SOUTHWEST BANCORP INC
10-Q, 1997-08-14
SAVINGS INSTITUTION, FEDERALLY CHARTERED
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<PAGE>
 
                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549
                      ----------------------------------  


                                   FORM 10-Q


                       [ x ]  QUARTERLY REPORT PURSUANT TO SECTION 13 OR
                              15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
                              For the quarterly period ended June 30, 1997.

                                      OR

                       [   ]  TRANSITION REPORT PURSUANT TO SECTION 13 OR
                              15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
                              For the transition period from      to
                                                            ------  ------

                       Commission File Number   0-23064


                            SOUTHWEST BANCORP, INC.
            -----------------------------------------------------   
            (Exact name of registrant as specified in its charter)


          Oklahoma                              #73-1136584
- -------------------------------           -----------------------
(State or other jurisdiction of           (I.R.S. Employer
 incorporation or organization)            Identification Number)


        608 South Main Street                      74074
        Stillwater, Oklahoma                     ----------  
- ---------------------------------------          (Zip Code)
(Address of principal executive office) 


Registrant's telephone number, including area code:  (405) 372-2230


Indicate by check mark whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the preceding twelve months (or for such shorter period that the registrant was
required to file such reports), and (2) has been subject to such filing
requirements for the past ninety days.

               [ x ] YES                                 [   ] NO

APPLICABLE ONLY TO CORPORATE ISSUERS:  Indicate the number of shares outstanding
of each of the issuer's classes of common stock, as of the latest practicable
date.

                                   3,770,764
                                   ---------



                                    1 of 19
<PAGE>
 
                            SOUTHWEST BANCORP, INC.

                              INDEX TO FORM 10-Q
<TABLE>
<CAPTION>
                                                                                   Page No.
                                                                                   --------
<S>                                                                                <C>
PART I.  FINANCIAL INFORMATION

     ITEM 1.  UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS
 
              Unaudited Consolidated Statements of Financial Condition at
                June 30, 1997 and December 31, 1996                                    3
 
              Unaudited Consolidated Statements of Operations for the
                three and six months ended June 30, 1997 and 1996                      4
 
              Unaudited Consolidated Statements of Shareholders' Equity for the 
                six months ended June 30, 1997 and 1996                                5
 
              Unaudited Consolidated Statements of Cash Flows for the
                six months ended June 30, 1997 and 1996                                6
 
              Notes to Unaudited Consolidated Financial Statements                     7
 
              Average Balances, Yields and Rates                                      11
 
     ITEM 2.  MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL 
              CONDITION AND RESULTS OF OPERATIONS                                     12 

PART II.  OTHER INFORMATION                                                           18

SIGNATURES                                                                            19
</TABLE>

                                       2
<PAGE>
 
SOUTHWEST BANCORP, INC.
UNAUDITED CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION
(Dollars in thousands except share data)
<TABLE> 
<CAPTION> 
                                                                             JUNE 30,                    DECEMBER 31,
                                                                               1997                          1996
                                                                         -----------------            -----------------
<S>                                                                      <C>                          <C> 
ASSETS                                                                                           
Cash and due from banks                                                      $ 31,271                     $ 22,914
Federal funds sold                                                              4,000                           -
                                                                             --------                     -------- 
        Cash and cash equivalents                                              35,271                       22,914
Investment securities:                                                                      
        Held to maturity, approximate fair value                                            
          of $87,105 (1997) and $83,963 (1996)                                 86,780                       83,589
        Available for sale, approximate amortized                                           
          cost of $91,390 (1997) and $63,419 (1996)                            91,903                       63,762
Loans receivable, net of allowance for loan losses                                          
  of $8,669 (1997) and $7,139 (1996)                                          703,225                      637,507
Accrued interest receivable                                                     9,052                        7,400
Premises and equipment, net                                                    12,993                        9,649
Other assets                                                                    8,748                        4,296
                                                                             --------                     --------
                Total assets                                                 $947,972                     $829,117
                                                                             ========                     ======== 
                                                                                            
LIABILITIES & SHAREHOLDERS' EQUITY                                                          
Deposits:                                                                                   
        Noninterest-bearing demand                                           $ 94,046                     $ 83,729
        Interest-bearing demand                                                42,232                       34,309
        Money market accounts                                                  89,149                       86,910
        Savings accounts                                                        4,013                        4,086
        Time deposits                                                         617,852                      544,911
                                                                             --------                     -------- 
                Total deposits                                                847,292                      753,945
                                                                             --------                     --------       
Income taxes payable                                                               -                           187
Accrued interest payable                                                        6,111                        5,061
Other liabilities                                                               3,357                        4,892
Long-term debt:                                                                              
        Guaranteed preferred beneficial interests                                           
          in the Company's subordinated debentures                             25,013                           -
                                                                             --------                     --------      
                        Total liabilities                                     881,773                      764,085
                                                                             --------                     --------      
                                                                                            
Commitments and contingencies                                                      -                            -
Shareholders' equity:                                                                       
        Serial preferred stock -                                                            
          Series A, 9.20% Redeemable, Cumulative Preferred                                  
            Stock; $1 par value; 1,000,000 shares authorized;                               
            liquidation value $17,250,000; 690,000 shares                                   
            issued and outstanding                                                690                          690
          Series B, $1 par value; 1,000,000 shares authorized;                              
            none issued                                                            -                            -
        Common stock - $1 par value; 10,000,000 shares                                      
            authorized; issued and outstanding 3,768,969 (1997)                             
            and 3,764,216 (1996)                                                3,769                        3,764
        Capital surplus                                                        24,426                       24,332
        Retained earnings                                                      37,007                       36,041
        Unrealized gain/(loss) on investment securities                                     
          available for sale, net of tax                                          307                          205
                                                                             --------                     --------      
                        Total shareholders' equity                             66,199                       65,032
                                                                             --------                     --------      
                        Total liabilities & shareholders' equity             $947,972                     $829,117
                                                                             ========                     ========      
</TABLE>

                                       3
<PAGE>
 
SOUTHWEST BANCORP, INC.
UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS
(Dollars in thousands except share data)
<TABLE> 
<CAPTION> 

                                                                 FOR THE THREE MONTHS             FOR THE SIX MONTHS
                                                                   ENDED JUNE 30,                   ENDED JUNE 30,
                                                               1997             1996            1997              1996
                                                            ----------       ----------       ----------       ----------
<S>                                                         <C>              <C>              <C>              <C> 
Interest income:                                                                                           
    Interest and fees on loans                              $   16,291       $   13,271       $   31,807       $   26,103
    Investment securities:                                                                                 
      U.S. Government and agency obligations                     2,061            1,651            3,803            3,291
      State and political subdivisions                             135              146              271              286
      Mortgage-backed securities                                   312              391              673              781
      Other securities                                              15               19               30               32
    Federal funds sold                                             189              144              270              218
                                                            ----------       ----------       ----------       ----------
      Total interest income                                     19,003           15,622           36,854           30,711
                                                                                                           
Interest expense:                                                                                          
    Interest-bearing demand                                        219              206              428              409
    Money market accounts                                          938              745            1,857            1,418
    Savings accounts                                                25               30               50               60
    Time deposits                                                8,843            6,775           16,879           13,397
    Short-term borrowings                                           21               13               91               71
    Long-term debt                                                 174               -               174               -
                                                            ----------       ----------       ----------       ----------
      Total interest expense                                    10,220            7,769           19,479           15,355
                                                            ----------       ----------       ----------       ----------
                                                                                                           
Net interest income                                              8,783            7,853           17,375           15,356
    Provision for loan losses                                      801              775            3,802            1,650
                                                            ----------       ----------       ----------       ----------
Net interest income after provision for loan losses              7,982            7,078           13,573           13,706
                                                                                                           
