock.........................................................   A-3
1.7    Options.........................................................................   A-3
1.8    Certificate of Incorporation; Articles of Amendment.............................   A-3
1.9    Bylaws..........................................................................   A-3
1.10   Tax Consequences................................................................   A-4
1.11   Board of Directors..............................................................   A-4
                                         ARTICLE II
                                     EXCHANGE OF SHARES
2.1    Parent to Make Shares Available.................................................   A-4
2.2    Exchange of Shares..............................................................   A-4
                                         ARTICLE III
                      REPRESENTATIONS AND WARRANTIES OF SUBJECT COMPANY
3.1    Corporate Organization..........................................................   A-5
3.2    Capitalization..................................................................   A-6
3.3    Authority; No Violation.........................................................   A-7
3.4    Consents and Approvals..........................................................   A-8
3.5    Reports.........................................................................   A-8
3.6    Financial Statements............................................................   A-9
3.7    Broker's Fees...................................................................   A-9
3.8    Absence of Certain Changes or Events............................................   A-9
3.9    Legal Proceedings...............................................................  A-10
3.10   Taxes...........................................................................  A-10
3.11   Employees.......................................................................  A-10
3.12   SEC Reports.....................................................................  A-11
3.13   Compliance with Applicable Law..................................................  A-12
3.14   Certain Contracts...............................................................  A-12
3.15   Agreements with Regulatory Agencies.............................................  A-12
3.16   Undisclosed Liabilities.........................................................  A-12
3.17   Rights Agreement; Anti-takeover Provisions......................................  A-13
3.18   Subject Company Information.....................................................  A-13
3.19   Environmental Liability.........................................................  A-13
3.20   Pooling of Interests............................................................  A-13
3.21   Opinions of Financial Advisors..................................................  A-13
3.22   Patents, Trademarks, Etc........................................................  A-13
3.23   Community Reinvestment Act Compliance...........................................  A-13
</TABLE>
 
                                       A-i
<PAGE>   113
 
<TABLE>
<CAPTION>
                                                                                         PAGE
                                                                                         ----
<S>    <C>                                                                               <C>
ARTICLE IV
REPRESENTATIONS AND WARRANTIES
OF PARENT
4.1    Corporate Organization..........................................................  A-14
4.2    Capitalization..................................................................  A-14
4.3    Authority; No Violation.........................................................  A-15
4.4    Consents and Approvals..........................................................  A-16
4.5    Reports.........................................................................  A-16
4.6    Financial Statements............................................................  A-16
4.7    Broker's Fees...................................................................  A-17
4.8    Absence of Certain Changes or Events............................................  A-17
4.9    Legal Proceedings...............................................................  A-17
4.10   Taxes...........................................................................  A-17
4.11   SEC Reports.....................................................................  A-17
4.12   Compliance with Applicable Law..................................................  A-17
4.13   Agreements with Regulatory Agencies.............................................  A-18
4.14   Undisclosed Liabilities.........................................................  A-18
4.15   Rights Agreement................................................................  A-18
4.16   Parent Information..............................................................  A-18
4.17   Environmental Liability.........................................................  A-18
4.18   Pooling of Interests............................................................  A-19
4.19   Opinion of Financial Advisor....................................................  A-19
4.20   Patents, Trademarks, Etc........................................................  A-19
4.21   Community Reinvestment Act Compliance...........................................  A-19
ARTICLE V
                          COVENANTS RELATING TO CONDUCT OF BUSINESS
5.1    Conduct of Businesses Prior to the Effective Time...............................  A-19
5.2    Forbearances....................................................................  A-19
ARTICLE VI
ADDITIONAL AGREEMENTS
6.1    Regulatory Matters..............................................................  A-22
6.2    Access to Information...........................................................  A-23
6.3    Stockholders' Approvals.........................................................  A-24
6.4    Legal Conditions to Merger......................................................  A-24
6.5    Affiliates......................................................................  A-24
6.6    Stock Exchange Listing..........................................................  A-24
6.7    Employee Benefit Plans..........................................................  A-24
6.8    Indemnification; Directors' and Officers' Insurance.............................  A-25
6.9    Additional Agreements...........................................................  A-27
6.10   Advice of Changes...............................................................  A-27
6.11   Subsequent Interim and Annual Financial Statements..............................  A-27
ARTICLE VII
CONDITIONS PRECEDENT
7.1    Conditions to Each Party's Obligation to Effect the Merger......................  A-27
7.2    Conditions to Obligations of Parent.............................................  A-28
7.3    Conditions to Obligations of Subject Company....................................  A-29
</TABLE>
 
                                      A-ii
<PAGE>   114
 
<TABLE>
<CAPTION>
                                                                                         PAGE
                                                                                         ----
<S>    <C>                                                                               <C>
ARTICLE VIII
TERMINATION AND AMENDMENT
8.1    Termination.....................................................................  A-30
8.2    Effect of Termination...........................................................  A-31
8.3    Amendment.......................................................................  A-32
8.4    Extension; Waiver...............................................................  A-32
ARTICLE IX
GENERAL PROVISIONS
9.1    Closing.........................................................................  A-32
9.2    Nonsurvival of Representations, Warranties and Agreements.......................  A-32
9.3    Expenses........................................................................  A-32
9.4    Notices.........................................................................  A-32
9.5    Interpretation..................................................................  A-33
9.6    Counterparts....................................................................  A-34
9.7    Entire Agreement................................................................  A-34
9.8    Governing Law...................................................................  A-34
9.9    Severability....................................................................  A-34
9.10   Publicity.......................................................................  A-34
9.11   Assignment; Third Party Beneficiaries...........................................  A-34
</TABLE>
 
                                      A-iii
<PAGE>   115
 
                          AGREEMENT AND PLAN OF MERGER
 
     AGREEMENT AND PLAN OF MERGER, dated as of March 5, 1997 (this "Agreement"),
by and among Washington Mutual, Inc., a Washington corporation ("Parent"), New
American Capital, Inc., a Delaware corporation and an indirect wholly owned
subsidiary of Parent ("Merger Sub"), and Great Western Financial Corporation, a
Delaware corporation ("Subject Company").
 
     WHEREAS, the Boards of Directors of Parent and Subject Company have each
approved, and deem it advisable and in the best interests of their respective
stockholders to consummate, the business combination transaction provided for
herein; and
 
     WHEREAS, the Boards of Directors of Parent and Subject Company have each
determined that the transactions provided for herein and contemplated hereby are
consistent with, and in furtherance of, their respective business strategies and
goals.
 
     NOW, THEREFORE,
 
     In consideration of the mutual covenants, representations, warranties and
agreements contained herein, and intending to be legally bound hereby, the
parties agree as follows:
 
                                   ARTICLE I
 
                                   THE MERGER
 
     1.1 The Merger.  Subject to the terms and conditions of this Agreement, in
accordance with the Delaware General Corporation Law (the "DGCL") at the
Effective Time (as defined in Section 1.2 hereof), Subject Company shall merge
(the "Merger") with and into Merger Sub. Merger Sub shall be the surviving
corporation (hereinafter sometimes called the "Surviving Corporation") in the
Merger, and shall continue its corporate existence under the laws of the State
of Delaware. The name of the Surviving Corporation shall be New American
Capital, Inc. Upon consummation of the Merger, the separate corporate existence
of Subject Company shall terminate.
 
     1.2 Effective Time.  The Merger shall become effective as set forth in the
certificate of merger (the "Certificate of Merger") which shall be filed with
the Secretary of State of the State of Delaware (the "Delaware Secretary") on
the Closing Date (as defined in Section 9.1 hereof). The term "Effective Time"
shall be the date and time when the Merger becomes effective, as set forth in
the Certificate of Merger.
 
     1.3 Effects of the Merger.  At and after the Effective Time, the Merger
shall have the effects set forth in the Section 253 of the DGCL.
 
     1.4 Conversion of Subject Company Common Stock, Subject Company 8.30%
Preferred Stock.  At the Effective Time, subject to Section 2.2(e) hereof, by
virtue of the Merger and without any action on the part of Parent, Merger Sub,
Subject Company or the holder of any of the following securities:
 
          (a) Each share of the common stock, par value $1.00 per share, of
     Subject Company (the "Subject Company Common Stock") issued and outstanding
     immediately prior to the Effective Time (other than shares of Subject
     Company Common Stock held (x) in Subject Company's treasury or (y) directly
     or indirectly by Parent or Subject Company or any of their respective
     Subsidiaries (as defined below) (except for Trust Account Shares and DPC
     shares, as such terms are defined below)), together with the rights (the
     "Subject Company Rights") attached thereto issued pursuant to the Rights
     Agreement, dated as of June 27, 1995, between Subject Company and First
     Chicago Trust Company of New York, as Rights Agent (the "Subject Company
     Rights Agreement"), shall, subject to Section 1.4(c) hereof, be converted
     into the right to receive .90 shares (the "Common Exchange Ratio") of the
     common stock, no par value, of Parent ("Parent Common Stock"), together
     with the number of rights ("Parent Rights") issued pursuant to the Parent
     Rights Agreement (as defined in Section 4.2 hereof) associated therewith.
 
          (b) Each share of 8.30% Cumulative Preferred Stock, par value $1.00,
     of Subject Company (the "Subject Company 8.30% Preferred Stock") issued and
     outstanding immediately prior to the Effective
 
                                       A-1
<PAGE>   116
 
     Time shall be converted into the right to receive one share of 8.30%
     Cumulative Preferred Stock of Parent (the "Parent New Preferred Stock").
     The terms of the Parent New Preferred Stock shall be substantially the same
     as the terms of the Subject Company 8.30% Preferred Stock. For purposes of
     this Agreement (i) the Subject Company Common Stock and Subject Company
     Preferred Stock (as defined below) are referred to herein as the "Subject
     Company Capital Stock," and (ii) the Parent Common Stock and Parent
     Preferred Stock (as defined below) are collectively referred to as the
     "Parent Capital Stock."
 
          (c) All of the shares of Subject Company Common Stock converted into
     the right to receive Parent Common Stock pursuant to this Article I shall
     no longer be outstanding and shall automatically be cancelled and shall
     cease to exist as of the Effective Time, and each certificate (each a
     "Common Certificate") previously representing any such shares of Subject
     Company Common Stock shall thereafter represent the right to receive (i) a
     certificate representing the number of whole shares of Parent Common Stock
     and (ii) the cash in lieu of fractional shares into which the shares of
     Subject Company Common Stock represented by such Common Certificate have
     been converted pursuant to this Section 1.4 and Section 2.2(e) hereof.
     Common Certificates previously representing shares of Subject Company
     Common Stock shall be exchanged for certificates representing whole shares
     of Parent Common Stock and cash in lieu of fractional shares issued in
     consideration therefor upon the surrender of such Common Certificates in
     accordance with Section 2.2 hereof, without any interest thereon. If prior
     to the Effective Time the outstanding shares of Parent Common Stock shall
     have been increased, decreased, changed into or exchanged for a different
     number or kind of shares or securities as a result of a reorganization,
     recapitalization, reclassification, stock dividend, stock split, reverse
     stock split, or other similar change in Parent's capitalization, then an
     appropriate and proportionate adjustment shall be made to the Common
     Exchange Ratio.
 
          (d) All of the shares of Subject Company 8.30% Preferred Stock
     converted into the right to receive Parent New Preferred Stock pursuant to
     this Article I shall no longer be outstanding and shall automatically be
     cancelled and shall cease to exist as of the Effective Time, and each
     certificate (each a "Preferred Certificate," and collectively with the
     Common Certificates, the "Certificates") previously representing any such
     shares of Subject Company 8.30% Preferred Stock shall thereafter represent
     the right to receive a certificate representing the number of shares of
     corresponding Parent New Preferred Stock into which the shares of Subject
     Company 8.30% Preferred Stock represented by such Preferred Certificate
     have been converted pursuant to this Section 1.4. Preferred Certificates
     previously representing shares of Subject Company 8.30% Preferred Stock
     shall be exchanged for certificates representing shares of corresponding
     Parent New Preferred Stock issued in consideration therefor upon the
     surrender of such Preferred Certificates in accordance with Section 2.2
     hereof, without any interest thereon.
 
          (e) At the Effective Time, all shares of Subject Company Capital Stock
     that are owned by Subject Company as treasury stock and all shares of
     Subject Company Capital Stock that are owned directly or indirectly by
     Parent or Subject Company or any of their respective Subsidiaries (other
     than shares of Subject Company Capital Stock held directly or indirectly in
     trust accounts, managed accounts and the like or otherwise held in a
     fiduciary or nominee capacity that are beneficially owned by third parties
     (any such shares, and shares of Parent Common Stock which are similarly
     held, whether held directly or indirectly by Parent or Subject Company or
     any of their respective Subsidiaries, as the case may be, being referred to
     herein as "Trust Account Shares") and other than any shares of Subject
     Company Capital Stock held by Parent or Subject Company or any of their
     respective Subsidiaries in respect of a debt previously contracted (any
     such shares of Subject Company Capital Stock, and shares of Parent Common
     Stock which are similarly held, whether held directly or indirectly by
     Parent or Subject Company or any of their respective Subsidiaries, being
     referred to herein as "DPC Shares")) shall be cancelled and shall cease to
     exist and no stock of Parent or other consideration shall be delivered in
     exchange therefor. All shares of Parent Common Stock that are owned by
     Subject Company or any of its Subsidiaries (other than Trust Account Shares
     and DPC Shares) shall become treasury stock of Parent.
 
          (f) At the Effective Time, Parent shall assume the obligations of
     Subject Company under the Deposit Agreement, dated as of September 2, 1992,
     between Subject Company and Harris Trust Co. of
 
                                       A-2
<PAGE>   117
 
     California, as depositary (relating to the Subject Company 8.30% Preferred
     Stock). Parent shall instruct the applicable depositary to treat the shares
     of Parent New Preferred Stock received by such depositary in exchange for
     and upon conversion of the shares of Subject Company 8.30% Preferred Stock
     as new deposited securities under the deposit agreement. In accordance with
     the terms of the deposit agreement, the depositary receipts then
     outstanding shall thereafter represent the shares of Parent New Preferred
     Stock so received upon conversion and exchange for the shares of Subject
     Company 8.30% Preferred Stock. Parent shall request that such depositary
     call for the surrender of all outstanding receipts to be exchanged for new
     receipts (the "New Parent Depositary Shares") specifically describing the
     series of Parent New Preferred Stock.
 
     1.5 Parent Common Stock; Parent Preferred Stock.  At and after the
Effective Time, each share of Parent Common Stock and each share of Parent
Preferred Stock issued and outstanding immediately prior to the Effective Time
shall remain an issued and outstanding share of common stock or preferred stock,
as the case may be, of Parent and shall not be affected by the Merger.
 
     1.6 Merger Sub Common Stock.  Each of the issued and outstanding shares of
the common stock of Merger Sub immediately prior to the Effective Time shall
remain issued and outstanding after the Merger as shares of the Surviving
Corporation, which shall thereafter constitute all of the issued and outstanding
shares of common stock of the Surviving Corporation. No capital stock of Merger
Sub will be issued or used in the Merger.
 
     1.7 Options.  At the Effective Time, each option granted by Subject Company
to purchase shares of Subject Company Common Stock (each a "Subject Company
Option") which is outstanding and unexercised immediately prior thereto shall
cease to represent a right to acquire shares of Subject Company Common Stock and
shall be converted automatically into an option to purchase shares of Parent
Common Stock in an amount and at an exercise price determined as provided below
(and otherwise subject to the terms of the Subject Company 1979 Stock Option and
Incentive Plan and the Subject Company 1988 Stock Option and Incentive Plan,
each as amended to date (together, the "Subject Company Stock Option Plans"),
and the agreements evidencing grants thereunder, including, but not limited to,
the accelerated vesting of such options which shall occur in connection with and
by virtue of the consummation of the Merger as and to the extent required by
such plans and agreements):
 
          (1) the number of shares of Parent Common Stock to be subject to the
     new option shall be equal to the product of the number of shares of Subject
     Company Common Stock subject to the original option and the Common Exchange
     Ratio, provided that any fractional shares of Parent Common Stock resulting
     from such multiplication shall be rounded down to the nearest share; and
 
          (2) the exercise price per share of Parent Common Stock under the new
     option shall be equal to the exercise price per share of Subject Company
     Common Stock under the original option divided by the Common Exchange
     Ratio, provided that such exercise price shall be rounded up to the nearest
     cent.
 
     In the case of any options which are "incentive stock options" (as defined
in Section 422 of the Internal Revenue Code of 1986, as amended (the "Code")),
the exercise price, the number of shares purchasable pursuant to such options
and the terms and conditions of exercise of such options shall be determined in
order to comply with Section 424(a) of the Code. The duration and other terms of
the new option shall be the same as the original option (subject to Section
6.7(b) hereof) except that all references to Subject Company shall be deemed to
be references to Parent.
 
     1.8 Certificate of Incorporation; Articles of Amendment.  At the Effective
Time, the Certificate of Incorporation of Merger Sub, as in effect at the
Effective Time, shall be the Certificate of Incorporation of the Surviving
Corporation. At or prior to the Effective Time, Parent shall duly execute and
file with the Secretary of State of the State of Washington (the "Washington
Secretary") articles of amendment (the "Preferred Stock Articles of Amendment")
establishing the Parent New Preferred Stock.
 
     1.9 Bylaws.  At the Effective Time, the Bylaws of Merger Sub, as in effect
immediately prior to the Effective Time, shall be the Bylaws of the Surviving
Corporation until thereafter amended in accordance with applicable law.
 
                                       A-3
<PAGE>   118
 
     1.10 Tax Consequences.  It is intended that the Merger shall constitute a
reorganization within the meaning of Section 368(a) of the Code, and that this
Agreement shall constitute a "plan of reorganization" for purposes of the Code.
 
     1.11 Board of Directors.  At the Effective Time, Parent shall take all
action necessary to appoint four representatives of Subject Company, mutually
agreeable to Parent and Subject Company, to Parent's Board of Directors.
 
                                   ARTICLE II
 
                               EXCHANGE OF SHARES
 
     2.1 Parent to Make Shares Available.  At or prior to the Effective Time,
Parent shall deposit, or shall cause to be deposited, with a bank or trust
company which may be a Subsidiary of Parent or the Parent's transfer agent (the
"Exchange Agent"), for the benefit of the holders of Certificates, for exchange
in accordance with this Article II, certificates representing the shares of
Parent Common Stock and Parent New Preferred Stock and an estimated amount of
cash in lieu of any fractional shares (the cash payable in lieu of fractional
shares of Parent Common Stock and certificates for shares of Parent Common Stock
and Parent New Preferred Stock, together with any dividends or distributions
with respect thereto, being hereinafter referred to as the "Exchange Fund") to
be issued pursuant to Section 1.4 and paid pursuant to Section 2.2(a) in
exchange for outstanding shares of Subject Company Capital Stock.
 
     2.2 Exchange of Shares.  (a) As soon as practicable after the Effective
Time, and in no event later than ten business days thereafter, the Exchange
Agent shall mail to each holder of record of a Certificate or Certificates a
form of letter of transmittal (which shall specify that delivery shall be
effected, and risk of loss and title to the Certificates shall pass, only upon
delivery of the Certificates to the Exchange Agent) and instructions for use in
effecting the surrender of the Certificates in exchange for certificates
representing, as the case may be, the shares of Parent Common Stock or Parent
New Preferred Stock and the cash in lieu of fractional shares of Parent Common
Stock, if any, into which the shares of Subject Company Capital Stock
represented by such Certificate or Certificates shall have been converted
pursuant to this Agreement. Upon proper surrender of a Certificate for exchange
and cancellation to the Exchange Agent, together with such properly completed
letter of transmittal, duly executed, the holder of such Certificate shall be
entitled to receive in exchange therefor, as applicable, (i) a certificate
representing that number of shares of Parent Common Stock to which such holder
of Subject Company Common Stock shall have become entitled pursuant to the
provisions of Article I hereof, (ii) a certificate representing that number of
shares of Parent New Preferred Stock to which such holder of Subject Company
8.30% Preferred Stock shall have become entitled pursuant to the provisions of
Article I hereof and (iii) a check representing the amount of cash in lieu of
fractional shares of Parent Common Stock, if any, which such holder has the
right to receive in respect of the Certificate surrendered pursuant to the
provisions of this Article II, and the Certificate so surrendered shall
forthwith be cancelled. No interest will be paid or accrued on the cash in lieu
of fractional shares and unpaid dividends and distributions, if any, payable to
holders of Certificates.
 
     (b) No dividends or other distributions with a record date after the
Effective Time with respect to Parent Common Stock or Parent New Preferred shall
be paid to the holder of any unsurrendered Certificate until the holder thereof
shall surrender such Certificate in accordance with this Article II. After the
surrender of a Certificate in accordance with this Article II, 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 Parent Common Stock or Parent New Preferred Stock represented by
such Certificate.
 
     (c) If any certificate representing shares of Parent Common Stock or Parent
New Preferred Stock is to be issued in a name other than that in which the
Certificate surrendered in exchange therefor is registered, it shall be a
condition of the issuance thereof that the Certificate so surrendered shall be
properly endorsed (or accompanied by an appropriate instrument of transfer) and
otherwise in proper form for transfer, and that the person requesting such
exchange shall pay to the Exchange Agent in advance any transfer or other taxes
required by reason of the issuance of a certificate representing shares of
Parent Common Stock or Parent New
 
                                       A-4
<PAGE>   119
 
Preferred Stock in any name other than that of the registered holder of the
Certificate surrendered, or required for any other reason, or shall establish to
the satisfaction of the Exchange Agent that such tax has been paid or is not
payable.
 
     (d) At or after the Effective Time, there shall be no transfers on the
stock transfer books of Subject Company of the shares of Subject Company Capital
Stock which were issued and outstanding immediately prior to the Effective Time.
If, after the Effective Time, Certificates representing such shares are
presented for transfer to the Exchange Agent, they shall be cancelled and
exchanged for certificates representing shares of Parent Capital Stock as
provided in this Article II.
 
     (e) Notwithstanding anything to the contrary contained herein, no
certificates or scrip representing fractional shares of Parent Common Stock
shall be issued upon the surrender for exchange of Common Certificates, no
dividend or distribution with respect to Parent Common Stock shall be payable on
or with respect to any fractional share, and such fractional share interests
shall not entitle the owner thereof to vote or to any other rights of a
stockholder of Parent. In lieu of the issuance of any such fractional share,
Parent shall pay to each former stockholder of Subject Company who otherwise
would be entitled to receive such fractional share an amount in cash determined
by multiplying (i) the average of the closing sale prices of Parent Common Stock
on The Nasdaq Stock Market ("Nasdaq") as reported by The Wall Street Journal for
the five trading days immediately preceding the date on which the Effective Time
occurs by (ii) the fraction of a share of Parent Common Stock to which such
holder would otherwise be entitled to receive pursuant to Section 1.4 hereto.
For the purposes of determining any such fractional share interests, all shares
of Subject Company Common Stock owned by any Subject Company stockholder shall
be combined so as to calculate the maximum number of shares of Parent Company
Common Stock issuable to such Subject Company Stockholder.
 
     (f) Any portion of the Exchange Fund that remains unclaimed by the
stockholders of Subject Company for twelve months after the Effective Time shall
be paid, at the request of Parent, to Parent. Any stockholders of Subject
Company who have not theretofore complied with this Article II shall thereafter
look only to Parent for payment of the shares of Parent Common Stock or Parent
New Preferred Stock, cash in lieu of any fractional shares and unpaid dividends
and distributions on the Parent Common Stock or Parent New Preferred Stock
deliverable in respect of each share of Subject Company Common Stock or Subject
Company 8.30% Preferred Stock, as the case may be, held by such stockholder at
the Effective Time as determined pursuant to this Agreement, in each case,
without any interest thereon. Notwithstanding anything to the contrary contained
herein, none of Parent, Merger Sub, Subject Company, the Exchange Agent or any
other person shall be liable to any former holder of shares of Subject Company
Common Stock or Subject Company 8.30% Preferred Stock for any amount properly
delivered to a public official pursuant to applicable abandoned property,
escheat or similar laws.
 
     (g) 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 Parent, the
posting by such person of a bond in such amount as Parent may determine is
reasonably necessary 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 Parent Common Stock and
cash in lieu of fractional shares or Parent New Preferred Stock, as the case may
be, deliverable in respect thereof pursuant to this Agreement.
 
                                  ARTICLE III
 
               REPRESENTATIONS AND WARRANTIES OF SUBJECT COMPANY
 
     Subject Company hereby represents and warrants to Parent as follows:
 
     3.1 Corporate Organization.  (a) Subject Company is a corporation duly
organized, validly existing and in good standing under the laws of the State of
Delaware. Subject Company has the corporate power and authority to own or lease
all of its properties and assets and to carry on its business as it is now being
conducted, and is duly licensed or qualified to do business in each jurisdiction
in which the nature of the
 
                                       A-5
<PAGE>   120
 
business conducted by it or the character or location of the properties and
assets owned or leased by it makes such licensing or qualification necessary,
except where the failure to be so licensed or qualified would not have nor
reasonably be expected to have a Material Adverse Effect (as defined below) on
Subject Company. As used in this Agreement, the term "Material Adverse Effect"
means, with respect to Parent, Subject Company or the Surviving Corporation, as
the case may be, a material adverse effect on the business, results of
operations, financial condition or prospects of such party and its Subsidiaries
taken as a whole or a material adverse effect on such party's ability to
consummate the transactions contemplated hereby on a timely basis; 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, savings association and similar laws, rules or
regulations of general applicability or interpretations thereof by courts or
governmental authorities, (ii) any change in generally accepted accounting
principles ("GAAP") or regulatory accounting requirements applicable to banks,
savings associations, or their holding companies generally, (iii) any action or
omission of Subject Company or Parent or any Subsidiary of either of them taken
with the prior written consent of Parent or Subject Company, as applicable, in
contemplation of the Merger and (iv) any changes in general economic conditions
affecting banks, savings associations, or their holding companies generally. As
used in this Agreement, the word "Subsidiary" when used with respect to any
party means any corporation, partnership or other organization, whether
incorporated or unincorporated, which is consolidated with such party for
financial reporting purposes. Subject Company is duly registered as a savings
and loan holding company under the Home Owners' Loan Act, as amended ("HOLA"),
and qualifies as a savings and loan holding company of the type described in
Section 10(c)(3)(A) of HOLA. The copies of the Restated Certificate of
Incorporation and Bylaws of Subject Company which have previously been made
available to Parent are true, complete and correct copies of such documents as
in effect as of the date of this Agreement.
 
     (b) Each Subject Company Subsidiary (i) is duly organized and validly
existing as a corporation or partnership under the laws of its jurisdiction of
organization, (ii) is duly qualified to do business and is in good standing in
all jurisdictions (whether federal, state, local or foreign) where its ownership
or leasing of property or the conduct of its business requires it to be so
qualified and in which the failure to be so qualified would have or reasonably
be expected to have a Material Adverse Effect on Subject Company, and (iii) has
all requisite corporate power and authority to own or lease its properties and
assets and to carry on its business as now conducted.
 
     (c) Except for its ownership of Great Western Bank, a Federal Savings Bank
("Great Western Bank"), First Community Industrial Bank and Great Western Thrift
and Loan, Subject Company does not own any stock of or equity interest in any
depository institution (as defined in 12 U.S.C. sec. 1813(c)(1)). Great Western
Bank is a qualified thrift lender pursuant to Section 10(m) of HOLA and its
deposits are insured by the Federal Deposit Insurance Corporation (the "FDIC")
through the Savings Association Insurance Fund ("SAIF") to the fullest extent
permitted by law. Great Western Bank is a member in good standing of the Federal
Home Loan Bank ("FHLB") of San Francisco. The deposits of each of First
Community Industrial Bank and Great Western Thrift and Loan are insured by the
FDIC through the Bank Insurance Fund ("BIF") to the fullest extent permitted by
law. Each of First Community Industrial Bank and Great Western Thrift and Loan
is an institution described in Section 2(c)(2)(H) of the Bank Holding Company
Act of 1956, as amended. Neither Subject Company nor First Community Industrial
Bank or Great Western Thrift and Loan has received a notice from either the
Office of Thrift Supervision (the "OTS") or the FDIC to the effect that either
regulator deems First Community Industrial Bank or Great Western Thrift and Loan
a savings association under Section 10(a)(1) of HOLA or 12 CFR sec. 583.21.
 
     3.2 Capitalization.  (a) The authorized capital stock of Subject Company
consists of 200,000,000 shares of Subject Company Common Stock and 10,000,000
shares of preferred stock, par value $1.00 per share (the "Subject Company
Preferred Stock"). At the close of business on March 4, 1997, there were
137,574,634 shares of Subject Company Common Stock outstanding, 660,000 shares
of Subject Company 8.30% Preferred Stock outstanding (evidenced by 6,600,000
Subject Company Depositary Shares, each of which represent a one-tenth interest
in a share of Subject Company 8.30% Preferred Stock) and 437,639 shares of
Subject Company Common Stock held in Subject Company's treasury. As of March 4,
1997, no
 
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shares of Subject Company Common Stock or Subject Company Preferred Stock were
reserved for issuance, except (i) 4,121,941 shares of Subject Company Common
Stock were reserved for issuance pursuant to Subject Company's dividend
reinvestment and stock purchase plans, (ii) 9,859,477 shares of Subject Company
Common Stock were reserved for issuance upon the exercise of stock options
pursuant to the Subject Company Stock Option Plans, (iii) 4,000,000 shares of
the Subject Company Common Stock are reserved for issuance pursuant to the
Subject Company Employee Savings Incentive Plan (the "ESIP") and (iv) the shares
of Subject Company Preferred Stock reserved for issuance upon exercise of the
Subject Company Rights distributed to holders of Subject Company Common Stock
pursuant to the Subject Company Rights Agreement. All of the issued and
outstanding shares of Subject Company Common Stock and Subject Company 8.30%
Preferred Stock have been duly authorized and validly issued and are fully paid,
nonassessable and free of preemptive rights, with no personal liability
attaching to the ownership thereof. As of the date of this Agreement, except (i)
as set forth in Section 3.2(a) of the disclosure schedule of Subject Company
delivered to Parent concurrently herewith (the "Subject Company Disclosure
Schedule"), (ii) for the Subject Company Rights Agreement (a true and correct
copy of which, including all amendments thereto, has been made available to
Parent) and (iii) as set forth elsewhere in this Section 3.2(a), Subject Company
does not have and is not bound by any outstanding subscriptions, options,
warrants, calls, commitments or agreements of any character calling for the
purchase or issuance of any shares of Subject Company Common Stock or Subject
Company Preferred Stock or any other equity securities of Subject Company or any
securities representing the right to purchase or otherwise receive any shares of
Subject Company Common Stock or Subject Company Preferred Stock. Except as set
forth in Section 3.2(a) of the Subject Company Disclosure Schedule, since March
4, 1997, Subject Company has not issued any shares of its capital stock or any
securities convertible into or exercisable for any shares of its capital stock,
other than pursuant to Subject Company's dividend reinvestment and stock
purchase plans and the ESIP, the exercise of employee stock options granted
prior to such date and as disclosed in Section 3.2(a) of the Subject Company
Disclosure Schedule, and the issuance of Subject Company Rights pursuant to the
Subject Company Rights Agreement.
 
     (b) Section 3.2(b) of the Subject Company Disclosure Schedule lists all
"Significant Subsidiaries" of the Subject Company (as such term is defined in
Rule 1-02 of Regulation S-X). Each Subsidiary in which Subject Company or any
Subject Company Subsidiary beneficially owns or controls, directly or
indirectly, more than 9.9% equity interest is a legal investment for a unitary
savings and loan holding company and, for those owned by Great Western Bank, for
a federal savings association. Except as set forth in Section 3.2(b) of the
Subject Company Disclosure Schedule, Subject Company owns, directly or
indirectly, all of the issued and outstanding shares of capital stock of or all
other equity interests in each of the Subject Company Subsidiaries, free and
clear of any liens, charges, encumbrances, adverse rights or claims and security
interests whatsoever ("Liens"), and all of such shares are duly authorized and
validly issued and are fully paid, nonassessable and free of preemptive rights,
with no personal liability attaching to the ownership thereof. Neither Subject
Company nor any Subject Company Subsidiary has or is bound by any outstanding
subscriptions, options, warrants, calls, commitments or agreements of any
character calling for the purchase, sale or issuance of any shares of capital
stock or any other equity security of any Subsidiary of Subject Company or any
securities representing the right to purchase or otherwise receive any shares of
capital stock or any other equity security of any such Subsidiary.
 
     3.3 Authority; No Violation.  (a) Subject Company 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 approved by the Board of Directors of Subject Company. The Board of
Directors of Subject Company has directed that the agreement of merger (within
the meaning of Section 251 of the DGCL) contained in this Agreement and the
transactions contemplated hereby be submitted to Subject Company's stockholders
for approval at a meeting of such stockholders and, except for the adoption of
such agreement of merger by the affirmative vote of the holders of a majority of
the outstanding shares of Subject Company Common Stock, no other corporate
proceedings on the part of Subject Company are necessary to approve this
Agreement and to consummate the transactions contemplated hereby. This Agreement
has been duly and validly executed and delivered by Subject Company and
(assuming due authorization, execution and delivery by Parent and Merger Sub)
constitutes a valid and binding obligation of Subject Company, enforceable
 
                                       A-7
<PAGE>   122
 
against Subject Company in accordance with its terms, except as enforcement may
be limited by general principles of equity whether applied in a court of law or
a court of equity and by bankruptcy, insolvency and similar laws affecting
creditors' rights and remedies generally. Subject Company acknowledges that
Parent intends promptly after the Effective Time to cause the merger of Great
Western Bank and one of Parent's wholly owned depository institution
subsidiaries (the "Association Merger"); provided, however, that Parent agrees
that the structure of the Association Merger shall not adversely affect the
ability of the Merger to be treated as a reorganization within the meaning of
Section 368(a) of the Code. Great Western Bank has full corporate power and
authority to consummate the Association Merger.
 
     (b) Except as set forth in Section 3.3(b) of the Subject Company Disclosure
Schedule, neither the execution and delivery of this Agreement by Subject
Company nor the consummation by Subject Company of the transactions contemplated
hereby nor the consummation of the Association Merger, nor compliance by Subject
Company with any of the terms or provisions hereof, will (i) violate any
provision of the Restated Certificate of Incorporation or Bylaws of Subject
Company or any of the similar governing documents of any of its Subsidiaries or
(ii) assuming that the consents and approvals referred to in Section 3.4 are
duly obtained, (x) violate any statute, code, ordinance, rule, regulation,
judgment, order, writ, decree or injunction applicable to Subject Company or any
of its Subsidiaries or any of their respective properties or assets, or (y)
violate, conflict with, result in a breach of any provision of or the loss of
any benefit under, constitute a default (or an event which, with notice or lapse
of time, or both, would constitute a default) under, result in the termination
of or a right of termination or cancellation under, accelerate the performance
required by, or result in the creation of any Lien upon any of the respective
properties or assets of Subject Company or any of its Subsidiaries under, any of
the terms, conditions or provisions of any note, bond, mortgage, indenture, deed
of trust, license, lease, agreement or other instrument or obligation to which
Subject Company or any of its Subsidiaries is a party, or by which they or any
of their respective properties or assets may be bound or affected, except (in
the case of clause (y) above) for such violations, conflicts, breaches or
defaults which, either individually or in the aggregate, will not have and would
not reasonably be expected to have a Material Adverse Effect on Subject Company.
 
     3.4 Consents and Approvals.  Except for (i) the approval of the Merger and
the Association Merger by the OTS, (ii) approval of the listing of the Parent
Capital Stock to be issued in the Merger on Nasdaq, (iii) the filing with the
Securities and Exchange Commission (the "SEC") of a joint proxy statement in
definitive form relating to the meetings of Parent's and Subject Company's
stockholders to be held in connection with this Agreement and the transactions
contemplated hereby (the "Joint Proxy Statement") and the filing and declaration
of effectiveness of the registration statement on Form S-4 (the "S-4") in which
the Joint Proxy Statement will be included as a prospectus and any filings or
approvals under applicable state securities laws, (iv) the filing of the
Certificate of Merger with the Delaware Secretary pursuant to the DGCL and the
filing of the Preferred Stock Articles of Amendment with the Washington
Secretary, (v) the adoption of the agreement of merger (within the meaning of
Section 251 of the DGCL) contained in this Agreement by the requisite votes of
the stockholders of Subject Company and the issuance of the shares of Parent
Common Stock in the Merger by the stockholders of Parent, (vi) the consents and
approvals set forth in Section 3.4 of the Subject Company Disclosure Schedule,
and (vii) the consents and approvals of third parties which are not Governmental
Entities (as defined below), the failure of which to obtain will not have and
would not be reasonably expected to have a Material Adverse Effect, no consents
or approvals of, or filings or registrations with, any court, administrative
agency or commission or other governmental authority or instrumentality or
self-regulatory organization (each a "Governmental Entity") or with any third
party are necessary in connection with (A) the execution and delivery by Subject
Company of this Agreement and (B) the consummation by Subject Company of the
Merger and the other transactions contemplated hereby.
 
     3.5 Reports.  Subject Company and each of its Subsidiaries have timely
filed all material reports, registrations and statements, together with any
amendments required to be made with respect thereto, that they were required to
file since January 1, 1994 with any Governmental Entity and have paid all fees
and assessments due and payable in connection therewith. Except for normal
examinations conducted by a Governmental Entity in the regular course of the
business of Subject Company and its Subsidiaries or as set forth in Section 3.5
of the Subject Company Disclosure Schedule, no Governmental Entity has initiated
any
 
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<PAGE>   123
 
proceeding or, to the best knowledge of Subject Company, investigation into the
business or operations of Subject Company or any of its Subsidiaries since
January 1, 1994. Except as set forth in Section 3.5 of the Subject Company
Disclosure Schedule, there is no material unresolved violation, criticism or
exception by any Governmental Entity with respect to any report or statement
relating to any examinations of Subject Company or any of its Subsidiaries.
 
     3.6 Financial Statements.  Subject Company has previously made available to
Parent copies of (a) the consolidated balance sheets of Subject Company and its
Subsidiaries, as of December 31, for the fiscal years 1994 and 1995, and the
related consolidated statements of operations, shareholders' equity and cash
flows for the fiscal years 1993 through 1995, inclusive, as reported in Subject
Company's Annual Report on Form 10-K for the fiscal year ended December 31, 1995
filed with the SEC under the Securities Exchange Act of 1934, as amended (the
"Exchange Act"), in each case accompanied by the audit report of Price
Waterhouse LLP, independent auditors with respect to Subject Company and (b) the
unaudited consolidated balance sheets of Subject Company and its Subsidiaries as
of September 30, 1995 and September 30, 1996 and the related unaudited
consolidated statements of operations, shareholders' equity and cash flows for
the periods then ended, as reported in Subject Company's Quarterly Report on
Form 10-Q for the period ended September 30, 1996 filed with the SEC under the
Exchange Act. Each of the financial statements referred to in this Section 3.6
(including the related notes, where applicable) fairly present, and the
financial statements referred to in Section 6.11 hereof will fairly present
(subject, in the case of the unaudited statements, to normal recurring
adjustments, none of which are expected to be material in nature or amount), the
results of the consolidated operations and changes in stockholders' equity and
consolidated financial position of Subject Company and its Subsidiaries for the
respective fiscal periods or as of the respective dates therein set forth. Each
of such statements (including the related notes, where applicable) complies, and
the financial statements referred to in Section 6.11 hereof will comply, in all
material respects with applicable accounting requirements and with the published
rules and regulations of the SEC with respect thereto and each of such
statements (including the related notes, where applicable) has been, and the
financial statements referred to in Section 6.11 will be, prepared in accordance
with GAAP consistently applied during the periods involved, except in each case
as indicated in such statements or in the notes thereto or, in the case of
unaudited statements, as permitted by Form 10-Q. The books and records of
Subject Company and its Subsidiaries have been, and are being, maintained in all
material respects in accordance with GAAP and any other applicable legal and
accounting requirements and reflect only actual transactions.
 
     3.7 Broker's Fees.  Except as set forth in Section 3.7 of the Subject
Company Disclosure Schedule, neither Subject Company nor any Subject Company
Subsidiary nor any of their respective officers or directors has employed any
broker or finder or incurred any liability for any broker's fees, commissions or
finder's fees in connection with any of the transactions contemplated by this
Agreement. Copies of all agreements with each broker or finder listed in Section
3.7 of the Subject Company Disclosure Schedule have previously been furnished to
Parent.
 
     3.8 Absence of Certain Changes or Events.  (a) Except as publicly disclosed
in Subject Company Reports (as defined in Section 3.12) filed prior to the date
hereof, or as set forth in Section 3.8(a) of the Subject Company Disclosure
Schedule, since September 30, 1996, no event has occurred which has had or would
reasonably be expected to have, individually or in the aggregate, a Material
Adverse Effect on Subject Company or the Surviving Corporation.
 
     (b) Except as set forth in Section 3.8(b) of the Subject Company Disclosure
Schedule, since September 30, 1996, Subject Company and its Subsidiaries have
carried on their respective businesses in all material respects in the ordinary
course of business, and neither Subject Company nor any of its Subsidiaries has
(i) except for normal increases in the ordinary course of business consistent
with past practice and except as required by applicable law, increased the
wages, salaries, compensation, pension or other fringe benefits or perquisites
payable to any officer or director, other than persons newly hired for such
position, from the amount thereof in effect as of September 30, 1996, or granted
any severance or termination pay, entered into any contract to make or grant any
severance or termination pay, or paid any bonus, in each case to any such
officer or director, other than pursuant to preexisting agreements or
arrangements or (ii) suffered any strike, work stoppage, slow-down or other
labor disturbance.
 
                                       A-9
<PAGE>   124
 
     3.9 Legal Proceedings.  (a) Except as set forth in Section 3.9 of the
Subject Company Disclosure Schedule, neither Subject Company nor any of its
Subsidiaries is a party to any, and there are no pending or, to the best of
Subject Company's knowledge, threatened, legal, administrative, arbitral or
other proceedings, claims, actions or governmental or regulatory investigations
of any nature against Subject Company or any of its Subsidiaries or challenging
the validity or propriety of the transactions contemplated by this Agreement as
to which there is a significant possibility of an adverse determination and
which, if adversely determined, would, individually or in the aggregate, have or
reasonably be expected to have a Material Adverse Effect on Subject Company.
 
     (b) There is no injunction, order, judgment, decree or regulatory
restriction imposed upon Subject Company, any of its Subsidiaries or the assets
of Subject Company or any of its Subsidiaries which has had, or would reasonably
be expected to have, a Material Adverse Effect on Subject Company or the
Surviving Corporation.
 