                                                                                                           
Other Income:                                                                                              
    Service charges and fees                                       788              720            1,540            1,428
    Credit cards                                                   180              233              373              440
    Other noninterest income                                       215              101              358              218
    Gain on sales of  loans receivable                             379              375              705              823
    Gain/(loss) on sales of investment securities                   -                49               -               171
                                                            ----------       ----------       ----------       ----------
      Total other income                                         1,562            1,478            2,976            3,080
                                                                                                           
                                                                                                           
Other expenses:                                                                                            
    Salaries and employee benefits                               3,561            3,006            7,048            5,834
    Occupancy                                                    1,180              866            2,223            1,625
    FDIC and other insurance                                        66              153              129              285
    Credit cards                                                    82               60              158              164
    General and administrative                                   1,695            1,380            3,385            2,776
                                                            ----------       ----------       ----------       ----------
      Total other expenses                                       6,584            5,465           12,943           10,684
                                                            ----------       ----------       ----------       ----------
Income before taxes                                              2,960            3,091            3,606            6,102
    Taxes on income                                              1,057            1,115            1,243            2,194
                                                            ----------       ----------       ----------       ----------
                                                                                                           
Net income                                                  $    1,903       $    1,976       $    2,363       $    3,908
                                                            ==========       ==========       ==========       ==========
Net income available to common shareholders                 $    1,506       $    1,579       $    1,569       $    3,114
                                                            ==========       ==========       ==========       ==========
Earnings  per common share                                  $     0.40       $     0.42       $     0.42       $     0.83
                                                            ==========       ==========       ==========       ==========
Weighted average common shares outstanding                   3,768,662        3,759,198        3,767,423        3,758,029
                                                            ==========       ==========       ==========       ==========
</TABLE>

                                       4
<PAGE>
 
SOUTHWEST BANCORP, INC.
UNAUDITED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY
(Dollars in thousands except share data)
<TABLE> 
<CAPTION>

                                                                                                              UNREALIZED
                                                                                                              GAIN (LOSS)   TOTAL
                                                                                                             ON AVAILABLE   SHARE-
                                          PREFERRED STOCK           COMMON STOCK        CAPITAL     RETAINED   FOR SALE    HOLDERS'
                                        SHARES     AMOUNT       SHARES       AMOUNT     SURPLUS     EARNINGS  SECURITIES    EQUITY
                                        -------    ------     ---------     -------     --------    --------  ----------   -------- 
<S>                                     <C>         <C>       <C>           <C>         <C>         <C>          <C>       <C> 
Balance, January 1, 1996                690,000     $ 690     3,755,228     $ 3,755     $ 24,171    $ 31,129     $  612    $ 60,357

Cash dividends paid:    
    Preferred, $1.15 per share               -         -             -           -            -         (794)        -         (794)
    Common, $0.07 per share                  -         -             -           -            -         (263)        -         (263)
Cash dividends declared:
    Common, $0.07 per share                  -         -             -           -            -         (262)        -         (262)
Common stock issued:
    Employee Stock Purchase
       Plan                                  -         -          1,633           2           29          -          -           31
    Dividend Reinvestment Plan               -         -          2,631           2           45          -          -           47
Change in unrealized gain
    (loss) on available for sale
    securities, net of tax                   -         -             -           -            -                    (862)       (862)
Net income                                   -         -             -           -            -        3,908         -        3,908
                                        -------     -----     ---------     -------     --------    --------     ------    -------- 
Balance, June 30, 1996                  690,000     $ 690     3,759,492     $ 3,759     $ 24,245    $ 33,718     $ (250)   $ 62,162
                                        =======     =====     =========     =======     ========    ========     ======    ========


Balance, January 1, 1997                690,000     $ 690     3,764,216     $ 3,764     $ 24,332    $ 36,041     $  205    $ 65,032

Cash dividends paid:    
    Preferred, $1.15 per share               -         -             -           -            -         (794)        -         (794)
    Common, $0.08 per share                  -         -             -           -            -         (301)        -         (301)
Cash dividends declared:
    Common, $0.08 per share                  -         -             -           -            -         (302)        -         (302)
Common stock issued:
    Employee Stock Purchase
       Plan                                  -         -          1,877           2           38          -          -           40
    Dividend Reinvestment Plan               -         -          2,876           3           56          -          -           59
Change in unrealized gain
    (loss) on available for sale
    securities, net of tax                   -         -             -           -            -                     102         102
Net income                                   -         -             -           -            -        2,363         -        2,363
                                        -------     -----     ---------     -------     --------    --------     ------    -------- 
Balance, June 30, 1997                  690,000     $ 690     3,768,969     $ 3,769     $ 24,426    $ 37,007     $  307    $ 66,199
                                        =======     =====     =========     =======     ========    ========     ======    ========
</TABLE>

                                       5
<PAGE>
 
SOUTHWEST BANCORP, INC.
UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS
(DOLLARS IN THOUSANDS)
<TABLE> 
<CAPTION> 

                                                                              FOR THE SIX MONTHS
                                                                                ENDED JUNE 30,
                                                                           1997                1996
                                                                         ---------          ----------
<S>                                                                      <C>                <C> 
Operating activities:                                                                  
    Net income                                                           $   2,363           $  3,908
    Adjustments to reconcile net income to net                                         
      cash provided from operating activities:                                         
         Provision for loan losses                                           3,802              1,650
         Depreciation and amortization expense                                 768                584
         Amortization of premiums and accretion of                                     
            discount on securities, net                                         85                122
         Amortization of intangibles                                            97                 64
         (Gain) Loss on sales of securities                                      -               (171)
         (Gain) Loss on sales of loans receivable                             (705)              (823)
         (Gain) Loss on sales of premises/equipment                            (22)               (10)
         (Gain) Loss on other real estate owned, net                             2                 (2)
         Proceeds from sales of residential mortgage loans                  32,734             26,837
         Residential mortgage loans originated for resale                  (30,513)           (36,045)
    Changes in assets and liabilities:                                                 
      Accrued interest receivable                                           (1,652)              (287)
      Other assets                                                          (4,063)              (734)
      Income taxes payable                                                    (187)              (168)
      Accrued interest payable                                               1,050                (50)
      Other liabilities                                                     (1,779)            (8,705)
                                                                           -------           -------- 
         Net cash (used in) provided from operating activities               1,980            (13,830)
                                                                           -------           -------- 
Investing activities:                                                                  
    Proceeds from principal repayments and maturities:                                 
      Held to maturity securities                                            7,860             14,824
      Available for sale securities                                          7,382             17,377
    Purchases of held to maturity securities                               (11,150)           (21,848)
    Purchases of available for sale securities                             (35,339)            (6,303)
    Loans originated and principal repayments, net                         (92,926)           (54,968)
    Proceeds from sales of guaranteed student loans                         21,522             17,235
    Purchases of premises and equipment                                     (4,180)            (2,191)
    Proceeds from sales of premises and equipment                               90                 24
    Proceeds from sales of other real estate                                    17                 79
                                                                           -------           --------
         Net cash (used in) provided from investing activities            (106,724)           (35,771)
                                                                           -------           -------- 
Financing activities:                                                                  
    Net increase in deposits                                                93,347             69,307
    Net proceeds from issuance of common stock                                  99                 78
    Proceeds from issuance of subordinated debentures                       25,013                  -
    Common stock dividends paid                                               (564)              (488)
    Preferred stock dividends paid                                            (794)              (794)
          Net cash provided from financing activities                      117,101             68,103
                                                                           -------           --------
Net increase (decrease) in cash and cash equivalents                        12,357             18,502
                                                                           -------           -------- 
Cash and cash equivalents,                                                             
    Beginning of period                                                     22,914             20,789
                                                                           -------           -------- 
    End of period                                                        $  35,271           $ 39,291
                                                                         =========           ========
</TABLE>


                                       6
<PAGE>
 
                            SOUTHWEST BANCORP, INC.