     3.10 Taxes.  (a) Except as set forth in Section 3.10(a) of Subject Company
Disclosure Schedule or except to the extent of any failure to correctly file
which results in aggregate Taxes of less than $20,000,000 or a reduction in net
operating loss carryforward deductions of less than $60,000,000, each of Subject
Company and its Subsidiaries has (i) duly and timely filed (including pursuant
to applicable extensions granted without penalty) all Tax Returns (as
hereinafter defined) required to be filed at or prior to the Effective Time, and
such Tax Returns are to the best knowledge of Subject Company true, correct and
complete in all respects, and (ii) paid in full or made adequate provision in
the financial statements of Subject Company (in accordance with GAAP) for all
Taxes (as hereinafter defined) related to such Tax Returns. Except as set forth
in Section 3.10(a) of the Subject Company Disclosure Schedule or except to the
extent the aggregate Taxes described in this sentence or otherwise described in
this paragraph (a) (relating to undisclosed failures to file or pay taxes or the
existence of undisclosed liens for Taxes) are less than $20,000,000, no
deficiencies for any Taxes have been proposed, asserted or assessed against or
with respect to Subject Company or any of its Subsidiaries. Except as set forth
in Section 3.10(a) of the Subject Company Disclosure Schedule or except to the
extent the aggregate Taxes described in this sentence or otherwise described in
this paragraph (a) (relating to undisclosed failures to file or pay taxes on
undisclosed proposed deficiencies for Taxes) are less than $20,000,000, to the
best knowledge of Subject Company there are no liens for Taxes upon the assets
of either Subject Company or its Subsidiaries except for statutory liens for
current Taxes not yet due.
 
     (b) For purposes of this Agreement, "Taxes" shall mean all taxes, charges,
fees, levies, penalties or other assessments imposed by any United States
federal, state, local or foreign taxing authority, including, but not limited to
income, excise, property, sales, transfer, franchise, payroll, withholding,
social security or other similar taxes, including any interest or penalties
attributable thereto.
 
     (c) For purposes of this Agreement, "Tax Return" shall mean any return,
report, information return or other document (including any related or
supporting information) with respect to Taxes.
 
     (d) Neither Subject Company nor any of its Subsidiaries has filed a consent
to the application of Section 341(f) of the Code.
 
     3.11 Employees.  (a) Section 3.11(a) of the Subject Company Disclosure
Schedule sets forth a true and complete list of each material employee benefit
plan, arrangement or agreement and any amendments or modifications thereof
(including, without limitation, all stock purchase, stock option, severance,
employment, change-in-control, health/welfare and section 125 plans, fringe
benefit, bonus, incentive, deferred compensation and other agreements, programs,
policies and arrangements, whether or not subject to the Employee Retirement
Income Security Act of 1974, as amended ("ERISA")) that is maintained as of the
date of this Agreement (the "Plans") by Subject Company or any of its
Subsidiaries or by any trade or business, whether or not incorporated (an "ERISA
Affiliate"), all of which together with Subject Company would be deemed a
"single employer" within the meaning of Section 4001 of ERISA.
 
     (b) Subject Company has previously made available to Parent true and
complete copies of each of the Plans and all related documents, including but
not limited to (i) the actuarial report for such Plan (if
 
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<PAGE>   125
 
applicable) for each of the last two years, and (ii) the most recent
determination letter from the Internal Revenue Service (if applicable) for such
Plan.
 
     (c) Except as set forth in Section 3.11(c) of the Subject Company
Disclosure Schedule, (i) each of the Plans has been operated and administered in
all material respects in accordance with applicable laws, including but not
limited to ERISA and the Code, (ii) each of the Plans intended to be "qualified"
within the meaning of Section 401(a) of the Code is so qualified, (iii) with
respect to each Plan which is subject to Title IV of ERISA, the present value of
accrued benefits under such Plan, based upon the actuarial assumptions used for
funding purposes in the most recent actuarial report prepared by such Plan's
actuary with respect to such Plan, did not, as of its latest valuation date,
exceed the then current value of the assets of such Plan allocable to such
accrued benefits, (iv) no Plan provides benefits, including without limitation
death or medical benefits (whether or not insured), with respect to current or
former employees of Subject Company, its Subsidiaries or any ERISA Affiliate
beyond their retirement or other termination of service, other than (w) coverage
mandated by applicable law, (x) death benefits or retirement benefits under any
"employee pension plan," as that term is defined in Section 3(2) of ERISA, (y)
deferred compensation benefits accrued as liabilities on the books of Subject
Company, its Subsidiaries or the ERISA Affiliates or (z) benefits the full cost
of which is borne by the current or former employee (or his beneficiary), (v) no
liability under Title IV of ERISA has been incurred by Subject Company, its
Subsidiaries or any ERISA Affiliate that has not been satisfied in full (other
than payment of premiums to the Pension Benefit Guaranty Corporation (the
"PBGC")), and no condition exists that presents a material risk to Subject
Company, its Subsidiaries or any ERISA Affiliate of incurring a material
liability thereunder, (vi) no Plan is a "multiemployer pension plan," as such
term is defined in Section 3(37) of ERISA, (vii) all contributions or other
amounts payable by Subject Company or its Subsidiaries as of the Effective Time
with respect to each Plan in respect of current or prior plan years have been
paid or accrued in accordance with generally accepted accounting practices and
Section 412 of the Code, (viii) neither Subject Company, its Subsidiaries nor
any ERISA Affiliate has engaged in a transaction in connection with which
Subject Company, its Subsidiaries or any ERISA Affiliate could be subject to
either a material civil penalty assessed pursuant to Section 409 or 502(i) of
ERISA or a material tax imposed pursuant to Section 4975 or 4976 of the Code,
and (ix) to the best knowledge of Subject Company there are no pending,
threatened or anticipated claims (other than routine claims for benefits) by, on
behalf of or against any of the Plans or any trusts related thereto which would,
individually or in the aggregate, have or be reasonably expected to have a
Material Adverse Effect on Subject Company.
 
     (d) Except as set forth in Section 3.11(d) of the Subject Company
Disclosure Schedule, no Plan exists which provides for or could result in the
payment to any Subject Company employee of any money or other property or rights
or accelerate the vesting or payment of such amounts or rights to any Subject
Company employee as a result of the transactions contemplated by this Agreement,
including the Merger and the Association Merger, whether or not such payment or
acceleration would constitute a parachute payment within the meaning of Code
Section 280G. Since December 31, 1996, neither Subject Company nor any of its
Subsidiaries has taken any action that would result in the payment of any
amounts, or the accelerated vesting of any rights or benefits, under the Plans
set forth in Section 3.11(d) of the Subject Company Disclosure Schedule.
 
     3.12 SEC Reports.  Subject Company has previously made available to Parent
an accurate and complete copy of each final registration statement, prospectus,
report, schedule and definitive proxy statement filed since January 1, 1994 and
prior to the date hereof by Subject Company with the SEC pursuant to the
Securities Act of 1933, as amended (the "Securities Act"), or the Exchange Act
(the "Subject Company Reports"), and no such registration statement, prospectus,
report, schedule or proxy statement contained any untrue statement of a material
fact or omitted to state any material fact required to be stated therein or
necessary in order to make the statements therein, in light of the circumstances
in which they were made, not misleading. Subject Company has timely filed all
Subject Company Reports and other documents required to be filed by it under the
Securities Act and the Exchange Act, and, as of their respective dates, all
Subject Company Reports complied in all material respects with the published
rules and regulations of the SEC with respect thereto.
 
     3.13 Compliance with Applicable Law.  Except as disclosed in Section 3.13
of the Subject Company Disclosure Schedule, Subject Company and each of its
Subsidiaries hold, and have at all times held, all
 
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material licenses, franchises, permits and authorizations necessary for the
lawful conduct of their respective businesses under and pursuant to all, and
have complied with and are not in default in any material respect under any,
applicable law, statute, order, rule, regulation, policy and/or guideline of any
Governmental Entity relating to Subject Company or any of its Subsidiaries,
except where the failure to hold such license, franchise, permit or
authorization or such noncompliance or default would not, individually or in the
aggregate, have or reasonably be expected to have a Material Adverse Effect on
Subject Company, and neither Subject Company nor any of its Subsidiaries knows
of, or has received notice of, any violations of any of the above which,
individually or in the aggregate, would have or would reasonably be expected to
have a Material Adverse Effect on Subject Company.
 
     3.14 Certain Contracts.  (a) Except as set forth in Section 3.14(a) of the
Subject Company Disclosure Schedule, neither Subject Company nor any of its
Subsidiaries is a party to or is bound by any contract, arrangement, commitment
or understanding (whether written or oral) (i) which is a material contract (as
defined in Item 601(b)(10) of Regulation S-K of the SEC) to be performed after
the date of this Agreement, (ii) which limits the freedom of Subject Company or
any of its Subsidiaries to compete in any line of business, in any geographic
area or with any person, or (iii) with or to a labor union or guild (including
any collective bargaining agreement). Each contract, arrangement, commitment or
understanding of the type described in this Section 3.14(a), whether or not set
forth in Section 3.14(a) of the Subject Company Disclosure Schedule, is referred
to herein as a "Subject Company Contract," and neither Subject Company nor any
of its Subsidiaries knows of, or has received notice of, any violation of the
above by any of the other parties thereto which, individually or in the
aggregate, would have or would reasonably be expected to have a Material Adverse
Effect on Subject Company. Subject Company has made available or will make
available within five days after the date hereof all contracts which involved
payments by Subject Company or any of its Subsidiaries in 1996 of more than
$1,000,000 or which could reasonably be expected to involve payments during 1997
of $1,000,000.
 
     (b) (i) Each Subject Company Contract is valid and binding and in full
force and effect, (ii) Subject Company and each of its Subsidiaries has in all
material respects performed all obligations required to be performed by it to
date under each Subject Company Contract, and (iii) no event or condition exists
which constitutes or, after notice or lapse of time or both, would constitute a
material default on the part of Subject Company or any of its Subsidiaries under
any such Subject Company Contract, except, in each case, where such invalidity,
failure to be binding, failure to so perform or default, individually or in the
aggregate, would not have or reasonably be expected to have a Material Adverse
Effect on Subject Company.
 
     3.15 Agreements with Regulatory Agencies.  Except as set forth in Section
3.15 of the Subject Company Disclosure Schedule, neither Subject Company nor any
of its Subsidiaries is subject to any cease-and-desist or other order issued by,
or is a party to any written agreement, consent agreement or memorandum of
understanding with, or is a party to any commitment letter or similar
undertaking to, or is subject to any order or directive by, or has adopted any
board resolutions at the request of (each, whether or not set forth in Section
3.15 of the Subject Company Disclosure Schedule, a "Regulatory Agreement"), any
Governmental Entity that restricts the conduct of its business or that in any
manner relates to its capital adequacy, its credit policies, its management or
its business, nor has Subject Company or any of its Subsidiaries been advised by
any Governmental Entity that it is considering issuing or requesting any
Regulatory Agreement.
 
     3.16 Undisclosed Liabilities.  Except (i) for those liabilities that are
fully reflected or reserved against on the consolidated balance sheet of Subject
Company included in the Subject Company Form 10-Q for the quarter ended
September 30, 1996 or (ii) for liabilities incurred in the ordinary course of
business consistent with past practice since September 30, 1996, neither Subject
Company nor any of its Subsidiaries has incurred any liability of any nature
whatsoever (whether absolute, accrued or contingent or otherwise and whether due
or to become due) that, either alone or when combined with all similar
liabilities, has had, or would be reasonably expected to have, a Material
Adverse Effect on Subject Company.
 
     3.17 Rights Agreement; Anti-takeover Provisions.  Subject Company has taken
all action so that the entering into of this Agreement and the consummation of
the transactions contemplated hereby do not and will not result in the grant of
any rights to any person under the Subject Company Rights Agreement or enable
 
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<PAGE>   127
 
or require the Subject Company Rights to be exercised, distributed or triggered.
The Board of Directors of Subject Company has taken all necessary action so that
the provisions of Section 203 of the DGCL (and any applicable provisions of the
takeover laws of any other state) and any comparable provisions of Subject
Company's Restated Certificate of Incorporation do not and will not apply to
this Agreement, the Merger or the transactions contemplated hereby.
 
     3.18 Subject Company Information.  The information relating to Subject
Company and its Subsidiaries to be provided by Subject Company for inclusion in
the Joint Proxy Statement and the S-4, or in any other document filed with any
other Governmental Entity in connection herewith, will not contain any untrue
statement of a material fact or omit to state a material fact necessary to make
the statements therein, in light of the circumstances in which they are made,
not misleading. The Joint Proxy Statement (except for such portions thereof as
relate only to Parent or any of its Subsidiaries) will comply as to form in all
material respects with the provisions of the Exchange Act and the rules and
regulations thereunder.
 
     3.19 Environmental Liability.  Except as set forth in Section 3.19 of the
Subject Company Disclosure Schedule, there are no legal, administrative,
arbitral or other proceedings, claims, actions, causes of action, private
environmental investigations or remediation activities or governmental
investigations of any nature seeking to impose, or that reasonably could be
expected to result in the imposition, on Subject Company or any of its
Subsidiaries of any liability or obligation arising under common law standards
relating to environmental protection, human health or safety, or 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 (collectively, the
"Environmental Laws"), pending or, to the knowledge of Subject Company,
threatened, against Subject Company or any of its Subsidiaries, which liability
or obligation would have or would reasonably be expected to have a Material
Adverse Effect on Subject Company. To the knowledge of Subject Company or any of
its Subsidiaries, there is no reasonable basis for any such proceeding, claim,
action or governmental investigation that would impose any liability or
obligation that would have or would reasonably be expected to have a Material
Adverse Effect on Subject Company. To the knowledge of Subject Company, during
or prior to the period of (i) its or any of its Subsidiaries' ownership or
operation of any of their respective current properties, (ii) its or any of its
Subsidiaries' participation in the management of any property, or (iii) its or
any of its Subsidiaries' holding of a security interest or other interest in any
property, there were no releases or threatened releases of hazardous, toxic,
radioactive or dangerous materials or other materials regulated under
Environmental Laws in, on, under or affecting any such property which would
reasonably be expected to have a Material Adverse Effect. Neither Subject
Company nor any of its Subsidiaries is subject to any agreement, order,
judgment, decree, letter or memorandum by or with any court, governmental
authority, regulatory agency or third party imposing any material liability or
obligation pursuant to or under any Environmental Law that would have or would
reasonably be expected to have a Material Adverse Effect on Subject Company.
 
     3.20 Pooling of Interests.  As of the date of this Agreement, Subject
Company has no reason to believe that the Merger will not qualify as a pooling
of interests for accounting purposes.
 
     3.21 Opinions of Financial Advisors.  Subject Company has received the
opinions of each of Goldman, Sachs & Co. and Merrill Lynch & Co., dated March 5,
1997, to the effect that, as of such date, the Common Exchange Ratio is fair
from a financial point of view to the holders of Subject Company Common Stock.
 
     3.22 Patents, Trademarks, Etc.  Subject Company owns or possesses all legal
rights to use all proprietary rights, including without limitation all
trademarks, trade names, service marks and copyrights, that are material to the
conduct of Subject Company's existing and proposed businesses. Except for the
agreements listed on Section 3.22 of the Subject Company Disclosure Schedule,
Subject Company is not bound by or a party to any options, licenses or
agreements of any kind with respect to any trademarks, service marks or trade
names which Subject Company claims to own. Subject Company has not received any
communications alleging that it or its Subsidiaries has violated or would
violate any of the patents, trademarks, service marks, trade names, copyrights
or trade secrets or other proprietary rights of any other person or entity.
 
     3.23 Community Reinvestment Act Compliance.  Great Western Bank is in
substantial compliance with the applicable provisions of the Community
Reinvestment Act of 1977 and the regulations promulgated
 
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thereunder (collectively, "CRA") and has received a CRA rating of "outstanding"
from the OTS in its most recent exam, and Subject Company has no knowledge of
the existence of any fact or circumstance or set of facts or circumstances which
could be reasonably expected to result in Great Western Bank failing to be in
substantial compliance with such provisions or having its current rating
lowered.
 
                                   ARTICLE IV
 
                         REPRESENTATIONS AND WARRANTIES
                                   OF PARENT
 
     Parent hereby represents and warrants to Subject Company as follows:
 
     4.1 Corporate Organization.  (a) Parent is a corporation duly organized,
validly existing and in good standing under the laws of the State of Washington.
Parent has the corporate power and authority to own or lease all of its
properties and assets and to carry on its business as it is now being conducted,
and is duly licensed or qualified to do business in each jurisdiction in which
the nature of the business conducted by it or the character or location of the
properties and assets owned or leased by it makes such licensing or
qualification necessary, except where the failure to be so licensed or qualified
would not have or reasonably be expected to have a Material Adverse Effect on
Parent. Parent is duly registered as a savings and loan holding company under
HOLA and qualifies as a savings and loan holding company of the type described
in Section 10(c)(3)(B) of HOLA. The copies of the Articles of Incorporation and
Bylaws of Parent which have previously been made available to Subject Company
are true, complete and correct copies of such documents as in effect as of the
date of this Agreement.
 
     (b) Merger Sub is a corporation duly organized, validly existing and in
good standing under the laws of the State of Delaware. Merger Sub will be a
wholly owned direct subsidiary of Parent at least one day prior to, and as of,
the Effective Time. Each Parent Subsidiary (i) is duly organized and validly
existing as a bank, savings association, corporation or partnership under the
laws of its jurisdiction of organization, (ii) is duly qualified to do business
and in good standing in all jurisdictions (whether federal, state, local or
foreign) where its ownership or leasing of property or the conduct of its
business requires it to be so qualified and in which the failure to be so
qualified would have or reasonably be expected to have a Material Adverse Effect
on Parent, and (iii) has all requisite corporate power and authority to own or
lease its properties and assets and to carry on its business as now conducted.
 
     (c) Except for its ownership of Washington Mutual Bank, Washington Mutual
Bank fsb, American Savings Bank, F.A. and Family Savings Bank, FSB, Parent does
not own any stock of or equity interest in any depository institution (as
defined in 12 U.S.C. sec. 1813(c)(1)). Washington Mutual Bank is a qualified
thrift lender pursuant to Section 10(m) of HOLA and its deposits are insured by
the FDIC through the SAIF and the BIF to the fullest extent permitted by law.
Washington Mutual Bank is a member in good standing of the FHLB of Seattle.
Washington Mutual Bank fsb and American Savings Bank are each qualified thrift
lenders pursuant to Section 10(m) of HOLA and their deposits are insured by the
FDIC through the SAIF to the fullest extent permitted by law. Washington Mutual
Bank fsb is a member in good standing of the FHLB of Seattle. American Savings
Bank is a member in good standing of the FHLB of San Francisco.
 
     4.2 Capitalization.  (a) The authorized capital stock of Parent consists of
350,000,000 shares of Parent Common Stock and 10,000,000 shares of Preferred
Stock, no par value ("Parent Preferred Stock"). At the close of business on
December 31, 1996, there were 126,255,891 shares of Parent Common Stock
outstanding, 2,752,500 shares of Parent Preferred Stock designated Series C
issued and outstanding, and 1,970,000 shares of Parent Preferred Stock
designated Series E issued and outstanding. On December 31, 1996, no shares of
Parent Common Stock or Parent Preferred Stock were reserved for issuance. All of
the issued and outstanding shares of Parent Common Stock and Parent Preferred
Stock have been duly authorized and validly issued and are fully paid,
nonassessable and free of preemptive rights, with no personal liability
attaching to the ownership thereof. As of the date of this Agreement, except (i)
as set forth in Section 4.2(a) of the Parent Disclosure Schedule (as defined
below), (ii) the Rights Agreement, dated as of October 16, 1990, between Parent
and First Interstate Bank of Washington (as amended and supplemented, the
"Parent Rights Agreement"), and
 
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<PAGE>   129
 
(iii) as set forth elsewhere in this Section 4.2(a), Parent does not have and is
not bound by any outstanding subscriptions, options, warrants, calls,
commitments or agreements of any character calling for the purchase or issuance
of any shares of Parent Common Stock or Parent Preferred Stock or any other
equity securities of Parent or any securities representing the right to purchase
or otherwise receive any shares of Parent Common Stock or Parent Preferred
Stock. Except (i) as set forth in Section 4.2(a) of the disclosure schedule of
Parent delivered to Subject Company concurrently herewith (the "Parent
Disclosure Schedule"), (ii) for options and restricted shares of Parent Common
Stock permitted by this Agreement to be granted subsequent to the date of this
Agreement, and (iii) for shares and other securities issued in connection with
transactions permitted by Section 5.2, since December 31, 1996, Parent has not
issued any shares of its capital stock or any securities convertible into or
exercisable for any shares of its capital stock, other than pursuant to Parent's
dividend reinvestment and employee stock purchase plans, the exercise of
employee stock options granted prior to such date or thereafter as permitted by
or disclosed in this Agreement, or as disclosed in Section 4.2(a) of the Parent
Disclosure Schedule. The shares of Parent Capital Stock to be issued pursuant to
the Merger will be duly authorized and validly issued and, at the Effective
Time, all such shares will be fully paid, nonassessable and free of preemptive
rights, with no personal liability attaching to the ownership thereof.
 
     (b) Except as set forth in Section 4.2(b) of the Parent Disclosure
Schedule, Parent owns, directly or indirectly, all of the issued and outstanding
shares of capital stock of or all other equity interests in each of the Parent
Subsidiaries, free and clear of any Liens, and all of such shares are duly
authorized and validly issued and are fully paid, nonassessable and free of
preemptive rights, with no personal liability attaching to the ownership
thereof. No Parent Subsidiary has or is bound by any outstanding subscriptions,
options, warrants, calls, commitments or agreements of any character calling for
the purchase or issuance of any shares of capital stock or any other equity
security of such Subsidiary or any securities representing the right to purchase
or otherwise receive any shares of capital stock or any other equity security of
such Subsidiary.
 
     4.3 Authority; No Violation.  (a) Parent 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 approved by the Board of Directors of Parent. The Board of Directors of
Parent will direct that the issuance of shares of Parent Common Stock in the
Merger be submitted to Parent's stockholders for approval at a meeting of such
stockholders and, except for the approval of such issuance by the affirmative
vote of the holders of a majority of the votes cast at such meeting, no other
corporate proceedings on the part of Parent are necessary to approve this
Agreement and to consummate the transactions contemplated hereby. This Agreement
has been duly and validly executed and delivered by Parent and (assuming due
authorization, execution and delivery by Subject Company) constitutes a valid
and binding obligation of Parent, enforceable against Parent in accordance with
its terms, except as enforcement may be limited by general principles of equity
whether applied in a court of law or a court of equity and by bankruptcy,
insolvency and similar laws affecting creditors' rights and remedies generally.
 