             NOTES TO UNAUDITED CONSOLIDATED FINANCIAL STATEMENTS


NOTE 1:  GENERAL

The accompanying unaudited consolidated financial statements were prepared in
accordance with instructions for Form 10-Q and, therefore, do not include all
information and footnotes necessary for a complete presentation of financial
position, results of operations, changes in shareholders' equity, and cash flows
in conformity with generally accepted accounting principles.  However, the
financial statements include all adjustments (consisting only of normal
recurring accruals) which, in the opinion of management, are necessary for a
fair presentation.  The results of operations and cash flows for the six months
ended June 30, 1997 and 1996 should not be considered indicative of the results
to be expected for the full year.  These financial statements should be read in
conjunction with the financial statements and notes thereto included in the
Southwest Bancorp, Inc. Annual Report on Form 10-K for the year ended December
31, 1996.


NOTE 2:  PRINCIPLES OF CONSOLIDATION

The accompanying unaudited consolidated financial statements include the
accounts of Southwest Bancorp, Inc. (the Company) and its wholly owned
subsidiaries, The Stillwater National Bank and Trust Company (the Bank) and SBI
Capital Trust (SBI Capital).  All significant intercompany transactions and
balances have been eliminated in consolidation.


NOTE 3:  RECENTLY ADOPTED ACCOUNTING STANDARDS

In February 1997, the Financial Accounting Standards Board (the "FASB") issued
Statement of Financial Accounting Standards ("SFAS") No. 129, Disclosure of
Information About Capital Structure.  SFAS No. 129 establishes standards for
disclosure of information regarding an entity's capital structure.  The adoption
of SFAS No. 129 did not affect the Company's consolidated financial position or
results of operations.


NOTE 4:  ACCOUNTING STANDARDS ISSUED BUT NOT YET ADOPTED

In June 1996, the FASB issued SFAS No. 125, Accounting for Transfers and
Servicing of Financial Assets and Extinguishments of Liabilities.  SFAS No. 125
requires the Company to recognize the financial and servicing assets it controls
and liabilities it has incurred, derecognize financial assets when control has
been surrendered, and derecognize liabilities when extinguished.  The Company
will adopt SFAS No. 125 for transfers and servicing of financial assets and
extinguishment of liabilities occurring after December 31, 1997 as required.
Management believes that adoption of SFAS No. 125 will not have a material
impact on the Company's consolidated financial position or results of
operations.

In February 1997, the FASB issued SFAS No. 128, Earnings Per Share, which
establishes standards for computing and presenting earnings per share.  SFAS No.
128 is effective for periods ending after December 15, 1997.  Management
believes that SFAS No. 128 will not have a significant effect on the Company's
calculation of earnings per share considering its current capital structure.

In June 1997, the FASB issued SFAS No. 130, Reporting Comprehensive Income,
which establishes standards for reporting and displaying comprehensive income
and its components (revenues, expenses, gains and losses) in financial
statements.  In addition, SFAS No. 130 requires the Company to classify items of
other comprehensive income by their nature in a financial statement and display
the accumulated balance of other comprehensive income 

                                       7
<PAGE>
 
separately in the shareholders' equity section of the statement of financial
condition. The Company will adopt SFAS No. 130 on January 1, 1998 as required.

Also in June 1997, the FASB issued SFAS No. 131, Disclosures about Segments of
an Enterprise and Related Information.  SFAS No. 131 establishes reporting
standards for public companies concerning annual and interim financial
statements of their operating segments.  Operating segments are components of a
company about which separate financial information is available that is
regularly evaluated by the chief operating decision maker in deciding how to
allocate resources and assess performance.  The Standard sets criteria for
reporting disclosures about a company's products and services, geographic areas
and major customers.  The Company will adopt SFAS No. 131 on January 1, 1998 as
required.


NOTE 5:  ALLOWANCE FOR LOAN LOSSES
 
Activity in the allowance for loan losses is shown below for the indicated 
periods.
<TABLE>
<CAPTION> 
                                                      For the six          For the
                                                     months ended         year ended
                                                     June 30, 1997     December 31, 1996
                                                    --------------     -----------------
                                                            (Dollars in thousands)
<S>                                                 <C>               <C>
Balance at beginning of period                            $  7,139              $  5,813
Loans charged-off:                                                          
   Real estate mortgage                                        123                   148
   Real estate construction                                      -                     -
   Commercial                                                1,821                 1,064
   Installment and consumer                                    591                 1,089
                                                    --------------     -----------------
                                                                               
               Total charge-offs                             2,535                 2,301
Recoveries:                                                                    
   Real estate mortgage                                         56                    25
   Real estate construction                                      -                     -
   Commercial                                                  126                   288
   Installment and consumer                                     81                   214
                                                    --------------     -----------------
               Total recoveries                                263                   527
                                                    --------------     -----------------

Net loans charged-off                                        2,272                 1,774
Provision for loan losses                                    3,802                 3,100
                                                    --------------     -----------------
Balance at end of period                                  $  8,669              $  7,139
                                                    ==============     =================
Loans outstanding:                                  
   Average                                                $682,539             $ 580,590
   End of period                                           711,894               644,646
Net charge-offs to total average loans (annualized)           0.67%                 0.31%
Allowance for loan losses to total loans                      1.22%                 1.11%
</TABLE>                                                

                                       8
<PAGE>
 
Nonperforming assets and other risk elements of the loan portfolio are shown
below as of the indicated dates.

<TABLE>
<CAPTION> 
                                                                As of                  As of
                                                            June 30, 1997        December 31, 1996
                                                            -------------        -----------------         
                                                                    (Dollars in thousands)
<S>                                                         <C>               <C>
Nonaccrual loans (1)                                          $  5,942              $  4,635
Past due 90 days or more (2)                                     3,960                 1,437
Restructured terms                                                 560                   577
                                                              --------              --------   
   Total nonperforming loans                                    10,462                 6,649
Other real estate owned                                            413                    64
                                                              --------              --------   
   Total nonperforming assets                                 $ 10,875              $  6,713
                                                              ========              ======== 
                                                   
Nonperforming loans to loans receivable                           1.47%                 1.03%
Allowance for loan losses to nonperforming loans                 82.86%               107.37%
Nonperforming assets to loans receivable and                                
   other real estate owned                                        1.53%                 1.04%
</TABLE>
- ------------ 
(1) The government-guaranteed portion of loans included in these totals was $0
    (1997) and $344 (1996).
(2) The government-guaranteed portion of loans included in these totals was $657
    (1997) and $0 (1996).
  
The allowance for loan losses is a valuation reserve established by management
in an amount it deems adequate to provide for losses in the loan portfolio.
Management assesses the adequacy of the allowance for loan losses based upon a
number of factors including, among others, analytical reviews of loan loss
experience in relationship to outstanding loans and commitments; unfunded loan
commitments; problem and nonperforming loans and other loans presenting credit
concerns; trends in loan growth, portfolio composition and quality; use of
appraisals to estimate the value of collateral; and management's judgment with
respect to current and expected economic conditions and their impact on the
existing loan portfolio.  The allowance for loan losses is increased by
provisions for loan losses charged to expense.  Charge-offs of loan amounts
determined by management to be uncollectible or impaired decrease the allowance
and recoveries of previous charge-offs, if any, are added to the allowance.
Management believes that the allowance for loan losses was adequate at December
31, 1996 and June 30, 1997.  The amount of the allowance deemed appropriate by
management, and the levels of loan charge-offs and nonperforming loans, are
affected by changing economic conditions and economic prospects and the
financial position of borrowers.  At any time, there are loans included in the
portfolio that will result in losses to the Company, but that have not been
identified as nonperforming or potential problem loans.  Because the loan
portfolio contains a significant number of commercial and commercial real estate
loans with relatively large balances, the unexpected deterioration of one or a
few of such loans may cause a significant increase in nonperforming assets, and
lead to a material increase in charge-offs and the provision for loan losses.
Since problems with commercial and commercial real estate loans do not
necessarily appear early in their lives, the Company may experience increased
levels of nonperforming loans and loan charge-offs as the relatively large
volume of recently originated loans mature.  In addition, the Comptroller of the
Currency ("OCC"), as an integral part of its examination process, periodically
reviews the Bank's allowance for loan losses, and may require the Bank to
recognize additions to the allowance based upon judgments of OCC examiners about
information available to them at the time of their examination.

NOTE 6:  LOANS RECEIVABLE

The Bank extends commercial and consumer credit primarily to customers in the
State of Oklahoma which subjects the loan portfolio to the general economic
conditions within this area.  At June 30, 1997 and December 31, 1996,
substantially all of the Bank's loans, except for credit cards, are
collateralized with real estate, inventory, accounts receivable and/or other
assets, or are guaranteed by agencies of the United States Government.

                                       9
<PAGE>
 
At June 30, 1997, loans to individuals and businesses in the healthcare industry
totaled approximately $81.9 million, or 12% of total loans.  The loan portfolio
also includes $23.7 million, or 3% of total loans, in hotel/motel loans, $24.0
million, or 3% of total loans, in residential construction loans and $15.9
million, or 2% of total loans, in restaurant loans.  In the event of total
nonperformance by the borrowers, the Company's accounting loss would be limited
to the recorded investment in the loans receivable reduced by proceeds received
from disposition of the related collateral.

The principal balance of loans for which accrual of interest has been
discontinued totaled approximately $5.9 million at June 30, 1997.  During the
first six months of 1997, $20,000 in interest income was received on nonaccruing
loans.  If interest on those loans had been accrued, total interest income of
$228,000 would have been recorded.

Those performing loans considered potential problem loans, as defined and
identified by management, amounted to approximately $19.7 million at June 30,
1997, compared to $23.0 million at December 31, 1996.  Although these are loans
where known information about the borrowers' possible credit problems cause
management to have doubts as to their ability to comply with the present loan
repayment terms, most are well collateralized and are not believed to present
significant risk of loss.  The Company's loan portfolio contains a significant
number of commercial and commercial real estate loans with relatively large
balances.  The deterioration of one or a few of such loans may cause a
significant increase in potential problem loans or in nonperforming loans.


NOTE 7:  LONG-TERM DEBT

On June 4, 1997, SBI Capital Trust, a newly-formed subsidiary of the Company,
issued 1,000,500 of its 9.30% Cumulative Trust Preferred Securities (the
"Preferred Securities") in an underwritten public offering for an aggregate
price of $25,012,500.  Proceeds of the Preferred Securities were invested in the
9.30% Subordinated Debentures (the "Subordinated Debentures") of the Company.
After deducting underwriter's compensation and other expenses of the offering,
the net proceeds are available to the Company to increase capital and for
general corporate purposes, including use in the Bank's lending and investment
activities, and, after September 1, 1998, possible redemption, in whole or in
part, of the Company's 9.20% Redeemable Cumulative Preferred Stock, Series A
(the "Series A Preferred Stock").  Unlike interest payments on the Subordinated
Debentures, dividends paid on the Series A Preferred Stock are not deductible
for federal income tax purposes.

The Preferred Securities and the Subordinated Debentures each mature on July 31,
2027.  If certain conditions are met, the maturity dates of the Preferred
Securities and the Subordinated Debentures may be shortened to a date not
earlier than July 21, 2002, or extended to a date not later than July 31, 2036.
The Preferred Securities and the Subordinated Debentures also may be redeemed
prior to maturity if certain events occur.  The Preferred Securities are subject
to mandatory redemption, in whole or in part, upon repayment of the Subordinated
Debentures at maturity or their earlier redemption.  The Company also has the
right, if certain conditions are met, to defer payment of interest on the
Subordinated Debentures, which would result in a deferral of dividend payments
on the Preferred Securities, at any time or from time to time for a period not
to exceed 20 consecutive quarters in a deferral period.

The Company and SBI Capital believe that, taken together, the obligations of the
Company under the Preferred Securities Guarantee Agreement, the Amended and
Restated Trust Agreement, the Subordinated Debentures, the Indenture and the
Agreement As To Expenses and Liabilities, entered into in connection with the
offering of the Preferred Securities and the Subordinated Debentures, in the
aggregate constitute a full and unconditional guarantee by the Company of the
obligations of  SBI Capital under the Preferred Securities.

SBI Capital Trust is a Delaware business trust created for the purpose of
issuing the Preferred Securities and purchasing the Subordinated Debentures,
which are its sole assets.  The Company owns all of the 30,960 outstanding
common securities, liquidation value $25, (the "Common Securities") of SBI
Capital Trust.

                                      10
<PAGE>
 
The Company believes that the Preferred Securities meet the regulatory criteria
for Tier I capital, subject to Federal Reserve guidelines that limit the amount
of the Preferred Securities and cumulative perpetual preferred stock to an
aggregate of 25% of Tier I capital.

For accounting purposes, the Preferred Securities and the Common Securities are
presented on the Consolidated Statements of Financial Condition as a separate
category of long-term debt entitled "Guaranteed Preferred Beneficial Interests
in the Company's Subordinated Debentures".

<TABLE>
<CAPTION>
 
SOUTHWEST BANCORP, INC.
AVERAGE BALANCES, YIELDS AND RATES
(Dollars in thousands except share data)

                                                              For the six months ended June 30,
                                                                1997                     1996
                                                     -------------------------------------------------
                                                        Average     Average      Average     Average
                                                        Balance    Yield/Rate    Balance    Yield/Rate
                                                     -------------------------------------------------
<S>                                                    <C>         <C>          <C>         <C>
Assets:
       Loans receivable                                 $682,539         9.40%   $547,156         9.59%
       Investment securities                             155,734         6.19     144,555         6.11
       Other interest-earning assets                       9,974         5.46       8,239         5.32
                                                       ---------                ---------        
           Total interest-earning assets                 848,247         8.76     699,950         8.82
       Noninterest-earning assets                         44,933                   33,699
                                                       ---------                ---------        
           Total assets                                 $893,180                 $733,649
                                                       =========                =========
 
Liabilities and shareholders' equity:
       NOW accounts                                     $ 37,177         2.32%   $ 35,171         2.34%
       Money market accounts                              90,297         4.15      78,045         3.65
       Savings accounts                                    4,017         2.51       4,825         2.50
       Time deposits                                     595,690         5.71     467,217         5.77
                                                       ---------                ---------        
           Total interest-bearing deposits               727,181         5.33     585,258         5.25
       Short-term borrowings                               3,166         5.80       2,592         5.51
       Long-term debt                                      3,731         9.30           -            -
                                                       ---------                ---------         
           Total interest-bearing liabilities            734,078         5.35     587,850         5.25
       Demand deposits                                    84,581                   78,984
       Other noninterest-bearing liabilities               9,462                    5,636
       Shareholders' equity                               65,059                   61,179
                                                       ---------                ---------        
           Total liabilities and shareholders' equity   $893,180                 $733,649
                                                       =========               ==========
 
       Interest rate spread                                              3.41%                    3.57%
                                                                    =========                =========
       Net interest margin                                               4.13%                    4.41%
                                                                    =========                =========
       Ratio of average interest-earning assets
           to average interest-bearing liabilities        115.55%                  119.07%
                                                       =========                 ========
</TABLE>
                                      11

<PAGE>
 
                            SOUTHWEST BANCORP, INC.