     (b) Merger Sub 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 has been duly and validly approved by the Board
of Directors of Merger Sub and will be duly and validly approved by the sole
shareholder of Merger Sub, and, upon such approval, no other corporate
proceedings on the part of Merger Sub will be necessary to consummate the
transactions contemplated hereby. This Agreement has been duly and validly
executed and delivered by Merger Sub and (assuming due authorization, execution
and delivery by the Subject Company) constitutes a valid and binding obligation
of Merger Sub, enforceable against Merger Sub in accordance with its terms,
except as enforcement may be limited by general principles of equity whether
applied in a court of law or a court of equity and by bankruptcy, insolvency and
similar laws affecting creditors' rights and remedies generally.
 
     (c) Except as set forth in Section 4.3(c) of the Parent Disclosure
Schedule, neither the execution and delivery of this Agreement by Parent or
Merger Sub, nor the consummation by Parent of the transactions contemplated
hereby, nor compliance by Parent with any of the terms or provisions hereof will
(i) violate any provision of the Articles of Incorporation or Bylaws of Parent
or any of the similar governing documents of any of its Subsidiaries or (ii)
assuming that the consents and approvals referred to in Section 4.4 are duly
 
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<PAGE>   130
 
obtained, (x) violate any statute, code, ordinance, rule, regulation, judgment,
order, writ, decree or injunction applicable to Parent or any of its
Subsidiaries (including Merger Sub) or any of their respective properties or
assets, or (y) violate, conflict with, result in a breach of any provision of or
the loss of any benefit under, constitute a default (or an event which, with
notice or lapse of time or both, would constitute a default) under, result in
the termination of or a right of termination or cancellation under, accelerate
the performance required by, or result in the creation of any Lien upon any of
the respective properties or assets of Parent or any of its Subsidiaries
(including Merger Sub) under, any of the terms, conditions or provisions of any
note, bond, mortgage, indenture, deed of trust, license, lease, agreement or
other instrument or obligation to which Parent or any of its Subsidiaries
(including Merger Sub) is a party, or by which they or any of their respective
properties or assets may be bound or affected, except (in the case of clause (y)
above) for such violations, conflicts, breaches or defaults which either
individually or in the aggregate will not have and would not reasonably be
expected to have a Material Adverse Effect on Parent.
 
     4.4 Consents and Approvals.  Except for (i) the approval of the Merger and
the Association Merger by the OTS, (ii) approval of the listing of the Parent
Capital Stock to be issued in the Merger on Nasdaq, (iii) the filing with the
SEC of the Joint Proxy Statement and the filing and declaration of effectiveness
of the S-4 and any filings or approvals under applicable state securities laws,
(iv) the filing of the Certificate of Merger with the Delaware Secretary
pursuant to the DGCL and the filing of the Preferred Stock Articles of Amendment
with the Washington Secretary, (v) the adoption of the agreement of merger
(within the meaning of Section 251 of the DGCL) contained in this Agreement by
the requisite votes of the stockholders of Subject Company and the approval of
the issuance of the shares of Parent Common Stock in the Merger by the
stockholders of Parent as required by Nasdaq, (vi) the consents and approvals
set forth in Section 4.4 of the Parent Disclosure Schedule, and (vii) the
consents and approvals of third parties which are not Governmental Entities, the
failure of which to obtain will not have and would not be reasonably expected to
have a Material Adverse Effect, no consents or approvals of, or filings or
registrations with, any Governmental Entity or any third party are necessary in
connection with (A) the execution and delivery by Parent or Merger Sub of this
Agreement and (B) the consummation by Parent and Merger Sub of the Merger and
the other transactions contemplated hereby.
 
     4.5 Reports.  Parent and each of its Subsidiaries have timely filed all
material reports, registrations and statements, together with any amendments
required to be made with respect thereto, that they were required to file since
January 1, 1994 with any Governmental Entities, and have paid all fees and
assessments due and payable in connection therewith. Except as set forth in
Section 4.5 of the Parent Disclosure Schedule and except for normal examinations
conducted by a Governmental Entity in the regular course of the business of
Parent and its Subsidiaries, no Governmental Entity has initiated any proceeding
or, to the best knowledge of Parent, investigation into the business or
operations of Parent or any of its Subsidiaries since January 1, 1994. There is
no material unresolved violation, criticism, or exception by any Government
Entity with respect to any report or statement relating to any examinations of
Parent or any of its Subsidiaries.
 
     4.6 Financial Statements.  Parent has previously made available to Subject
Company copies of (a) the consolidated balance sheets of Parent and its
Subsidiaries, as of December 31, for the fiscal years 1994 and 1995, and the
related consolidated statements of income, changes in stockholders' equity and
cash flows for the fiscal years 1993 through 1995, inclusive, as reported in
Parent's Annual Report on Form 10-K for the fiscal year ended December 31, 1995
filed with the SEC under the Exchange Act, in each case accompanied by the audit
report of Deloitte & Touche, LLP, independent public accountants with respect to
Parent and (b) the unaudited consolidated balance sheets of Parent and its
Subsidiaries as of September 30, 1995 and September 30, 1996 and the related
unaudited consolidated statements of income, cash flows and changes in
stockholders' equity for the periods then ended, as reported in Parent's
Quarterly Report on Form 10-Q for the period ended September 30, 1996 filed with
the SEC under the Exchange Act. Each of the financial statements referred to in
this Section 4.6 (including the related notes, where applicable) fairly present,
and the financial statements referred to in Section 6.11 hereof will fairly
present (subject, in the case of the unaudited statements, to normal recurring
adjustments, none of which are expected to be material in nature and amount),
the results of the consolidated operations and changes in stockholders' equity
and consolidated financial position of Parent and its Subsidiaries for the
respective fiscal periods or as of the respective dates
 
                                      A-16
<PAGE>   131
 
therein set forth. Each of such statements (including the related notes, where
applicable) complies, and the financial statements referred to in Section 6.11
hereof will comply, in all material respects with applicable accounting
requirements and with the published rules and regulations of the SEC with
respect thereto; and each of such statements (including the related notes, where
applicable) has been, and the financial statements referred to in Section 6.11
will be, prepared in accordance with GAAP consistently applied during the
periods involved, except in each case as indicated in such statements or in the
notes thereto or, in the case of unaudited statements, as permitted by Form
10-Q. The books and records of Parent and its Subsidiaries have been, and are
being, maintained in all material respects in accordance with GAAP and any other
applicable legal and accounting requirements and reflect only actual
transactions.
 
     4.7 Broker's Fees.  Except as set forth in Section 4.7 of the Parent
Disclosure Schedule, neither Parent nor any Parent Subsidiary nor any of their
respective officers or directors has employed any broker or finder or incurred
any liability for any broker's fees, commissions or finder's fees in connection
with any of the transactions contemplated by this Agreement. Copies of all
agreements with each broker or finder listed in Section 4.7 of the Parent
Disclosure Schedule have previously been furnished to Subject Company.
 
     4.8 Absence of Certain Changes or Events.  Except as publicly disclosed in
Parent Reports (as defined below) filed prior to the date hereof, since
September 30, 1996, no event has occurred which has had or would reasonably be
expected to have, individually or in the aggregate, a Material Adverse Effect on
Parent.
 
     4.9 Legal Proceedings.  (a) Neither Parent nor any of its Subsidiaries is a
party to any, and there are no pending or, to the best of Parent's knowledge,
threatened, legal, administrative, arbitral or other proceedings, claims,
actions or governmental or regulatory investigations of any nature against
Parent or any of its Subsidiaries or challenging the validity or propriety of
the transactions contemplated by this Agreement as to which there is a
significant possibility of an adverse determination and which, if adversely
determined, would, individually or in the aggregate, have or reasonably be
expected to have a Material Adverse Effect on Parent.
 
     (b) There is no injunction, order, judgment, decree, or regulatory
restriction imposed upon Parent, any of its Subsidiaries or the assets of Parent
or any of its Subsidiaries which has had, or would reasonably be expected to
have, a Material Adverse Effect on Parent or the Surviving Corporation.
 
     4.10 Taxes.  Except as set forth in Section 4.10 of the Parent Disclosure
Schedule, each of Parent and its Subsidiaries has (i) duly and timely filed
(including pursuant to applicable extensions granted without penalty) all
material Tax Returns required to be filed at or prior to the Effective Time, and
such Tax Returns are to the best knowledge of the Parent true, correct and
complete in all material respects, and (ii) paid in full or made adequate
provision in the financial statements of Parent (in accordance with GAAP) for
all Taxes related to such Tax Returns. Except as set forth in Section 4.10 of
the Parent Disclosure Schedule, no material deficiencies for any Taxes have been
proposed, asserted or assessed against or with respect to Parent or any of its
Subsidiaries, and, to the best knowledge of Parent, there are no material liens
for Taxes upon the assets of either Parent or its Subsidiaries except for
statutory liens for current Taxes not yet due.
 
     4.11 SEC Reports.  Parent has previously made available to Subject Company
an accurate and complete copy of each final registration statement, prospectus,
report, schedule and definitive proxy statement filed since January 1, 1994 and
prior to the date hereof by Parent with the SEC pursuant to the Securities Act
or the Exchange Act (the "Parent Reports"), and no such registration statement,
prospectus, report, schedule or proxy statement contained any untrue statement
of a material fact or omitted to state any material fact required to be stated
therein or necessary in order to make the statements therein, in light of the
circumstances in which they were made, not misleading. Parent has timely filed
all Parent Reports and other documents required to be filed by it under the
Securities Act and the Exchange Act, and, as of their respective dates, all
Parent Reports complied in all material respects with the published rules and
regulations of the SEC with respect thereto.
 
     4.12 Compliance with Applicable Law.  Except as disclosed in Section 4.12
of the Parent Disclosure Schedule, Parent and each of its Subsidiaries hold, and
have at all times held, all material licenses, franchises, permits and
authorizations necessary for the lawful conduct of their respective businesses
under and pursuant to all, and have complied with and are not in default in any
material respect under any, applicable law, statute,
 
                                      A-17
<PAGE>   132
 
order, rule, regulation, policy and/or guideline of any Governmental Entity
relating to Parent or any of its Subsidiaries, except where the failure to hold
such license, franchise, permit or authorization or such noncompliance or
default would not, individually or in the aggregate, have or reasonably be
expected to have a Material Adverse Effect on Parent, and neither Parent nor any
of its Subsidiaries knows of, or has received notice of, any material violations
of any of the above which, individually or in the aggregate, would have or
reasonably be expected to have a Material Adverse Effect on Parent.
 
     4.13 Agreements with Regulatory Agencies.  Except as set forth in Section
4.13 of the Parent Disclosure Schedule, neither Parent nor any of its
Subsidiaries is subject to any cease-and-desist or other order issued by, or is
a party to any written agreement, consent agreement or memorandum of
understanding with, or is a party to any commitment letter or similar
undertaking to, or is subject to any order or directive by, or has adopted any
board resolutions at the request of (each, whether or not set forth in Section
4.13 of the Parent Disclosure Schedule, a "Parent Regulatory Agreement"), any
Governmental Entity that restricts the conduct of its business or that in any
manner relates to its capital adequacy, its credit policies, its management or
its business, nor has Parent or any of its Subsidiaries been advised by any
Governmental Entity that it is considering issuing or requesting any Regulatory
Agreement.
 
     4.14 Undisclosed Liabilities.  Except for those liabilities that are fully
reflected or reserved against on the consolidated balance sheet of Parent
included in the Parent Form 10-Q for the quarter ended September 30, 1996 or for
liabilities incurred in the ordinary course of business consistent with past
practice since September 30, 1996, neither Parent nor any of its Subsidiaries
has incurred any liability of any nature whatsoever (whether absolute, accrued,
contingent or otherwise and whether due or to become due) that, either alone or
when combined with all similar liabilities, has had, or would reasonably be
expected to have, a Material Adverse Effect on Parent.
 
     4.15 Rights Agreement; Anti-takeover Provisions.  Parent has taken all
action (including, if required, redeeming all of the outstanding Rights issued
pursuant to the Parent Company Rights Agreement or amending or terminating the
Parent Rights Agreement) so that the entering into of this Agreement and the
consummation of the transactions contemplated hereby do not and will not result
in the grant of any rights to any person under the Parent Rights Agreement or
enable or require the Parent Rights to be exercised, distributed or triggered.
The Board of Directors of Parent has taken all necessary action so that the
takeover laws of the Washington Business Corporation Act (and any applicable
provisions of the takeover laws of any other state) and any comparable
provisions of Parent's Articles of Incorporation do not and will not apply to
this Agreement, the Merger or the transactions contemplated hereby.
 
     4.16 Parent Information.  The information relating to Parent and its
Subsidiaries to be provided by Parent to be contained in the Joint Proxy
Statement and the S-4, or in any other document filed with any other
Governmental Entity in connection herewith, will not contain any untrue
statement of a material fact or omit to state a material fact necessary to make
the statements therein, in light of the circumstances in which they are made,
not misleading. The Joint Proxy Statement (except for such portions thereof that
relate only to Subject Company or any of its Subsidiaries) will comply in all
material respects with the provisions of the Exchange Act and the rules and
regulations thereunder. The S-4 will comply as to form in all material respects
with the provisions of the Securities Act and the rules and regulations
thereunder.
 
     4.17 Environmental Liability.  Except as set forth in Section 4.17 of the
Parent Disclosure Schedule, there are no legal, administrative, arbitral or
other proceedings, claims, actions, causes of action, private environmental
investigations or remediation activities or governmental investigations of any
nature seeking to impose, or that reasonably would be expected to result in the
imposition, on Parent or any of its Subsidiaries of any liability or obligation
arising under any Environmental Law, pending or, to the knowledge of Parent,
threatened, against Parent or any of its Subsidiaries, which liability or
obligation would reasonably be expected to have a Material Adverse Effect on
Parent. To the knowledge of Parent, there is no reasonable basis for any such
proceeding, claim, action or governmental investigation that would impose any
liability or obligation that would reasonably be expected to have a Material
Adverse Effect on Parent. To the knowledge of Parent, during or prior to the
period of (i) its or any of its Subsidiaries' ownership or operation of any of
their respective current properties, (ii) its or any of its Subsidiaries'
participation in the management of any
 
                                      A-18
<PAGE>   133
 
property, or (iii) its or any of its Subsidiaries' holding of a security
interest or other interest in any property, there were no releases or threatened
releases of hazardous, toxic, radioactive or dangerous materials or other
materials regulated under Environmental Laws in, on, under or affecting any such
property, which would reasonably be expected to have a Material Adverse Effect
on Parent. Neither Parent nor any of its Subsidiaries is subject to any
agreement, order, judgment, decree, letter or memorandum by or with any court,
governmental authority, regulatory agency or third party imposing any material
liability or obligation pursuant to or under any Environmental Law that would
reasonably be expected to have a Material Adverse Effect on Parent.
 
     4.18 Pooling of Interests.  As of the date of this Agreement, Parent has no
reason to believe that the Merger will not qualify as a pooling of interests for
accounting purposes.
 
     4.19 Opinion of Financial Advisor.  Parent has received the opinion of
Lehman Brothers Inc., to the effect that, as of the date of this Agreement, the
Common Exchange Ratio is fair from a financial point of view to Parent.
 
     4.20 Patents, Trademarks, Etc.  Parent owns or possesses all legal rights
to use all proprietary rights, including without limitation all trademarks,
trade names, service marks and copyrights, that are material to the conduct of
Parent's existing and proposed businesses. Except for the agreements listed on
Section 4.20 of the Parent Disclosure Schedule, Parent is not bound by or a
party to any options, licenses or agreements of any kind with respect to any
trademarks, service marks or trade names which Parent claims to own. Parent has
not received any communications alleging that it or its Subsidiaries has
violated or would violate any of the patents, trademarks, service marks, trade
names, copyrights or trade secrets or other proprietary rights of any other
person or entity.
 
     4.21 Community Reinvestment Act Compliance.  Each of Washington Mutual Bank
and American Savings Bank, F.A. is in substantial compliance with the applicable
provisions of the CRA and has received a CRA rating of "outstanding" from the
OTS in its most recent exam, and Parent has no knowledge of the existence of any
fact or circumstances or set of facts or circumstances which could be reasonably
expected to result in Washington Mutual Bank or American Savings Bank, F.A.
failing to be in substantial compliance with such provisions or having its
current rating lowered.
 
                                   ARTICLE V
 
                   COVENANTS RELATING TO CONDUCT OF BUSINESS
 
     5.1 Conduct of Businesses Prior to the Effective Time.  Except as set forth
in the Subject Company Disclosure Schedule or the Parent Disclosure Schedule, as
the case may be, as expressly contemplated or permitted by this Agreement, or as
required by applicable law, rule or regulation, during the period from the date
of this Agreement to the Effective Time, each of Parent and Subject Company
shall, and shall cause each of their respective Subsidiaries to, (i) conduct its
business in the usual, regular and ordinary course consistent with past
practice, (ii) use reasonable best efforts to maintain and preserve intact its
business organization, employees and advantageous business relationships and
retain the services of its officers and key employees and (iii) take no action
which would reasonably be expected to adversely affect or delay the ability of
either Parent or Subject Company to obtain any approvals of any Governmental
Entity required to consummate the transactions contemplated hereby or to
consummate the transactions contemplated hereby.
 
     5.2 Forbearances.  Except as set forth in Section 5.2 of the Subject
Company Disclosure Schedule or Section 5.2 of the Parent Disclosure Schedule, as
the case may be, as expressly contemplated or permitted by this Agreement, or as
required by applicable law, rule or regulation, during the period from the date
of this Agreement to the Effective Time, neither Parent nor Subject Company
shall, and neither Parent nor Subject Company shall permit any of their
respective Subsidiaries to, without the prior written consent of the other:
 
          (a) adjust, split, combine or reclassify any capital stock; set any
     record or payment dates for the payment of any dividends or distributions
     on its capital stock except in the ordinary and usual course of business
     consistent with past practice; make, declare or pay any dividend or make
     any other distribution
 
                                      A-19
<PAGE>   134
 
     on, or directly or indirectly redeem, purchase or otherwise acquire, any
     shares of its capital stock or any securities or obligations convertible
     into or exchangeable for any shares of its capital stock, or except as
     otherwise permitted by this paragraph (a) grant any stock appreciation
     rights or grant any individual, corporation or other entity any right to
     acquire any shares of its capital stock (except for (i) regular quarterly
     cash dividends on Subject Company Common Stock and on Parent Common Stock
     at a rate equal to the rates paid by each of Subject Company and Parent, as
     the case may be, during the fiscal quarter immediately preceding the date
     hereof, as such rates may be increased, in the case of Parent only, in the
     ordinary course of business consistent with past practice; provided,
     however, that no dividend shall be paid by Subject Company on Subject
     Company Common Stock if Subject Company shall be required to borrow to do
     so; (ii) in the case of Subject Company 8.30% Preferred Stock and Parent
     Preferred Stock, for regular quarterly or semiannual cash dividends thereon
     at the rates set forth in the applicable certificate of incorporation or
     certificate of designation for such securities; (iii) dividends paid by any
     of the wholly owned Subsidiaries of each of Parent and Subject Company to
     Parent or Subject Company or any of their wholly owned Subsidiaries,
     respectively, provided that no such dividend shall cause Great Western Bank
     to cease to qualify as a "well capitalized" institution under 12 CFR Part
     565; and (iv) in the case of Parent only, the issuance of employee stock
     options and restricted stock consistent with past practices); or issue any
     additional shares of capital stock except (A) pursuant to the exercise of
     stock options outstanding as of the date hereof or, in the case of Parent
     only, issued after the date hereof in a manner consistent with past
     practice, (B) in the case of Parent only, the award of restricted shares of
     Parent Common Stock in a manner consistent with past practice, (C) pursuant
     to the Subject Company Rights Agreement, (D) pursuant to the Parent Rights
     Agreement, (E) pursuant to contracts or agreements in force at the date of
     this Agreement and set out in Section 5.2 of the Subject Company Disclosure
     Schedule and Section 5.2 of the Parent Disclosure Schedule, as the case may
     be, and (F) in connection with acquisitions and investments permitted by
     paragraph (c) hereof;
 
          (b) sell, transfer, mortgage, encumber or otherwise dispose of any of
     its properties or assets to any individual, corporation or other entity
     (other than a direct or indirect wholly owned Subsidiary), or cancel,
     release or assign any indebtedness to any such person or any claims held by
     any such person, in each case that is material to such party, except (i) in
     the ordinary course of business consistent with past practice or (ii)
     pursuant to contracts or agreements in force at the date of this Agreement
     and set out in Section 5.2 of the Subject Company Disclosure Schedule or
     Section 5.2 of the Parent Disclosure Schedule, as the case may be;
 
          (c) except for transactions in the ordinary course of business
     consistent with past practice, make any material acquisition or investment
     either by purchase of stock or securities, merger or consolidation,
     contributions to capital, property transfers, or purchases of any property
     or assets of any other individual, corporation or other entity other than a
     wholly owned Subsidiary thereof; provided, however, that subject to clause
     (iii) of Section 5.1, Parent may enter into an agreement or agreements for,
     and may consummate, business combination transactions with other companies
     provided that the aggregate amount of assets of such companies does not
     exceed $5,000,000,000; provided, further, however that, notwithstanding
     anything to the contrary contained herein, Parent shall not make any
     acquisition that would require it to register as a bank holding company
     under the Bank Holding Company Act of 1956, as amended;
 