                     MANAGEMENT'S DISCUSSION AND ANALYSIS
               OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS


Forward Looking Statements.  Portions of this Management's Discussion and
Analysis contain forward-looking statements, including statements of goals,
intentions, and expectations, regarding or based upon general economic
conditions, interest rates, developments in national and local markets, and
other matters, which, by their nature, are subject to significant uncertainties.
Because of these uncertainties and the assumptions on which statements in this
report are based, the actual future results may differ materially from those
indicated in this report.  Past results also are not necessarily indicative of
future performance.


FINANCIAL CONDITION

The Company's total assets increased by $118.9 million, or 14%, from $829.1
million at December 31, 1996 to $948.0 million at June 30, 1997.

Loans were $711.9 million at June 30, 1997, an increase of $67.3 million, or
10%, compared to December 31, 1996.  The Company experienced increases in the
categories of commercial mortgages ($24.0 million, or 12%), commercial loans
($20.7 million, or 9%),  real estate construction loans ($11.0 million, or 20%),
other consumer loans ($5.1 million, or 16%), and residential mortgages ($9.5
million, or 16%).  These increases were offset by a reduction in government-
guaranteed student loans ($1.3 million, or 2%), and a $1.7 million, or 8%
reduction in credit card loans, which ended the quarter with total outstandings
of $19.1 million.  See "Recent Development".  The allowance for loan losses
increased by $1.5 million, or 21%, from December 31, 1996 to June 30, 1997.   At
June 30, 1997, the allowance for loan losses was $8.7 million, or 1.22% of total
loans, compared to $7.1 million, or 1.11% of total loans, at December 31, 1996.

Investment securities were $178.7 at June 30, 1997, an increase of $31.3
million, or 21%, compared to December 31, 1996.

Premises and equipment increased by $3.3 million primarily due to the
acquisition of land for a new Tulsa Banking Center at 15th and Utica to be
opened in late 1998.

The Company's deposits increased by $93.4 million, or 12%, from $753.9 million
at December 31, 1996 to $847.3 million at June 30, 1997.  This increase occurred
primarily in time deposits, which increased by $72.9 million, or 13%.  Interest-
bearing demand deposits and money market accounts increased by $7.9 million, or
23%, and $2.2 million, or 3%,  respectively, from December 31, 1996 to June 30,
1997.

Shareholders' equity increased by $1.2 million, or 2%, due primarily to earnings
for the first six months of 1997, net of dividends declared on common and
preferred stock, and a $102,000 increase attributable to a change in the
unrealized gain/loss, net of taxes, on investment securities available for sale.


RESULTS OF OPERATIONS

FOR THE SIX MONTH PERIODS ENDED JUNE 30, 1997 AND 1996

NET INCOME

For the first six months of 1997, the Company recorded net income of $2.4
million, 40% less than the $3.9 million recorded for the first six months of
1996.  Net income available to common shareholders, after deduction of dividends
on preferred stock, was $1.6 million ($0.42 per share), compared with $3.1
million ($0.83 per share) for 

                                      12
<PAGE>
 
the first six months of 1996. The substantial decrease in quarterly earnings was
primarily the result of a $2.1 million increase in the provision for loan
losses. Average common shares outstanding were 3,767,423 and 3,758,029,
respectively.

During the first quarter of 1997, the Company received information regarding
events that adversely affected a borrower's ability to fully repay its
commercial loan, which had a carrying amount of $1.9 million.  As a result of
this event, and management's regular evaluation of the adequacy of the allowance
for loan losses relative to other loans in the portfolio, the Company recorded a
provision for loan losses of $3.0 million for the first quarter of 1997,
compared with a provision of $875,000 for the first quarter of 1996.  See
"Provision for loan losses".  For the second quarter of 1997, the provision for
loan losses was $801,000, compared to $775,000 for the second quarter of 1996,
an increase of 3%.

Net interest income increased $2.1 million, or 13%, for the first six months of
1997 compared to the same period in 1996.  This increase in net interest income,
as well as a $951,000, or 43%, reduction in taxes, partially offset the $2.1
million, or 130%, increase in provision for loan losses, a $2.3 million, or 21%,
increase in other expenses and a $104,000, or 3% reduction in other income.  For
the first six months of 1997, the return on average total equity was 7.32% and
the return on average common equity was 6.62% compared to a 12.85% return on
average total equity and a 14.27% return on average common equity for the first
six months of 1996.

NET INTEREST INCOME

Net interest income increased to $17.4 million for the first six months of 1997
from $15.3 million for the same period in 1996 as continued growth in the loan
portfolio enabled the Company to post a $6.2 million increase in interest income
that exceeded the $4.1 million increase in interest expense during the period.
Yields on the Company's interest-earning assets declined by 6 basis point, and
the rates paid on the Company's interest-bearing liabilities increased by 10
basis point, resulting in an reduction in the interest rate spread to 3.41% for
the first six months of 1997 from 3.57% for the first six months of 1996.  The
ratio of average interest-earning assets to average interest-bearing liabilities
declined to 115.55% for the first six months of 1997 from 119.07% for the first
six months of 1996, as a substantial portion of the increase in loans was funded
by time deposits.

Total interest income for the first six months of 1997 was $36.9 million, up 20%
from $30.7 million during the same period in 1996.  The principal factor
providing greater interest income was the $135.4 million, or 25%, increase in
the volume of average loans outstanding.  The Company's loan yields declined to
9.40% for the first six months of 1997 from 9.59% in 1996.  During the same
period, the Company's yield on investment securities increased to 6.19% from
6.11%.

Total interest expense for the first six months of 1997 was $19.5 million, an
increase of 27% from $15.4 million for the same period in 1996.  The increase in
total interest expense can be attributed to an increase in average interest-
bearing liabilities of $146.2 million, or 25%.  During the same period, the
rates paid on average interest-bearing liabilities increased to 5.35%  from
5.25%, as a 6 basis point decline in the average rate paid on time deposits (to
5.71%) was more than offset by a 50 basis point increase (to 4.15%) in the
average rate paid on money market accounts.  The issuance of the Subordinated
Debentures on June 4, 1997 had a minimal effect on interest expense for the
first half of the year.

OTHER INCOME

Other income declined by $104,000 for the first six months of 1997 compared to
the first six months of 1996 primarily as a result of the $171,000 reduction in
gains on sales of investment securities  A gain on sale of investment securities
occurred during the first quarter of 1996 when $4.6 million in Agency securities
classified as "held to maturity" and $7.7 million in Agency securities
classified as "available for sale", originally purchased at a discount, were
called prior to their stated maturity date.  No securities were sold or called
during the first six months of 1997.

                                      13
<PAGE>
 
OTHER EXPENSES

The Company's other expenses increased $2.3 million for the first six months of
1997 compared to the first six months of 1996.  This increase was primarily the
result of an increase in salaries and employee benefits, which increased $1.2
million as a result of a 16% increase in staffing.  The increase in staffing is
related to the expansion of the Company's asset and deposit bases.  In addition,
general and administrative expense increased $609,000 and occupancy expense
increased $598,000 compared to 1996.  The increase in occupancy expense was due
primarily to the leasing of additional office space and the depreciation on
furniture and equipment purchased to furnish those new offices.  These increases
were partially offset by reductions in both FDIC and other insurance and credit
card expenses.


FOR THE THREE MONTH PERIODS ENDED JUNE 30, 1997 AND 1996

NET INCOME

For the second quarter of 1997, the Company recorded net income of $1.9 million,
4% less than the $2.0 million recorded for the second quarter of 1996.  Net
income available to common shareholders, after deduction of dividends on
preferred stock, was $1.5 million ($0.40 per share), compared with $1.6 million
($0.42 per share) for the second quarter of 1996.  Average common shares
outstanding were 3,768,662 and 3,759,198, respectively.