          (d) in the case of the Subject Company, only enter into, renew or
     terminate any contract or agreement, other than loans made in the ordinary
     course of business, that calls for aggregate annual payments of $500,000
     and which is not either (i) terminable at will on 60 days or less notice
     without payment of a penalty or (ii) has a term of less than one year; or
     make any material change in any of its leases or contracts, other than
     renewals of contracts or leases for a term of one year or less without
     materially adverse changes to the terms thereof;
 
          (e) in the case of Subject Company only, other than general salary
     increases consistent with past practice, increase in any material respect
     the compensation or fringe benefits of any of its employees or pay any
     pension or retirement allowance not required by any existing plan or
     agreement to any such employees or become a party to, amend or commit
     itself to any pension, retirement, profit-sharing or
 
                                      A-20
<PAGE>   135
 
     welfare benefit plan or agreement or employment agreement with or for the
     benefit of any employee or accelerate the vesting of any stock options or
     other stock-based compensation;
 
          (f) authorize or permit any of its officers, directors, employees,
     representatives or agents (collectively, "Representatives") to directly or
     indirectly solicit, initiate or encourage any inquiries relating to or that
     may reasonably be expected to lead to, or the making of any proposal which
     constitutes, a Takeover Proposal (as defined below), or 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, at any time prior to the time its stockholders shall have voted to
     approve this Agreement, each of Parent and Subject Company may, and may
     authorize and permit its Representatives to, provide third parties with
     nonpublic information, otherwise facilitate any effort or attempt by any
     third party to make or implement a Takeover Proposal, recommend or endorse
     any Takeover Proposal with or by any third party, and participate in
     discussions and negotiations with any third party relating to any Takeover
     Proposal, if such party's Board of Directors, after having consulted with
     and considered the advice of its financial advisers and outside counsel,
     has determined in good faith that the failure to do so would create a
     reasonable possibility of a breach of the fiduciary duties of such party's
     Board of Directors. Each of Parent and Subject Company shall (i) advise the
     other orally (within one day) and in writing (as promptly as practicable)
     of the receipt of any such inquiry or proposal by it or by any of its
     Subsidiaries or any of its Representatives and (ii) unless its Board of
     Directors, after consulting with, and considering the advice of, its
     outside counsel, has determined in good faith that such action would create
     a reasonable possibility of a breach of the fiduciary duties of such Board
     of Directors, inform the other party orally and in writing, as promptly as
     practicable after the receipt thereof, of the material terms and conditions
     of any such inquiries or proposals (including the identity of the party
     making such inquiry or proposal) and shall keep the other party informed of
     the status thereof. Subject Company shall not furnish any nonpublic
     information to any other party pursuant to this Section 5.2(f) except
     pursuant to the terms of a confidentiality agreement containing terms
     substantially identical to the terms contained in the Confidentiality
     Agreement (as defined in Section 6.2(b) hereof). Subject Company will
     immediately cease and cause to be terminated any activities, discussions or
     negotiations conducted prior to the date of this Agreement with any parties
     other than Parent with respect to any of the foregoing and require the
     return (or if permitted by the terms of the applicable confidentiality
     agreement, the certified destruction) of all confidential information
     previously provided to such parties. As used in this Agreement, "Takeover
     Proposal" shall mean, with respect to any Person, any tender or exchange
     offer, proposal for a merger, consolidation or other business combination
     involving Subject Company or Parent or any of their respective Subsidiaries
     or any proposal or offer to acquire in any manner a substantial equity
     interest in, or a substantial portion of the assets of, Subject Company or
     Parent or any of their respective Subsidiaries, other than the transactions
     contemplated or permitted by this Agreement; provided, however, that any
     proposal or offer involving the acquisition by Parent of any equity
     interest in or assets of any person, whether by tender or exchange offer,
     merger, consolidation or otherwise, or the disposition by Parent of assets,
     deposits or Subsidiaries, which is permitted by the terms of Section 5.2 of
     this Agreement shall not constitute a Takeover Proposal;
 
          (g) in the case of Subject Company only, make any capital expenditures
     in excess of (A) $500,000 per project or related series of projects or (B)
     $3,000,000 in the aggregate, other than expenditures necessary to maintain
     existing assets in good repair;
 
          (h) in the case of Subject Company only, make application for the
     opening, relocation or closing of any, or open, relocate or close any,
     branch or loan production office;
 
          (i) in the case of Subject Company only, make or acquire any loan or
     issue a commitment for any loan except for loans and commitments that are
     made in the ordinary course of business consistent with past practice or
     issue or agree to issue any letters of credit or otherwise guarantee the
     obligations of any other persons except in the ordinary course of business
     in order to facilitate the sale of REO;
 
                                      A-21
<PAGE>   136
 
          (j) except as otherwise permitted elsewhere in this Section 5.2,
     engage or participate in any material transaction or incur or sustain any
     material obligation not in the ordinary course of business;
 
          (k) in the case of Subject Company only, except as otherwise permitted
     hereby foreclose upon or otherwise acquire (whether by deed in lieu of
     foreclosure or otherwise) any real property (other than 1-to-4 family
     residential properties in the ordinary course of business);
 
          (l) in the case of Subject Company only, sell, transfer or otherwise
     convey or agree to sell, transfer or otherwise convey, Sierra Investment
     Management Corporation;
 
          (m) settle any claim, action or proceeding involving money damages
     which is material to Parent or Subject Company, as applicable, except in
     the ordinary course of business consistent with past practice;
 
          (n) take any action that would prevent or impede the Merger from
     qualifying (i) as a reorganization within the meaning of Section 368(a) of
     the Code or (ii) for pooling of interests accounting treatment;
 
          (o) amend its certificate of incorporation, bylaws or similar
     governing documents or the Subject Company Rights Agreement or the Parent
     Rights Agreement, as the case may be, in a manner that would materially and
     adversely affect either party's ability to consummate the Merger or the
     economic benefits of the Merger to either party; provided, however that
     prior to the meeting of Subject Company's stockholders held to vote on this
     Agreement, Subject Company shall not amend the Subject Company Rights
     Agreement without Parent's prior written consent;
 
          (p) in the case of Subject Company only, except in the ordinary course
     of business consistent with past practice or following prior consultation
     with Parent, materially change its investment securities portfolio policy,
     or the manner in which the portfolio is classified or reported;
 
          (q) take any action that is intended or may reasonably be expected to
     result in any of its representations and warranties set forth in this
     Agreement being or becoming untrue in any material respect at any time
     prior to the Effective Time, or in any of the conditions to the Merger set
     forth in Article VII not being satisfied or in a violation of any provision
     of this Agreement, except, in every case, as may be required by applicable
     law;
 
          (r) make any changes in its accounting methods, except as may be
     required under law, rule, regulation or GAAP, in each case as concurred in
     by such party's independent public accountants;
 
          (s) in the case of Subject Company only, engage in the business of
     making or make any VA guaranteed or FHA insured mortgage loans;
 
          (t) in the case of Subject Company only, enter into any contracts or
     agreements or amendments or supplements thereto pertaining to any further
     development of specialized software for Subject Company or its
     Subsidiaries; or
 
          (u) agree to, or make any commitment to, take any of the actions
     prohibited by this Section 5.2.
 
                                   ARTICLE VI
 
                             ADDITIONAL AGREEMENTS
 
     6.1 Regulatory Matters.  (a) Parent and Subject Company shall promptly
prepare and file with the SEC a Joint Proxy Statement and Parent shall promptly
prepare and file with the SEC the S-4, in which the Joint Proxy Statement will
be included as a prospectus. Each of Parent and Subject Company shall use all
reasonable efforts to have the S-4 declared effective under the Securities Act
as promptly as practicable after such filing, and Parent and Subject Company
shall thereafter mail the Joint Proxy Statement to their respective
stockholders.
 
     (b) The parties hereto shall cooperate with each other and use reasonable
best efforts to promptly prepare and file all necessary documentation, to effect
all applications, notices, petitions and filings, to obtain
 
                                      A-22
<PAGE>   137
 
as promptly as practicable all permits, consents, approvals and authorizations
of all third parties and Governmental Entities which are necessary or advisable
to consummate the transactions contemplated by this Agreement (including without
limitation the Merger and the Association Merger) and to comply with the terms
and conditions of all such permits, consents, approvals and authorizations of
all such Governmental Entities. Parent and Subject Company shall have the right
to review in advance and to the extent practicable each will consult the other
on, in each case subject to applicable laws relating to the exchange of
information, all the information relating to Subject Company or Parent, as the
case may be, and any of their respective Subsidiaries which appears in any
filing made with, or written materials submitted to, any third party or any
Governmental Entity in connection with the transactions contemplated by this
Agreement. In exercising the foregoing right, each of the parties hereto shall
act reasonably and as promptly as practicable. The parties hereto agree that
they will consult with each other with respect to the obtaining of all permits,
consents, approvals and authorizations of all third parties and Governmental
Entities necessary or advisable to consummate the transactions contemplated by
this Agreement (including without limitation the Merger and the Association
Merger) and each party will keep the other apprised of the status of matters
relating to completion of the transactions contemplated herein.
 
     (c) Parent and Subject Company shall, upon request, furnish each other with
all information concerning themselves, their Subsidiaries, directors, officers
and stockholders and such other matters as may be reasonably necessary or
advisable in connection with the Joint Proxy Statement, the S-4 or any other
statement, filing, notice or application made by or on behalf of Parent, Subject
Company or any of their respective Subsidiaries to any Governmental Entity in
connection with the Merger and the other transactions contemplated by this
Agreement.
 
     (d) Parent and Subject Company shall promptly advise each other upon
receiving any communication from any Governmental Entity whose consent or
approval is required for consummation of the transactions contemplated by this
Agreement which causes such party to believe that there is a reasonable
likelihood that any Requisite Regulatory Approval (as defined below) will not be
obtained or that the receipt of any such approval will be materially delayed.
 
     6.2 Access to Information.  (a) Upon reasonable notice and subject to
applicable laws relating to the exchange of information, each of Parent and
Subject Company shall, and shall cause each of their respective Subsidiaries to,
afford to the officers, employees, accountants, counsel and other
representatives of the other party access, during normal business hours during
the period prior to the Effective Time, to all its properties, books, contracts,
commitments and records, and to its officers, employees, accountants, counsel
and other representatives and, during such period, each of Parent and Subject
Company shall, and shall cause their respective Subsidiaries to, make available
to the other party (i) a copy of each report, schedule, registration statement
and other document filed or received by it during such period pursuant to the
requirements of Federal securities laws or Federal or state banking laws (other
than reports or documents which Parent or Subject Company, as the case may be,
is not permitted to disclose under applicable law) and (ii) all other
information concerning its business, properties and personnel as such other
party may reasonably request. Neither Parent nor Subject Company nor any of
their respective Subsidiaries shall be required to provide access to or to
disclose information where such access or disclosure would violate or prejudice
the rights of its customers, jeopardize the attorney-client privilege of the
institution in possession or control of such information or contravene any law,
rule, regulation, order, judgment, decree, fiduciary duty or binding agreement
entered into prior to the date of this Agreement. The parties hereto will make
appropriate substitute disclosure arrangements under circumstances in which the
restrictions of the preceding sentence apply.
 
     (b) Each of Parent and Subject Company shall hold all information furnished
by the other party or any of such party's Subsidiaries or representatives
pursuant to Section 6.2(a) in confidence to the extent required by, and in
accordance with, the provisions of the Confidentiality Agreement, dated February
21, 1997, between Parent and Subject Company (the "Confidentiality Agreement").
 
     (c) No investigation by either of the parties or their respective
representatives shall affect the representations, warranties, covenants or
agreements of the other set forth herein.
 
                                      A-23
<PAGE>   138
 
     6.3 Stockholders' Approvals.  Each of Parent and Subject Company shall duly
call, give notice of, convene and hold a meeting of its stockholders to be held
as soon as practicable following the date hereof for the purpose of obtaining
the requisite stockholder approvals required in connection with this Agreement
and the Merger, and each shall use its best efforts to cause such meetings to
occur on the same date. Subject Company shall, through its Board of Directors,
recommend to its stockholders approval of the Merger and Parent shall, through
its Board of Directors, recommend to its stockholders approval of the issuance
of the shares of Parent Common Stock in the Merger as required by Nasdaq;
provided, however, that this Section 6.3(a) shall not prohibit accurate
disclosure by either party of information that is required in the S-4 or the
Joint Proxy Statement or any other document required to be filed with the SEC
(including without limitation a disclosure statement on Schedule 14D-9) or
otherwise required by applicable law or regulation or the rules of the NYSE or
Nasdaq to be publicly disclosed.
 
     6.4 Legal Conditions to Merger.  (a) Subject to the terms and conditions of
this Agreement, each of Parent and Subject Company shall, and shall cause its
Subsidiaries to, use their reasonable best efforts (i) to take, or cause to be
taken, all actions necessary, proper or advisable to comply promptly with all
legal requirements which may be imposed on such party or its Subsidiaries with
respect to the Merger and the Association Merger and, subject to the conditions
set forth in Article VII hereof, to consummate the transactions contemplated by
this Agreement and (ii) to obtain (and to cooperate with the other party to
obtain) any consent, authorization, order or approval of, or any exemption by,
any Governmental Entity and any other third party which is required to be
obtained by Subject Company or Parent or any of their respective Subsidiaries in
connection with the Merger and the Association Merger and the other transactions
contemplated by this Agreement.
 
     (b) Subject to the terms and conditions of this Agreement, each of Parent
and Subject Company agrees to use reasonable best efforts to take, or cause to
be taken, all actions, and to do, or cause to be done, all things necessary,
proper or advisable to consummate and make effective, as soon as practicable
after the date of this Agreement, the transactions contemplated hereby,
including, without limitation, using reasonable best efforts to (i) modify or
amend any contracts, plans or arrangements to which Parent or Subject Company is
a party (to the extent permitted by the terms thereof) if necessary in order to
satisfy the conditions to Closing set forth in Article VII hereof, (ii) lift or
rescind any injunction or restraining order or other order adversely affecting
the ability of the parties to consummate the transactions contemplated hereby,
and (iii) defend any litigation seeking to enjoin, prevent or delay the
consummation of the transactions contemplated hereby or seeking material
damages.
 
     6.5 Affiliates.  Each of Parent and Subject Company shall use its
reasonable best efforts to cause each director, executive officer and other
person who is an "affiliate" (for purposes of Rule 145 under the Securities Act,
in the case of affiliates of Subject Company, and for purposes of qualifying the
Merger for pooling of interests accounting treatment, in the case of affiliates
of either Parent or Subject Company) of such party to deliver to the other
party, as soon as practicable after the date of this Agreement, and in any event
prior to the date of the stockholders meetings called by Parent and Subject
Company pursuant to Section 6.3 hereof, a written agreement, in the form and
substance reasonably satisfactory to Subject Company (in the case of affiliates
of Parent) and Parent (in the case of affiliates of Subject Company).
 
     6.6 Stock Exchange Listing.  Parent shall use its best efforts to cause the
shares of Parent Common Stock to be issued in the Merger and the New Parent
Depositary Shares to be approved for listing on Nasdaq, subject to official
notice of issuance, prior to the Effective Time.
 
     6.7 Employee Benefit Plans.  (a) Parent agrees that, for a period of at
least one year from and after the Effective Time, it shall, and shall cause its
Subsidiaries to, provide to employees of the Subject Company immediately prior
to the Effective Time (such employees, the "Subject Company Employees")
compensation and benefits on terms no less favorable in the aggregate than those
provided to similarly situated employees of Parent and its Subsidiaries. For
purposes of all employee benefit plans of Parent or its Subsidiaries in which
Subject Company Employees participate from and after the Effective Time
(including all policies and employee fringe benefit programs, including vacation
policies, of Parent or its Subsidiaries but excluding Parent's Service Award
plan) and under which an employee's benefit depends, in whole or in part, on
length of
 
                                      A-24
<PAGE>   139
 
service, credit will be given to Subject Company Employees for service
previously credited with the Subject Company or its Subsidiaries prior to the
Effective Time to the extent that such crediting of service does not result in
duplication of benefits; provided, however, that Parent shall determine each
employee's length of service in a manner consistent with Parent's customary
practice with respect to its employees. Parent shall also cause each employee
benefit plan in which Subject Company Employees participate from and after the
Effective Time to waive (i) any preexisting condition restriction which was
waived under the terms of any analogous Plan immediately prior to the Effective
Time or (ii) any waiting period limitation which would otherwise be applicable
to a Subject Company Employee on or after the Effective Time to the extent such
Subject Company Employee had satisfied any similar waiting period limitation
under an analogous Plan prior to the Effective Time. Notwithstanding the
generality of the foregoing, for a period of three (3) years, in the case of
those beneficiaries who are entitled to participate in such Program pursuant to
employment agreements, or two (2) years, in the case of those beneficiaries who
are otherwise entitled to participate in such Program, commencing on the
Effective Date, Parent agrees that it shall continue to maintain the Subject
Company's Executive Medical Program, on terms no less favorable that those in
effect as of the date hereof, for the benefit of those Subject Company Employees
who are currently eligible to participate in such Program.
 
     (b) Notwithstanding the foregoing, Parent shall, and shall cause its
Subsidiaries to, honor in accordance with their terms all Plans, each as amended
to the date hereof, and other contracts, arrangements, commitments or
understandings described in the Subject Company Disclosure Schedule; provided,
however, that this paragraph (b) shall be subject to the provisions of paragraph
(f) hereof. Parent and Subject Company hereby acknowledge that consummation of
the Merger will constitute a "Change in Control" for purposes of all Plans,
contracts, arrangements and commitments that contain change in control
provisions and agree to abide by the provisions of any Plan, contract,
arrangement or commitment which relate to a Change in Control, including, but
not limited to, the accelerated vesting and/or payment of equity-based awards
under the Subject Company Stock Option Plans.
 
     (c) Subject Company and its Subsidiaries shall take all action necessary to
ensure that no further mortgage loans will be made to employees under the Great
Western employee loan program and to amend the retiree medical plans so that no
additional retirees shall become entitled to continuing medical insurance
benefits thereunder.
 
     (d) Subject Company and its Subsidiaries agree to amend their 401(k) plan
prior to Closing (as hereinafter defined) so that participant loans are no
longer available, and may amend their 401(k) plan to allow partial repayment of
existing loans thereunder.
 
     (e) Subject Company shall consult with Parent and, to the extent permitted
by applicable law and the governing instrument of the respective trusts, obtain
Parent's prior approval which shall not be unreasonably withheld regarding the
investments used to fund the two umbrella trusts for the nonqualified plans for
directors and officers.
 
     (f) Except as otherwise provided herein, nothing in this Section 6.7 shall
be interpreted as preventing Parent or its Subsidiaries from amending, modifying
or terminating any of the Plans, or other contracts, arrangements, commitments
or understandings, in accordance with their terms and applicable law.
 
     6.8 Indemnification; Directors' and Officers' Insurance.  (a) 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 Time, a director, officer or employee of Subject Company
or any of its Subsidiaries (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 Subject Company, any of the Subject Company Subsidiaries or any of
their respective predecessors or was prior to the Effective Time serving at the
request of any such party as a director, officer, employee, fiduciary or agent
of another corporation, partnership, trust or other enterprise or (ii) this
Agreement, or any of the transactions contemplated hereby and all actions taken
by an Indemnified Party in connection herewith, whether in any case asserted or
arising before or after the Effective Time, the parties hereto agree to
cooperate and use their best efforts to defend
 
                                      A-25
<PAGE>   140
 
against and respond thereto to the extent set forth in the next sentence. It is
understood and agreed that after the Effective Time, Parent shall indemnify and
hold harmless, as and to the fullest extent permitted by the corporate
governance documents of Subject Company or its Subsidiaries and the
indemnification letters between the Subject Company and each of the directors
and executive officers of Subject Company (the "Indemnification Letters") and by
law, each such Indemnified Party against any losses, claims, damages,
liabilities, costs, expenses (including reasonable attorney's fees and 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 an undertaking from such Indemnified Party to repay such
advanced expenses if it is finally and unappealably determined that such
Indemnified Party was not entitled to indemnification hereunder), 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 Time), the
Indemnified Parties may retain counsel reasonably satisfactory to them after
consultation with Parent; provided, however, that (1) Parent shall have the
right to assume the defense thereof and upon such assumption Parent 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 Parent elects not to assume such defense or
counsel for the Indemnified Parties reasonably advises the Indemnified Parties
that there are or may be (whether or not any have yet actually arisen) issues
which raise conflicts of interest between Parent and the Indemnified Parties,
the Indemnified Parties may retain counsel reasonably satisfactory to them, and
Parent shall pay the reasonable fees and expenses of such counsel for the
Indemnified Parties, (2) Parent shall be obligated pursuant to this paragraph to
pay for only one firm of counsel for all Indemnified Parties, (3) Parent shall
not be liable for any settlement effected without its prior written consent
(which consent shall not be unreasonably withheld) and (4) Parent 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 the corporate governance
documents of Subject Company or its Subsidiaries, the Indemnification Letters or
applicable law. Any Indemnified Party wishing to claim indemnification under
this Section 6.8, upon learning of any such claim, action, suit, proceeding or
investigation, shall notify Parent thereof, provided that the failure to so
notify shall not affect the obligations of Parent under this Section 6.8 except
(and only) to the extent such failure to notify materially prejudices Parent.
Parent's obligations under this Section 6.8 shall continue in full force and
effect for a period of six (6) years from the Effective Time; provided, however,
that all rights to indemnification in respect of any claim (a "Claim") asserted
or made within such period shall continue until the final disposition of such
Claim.
 
     (b) Without limiting any of the obligations under paragraph (a) of this
Section 6.8, Parent agrees that all rights to indemnification and all
limitations of liability existing in favor of the Indemnified Parties as
provided in Subject Company's Restated Certificate of Incorporation or ByLaws or
in the similar governing documents of any of Subject Company's Subsidiaries as
in effect as of the date of this Agreement or as provided in the Indemnification
Letters of Subject Company with respect to matters occurring on or prior to the
Effective Time shall survive the Merger and shall continue in full force and
effect, without any amendment thereto, for a period of six years from the
Effective Time; provided, however, that all rights to indemnification in respect
of any Claim asserted or made within such period shall continue until the final
disposition of such Claim; provided, further, however, that nothing contained in
this Section 6.8(b) shall be deemed to preclude the liquidation, consolidation
or merger of Subject Company or any Subject Company Subsidiary, in which case
all of such rights to indemnification and limitations on liability shall be
deemed to so survive and continue notwithstanding any such liquidation,
consolidation or merger and shall constitute rights which may be asserted
against Parent. Nothing contained in this Section 6.8(b) shall be deemed to
preclude any rights to indemnification or limitations on liability provided in
Subject Company's Restated Certificate of Incorporation or Bylaws or the similar
governing documents of any of Subject Company's Subsidiaries with respect to
matters occurring subsequent to the Effective Time to the extent that the
provisions establishing such rights or limitations are not otherwise amended to
the contrary.
 
     (c) Parent shall use its best efforts to cause the persons serving as
officers and directors of Subject Company immediately prior to the Effective
Time to be covered for a period of six (6) years from the
 
                                      A-26
<PAGE>   141
 
Effective Time by the directors' and officers' liability insurance policy
maintained by Subject Company (provided that Parent may substitute therefor
policies of at least the same coverage and amounts containing terms and
conditions which are not less advantageous to such directors and officers of
Subject Company than the terms and conditions of such existing policy) with
respect to acts or omissions occurring prior to the Effective Time which were
committed by such officers and directors in their capacity as such.
 
     (d) In the event Parent 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 Parent
shall assume the obligations set forth in this Section 6.8.
 
     (e) The provisions of this Section 6.8 are intended to be for the benefit
of, and shall be enforceable by, each Indemnified Party and his or her heirs and
representatives.
 
     6.9 Additional Agreements.  In case at any time after the Effective Time
any further action is necessary or desirable to carry out the purposes of this
Agreement (including, without limitation, any merger between a Subsidiary of
Parent and a Subsidiary of Subject Company) or to vest the Surviving Corporation
with full title to all properties, assets, rights, approvals, immunities and
franchises of any of the parties to the Merger, the proper officers and
directors of each party to this Agreement and their respective Subsidiaries
shall take all such necessary action as may be reasonably requested by, and at
the sole expense of, Parent.
 
     6.10 Advice of Changes.  Parent and Subject Company shall promptly advise
the other party of any change or event which, individually or in the aggregate
with other such changes or events, has a Material Adverse Effect on it or which
it believes would or would be reasonably likely to cause or constitute a
material breach of any of its representations, warranties or covenants contained
herein.
 
     6.11 Subsequent Interim and Annual Financial Statements.  As soon as
reasonably available, but in no event more than 45 days after the end of each
fiscal quarter (other than the fourth quarter of a fiscal year) or 90 days after
December 31, 1996 or the end of each fiscal year ending after the date of this
Agreement, each party will deliver to the other party its Quarterly Report on
Form 10-Q or its Annual Report on Form 10-K, as the case may be, as filed with
the SEC under the Exchange Act.
 
                                  ARTICLE VII
 
                              CONDITIONS PRECEDENT
 
     7.1 Conditions to Each Party's Obligation to Effect the Merger.  The
respective obligations of each party to effect the Merger shall be subject to
the satisfaction at or prior to the Effective Time of the following conditions:
 
          (a) Stockholder Approval.  The agreement of merger contained in this
     Agreement shall have been approved and adopted by the requisite affirmative
     vote of the holders of Subject Company Common Stock entitled to vote
     thereon and the issuance of shares of Parent Common Stock in the Merger
     shall have been approved by the requisite affirmative vote of the holders
     of Parent Common Stock entitled to vote thereon as required by Nasdaq.
 
          (b) Nasdaq Listing.  The shares of Parent Common Stock which shall be
     issued to the stockholders of Subject Company upon consummation of the
     Merger and the New Parent Depositary Shares shall have been authorized for
     listing on Nasdaq, subject to official notice of issuance.
 
          (c) Other Approvals.  All regulatory approvals required to consummate
     the transactions contemplated hereby shall have been obtained and shall
     remain in full force and effect and all statutory waiting periods in
     respect thereof shall have expired (all such approvals and the expiration
     of all such waiting periods being referred to herein as the "Requisite
     Regulatory Approvals").
 
                                      A-27
<PAGE>   142
 
          (d) S-4.  The S-4 shall have become effective under the Securities
     Act, no stop order suspending the effectiveness of the S-4 shall have been
     issued and no proceedings for that purpose shall have been initiated or
     threatened by the SEC.
 
          (e) No Injunctions or Restraints; Illegality.  No order, injunction or
     decree issued by any court or agency of competent jurisdiction or other
     legal restraint or prohibition (an "Injunction") preventing the
     consummation of the Merger or any of the other transactions contemplated by
     this Agreement shall be in effect. No statute, rule, regulation, order,
     injunction or decree shall have been enacted, entered, promulgated or
     enforced by any Governmental Entity which prohibits or makes illegal the
     consummation of the Merger.
 
          (f) Pooling.  Each of Parent and Subject Company shall have received a
     letter from its independent public accountants, dated the Closing Date, in
     form and substance reasonably satisfactory to Parent and Subject Company,
     respectively, to the effect that the Merger will qualify for "pooling of
     interests" accounting treatment.
 
     7.2 Conditions to Obligations of Parent.  The obligation of Parent to
effect the Merger is also subject to the satisfaction or waiver by Parent at or
prior to the Effective Time of the following conditions:
 
          (a) Representations and Warranties.  The representations and
     warranties of Subject Company set forth in this Agreement shall be true and
     correct in all respects as of the date of this Agreement and (except to the
     extent such representations and warranties speak as of an earlier date) as
     of the Closing Date as though made on and as of the Closing Date; provided,
     however, that for purposes of determining the satisfaction of this
     condition, no effect shall be given to any exception in such
     representations and warranties relating to materiality or a Material
     Adverse Effect, and provided, further, however, that, for purposes of this
     condition, such representations and warranties (other than the
     representations and warranties contained in Section 3.2(a), which shall be
     true and correct in all material respects) shall be deemed to be true and
     correct in all respects unless the failure or failures of such
     representations and warranties to be so true and correct, individually or
     in the aggregate, results or would reasonably be expected to result in a
     Material Adverse Effect on Subject Company and its Subsidiaries taken as a
     whole. Parent shall have received a certificate signed on behalf of the
     Subject Company by the Chief Executive Officer and Chief Financial Officer
     of Subject Company to the foregoing effect.
 
          (b) Performance of Obligations of Subject Company.  Subject Company
     shall have performed in all material respects all obligations required to
     be performed by it under this Agreement at or prior to the Closing Date,
     and Parent shall have received a certificate signed on behalf of Subject
     Company by the Chief Executive Officer and the Chief Financial Officer of
     Subject Company to such effect.
 
          (c) Subject Company Rights Agreement.  The rights issued pursuant to
     the Subject Company Rights Agreement shall not have become nonredeemable,
     exercisable, distributed or triggered pursuant to the terms of such
     agreement.
 
          (d) Federal Tax Opinion.  Parent shall have received an opinion of
     Foster, Pepper & Shefelman, counsel to Parent ("Parent's Counsel"), in form
     and substance reasonably satisfactory to Parent, dated as of the Effective
     Time, substantially to the effect that, on the basis of facts,
     representations and assumptions set forth in such opinion which are
     consistent with the state of facts existing at the Effective Time, the
     Merger will be treated as a reorganization within the meaning of Section
     368(a) of the Code and that, accordingly, for federal income tax purposes:
 
             (1) No gain or loss will be recognized by the shareholders of
        Subject Company who exchange (i) all of their Subject Company Common
        Stock solely for Parent Common Stock pursuant to the Merger (except with
        respect to cash received in lieu of a fractional share interest in
        Parent Common Stock) and (ii) all of their Subject Company 8.30%
        Preferred Stock solely for Parent New Preferred Stock pursuant to the
        Merger; and
 
             (2) The aggregate tax basis of (i) the Parent Common Stock received
        by shareholders who exchange all of their Subject Company Common Stock
        solely for Parent Common Stock pursuant to
 
                                      A-28
<PAGE>   143
 
        the Merger will be the same as the aggregate tax basis of the Subject
        Company Common Stock surrendered in exchange therefor (reduced by any
        amount allocable to a fractional share interest for which cash is
        received) and (ii) the Parent New Preferred Stock received by
        shareholders who exchange all of their Subject Company 8.30% Preferred
        Stock solely for Parent New Preferred Stock pursuant to the Merger will
        be the same as the aggregate tax basis of the Subject Company 8.30%
        Preferred Stock surrendered in exchange therefor .
 
          In rendering such opinion, Parent's Counsel may require and rely upon
     representations and covenants contained in certificates of officers of
     Parent, Subject Company and others.
 
     7.3 Conditions to Obligations of Subject Company.  The obligation of
Subject Company to effect the Merger is also subject to the satisfaction or
waiver by Subject Company at or prior to the Effective Time of the following
conditions:
 
          (a) Representations and Warranties.  The representations and
     warranties of Parent set forth in this Agreement shall be true and correct
     in all respects as of the date of this Agreement and (except to the extent
     such representations and warranties speak as of an earlier date) as of the
     Closing Date as though made on and as of the Closing Date; provided,
     however, that for purposes of determining the satisfaction of this
     condition, no effect shall be given to any exception in such
     representations and warranties relating to materiality or a Material
     Adverse Effect, and provided, further, however, that, for purposes of this
     condition, such representations and warranties shall be deemed to be true
     and correct in all respects unless the failure or failures of such
     representations and warranties to be so true and correct, individually or
     in the aggregate, results or would reasonably be expected to result in a
     Material Adverse Effect on Parent and its Subsidiaries taken as a whole.
     Subject Company shall have received a certificate signed on behalf of
     Parent by the Chief Executive Officer and the Chief Financial Officer of
     Parent to the foregoing effect.
 
          (b) Performance of Obligations of Parent.  Parent shall have performed
     in all material respects all obligations required to be performed by it
     under this Agreement at or prior to the Closing Date, and Subject Company
     shall have received a certificate signed on behalf of Parent by the Chief
     Executive Officer and the Chief Financial Officer of Parent to such effect.
 
          (c) Parent Rights Agreement.  The rights issued pursuant to the Parent
     Rights Agreement shall not have become nonredeemable, exercisable,
     distributed or triggered pursuant to the terms of such agreement.
 
          (d) Federal Tax Opinion.  Subject Company shall have received an
     opinion of Skadden, Arps, Slate, Meagher & Flom LLP ("Subject Company's
     Counsel"), in form and substance reasonably satisfactory to Subject
     Company, dated as of the Effective Time, substantially to the effect that,
     on the basis of facts, representations and assumptions set forth in such
     opinion which are consistent with the state of facts existing at the
     Effective Time, the Merger will be treated as a reorganization within the
     meaning of Section 368(a) of the Code and that, accordingly, for federal
     income tax purposes:
 
             (1) No gain or loss will be recognized by the shareholders of
        Subject Company who exchange (i) all of their Subject Company Common
        Stock solely for Parent Common Stock pursuant to the Merger (except with
        respect to cash received in lieu of a fractional share interest in
        Parent Common Stock) and (ii) all of their Subject Company 8.30%
        Preferred Stock solely for Parent New Preferred Stock pursuant to the
        Merger; and
 
             (2) The aggregate tax basis of (i) the Parent Common Stock received
        by shareholders who exchange all of their Subject Company Common Stock
        solely for Parent Common Stock pursuant to the Merger will be the same
        as the aggregate tax basis of the Subject Company Common Stock
        surrendered in exchange therefor (reduced by any amount allocable to a
        fractional share interest for which cash is received) and (ii) the
        Parent New Preferred Stock received by shareholders who exchange all of
        their Subject Company 8.30% Preferred Stock solely for Parent New
        Preferred Stock pursuant to the Merger will be the same as the aggregate
        tax basis of the Subject Company 8.30% Preferred Stock surrendered in
        exchange therefor.
 
                                      A-29
<PAGE>   144
 
          In rendering such opinion, Subject Company's Counsel may require and
     rely upon representations and covenants contained in certificates of
     officers of Parent, Subject Company and others.
 
                                  ARTICLE VIII
 
                           TERMINATION AND AMENDMENT
 
     8.1 Termination.  This Agreement may be terminated at any time prior to the
Effective Time:
 
          (a) by mutual consent of Parent and Subject Company in a written
     instrument, if the Board of Directors of each so determines;
 
          (b) by either the Board of Directors of Parent or the Board of
     Directors of Subject Company if (i) any Governmental Entity which must
     grant a Requisite Regulatory Approval has denied approval of the Merger and
     such denial has become final and nonappealable or (ii) any Governmental
     Entity of competent jurisdiction shall have issued a final nonappealable
     order enjoining or otherwise prohibiting the consummation of the
     transactions contemplated by this Agreement;
 
          (c) by either the Board of Directors of Parent or the Board of
     Directors of Subject Company if the Merger shall not have been consummated
     on or before March 31, 1998, 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 of such
     party set forth herein;
 
          (d) by either the Board of Directors of Parent or the Board of
     Directors of Subject Company (provided that the terminating party is not
     then in material breach of any representation, warranty, covenant or other
     agreement contained herein) if the other party shall have breached (i) any
     of the covenants or agreements made by such other party herein or (ii) any
     of the representations or warranties made by such other party herein, and
     in either case, such breach (x) is not cured within thirty (30) days
     following written notice to the party committing such breach, or which
     breach, by its nature, cannot be cured prior to the Closing and (y) would
     entitle the non-breaching party not to consummate the transactions
     contemplated hereby under Article VII hereof;
 
          (e) by either the Board of Directors of Parent or the Board of
     Directors of Subject Company if any approval of the stockholders of Parent
     or the Subject Company contemplated by this Agreement shall not have been
     obtained by reason of the failure to obtain the required vote at a duly
     held meeting of stockholders or at any adjournment or postponement thereof;
 
          (f) by either the Board of Directors of Parent or the Board of
     Directors of Subject Company, if the Board of Directors of the other party
     shall have withdrawn, modified or changed in a manner adverse to the
     terminating party its approval or recommendation of this Agreement and the
     transactions contemplated hereby; and
 
          (g) by (i) the Board of Directors of Parent if a tender offer or
     exchange offer for 25% or more of the outstanding shares of Subject Company
     Common Stock is commenced (other than by Parent or a Parent Subsidiary),
     and the Board of Directors of the Subject Company recommends that the
     stockholders of Subject Company tender their shares in such tender or
     exchange offer or otherwise fails to recommend that such stockholders
     reject such tender offer or exchange offer within ten business days after
     the commencement thereof (which, in the case of an exchange offer, shall be
     the effective date of the registration statement relating to such exchange
     offer); or (ii) the Board of Directors of Subject Company if a tender offer
     or exchange offer for 25% or more of the outstanding shares of Parent
     Common Stock is commenced and the Board of Directors of Parent recommends
     that the stockholders of Parent tender their shares in such tender or
     exchange offer or otherwise fails to recommend that such stockholders
     reject such tender or exchange offer within ten business days after the
     commencement thereof (which, in the case of an exchange offer, shall be the
     effective date of the registration statement relating to such exchange
     offer).
 
                                      A-30
<PAGE>   145
 
     8.2 Effect of Termination.  (a) In the event of termination of this
Agreement by either Parent or Subject Company as provided in Section 8.1, this
Agreement shall forthwith become void and have no effect, and none of Parent,
Subject Company, any of their respective Subsidiaries or any of the officers or
directors of any of them shall have any liability of any nature whatsoever
hereunder, or in connection with the transactions contemplated hereby, except
that (i) Sections 6.2(b), 8.2, and 9.3 shall survive any termination of this
Agreement and (ii) notwithstanding anything to the contrary contained in this
Agreement, neither Parent nor Subject Company shall be relieved or released from
any liabilities or damages arising out of its willful breach of any provision of
this Agreement.
 
     (b) If this Agreement is terminated (A) by Parent pursuant to Section
8.1(f) or (g)(i), (B) by Parent or Subject Company pursuant to Section 8.1(e)
because of a failure to obtain the required approval of the stockholders of
Subject Company after a Takeover Proposal for Subject Company shall have been
publicly disclosed, or any person shall have publicly disclosed an intention
(whether or not conditional) to make a Takeover Proposal (it being agreed and
understood that the proposal made with respect to Subject Company prior to the
date hereof by H.F. Ahmanson & Company ("Ahmanson"), if not unconditionally
withdrawn prior to the mailing of the Joint Proxy Statement to Subject Company's
stockholders, shall be deemed to be a Takeover Proposal within the meaning of
this clause), or (C) by Parent pursuant to Section 8.1(d) if the breach giving
rise to such termination was willful and, at or prior to such termination, a
Takeover Proposal shall have been made known to Subject Company or any of its
Subsidiaries or shall have been publicly disclosed to Subject Company's
stockholders, or any person shall have made known to Subject Company or any of
its Subsidiaries or otherwise publicly disclosed an intention (whether or not
conditional) to make a Takeover Proposal, and regardless of whether such
Takeover Proposal shall have been rejected by Subject Company or withdrawn prior
to the time of such termination, then in any such case Subject Company shall pay
to Parent a termination fee of $75 million and reimburse Parent for its
documented reasonable out-of-pocket expenses incurred by it in connection with
this Agreement and the transactions contemplated hereby (including fees and
expenses of legal, financial and accounting advisors), up to a maximum of $20
million in the aggregate (collectively, the "Initial Subject Company Termination
Fee"). In addition, if, within 18 months after any such termination described in
the preceding sentence that gave rise to an obligation to pay the Initial
Subject Company Termination Fee, Subject Company enters into a definitive
agreement with respect to or consummates a transaction contemplated in any
Takeover Proposal with any party, Subject Company shall pay to Parent an
additional termination fee equal to $100 million (the "Subsequent Subject
Company Termination Fee").
 
     (c) Any Initial Subject Company Termination Fee that becomes payable
pursuant to Section 8.1(b) shall be paid within one business day following the
termination of this Agreement or the receipt of a request from Parent for such
reimbursement, as the case may be. Any Subsequent Subject Company Termination
Fee that becomes payable pursuant to Section 8.1(b) shall be paid within one
business day following the earlier of the consummation of any such Takeover
Proposal or the execution and delivery by Subject Company of a definitive
agreement with respect to any such Takeover Proposal. Notwithstanding the
foregoing, in no event shall Subject Company be obligated to pay any such fees
to Parent if Parent was in material breach of its obligations under this
Agreement immediately prior to the termination thereof.
 
     (d) Subject Company and Parent agree that the agreements contained in
paragraph (b) above are an integral part of the transactions contemplated by
this Agreement, that without such agreements Parent would not have entered into
this Agreement, and that such amounts constitute liquidated damages and not a
penalty. If Subject Company fails to pay Parent the amounts due under paragraph
(b) within the time periods specified in paragraph (c), Subject Company shall
pay the costs and expenses (including legal fees and expenses) incurred by
Parent in connection with any action, including the filing of any lawsuit, taken
to collect payment of such amounts, together with interest on the amount of any
such unpaid amounts at the publicly announced prime rate of The Chase Manhattan
Bank from the date such amounts were required to be paid.
 
     (e) For purposes of Section 8.2(b)(C), the proposal made prior to the date
hereof by Ahmanson to enter into a business combination with Subject Company
shall not be deemed to constitute a Takeover Proposal that has been publicly
announced or otherwise made known to Subject Company; provided, however, that
any Takeover Proposal made by Ahmanson after the date hereof, or any amendment
or modification
 
                                      A-31
<PAGE>   146
 
made after the date hereof to the proposal made by Ahmanson prior to the date
hereof, shall constitute a Takeover Proposal for purposes of Section 8.2(b)(C).
 
     8.3 Amendment.  Subject to compliance with applicable law, this Agreement
may be amended by the parties hereto, by action taken or authorized by their
respective Boards of Directors, at any time before or after approval of the
matters presented in connection with the Merger by the stockholders of Subject
Company and Parent; provided, however, that after any approval of the
transactions contemplated by this Agreement by Subject Company's stockholders,
there may not be, without further approval of such stockholders, any amendment
of this Agreement which reduces the amount or changes the form of the
consideration to be delivered to the Subject Company stockholders hereunder
other than as contemplated by this Agreement. This Agreement may not be amended
except by an instrument in writing signed on behalf of each of the parties
hereto.
 
     8.4 Extension; Waiver.  At any time prior to the Effective Time, the
parties hereto, by action taken or authorized by their respective Board of
Directors, may, to the extent legally allowed, (a) extend the time for the
performance of any of the obligations or other acts of the other parties hereto,
(b) waive any inaccuracies in the representations and warranties contained
herein or in any document delivered pursuant hereto and (c) waive compliance
with any of the agreements or conditions contained herein. Any agreement on the
part of a party hereto to any such extension or waiver shall be valid only if
set forth in a written instrument signed on behalf of such party, but such
extension or waiver or failure to insist on strict compliance with an
obligation, covenant, agreement or condition shall not operate as a waiver of,
or estoppel with respect to, any subsequent or other failure.
 
                                   ARTICLE IX
 
                               GENERAL PROVISIONS
 
     9.1 Closing.  Subject to the terms and conditions of this Agreement, the
closing of the Merger (the "Closing") will take place at 10:00 a.m. on a date to
be specified by the parties, which shall be the first day which is (a) the tenth
business day of a month and (b) at least two business days after the
satisfaction or waiver (subject to applicable law) of the latest to occur of the
conditions set forth in Article VII hereof, other than conditions which by their
terms are to be satisfied at Closing, or such date or time as the parties may
mutually agree (the "Closing Date").
 