Net interest income increased $930,000, or 12%, for the second quarter of 1997
compared to the same period in 1996.  This increase in net interest income, as
well as an $84,000, or 6%, increase in other income and a $58,000, or 5%,
reduction in taxes, partially offset the $26,000, or 3%, increase in provision
for loan losses, and a $1.1 million, or 20%, increase in other expenses.  For
the second quarter of 1997, the return on average total equity was 11.76% and
the return on average common equity was 12.69% compared to a 12.92% return on
average total equity and a 14.36% return on average common equity for the second
quarter of 1996.

NET INTEREST INCOME

Net interest income increased to $8.8 million for the second quarter of 1997
from $7.9 million for the same period in 1996 as continued growth in the loan
portfolio enabled the Company to post a $3.4 million increase in interest income
that exceeded the $2.4 million increase in interest expense during the period.
Yields on the Company's interest-earning assets declined by 11 basis points, and
the rates paid on the Company's interest-bearing liabilities increased by 18
basis points, resulting in an reduction in the interest rate spread to 3.34% for
the second quarter of 1997 from 3.63% for the second quarter of 1996.  The ratio
of average interest-earning assets to average interest-bearing liabilities
declined to 114.72% for the second quarter of 1997 from 118.39% for the second
quarter of 1996, as a substantial portion of the increase in loans was funded by
time deposits.

Total interest income for the second quarter of 1997 was $19.0 million, up 22%
from $15.6 million during the same period in 1996.  The principal factor
providing greater interest income was the $141.8 million, or 26%, increase in
the volume of average loans outstanding.  The Company's loan yields declined to
9.39% for the second quarter of 1997 from 9.64% in 1996.  During the same
period, the Company's yield on investment securities increased to 6.18% from
6.09%.

Total interest expense for the second quarter of 1997 was $10.2 million, an
increase of 32% from $7.8 million for the same period in 1996.  The increase in
total interest expense can be attributed to an increase in average interest-
bearing liabilities of $160.9 million, or 27%.  During the same period, the
rates paid on average interest-bearing liabilities increased to 5.39%  from
5.21%, as a 5 basis point decline in the average rate paid on time deposits (to
5.72%) was more than offset by a 35 basis point increase (to 4.15%) in the
average rate paid on money market accounts.

                                      14
<PAGE>
 
OTHER INCOME

Other income increased by $84,000 for the second quarter of 1997 compared to the
second quarter of 1996 primarily as a result of a $109,000 increase in
originated mortgage servicing rights.

OTHER EXPENSES

The Company's other expenses increased $1.1 million for the second quarter of
1997 compared to the second quarter of 1996.  This increase was primarily the
result of an increase in salaries and employee benefits, which increased
$555,000 as a result of a 16% increase in staffing.  The increase in staffing is
related to the expansion of the Company's asset and deposit bases.  In addition,
general and administrative expense increased $316,000 and occupancy expense
increased $314,000 compared to 1996.  The increase in occupancy expense was due
primarily to the leasing of additional office space and the depreciation on
furniture and equipment purchased to furnish those new offices.  These increases
were offset by a reduction in FDIC and other insurance.


                           *   *   *   *   *   *   *


PROVISION FOR LOAN LOSSES

The Company makes provisions for loan losses in amounts deemed necessary to
maintain the allowance for loan losses at an appropriate level.  The adequacy of
the allowance for loan losses is determined by management based upon a number of
factors including, among others, analytical reviews of loan loss experience in
relationship to outstanding loans and commitments; unfunded loan commitments;
problem and nonperforming loans and other loans presenting credit concerns;
trends in loan growth, portfolio composition and quality; use of appraisals to
estimate the value of collateral; and management's judgment with respect to
current and expected economic conditions and their impact on the existing loan
portfolio.  Changes in the allowance may occur because of changing economic
conditions, and economic prospects or the financial position of borrowers.
Based upon this review, management established an allowance of $8.7 million, or
1.22% of total loans, at June 30, 1997 compared to an allowance of $7.1 million,
or 1.11% of total loans at December 31, 1996.  During the first six months of
1997 and 1996, the provisions for loan losses were $3.8 million and $1.7
million, respectively.

In establishing the level of the allowance for June 30, 1997, management
considered a number of factors that tend to indicate a potential need for an
increased allowance level, including the increased risk inherent in the amount
and percentage to total loans attributable to commercial and commercial real
estate loans, which are viewed as entailing greater risk than certain other
categories of loans, recent charge-off history, and the increased levels of
large loans and of identified nonperforming loans at June 30, 1997, versus
December 31, 1996.  At June 30, 1997, total nonperforming loans were $10.5
million, or 1.47% of total loans, compared to $6.6 million, or 1.03% of total
loans, at December 31, 1996.  Management also considered other factors,
including the levels of types of credits, such as residential mortgage loans,
deemed to be of relatively low risk, that tended to indicate the potential need
for a lower allowance.  The Company determined the level of the allowance for
loan losses at June 30, 1997 was appropriate, as a result of balancing these and
other factors it deemed relevant to the adequacy of the allowance.  Management
conducted a similar analysis in order to determine the appropriate allowance as
of June 30, 1996 and December 31, 1996.

Management strives to carefully monitor credit quality and the adequacy of the
allowance for loan losses, and to identify loans that may become nonperforming.
At any time, however, there are loans included in the portfolio that will result
in losses to the Company, but that have not been identified as nonperforming or
potential problem loans.  Because the loan portfolio contains a significant
number of commercial and commercial real estate loans with relatively large
balances, the unexpected deterioration of one or a few of such loans may cause a
significant increase in nonperforming assets, and lead to a material increase in
charge-offs and the provision for loan losses.


                                      15


<PAGE>
 
TAXES ON INCOME

The Company's income tax expense for the first six months of 1997 and 1996 was
$1.2 million and $2.2 million, respectively.  The Company's income tax expense
for the second quarters of 1997 and 1996 was $1.1 million.  The Company's
effective tax rates have been lower than the 34% Federal and 6% State statutory
rates primarily because of tax-exempt income on municipal obligations and loans.


                           *   *   *   *   *   *   *


LIQUIDITY

Liquidity is measured by a financial institution's ability to raise funds
through deposits, borrowed funds, capital, or the sale of highly marketable
assets such as residential mortgage loans.  The Company's portfolio of
government-guaranteed student loans and SBA loans are also readily salable.
Additional sources of liquidity, including cash flow from the repayment of
loans, are also considered in determining whether liquidity is satisfactory.
Liquidity is also achieved through growth of core deposits and liquid assets,
and accessibility to the capital and money markets.  These funds are used to
meet deposit withdrawals, maintain reserve requirements, fund loans and operate
the organization.  Core deposits, defined as demand deposits, interest-bearing
transaction accounts, savings deposits and certificates of deposit less than
$100,000 were 83% and 84% of total deposits at June 30, 1997 and 1996,
respectively.

The Company uses various forms of short-term borrowings for cash management and
liquidity purposes on a limited basis.  These forms of borrowings include
federal funds purchases and borrowings from the Federal Reserve Bank.  The Bank
has approved federal funds purchase lines with three other banks.  The Bank also
carries interest-bearing demand notes issued by the Bank to the U.S. Treasury as
a participant in the Treasury Tax and Loan note program.  In addition, the Bank
has available a $35.0 million line of credit from the Student Loan Marketing
Association (SLMA).  Borrowings under the SLMA line would be secured by student
loans.  During the first quarters of 1997 and 1996, no category of borrowings
averaged more than 30% of ending shareholders' equity.