     9.2 Nonsurvival of Representations, Warranties and Agreements.  None of the
representations, warranties, covenants and agreements in this Agreement or in
any instrument delivered pursuant to this Agreement shall survive the Effective
Time, except for those covenants and agreements contained herein and therein
which by their terms apply in whole or in part after the Effective Time.
 
     9.3 Expenses.  Except as provided in Section 8.2 hereof, all costs and
expenses incurred in connection with this Agreement and the transactions
contemplated hereby shall be paid by the party incurring such expense, provided,
however, that (i) the costs and expenses of printing and mailing the Joint Proxy
Statement, and all filing and other fees paid to the SEC in connection with the
Merger, shall be borne equally by Parent and Subject Company and (ii)
notwithstanding anything to the contrary contained in this Agreement, neither
Parent nor Subject Company shall be relieved or released from any liabilities or
damages arising out of its willful breach of any provision of this Agreement.
 
     9.4 Notices.  All notices and other communications hereunder shall be in
writing and shall be deemed given if delivered personally, telecopied (with
confirmation), mailed by registered or certified mail (return
 
                                      A-32
<PAGE>   147
 
receipt requested) or delivered by an express courier (with confirmation) to the
parties at the following addresses (or at such other address for a party as
shall be specified by like notice):
 
     (a) if to Parent, to:
 
     Washington Mutual, Inc.
     1201 Third Avenue
     Seattle, WA 98101
     Fax: (206) 554-2790
     Attn: Marc R. Kittner
         Senior Vice President and
         Corporate Counsel
 
     with a copy to:
 
     Foster Pepper & Shefelman
     1111 Third Avenue
     Suite 3400
     Seattle, WA 98101
     Attn: Fay L. Chapman, Esq.
 
     and
 
     Simpson Thacher & Bartlett
     425 Lexington Avenue
     New York, NY 10017
     Attn: Charles I. Cogut, Esq.
        Lee Meyerson, Esq.
 
     (b) if to Subject Company, to:
 
     Great Western Financial Corporation
     9200 Oakdale Avenue
     Chatsworth, California 91311
     Attn: John F. Maher, President and Chief
         Executive Officer
 
     and
 
     J. Lance Erickson, Esq.
     Executive Vice President and
      General Manager
 
     with a copy to:
 
     Skadden, Arps, Slate, Meagher & Flom LLP
     919 Third Avenue
     New York, New York 10022
     Fax: (212) 735-2000
     Attn: Peter Allan Atkins, Esq.
        Fred B. White, III, Esq.
 
     9.5 Interpretation.  When a reference is made in this Agreement to
Sections, Exhibits or Schedules, such reference shall be to a Section of or
Exhibit or Schedule to this Agreement unless otherwise indicated. The table of
contents and headings contained in this Agreement are for reference purposes
only and shall not affect in any way the meaning or interpretation of this
Agreement. Whenever the words "include," "includes" or "including" are used in
this Agreement, they shall be deemed to be followed by the words "without
limitation". No provision of this Agreement shall be construed to require
Subject Company, Parent or any of
 
                                      A-33
<PAGE>   148
 
their respective Subsidiaries or affiliates to take any action which would
violate or conflict with any applicable law (whether statutory or common), rule
or regulation.
 
     9.6 Counterparts.  This Agreement may be executed in counterparts, all of
which shall be considered one and the same agreement and shall become effective
when counterparts have been signed by each of the parties and delivered to the
other parties, it being understood that all parties need not sign the same
counterpart.
 
     9.7 Entire Agreement.  This Agreement (together with the documents and the
instruments referred to herein) constitutes the entire agreement and supersedes
all prior agreements and understandings, both written and oral, among the
parties with respect to the subject matter hereof, other than the
Confidentiality Agreement.
 
     9.8 Governing Law.  This Agreement shall be governed and construed in
accordance with the laws of the State of Delaware, without regard to any
applicable conflicts of law.
 
     9.9 Severability.  Any term or provision of this Agreement which is invalid
or unenforceable in any jurisdiction shall, as to that jurisdiction, be
ineffective to the extent of such invalidity or unenforceability without
rendering invalid or unenforceable the remaining terms and provisions of this
Agreement or affecting the validity or enforceability of any of the terms or
provisions of this Agreement in any other jurisdiction. If any provision of this
Agreement is so broad as to be unenforceable, the provision shall be interpreted
to be only so broad as is enforceable.
 
     9.10 Publicity.  Parent and Subject Company shall consult with each other
before issuing any press release with respect to the Merger or this Agreement
and shall not issue any such press release or make any such public statement
without the prior consent of the other party, which shall not be unreasonably
withheld; provided, however, that a party may, without the prior consent of the
other party (but after prior consultation, to the extent practicable in the
circumstances) issue such press release or make such public statement as may
upon the advice of outside counsel be required by law or the rules and
regulations of the NYSE (in the case of Subject Company) or Nasdaq (in the case
of Parent). Without limiting the reach of the preceding sentence, Parent and
Subject Company shall cooperate to develop all public announcement materials and
(b) make appropriate management available at presentations related to the
transactions contemplated by this Agreement as reasonably requested by the other
party. In addition, Subject Company and its Subsidiaries shall (a) consult with
Parent regarding communications with customers, shareholders, prospective
investors and employees related to the transactions contemplated hereby, (b)
provide Parent with shareholder lists of Subject Company and (c) allow and
facilitate Parent contact with shareholders of Subject Company and other
prospective investors.
 
     9.11 Assignment; Third Party Beneficiaries.  Neither this Agreement nor any
of the rights, interests or obligations of any party hereunder shall be assigned
by any of the parties hereto (whether by operation of law or otherwise) without
the prior written consent of the other party. Subject to the preceding sentence,
this Agreement will be binding upon, inure to the benefit of and be enforceable
by the parties and their respective successors and permitted assigns. Except as
otherwise specifically provided in Section 6.8 hereof, this Agreement (including
the documents and instruments referred to herein) is not intended to confer upon
any person other than the parties hereto any rights or remedies hereunder.
 
                                      A-34
<PAGE>   149
 
     IN WITNESS WHEREOF, Parent, Merger Sub and Subject Company have caused this
Agreement to be executed by their respective officers thereunto duly authorized
as of the date first above written.
 
                                          WASHINGTON MUTUAL, INC.
 
                                          By:          /s/  CRAIG TALL
 
                                            ------------------------------------
                                            Name:  Craig Tall
                                            Title:  Executive Vice President
                                                   Corporate Development
 
                                          GREAT WESTERN FINANCIAL CORPORATION
 
                                          By:          /s/  JOHN MAHER
 
                                            ------------------------------------
                                            Name:  John Maher
                                            Title:  President and Chief
                                              Executive Officer
 
                                          NEW AMERICAN CAPITAL, INC.
 
                                          By:      /s/  KERRY K. KILLINGER
 
                                            ------------------------------------
                                            Name:  Kerry K. Killinger
                                            Title:  President and Chief
                                              Executive Officer
 
                                      A-35
<PAGE>   150
 
                                                                      APPENDIX B
 
                          [LEHMAN BROTHERS LETTERHEAD]
 
                                                                   March 5, 1997
 
Board of Directors
Washington Mutual, Inc.
1201 Third Avenue
Seattle, WA 98101
 
Members of the Board:
 
     We understand that Washington Mutual, Inc. (the "Company") and Great
Western Financial Corporation ("Great Western") have entered into a definitive
merger agreement pursuant to which Great Western will be merged with and into
the Company and each share of common stock of Great Western will be converted
into the right to receive 0.9 shares (the "Exchange Ratio") of the Company's
common stock (the "Merger"). The terms and conditions of the Merger are set
forth in more detail in the Agreement and Plan of Merger dated as of March 5,
1997 by and among the Company, New American Capital, Inc. and Great Western (the
"Merger Agreement").
 
     We have been requested by the Board of Directors of the Company to render
our opinion with respect to the fairness, from a financial point of view, to the
Company of the Exchange Ratio to be offered by the Company to the stockholders
of Great Western in the Merger. We have not been requested to opine as to, and
our opinion does not in any manner address, the Company's underlying business
decision to proceed with or effect the Merger.
 
     In arriving at our opinion, we reviewed and analyzed: (1) the Merger
Agreement and the specific terms of the Merger, (2) such publicly available
information concerning the Company and Great Western that we believe to be
relevant to our analysis including, without limitation, the Forms 10-K for the
year ended December 31, 1995 and preliminary draft copies of Forms 10-K for the
year ended December 31, 1996, quarterly reports on Form 10-Q for the periods
ended March 31, June 30 and September 30, 1996 and recent press releases for the
Company and Great Western, (3) financial and operating information with respect
to the business, operations and prospects of the Company and Great Western
furnished to us by the Company and Great Western, (4) a trading history of the
common stock of the Company and Great Western and a comparison of that trading
history with those of other companies that we deemed relevant, (5) a comparison
of the historical financial results and present financial condition of the
Company and Great Western with those of other companies that we deemed relevant,
and (6) a comparison of the financial terms of the Merger with the financial
terms of certain other recent transactions that we deemed relevant. In addition,
we have had discussions with the management of the Company and Great Western
concerning their respective businesses, operations, assets, liabilities,
financial conditions and prospects, and the potential cost savings, operating
synergies, revenue enhancements and strategic benefits expected to result from a
combination of the businesses of the Company and Great Western, and have
undertaken such other studies, analyses and investigations as we deemed
appropriate.
 
     In arriving at our opinion, we have assumed and relied upon the accuracy
and completeness of the financial and other information used by us without
assuming any responsibility for independent verification of such information and
have further relied upon the assurances of management of the Company and Great
Western that they are not aware of any facts or circumstances that would make
such information inaccurate or misleading. With respect to the financial
projections of the Company and Great Western, upon advice of the Company, we
have assumed that such projections have been reasonably prepared on a basis
reflecting the best currently available estimates and judgments of the
respective managements of the Company and of Great Western, as to the future
financial performance of the Company and Great Western including, without
limitation, with respect to projected cost savings, operating synergies and
revenue enhancements expected to result from a combination of the businesses of
the Company and Great Western and that the Company and
<PAGE>   151
 
Great Western would perform, and that the combined company will perform,
substantially in accordance with such projections. Upon advice of the Company
and its legal and accounting advisors, we have assumed that the Merger will
qualify for pooling accounting treatment and as a reorganization within the
meaning of Section 368(a) of the Internal Revenue Code of 1986, as amended, and
therefore as a tax-free transaction. In arriving at our opinion, we have not
conducted a physical inspection of the properties and facilities of Great
Western or the Company and have not made or obtained any evaluations or
appraisals of the assets or liabilities of Great Western or the Company. In
addition, we are not experts in the evaluation of loan portfolios or allowances
for loan and real estate owned losses and, upon advice of the Company, we have
assumed that the allowances for loan and real estate owned losses provided to us
by the Company and used by us in our analysis and in arriving at our opinion are
in the aggregate adequate to cover all such losses. Our opinion necessarily is
based upon market, economic and other conditions as they exist on, and can be
evaluated as of, the date of this letter.
 
     Based upon and subject to the foregoing, we are of the opinion as of the
date hereof that, from a financial point of view, the Exchange Ratio to be
offered by the Company to the stockholders of Great Western in the Merger is
fair to the Company.
 
     We have acted as financial advisor to the Company in connection with the
Merger and will receive a fee for our services, a significant portion of which
is contingent upon the consummation of the Merger. In addition, the Company has
agreed to indemnify us for certain liabilities that may arise out of the
rendering of this opinion. We also have performed various investment banking
services for the Company (including underwriting of public offerings of the
Company's securities and acting as financial advisor to Keystone Holdings, Inc.
in its sale to the Company) and for Great Western (including underwriting of
public offerings of Great Western and its subsidiaries' securities and advising
Great Western Bank in its sale of Great Western Financial Services to Aristar,
Inc.) in the past and have received customary fees for such services. In the
ordinary course of our business, we actively trade in the debt and equity
securities of the Company and Great Western 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.
 
     This opinion is for the use and benefit of the Board of Directors of the
Company and is rendered to the Board of Directors in connection with its
consideration of the Merger. This opinion is not intended to be and does not
constitute a recommendation to any stockholder of the Company as to how such
stockholder should vote with respect to the Merger.
 
                                          Very truly yours,
 
                                          LEHMAN BROTHERS
 
                                        2
<PAGE>   152
 
                                                                      APPENDIX C
 
                       [GOLDMAN, SACHS & CO. LETTERHEAD]
 
PERSONAL AND CONFIDENTIAL
 
March 5, 1997
 
Board of Directors
Great Western Financial Corporation
9200 Oakdale Avenue
Chatsworth, California 91311
 
Gentlemen and Madame:
 
You have requested our opinion as to the fairness to the holders of the
outstanding shares of Common Stock, par value $1.00 per share (the "Shares"), of
Great Western Financial Corporation (the "Company") of the exchange ratio of 0.9
shares of Common Stock, no par value, of Washington Mutual, Inc. ("Washington
Mutual") to be received for each Share (the "Exchange Ratio") pursuant to the
merger (the "Merger") contemplated by the Agreement and Plan of Merger dated as
of March 5, 1997 by and among Washington Mutual, Inc., New American Capital,
Inc. and the Company (the "Agreement").
 
Goldman, Sachs & Co., as part of its investment banking business, is continually
engaged in the valuation of 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. We are familiar with
the Company having provided certain investment banking services to the Company
from time to time, including having acted as managing underwriter of its $300
million issue of Capital Securities in January 1997, and having acted as its
financial advisor in connection with, and participated in certain of the
negotiations leading to, the Agreement. We also have provided certain investment
banking services to Washington Mutual from time to time and may provide
investment banking services to Washington Mutual in the future. In addition,
Goldman Sachs is a full service securities firm and in the course of its trading
activities it may from time to time effect transactions, for its own account or
the account of customers, and hold positions in securities or options on
securities of the Company and Washington Mutual.
 
In connection with this opinion, we have reviewed, among other things, the
Agreement; Annual Reports to Stockholders and Annual Reports on Form 10-K of the
Company for the five years ended December 31, 1995; Annual Reports to
Stockholders and Annual Reports on Form 10-K of Washington Mutual for the two
years ended December 31, 1995; Annual Reports to Stockholders and Annual Reports
to the FDIC on Form F-2 of Washington Mutual Savings Bank, predecessor to
Washington Mutual, for the three years ended December 31, 1993; certain interim
reports to stockholders and Quarterly Reports on Form 10-Q of the Company and
Washington Mutual; certain other communications from the Company and Washington
Mutual to their respective stockholders; and certain internal financial analyses
and forecasts for the Company and Washington Mutual prepared by their respective
managements, including analyses and forecasts of certain cost savings, operating
efficiencies, revenue effects and financial synergies (collectively, the
"Synergies"). We also have held discussions with members of the senior
managements of the Company and Washington Mutual regarding the past and current
business operations, financial condition and future prospects of their
respective companies and each senior managements' assessment of the future
prospects of the combined company. In addition, we have reviewed the reported
price and trading activity for the Shares and Washington Mutual Common Stock,
compared certain financial and stock market information for the Company and
Washington Mutual with similar information for certain other companies the
securities of which are publicly traded, reviewed the financial terms of certain
recent business combinations in the savings and loan industry specifically and
in other industries generally and performed such other studies and analyses as
we considered appropriate.
<PAGE>   153
 
Great Western Financial Corporation
March 5, 1997
Page Two
 
We have relied without independent verification upon the accuracy and
completeness of all of the financial and other information reviewed by us for
purposes of this opinion. In that regard, we have assumed, with your consent,
that the financial forecasts, including, without limitation, the Synergies and
projections regarding under-performing and non-performing assets and net
charge-offs have been reasonably prepared on a basis reflecting the best
currently available judgments and estimates of the Company and Washington Mutual
and that such forecasts will be realized in the amounts and at the times
contemplated thereby. We are not experts in the evaluation of loan and lease
portfolios for purposes of assessing the adequacy of the allowances for losses
with respect thereto and have assumed, with your consent, that such allowances
for each of the Company and Washington Mutual are in the aggregate adequate to
cover all such losses. In addition, we have not reviewed individual credit files
nor have we made an independent evaluation or appraisal of the assets and
liabilities of the Company or Washington Mutual or any of their subsidiaries and
we have not been furnished with any such valuation or appraisal. We also have
assumed, with your consent, that the Merger will be accounted for as a pooling
of interests under generally accepted accounting principals. Our advisory
services and the opinion expressed herein are provided for the information and
assistance of the Board of Directors of the Company in connection with its
consideration of the transaction contemplated by the Agreement.
 
Based upon and subject to the foregoing and based upon such other matters as we
consider relevant, it is our opinion that as of the date hereof the Exchange
Ratio pursuant to the Agreement is fair to the holders of Shares.
 
Very truly yours,
 
/s/ GOLDMAN, SACHS & CO.
- ------------------------------------------------
GOLDMAN, SACHS & CO.
<PAGE>   154
 
                                                                      APPENDIX D
 
[MERRILL LYNCH LETTERHEAD]
 
                                 March 5, 1997
 
Board of Directors
Great Western Financial Corporation
9200 Oakdale Avenue
Chatsworth, CA 91311
 
Members of the Board:
 
     We understand that it is proposed that Washington Mutual, Inc. ("Washington
Mutual") and Great Western Financial Corporation ("Great Western") are proposing
to enter into an Agreement and Plan of Merger (the "Agreement") pursuant to
which Great Western will be merged with and into Washington Mutual in a
transaction (the "Merger") in which each outstanding share of Great Western's
common stock, par value $1.00 per share (the "Great Western Shares"), will be
converted into the right to receive 0.90 shares (the "Exchange Ratio") of the
common stock, no par value, of Washington Mutual (the "Washington Mutual
Shares"), all as set forth more fully in the Agreement.
 
     You have asked us whether, in our opinion, the proposed Exchange Ratio in
the Merger is fair to the shareholders of Great Western from a financial point
of view.
 
     In arriving at the opinion set forth below, we have, among other things:
 
      (1) Reviewed Great Western's Annual Reports on Form 10-K and related
          audited financial information for the five fiscal years ended December
          31, 1995, a draft of Great Western's Annual Report on Form 10-K for
          the period ended December 31, 1996, and Great Western's Quarterly
          Reports on Form 10-Q and the related unaudited financial information
          for the quarterly periods ending March 31, 1996, June 30, 1996 and
          September 30, 1996;
 
      (2) Reviewed Washington Mutual's Annual Reports on Form 10-K, a draft of
          Washington Mutual's Annual Report on Form 10-K for the period ended
          December 31, 1996, and related audited financial information for the
          five fiscal years ended December 31, 1995 and Washington Mutual's
          Quarterly Reports on Form 10-Q and the related unaudited financial
          information for the quarterly periods ending March 31, 1996, June 30,
          1996 and September 30, 1996;
 
      (3) Reviewed certain limited financial information, including financial
          forecasts, relating to the respective business, earnings, assets,
          liabilities and prospects of Great Western and Washington Mutual
          furnished to us by senior management of Great Western and Washington
          Mutual;
 
      (4) Conducted certain discussions with members of senior management of
          Great Western and Washington Mutual concerning respective financial
          condition, businesses, earnings, assets, liabilities, operations,
          regulatory condition, financial forecasts, contingencies and
          prospects, of Great Western and Washington Mutual and their respective
          view as to the future financial performance of Great Western,
          Washington Mutual and the combined entity, as the case may be,
          following the Merger;
 
      (5) Reviewed the historical market prices and trading activity for the
          Great Western Shares and the Washington Mutual Shares and compared
          them with that of certain publicly traded companies which we deemed to
          be relevant;
<PAGE>   155
 
[MERRILL LYNCH LETTERHEAD]
 
      (6) Compared the respective results of operations of Great Western and
          Washington Mutual with those of certain publicly traded companies
          which we deemed to be relevant;
 
      (7) Compared the proposed financial terms of the Merger contemplated by
          the Agreement with the financial terms of certain other mergers and
          acquisitions which we deemed to be relevant;
 
      (8) Reviewed the amount and timing of the projected cost savings, related
          expenses and revenue enhancements expected to result from the Merger
          (the "Expected Synergies"), as presented by the senior management of
          Washington Mutual;
 
      (9) Considered, based upon information provided by the senior management
          of Great Western and Washington Mutual, the pro forma impact of the
          transaction on the earnings and book value per share, consolidated
          capitalization and certain balance sheet and profitability ratios of
          Washington Mutual;
 
     (10) Reviewed a draft of the Agreement and Plan of Merger and related
          agreements; and
 
     (11) Reviewed such other financial studies and analyses and performed such
          other investigations and took into account such other matters as we
          deemed appropriate.
 
     In preparing our opinion, with your consent, we have assumed and relied on
the accuracy and completeness of all information supplied or otherwise made
available to us by Great Western and Washington Mutual, including that
contemplated in the numbered items above, and we have not assumed responsibility
for independently verifying such information or undertaken an independent
evaluation or appraisal of the assets or liabilities, contingent or otherwise,
of Great Western or Washington Mutual or any of their subsidiaries, nor have we
been furnished any such evaluation or appraisal. We are not experts in the
evaluation of allowances for loan losses and, with your consent, we have not
made an independent evaluation of the adequacy of the allowance for loan losses
of Great Western or Washington Mutual, nor have we reviewed any individual
credit files relating to Washington Mutual or Great Western and, with your
consent, we have assumed that the aggregate allowance for loan losses for each
of Washington Mutual and Great Western is adequate to cover such losses and will
be adequate on a pro forma basis for the combined entity. In addition, we have
not conducted any physical inspection of the properties or facilities of Great
Western or Washington Mutual. With your consent, we have also assumed and relied
upon the senior management of Great Western and Washington Mutual as to the
reasonableness and achievability of the financial forecasts (and the assumptions
and bases therefor) provided to, and discussed with, us. In that regard, we have
assumed and relied with your consent that such forecasts, including without
limitation, financial forecasts, evaluations of contingencies. Expected
Synergies and projections regarding underperforming and non-performing assets,
net charge-offs, adequacy of reserves, and future economic conditions reflect
the best currently available estimates, allocations and judgments of the senior
management of Great Western and Washington Mutual as to the future financial
performance of Great Western, Washington Mutual or the combined entity, as the
case may be. Our opinion is predicated on the Merger receiving the tax and
accounting treatment contemplated in the Agreement. Our opinion is necessarily
based on economic, market and other conditions as in effect on, and the
information made available to us as of, the date hereof.
 