Cash and cash equivalents, during the first six months of 1997, increased by
$12.4 million.  The increase was the result of cash generated from financing
activities (primarily increased deposits and the issuance of Subordinated
Debentures) of $117.1 million and  operating activities of $2.0 million offset
by $106.7 million in cash used in investing activities.

During the first six months of 1996, cash and cash equivalents increased by
$18.5 million.  This increase was the result of cash generated from financing
activities (primarily increased deposits) of $68.1 million offset by $13.8
million in cash used in operating activities and $35.8 million in cash used in
investing activities.


CAPITAL RESOURCES

During the second quarter of 1997, SBI Capital Trust (SBI Capital), a statutory
business trust and subsidiary of the Company sold 1,000,500 Preferred
Securities, having a liquidation amount of $25 per security, for a total price
of $25,012,500. The distributions payable on the preferred securities are based
on a 9.30% fixed annual rate. All accounts of SBI Capital are included in the
consolidated financial statements of the Company.

Bank holding companies are required to maintain capital ratios in accordance
with guidelines adopted by the Federal Reserve Board (FRB).  The Company
believes that the Preferred Securities meet the regulatory criteria for Tier I
capital, subject to Federal Reserve guidelines that limit the amount of the
Preferred Securities and cumulative perpetual preferred stock to an aggregate of
25% of Tier I capital.


                                      16


<PAGE>
 
On  June 30, 1997, the Company exceeded all applicable capital requirements,
having a total risk-based capital ratio of 13.79%, a Tier I risk-based capital
ratio of 9.10%, and a leverage ratio of 7.09%..  As of June 30, 1997, the Bank
also met the criteria for classification as a "well-capitalized" institution
under the prompt corrective action provisions of the Federal Deposit Insurance
Act.  Designation as a well-capitalized institution under these regulations does
not constitute a recommendation or endorsement of the Company or the Bank by
Federal bank regulators.

The Company declared a dividend of $.08 per common share payable on July 1, 1997
to shareholders of record as of June 17, 1997.  In April 1997, the Company
declared a dividend of $.575  per preferred share payable on June 2, 1997 to
shareholders of record as of May 19, 1997.


EFFECTS OF INFLATION

The consolidated financial statements and related consolidated financial data
presented herein have been prepared in accordance with generally accepted
accounting principles and practices within the banking industry which require
the measurement of financial position and operating results in terms of
historical dollars without considering the changes in the relative purchasing
power of money over time due to inflation. Unlike most industrial companies,
virtually all the assets and liabilities of a financial institution are monetary
in nature. As a result, interest rates have a more significant impact on a
financial institution's performance than the effects of general levels of
inflation.


RECENT DEVELOPMENT

During the third quarter of 1997, the Company announced that the Bank is
negotiating the terms of a possible sale of all or a substantial portion of its
existing credit card portfolio at a premium before taxes, but net of other,
related expenses, that is preliminarily estimated to range from $3.0 million to
$4.5 million. Any such sale is subject to negotiation of a definitive agreement
and the completion of a due diligence review by the potential acquirer, among
other things. The Company anticipates that, subject to satisfaction of those
conditions, such a sale would be completed during 1997. It is expected that any
agreement for sale would allow the Bank to maintain relationships with its
credit card customers.


                                      17


<PAGE>
 
PART II - OTHER INFORMATION


Item 1.   Legal proceedings
          None

Item 2.   Changes in securities
          None

Item 3.   Defaults upon senior securities
          None

Item 4.   Submission of matters to a vote of security holders

          At the Company's annual shareholders' meeting, held on April 24, 1997,
          the shareholders of the Company elected five Directors with terms
          expiring at the 2000 annual shareholders' meeting. The Directors
          elected and the shareholder vote in the election of each director was
          as follows:

 
<TABLE> 
<CAPTION> 
                                   For       Withheld
                                ---------    --------
           <S>                  <C>          <C>
           George M. Berry      3,150,568       500
           Joyce P. Berry       3,150,368       700
           Joe Berry Cannon     3,114,318       500
           Robert B. Rodgers    3,127,935       500
           Paul C. Wise         3,150,056       700
</TABLE>
           
          Other Directors continuing in office are Thomas D. Berry, W. Haskell
          Cudd, David P. Lambert, Linford R. Pitts, J. Berry Harrison, Erd M.
          Johnson, Robert L. McCormick, Jr., Lee A. Wise, and James B. Wise, MD.

Item 5.   Other information
          None

Item 6.   Exhibits and reports on Form 8-K
          (a) Exhibits.
                Exhibit
                Number    Description
                ------    -----------
                 4.2      Form of Debenture
                 4.3      Agreement As To Expenses and Liabilities
                 4.4      Preferred Securities Guarantee Agreement
                 4.5      Indenture
                 4.6      Amended and Restated Trust Agreement
                 27       Financial Data Schedule (EDGAR only)
                                
          (b) Reports on Form 8-K.
                Date                    Item Reported
                ----                    ------------- 
                April 2, 1997           Item 5.  The Company confirmed its
                                                 previously announced, expected
                                                 decline in earnings for the
                                                 first quarter of 1997.

                July 2, 1997            Item 5.  The Company announced the
                                                 potential sale of all or a
                                                 substantial portion of the
                                                 Bank's credit card portfolio.


                                      18
<PAGE>
 
                                  SIGNATURES


Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.


SOUTHWEST BANCORP, INC.
(Registrant)



By: /s/ Robert L. McCormick, Jr.                  August 5, 1997  
    ------------------------------                -------------- 
    Robert L. McCormick, Jr.                      Date           
    President                                      
    (Principal Executive Officer)                  
                                                   
                                                   
                                                   
By: /s/ Kerby E. Crowell                          August 5, 1997
    ------------------------------                --------------
    Kerby E. Crowell                              Date            
    Executive Vice President and
    Chief Financial Officer
    (Principal Financial and Accounting Officer)


                                      19



<PAGE>
 
                                                                     EXHIBIT 4.2
 
No. SB 0001                                                       $25,786,500.00
CUSIP No. 844 767 AA1

                            SOUTHWEST BANCORP, INC.
                         9.30% SUBORDINATED DEBENTURE
                               DUE JULY 31, 2027

     Southwest Bancorp, Inc., an Oklahoma corporation (the "Company," which term
includes any successor corporation under the Indenture hereinafter referred to),
for value received, hereby promises to pay to, State Street Bank and Trust
Company as Property Trustee for SBI Capital Trust or registered assigns, the
principal sum of Twenty Five Million Seven Hundred Eighty Six Thousand Five
Hundred Dollars and no cents ($25,786,500.00) on July 31, 2027 (the "Stated
Maturity"), and to pay interest on said principal sum from June 4, 1997, or from
the most recent interest payment date (each such date, an "Interest Payment
Date") to which interest has been paid or duly provided for, quarterly (subject
to deferral as set forth herein) in arrears on January 31, April 30, July 31 and
October 31 of each year commencing July 31, 1997, at the rate of 9.30% per annum
until the principal hereof shall have become due and payable, and on any overdue
principal and (without duplication) on any overdue installment of interest at
the same rate per annum compounded quarterly. The amount of interest payable on
any Interest Payment Date shall be computed on the basis of a 360-day year of
twelve 30-day months.  The amount of interest for any partial period shall be
computed on the basis of the number of days elapsed in a 360-day year of twelve
30-day months.  In the event that any date on which interest is payable on this
Debenture is not a business day, then payment of interest payable on such date
shall be made on the next succeeding day that is a business day (and without any
interest or other payment in respect of any such delay) with the same force and
effect as if made on such date. The interest installment so payable, and
punctually paid or duly provided for, on any Interest Payment Date shall, as
provided in the Indenture, be paid to the person in whose name this Debenture
(or one or more Predecessor Debentures, as defined in said Indenture) is
registered at the close of business on the regular record date for such interest
installment, which shall be the close of business on the fifteenth day of the
month in which the Interest Payment Date occurs, unless otherwise provided in
the Indenture. Any such interest installment not punctually paid or duly
provided for shall forthwith cease to be payable to the registered holders on
such regular record date and may be paid to the Person in whose name this
Debenture (or one or more Predecessor Debentures) is registered at the close of
business on a special record date to be fixed by the Trustee for the payment of
such defaulted interest, notice whereof shall be given to the registered holders
of the Debentures not less than 10 days prior to such special record date, or
may be paid at any time in any other lawful manner not inconsistent with the
requirements of any securities exchange on which the Debentures may be listed,
and upon such notice as may be required by such exchange, all as more fully
provided in the Indenture. The principal of and the interest on this Debenture
shall be payable at the office or agency of the Trustee maintained for that
purpose in any coin or currency of the United States of America that at the time
of payment is legal tender for payment of public and private debts; provided,
however, that payment of interest may be made at the option of the Company by
check mailed to the registered holder at such address as shall appear in the
Debenture Register. Notwithstanding the foregoing, so long as the holder of this
Debenture is the Property Trustee, the payment of the principal of and interest
on this Debenture shall be made at such place and to such account as may be
designated by the Trustee.