     Our opinion has been rendered without regard to the necessity for, or level
of, any restrictions, obligations, undertakings or divestitures which may be
imposed or required in the course of obtaining regulatory approval for the
Merger.
 
     We have been retained by the Board of Directors of Great Western as an
independent contractor to act as financial advisor to Great Western with respect
to the Merger Proposal and will receive a fee for our services. We have, in the
past, provided financial advisory and financing services to Great Western and
Washington Mutual and received customary fees for the rendering of such
services, including acting as lead underwriter for a 14.6 million share
secondary public offering of Washington Mutual common stock in January 1997. In
addition, in the ordinary course of our securities business, we may actively
trade debt and/or equity securities of Great Western and Washington Mutual and
their respective affiliates for our own account and the accounts
<PAGE>   156
 
[MERRILL LYNCH LETTERHEAD]
 
of our customers, and we therefore may from time to time hold a long or short
position in such securities. In addition, certain affiliates of Merrill Lynch &
Co. act as investment advisors to publicly held mutual funds which owned, as of
March 4, 1997, approximately 5.1 million shares of Great Western's Common Stock
and approximately 0.5 million shares of Washington Mutual's Common Stock.
 
     Our opinion is directed to the Board of Directors of Great Western and does
not constitute a recommendation to any shareholder of Great Western as to how
such shareholder should vote at any shareholder meeting of Great Western held in
connection with the Merger Proposal. This opinion is directed only to the
proposed Exchange Ratio and is for the confidential use of the Board of
Directors of Great Western
and may not be reproduced, summarized, described or referred to or given to any
other person without our consent.
 
     On the basis of, and subject to the foregoing, we are of the opinion that
the proposed Exchange Ratio in the Merger is fair to the shareholders of Great
Western from a financial point of view.
 
                                          Very truly yours,
 
                                          MERRILL LYNCH, PIERCE, FENNER & SMITH
                                                    INCORPORATED
<PAGE>   157
 
                                    PART II
 
                     INFORMATION NOT REQUIRED IN PROSPECTUS
 
ITEM 20. INDEMNIFICATION OF DIRECTORS AND OFFICERS
 
     Section 23B.08.320 of the Washington Business Corporation Act (the
"Corporation Act") provides that the personal liability of directors to a
corporation imposed by Section 23B.08.310 of the Corporation Act may be
eliminated by the articles of incorporation of the corporation, except in the
case of acts or omissions involving certain types of conduct. At Article XIII of
its Restated Articles of Incorporation, the Registrant has elected to eliminate
the liability of directors to the Registrant to the extent permitted by law.
Thus, a director of the Registrant is not personally liable to the Registrant or
its shareholders for monetary damages for conduct as a director, except for
liability of the director (i) for acts or omissions that involve intentional
misconduct by the director or a knowing violation of law by the director, (ii)
for conduct violating Section 23B.08.310 of the Corporation Act, or (iii) for
any transaction from which the director will personally receive a benefit in
money, property or services to which the director is not legally entitled. If
Washington law is amended to authorize corporate action that further eliminates
or limits the liability of directors, then the liability of Washington Mutual
directors will be eliminated or limited to the fullest extent permitted by
Washington law, as so amended.
 
     Section 23B.08.560 of the Corporation Act provides that if authorized by
(i) the articles of incorporation, (ii) a bylaw adopted or ratified by the
shareholders, or (iii) a resolution adopted or ratified, before or after the
event, by the shareholders, a corporation will have the power to indemnify
directors made party to a proceeding, or to obligate itself to advance or
reimburse expenses incurred in a proceeding, without regard to the limitations
on indemnification contained in Sections 23B.08.510 through 23B.08.550 of the
Corporation Act.
 
     Pursuant to Article X of Washington Mutual's Restated Articles of
Incorporation and Article VIII of Washington Mutual Bylaws, Washington Mutual
must, subject to certain exceptions, indemnify and defend its directors against
any expense, liability or loss arising from or in connection with any actual or
threatened action, suit or proceeding relating to service for or at the request
of Washington Mutual, including without limitation, liability under the
Securities Act. Washington Mutual is not permitted to indemnify a director from
or on account of acts or omissions of such director which are finally adjudged
to be intentional misconduct, or from or on account of conduct in violation of
RCW 23B.08.310, or a knowing violation of the law from or on account of any
transaction with respect to which it is finally adjudged that such director
received a benefit in money, property or services to which he or she was not
entitled. If Washington law is amended to authorize further indemnification of
directors, then Washington Mutual directors shall be indemnified to the fullest
extent permitted by Washington law, as so amended. Also, pursuant to Article X
of Washington Mutual's Restated Articles of Incorporation and Article VIII of
Washington Mutual's Bylaws, Washington Mutual may, by action of the Washington
Mutual Board, provide indemnification and pay expenses to officers, employees
and agents of Washington Mutual or another corporation, partnership, joint
venture, trust or other enterprise with the same scope and effect as above
described in relation to directors. Insofar as indemnification for liabilities
arising under the Securities Act may be permitted to directors, officers or
persons controlling Washington Mutual pursuant to the provisions described
above, Washington Mutual has been informed that in the opinion of the Commission
such indemnification is against public policy as expressed in the Securities Act
and is therefore unenforceable.
 
                                      II-1
<PAGE>   158
 
ITEM 21. EXHIBITS AND FINANCIAL STATEMENT SCHEDULES
 
<TABLE>
<CAPTION>
        EXHIBIT NO.                                   DESCRIPTION
        -----------     ------------------------------------------------------------------------
        <C>             <S>
            2.1         Agreement and Plan of Merger between the Registrant, NACI and Great
                        Western, dated March 5, 1997. (Incorporated by reference to Appendix A
                        of the Joint Proxy Statement/Prospectus included in this Registration
                        Statement). Registrant agrees to furnish supplementally to the
                        Commission upon request a copy of any omitted schedule.
            3.1*        Restated Articles of Incorporation of the Registrant, as amended (the
                        "Washington Mutual Articles").
            3.2*        Bylaws of the Registrant (Incorporated by reference to the Washington
                        Mutual, Inc. Annual Report to the Securities and Exchange Commission on
                        Form 10-K for the year ended December 31, 1995. File No. 0-25188).
            4.1*        Article II, Sections D(2), D(3), and D(4) of the Washington Mutual
                        Articles, which define the rights of holders of the Series C Preferred
                        Stock and the Series E Preferred Stock (filed together with Exhibit 3.1
                        hereto).
            4.2**       Rights Agreement, dated October 16, 1990.
            4.3**       Amendment No. 1 to the Rights Agreement, dated October 31, 1994.
            4.4**       Supplement to Rights Agreement, dated November 29, 1994.
            4.5*        Form of Indenture between the Registrant and Harris Trust and Savings
                        Bank, as Trustee, for the Washington Mutual Senior Unsecured 7 1/4%
                        Notes ("Senior Notes") (incorporated by reference to Washington Mutual,
                        Inc. Registration Statement on Form S-3, registration no. 33-93850).
            4.6*        First Supplemental Indenture dated November 26, 1996 and Second
                        Supplemental Indenture dated January 6, 1997 to the Indenture between
                        Washington Mutual, Inc. and Harris Trust and Savings Bank, as Trustee,
                        dated August 25, 1995, affecting the rights of the holders of the
                        Registrant's Senior Notes.
            4.7         Certificate of Designations of the Series F Preferred Stock (filed by
                        amendment).
            4.8         Deposit Agreement for the New Washington Mutual Depositary Shares, each
                        representing a one-tenth interest in a share of the Series F Preferred
                        Stock (filed by amendment).
            5.1         Opinion of Foster Pepper & Shefelman.
            8.1         Tax Opinion of Foster Pepper & Shefelman (filed by amendment).
           21.1*        List of Subsidiaries of the Registrant.
           23.1         Consent of Deloitte & Touche LLP.
           23.2         Consent of Price Waterhouse LLP.
           23.3         Consent of KPMG Peat Marwick LLP.
           23.4         Consent of Foster Pepper & Shefelman (included in its Opinion filed as
                        Exhibit 5.1).
           24.2         Powers of Attorney (included on the signature page of this Registration
                        Statement).
</TABLE>
 
- ---------------
 
 * Incorporated by reference to Washington Mutual, Inc. Annual Report to the
   Securities and Exchange Commission on Form 10-K for the year ended December
   31, 1996 (File No. 0-25188).
 
** Incorporated by reference to Washington Mutual, Inc. Current Report on Form
   8-K dated November 29, 1994 (File No. 025188).
 
                                      II-2
<PAGE>   159
 
ITEM 22. UNDERTAKINGS
 
     The Undersigned Registrant hereby undertakes:
 
          (1) To file, during any period in which offers or sales are being
     made, a post-effective amendment to this registration statement:
 
             (i) to include any prospectus required by Section 10(a)(3) of the
        Securities Act of 1933;
 
             (ii) to reflect in the prospectus any facts or events arising after
        the effective date of the registration statement (or the most recent
        post-effective amendment thereof) which, individually or in the
        aggregate, represent a fundamental change in the information set forth
        in the registration statement;
 
             (iii) to include any material information with respect to the plan
        of distribution not previously disclosed in the registration statement
        or any material change to such information in the registration
        statement;
 
          (2) That, for the purpose of determining any liability under the
     Securities Act of 1933, each such post-effective amendment shall be deemed
     to be a new registration statement relating to the securities offered
     therein, and the offering of such securities at that time shall be deemed
     to be the initial bona fide offering thereof.
 
          (3) To remove from registration by means of a post-effective amendment
     any of the securities being registered which remain unsold at the
     termination of the offering.
 
     The undersigned Registrant hereby undertakes that, for the purpose of
determining any liability under the Securities Act of 1933, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Securities Exchange Act of 1934 (and, where applicable, each filing of an
employee benefit plan's annual report pursuant to Section 15(d) of the
Securities Exchange Act of 1934) that is incorporated by reference in the
registration statement shall be deemed to be a new registration statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.
 
     Insofar as indemnification for liabilities arising under the Securities Act
of 1933 may be permitted to directors, officers and controlling persons of the
Registrant pursuant to the foregoing provisions, or otherwise, the Registrant
has been advised that in the opinion of the Securities and Exchange Commission
such indemnification is against public policy as expressed in the Act and is,
therefore, unenforceable. In the event that a claim for indemnification against
such liabilities (other than the payment by the Registrant of expenses incurred
by a director, officer or controlling person of the Registrant in the successful
defense of any action, suit or proceeding) is asserted by such director, officer
or controlling person in connection with the securities being registered, the
Registrant will, unless in the opinion of its counsel the matter has been
settled by controlling precedent, submit to a court of appropriate jurisdiction
the question whether such indemnification by it is against public policy as
expressed in the Act and will be governed by the final adjudication of such
issue.
 
     The undersigned registrant hereby undertakes to respond to requests for
information that is incorporated by reference into the prospectus pursuant to
Items 4, 10(b), 11 or 13 of this Form within one business day of receipt of such
request, and to send the incorporated documents by first class mail or other
equally prompt means. This includes information contained in documents filed
subsequent to the effective date of the registration statement through the date
of responding to the request.
 
     The undersigned registrant hereby undertakes to supply by means of a
post-effective amendment all information concerning a transaction, and the
company being acquired involved therein, that was not the subject of and
included in the registration statement when it became effective.
 
                                      II-3
<PAGE>   160
 
                                   SIGNATURES
 
     Pursuant to the requirements of the Securities Act of 1933, as amended, the
Registrant has duly caused this Registration Statement to be signed on its
behalf by the undersigned, thereunto duly authorized, in the City of Seattle,
State of Washington on March 11, 1997.
 
                                          WASHINGTON MUTUAL, INC.
 
                                          By:    /s/ KERRY K. KILLINGER
                                             -----------------------------------
                                             Kerry K. Killinger
                                          Title: President and Chief Executive
                                                 Officer
 
                               POWER OF ATTORNEY
 
     Each person whose signature appears below constitutes and appoints and
hereby authorizes Kerry K. Killinger and Marc R. Kittner, and each of them, with
the full power of substitution, as attorney-in-fact to sign in such person's
behalf, individually and in each capacity stated below, and to file any
amendments, including post-effective amendments to this Registration Statement.
 
     Pursuant to the requirement of the Securities Act of 1933, this
Registration Statement has been signed below by the following persons in the
capacities indicated below on the 5th day of March, 1997.
 
<TABLE>
<S>                                               <C>
           /s/ KERRY K. KILLINGER                           /s/ WILLIAM A. LONGBRAKE
- ---------------------------------------------     ---------------------------------------------
             Kerry K. Killinger                               William A. Longbrake
           Chairman, President and                        Executive Vice President and
      Chief Executive Officer; Director                      Chief Financial Officer
        (Principal Executive Officer)                     (Principal Financial Officer
 
                                                             /s/ DOUGLAS G. WISDORF
                                                  ---------------------------------------------
                                                               Douglas G. Wisdorf
                                                      Senior Vice President and Controller
                                                         (Principal Accounting Officer)
 
                                                               /s/ ANNE V. FARRELL
- ---------------------------------------------     ---------------------------------------------
              Douglas P.Beighle                                  Anne V. Farrell
                  Director                                          Director
 
                                                            /s/ WILLIAM P. GERBERDING
- ---------------------------------------------     ---------------------------------------------
               David Bonderman                                William P. Gerberding
                  Director                                          Director
 
                                                             /s/ SAMUEL B. MCKINNEY
- ---------------------------------------------     ---------------------------------------------
              Herbert M. Bridge                              Dr. Samuel B. McKinney
                  Director                                          Director
 
- ---------------------------------------------     ---------------------------------------------
             J. Taylor Crandall                                 Michael K. Murphy
                  Director                                          Director
 
             /s/ ROGER H. EIGSTI                               /s/ LOUIS H. PEPPER
- ---------------------------------------------     ---------------------------------------------
               Roger H. Eigsti                                   Louis H. Pepper
                  Director                                          Director
 
              /s/ JOHN W. ELLIS
- ---------------------------------------------     ---------------------------------------------
               John W. Elllis                                 William G. Reed, Jr.
                  Director                                          Director
 
             /s/ DANIEL J. EVANS
- ---------------------------------------------     ---------------------------------------------
               Daniel J. Evans                                   James H. Stever
                  Director                                          Director
</TABLE>
 
                                      II-4
<PAGE>   161
 
                                 EXHIBIT INDEX
 
<TABLE>
<CAPTION>
                                                                                       SEQUENTIALLY
EXHIBIT NO.                                 DESCRIPTION                                  NUMBERED
- -----------   -----------------------------------------------------------------------  ------------
<C>           <S>                                                                      <C>
    2.1       Agreement and Plan of Merger between the Registrant, NACI and Great
              Western, dated March 5, 1997. (Incorporated by reference to Appendix A
              of the Joint Proxy Statement/Prospectus included in this Registration
              Statement). Registrant agrees to furnish supplementally to the
              Commission upon request a copy of any omitted schedule.................
    3.1*      Restated Articles of Incorporation of the Registrant, as amended (the
              "Washington Mutual Articles")..........................................
    3.2*      Bylaws of the Registrant (Incorporated by reference to the Washington
              Mutual, Inc. Annual Report to the Securities and Exchange Commission on
              Form 10-K for the year ended December 31, 1995. File No. 0-25188)......
    4.1*      Article II, Sections D(2), D(3), and D(4) of the Washington Mutual
              Articles, which define the rights of holders of the Series C Preferred
              Stock and the Series E Preferred Stock (filed together with Exhibit 3.1
              hereto)................................................................
    4.2**     Rights Agreement, dated October 16, 1990...............................
    4.3**     Amendment No. 1 to the Rights Agreement, dated October 31, 1994........
    4.4**     Supplement to Rights Agreement, dated November 29, 1994................
    4.5*      Form of Indenture between the Registrant and Harris Trust and Savings
              Bank, as Trustee, for the Washington Mutual Senior Unsecured 7 1/4%
              Notes ("Senior Notes") (incorporated by reference to Washington Mutual,
              Inc. Registration Statement on Form S-3, registration no. 33-93850)....
    4.6*      First Supplemental Indenture dated November 26, 1996 and Second
              Supplemental Indenture dated January 6, 1997 to the Indenture between
              Washington Mutual, Inc. and Harris Trust and Savings Bank, as Trustee,
              dated August 25, 1995, affecting the rights of the holders of the
              Registrant's Senior Notes..............................................
    4.7       Certificate of Designations of the Series F Preferred Stock (filed by
              amendment).............................................................
    4.8       Deposit Agreement for the New Washington Mutual Depositary Shares, each
              representing a one-tenth interest in a share of the Series F Preferred
              Stock (filed by amendment).............................................
    5.1       Opinion of Foster Pepper & Shefelman...................................
    8.1       Tax Opinion of Foster Pepper & Shefelman (filed by amendment)..........
   21.1*      List of Subsidiaries of the Registrant.................................
   23.1       Consent of Deloitte & Touche LLP.......................................
   23.2       Consent of Price Waterhouse LLP........................................
   23.3       Consent of KPMG Peat Marwick LLP.......................................
   23.4       Consent of Foster Pepper & Shefelman (included in its Opinion filed as
              Exhibit 5.1)...........................................................
   24.2       Powers of Attorney (included on the signature page of this Registration
              Statement).............................................................
</TABLE>
 
- ---------------
 
 * Incorporated by reference to Washington Mutual, Inc. Annual Report to the
   Securities and Exchange Commission on Form 10-K for the year ended December
   31, 1996 (File No. 0-25188).
 
** Incorporated by reference to Washington Mutual, Inc. Current Report on Form
   8-K dated November 29, 1994 (File No. 025188).

<PAGE>   1
                                                             Exhibit 5.1


                           FOSTER PEPPER & SHEFELMAN

                                 March 11, 1997


Board of Directors
Washington Mutual, Inc.
1201 Third Avenue
Seattle, WA 
98101

        Re:  Registration Statement on Form S-4

Ladies and Gentlemen:

        We have acted as counsel for Washington Mutual, Inc., a Washington
corporation (the "Company"), in connection with the preparation and filing of a
Registration Statement on Form S-4 ("Registration Statement") under the
Securities Act of 1933, as amended, for up to 132,690,700 shares (the "Shares")
of common stock, no par value per share (the "Common Stock"), of the Company to
be issued to the common stockholders and holders of options to acquire shares
of common stock of Great Western Financial Corporation ("Great Western") upon
consummation of the merger of Great Western into New American Capital Inc.
("NACI"), a wholly-owned subsidiary of the Company, pursuant to the Agreement
of Merger dated March 5, 1997 among the Company, NACI and Great Western (the
"Merger Agreement").

        We have examined the Merger Agreement, the Registration Statement, the
actions of the Board of Directors of the Company in authorizing the Merger
Agreement and the issuance of the Shares pursuant thereto and such other
documents and records as we deem necessary for the purpose of this opinion.

        Based on the foregoing, we are of the opinion that, upon consummation
of the Merger and the issuance of the Shares in accordance with the terms of
the Merger Agreement, including the approval of the issuance of the Shares by
the Company's common shareholders, the Shares will be legally issued, fully
paid and nonassessable.

        We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to our firm under the heading
"Legal Matters" in the Prospectus included in the Registration Statement.


                                Very truly yours,

                                
                                Foster Pepper & Shefelman




<PAGE>   1
INDEPENDENT AUDITORS' CONSENT
- --------------------------------------------------------------------------------

We consent to the incorporation by reference in Registration Statement of
Washington Mutual, Inc. on Form S-4 dated March 11, 1997, of our report dated
February 14, 1997, appearing in the Annual Report on Form 10-K of Washington
Mutual, Inc. for the year ended December 31, 1996, and to the reference to
Deloitte & Touche LLP under the heading experts in the prospectus which is part
of this registration statement.


/s/ DELOITTE & TOUCHE LLP

DELOITTE & TOUCHE LLP

Seattle, Washington
March 11, 1997

<PAGE>   1

                                                                   EXHIBIT 23.2

                       CONSENT OF INDEPENDENT ACCOUNTANTS


We hereby consent to the incorporation by reference in the Prospectus
constituting part of this Registration Statement on Form S-4 of Washington
Mutual, Inc. of our report dated January 22, 1997, except as to Note 28, which
is as of March 7, 1997, appearing on page 105 of Great Western Financial
Corporation's Annual Report on Form 10-K for the year ended December 31, 1996.
We also consent to the references to us under the heading "Experts" in such
Prospectus. 




                                              PRICE WATERHOUSE LLP



Los Angeles, California
March 10, 1997

<PAGE>   1
                                                                   EXHIBIT 23.3



                         INDEPENDENT AUDITORS' CONSENT


We consent to the use of our report dated January 26, 1996, except as to Note 27
to the consolidated financial statements, which is as of February 8, 1996, on
the consolidated financial statements of Keystone Holdings, Inc. and
subsidiaries as of December 31, 1995, and for each of the years in the two-year
period ended December 31, 1995 incorporated herein by reference and to the
reference to our firm under the heading "Experts" in the prospectus.



                                                KPMG PEAT MARWICK LLP



Los Angeles, California
March 10, 1997





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