     The Stated Maturity may be shortened at any time by the Company to any date
not earlier than July 31, 2002, subject to the Company having received prior
approval of the Federal Reserve, if then required under applicable capital
guidelines or policies of the Federal Reserve. Such date may also be extended at
any time at the election of the Company for one or more periods, but in no event
to a date later than July 31, 2036, subject to certain limitations described in
the Indenture.

     The indebtedness evidenced by this Debenture is, to the extent provided in
the Indenture, subordinate and junior in right of payment to the prior payment
in full of all Senior Indebtedness, and this Debenture is issued subject to the
provisions of the Indenture with respect thereto. Each holder of this Debenture,
by accepting the same, (a) agrees to and shall be bound by such provisions; (b)
authorizes and directs the Trustee on his or her behalf to take such action as
may be necessary or appropriate to acknowledge or effectuate the subordination
so provided; and (c) appoints the Trustee his or her attorney-in-fact for any
and all such purposes. Each holder hereof, by his or her acceptance hereof,
hereby waives all notice of the acceptance of the subordination provisions
contained herein and in the Indenture by each holder of Senior Indebtedness,
whether now outstanding or hereafter incurred, and waives reliance by each such
holder upon said provisions.

     This Debenture shall not be entitled to any benefit under the Indenture
hereinafter referred to, be valid or become obligatory for any purpose until the
Certificate of Authentication hereon shall have been signed by or on behalf of
the Trustee.

     The provisions of this Debenture are continued on the reverse side hereof
and such continued provisions shall for all purposes have the same effect as
though fully set forth at this place.

     IN WITNESS WHEREOF, the Company has caused this instrument to be executed.

Dated: June 4, 1997

Attest: -SPECIMEN-                         SOUTHWEST BANCORP, INC.

By: ______________-SPECIMEN-_____    By:_-SPECIMEN____________________________
    Deborah T. Bradley, Secretary            Robert L. McCormick, Jr., President

                         CERTIFICATE OF AUTHENTICATION

  This is one of the Debentures described in the within-mentioned Indenture.

Dated: June 4, 1997

STATE STREET BANK AND TRUST COMPANY,
as Trustee

By ______________________________        
   Paul D. Allen, Vice President
<PAGE>
 
                         9.30% SUBORDINATED DEBENTURE
                                  (CONTINUED)

     This Debenture is one of the subordinated debentures of the Company (herein
sometimes referred to as the "Debentures"), specified in the Indenture, all
issued or to be issued under and pursuant to an Indenture dated as of June 4,
1997 (the "Indenture") duly executed and delivered between the Company and State
Street Bank and Trust Company, as Trustee (the "Trustee"), to which Indenture
reference is hereby made for a description of the rights, limitations of rights,
obligations, duties and immunities thereunder of the Trustee, the Company and
the holders of the Debentures. The Debentures are limited in aggregate principal
amount as specified in the Indenture.

     In certain circumstances, because of the occurrence and continuation of a
Special Event, this Debenture may become due and payable prior to its Stated
Maturity, at the principal amount together with any interest accrued thereon
(the "Redemption Price"). The Redemption Price shall be paid prior to 12:00
noon, Eastern Time, on the date of such redemption or at such earlier time as
the Company determines. The Company shall have the right to redeem this
Debenture at the option of the Company, without premium or penalty, in whole or
in part at any time on or after July 31, 2002 (an "Optional Redemption"), or at
any time in certain circumstances upon the occurrence of a Special Event, at a
Redemption Price equal to 100% of the principal amount plus any accrued but
unpaid interest, to the date of such redemption. Any redemption pursuant to this
paragraph shall be made upon not less than 30 days nor more than 60 days notice,
at the Redemption Price. If the Debentures are only partially redeemed by the
Company pursuant to an Optional Redemption, the Debentures shall be redeemed pro
rata or by lot or by any other method utilized by the Trustee.

     In the event of redemption of this Debenture in part only, a new Debenture
or Debentures for the unredeemed portion hereof shall be issued in the name of
the holder hereof, upon the cancellation hereof.

     In case an Event of Default, as defined in the Indenture, shall have
occurred and be continuing, the principal of all of the Debentures may be
declared, and upon such declaration shall become, due and payable, in the
manner, with the effect and subject to the conditions provided in the Indenture.

     The Indenture contains provisions permitting the Company and the Trustee,
with the consent of the holders of not less than a majority in aggregate
principal amount of the Debentures at the time outstanding, as defined in the
Indenture, to execute supplemental indentures for the purpose of adding any
provisions to or changing in any manner or eliminating any of the provisions of
the Indenture or of any supplemental indenture or of modifying in any manner the
rights of the holders of the Debentures; provided, however, that no such
supplemental indenture shall (i) extend the fixed maturity of the Debentures
except as provided in the Indenture, or reduce the principal amount thereof, or
reduce the rate or extend the time of payment of interest thereon, without the
consent of the holder of each Debenture so affected; or (ii) reduce the
aforesaid percentage of Debentures, the holders of which are required to consent
to any such supplemental indenture, without the consent of the holders of each
Debenture then outstanding and affected thereby. The Indenture also contains
provisions permitting the holders of a majority in aggregate principal amount of
the Debentures at the time outstanding, on behalf of all of the holders of the
Debentures, to waive any past default in the performance of any of the covenants
contained in the Indenture, or established pursuant to the Indenture, and its
consequences, except a default in the payment of the principal of or interest on
any of the Debentures. Any such consent or waiver by the registered holder of
this Debenture (unless revoked as provided in the Indenture) shall be conclusive
and binding upon such holder and upon all future holders and owners of this
Debenture and of any Debenture issued in exchange herefor or in place hereof
(whether by registration of transfer or in place hereof, irrespective of whether
or not any notation of such consent or waiver is made upon this Debenture).

     No reference herein to the Indenture and no provision of this Debenture or
of the Indenture shall alter or impair the obligation of the Company, which is
absolute and unconditional, to pay the principal and interest on this Debenture
at the time and place and at the rate and in the money herein prescribed.

     The Company shall have the right at any time during the term of the
Debentures and from time to time to extend the interest payment period of such
Debentures for up to 20 consecutive quarters (each, an "Extended Interest
Payment Period"), at the end of which period the Company shall pay all interest
then accrued and unpaid (together with interest thereon at the rate specified
for the Debentures to the extent that payment of such interest is enforceable
under applicable law). Before the termination of any such Extended Interest
Payment Period, the Company may further extend such Extended Interest Payment
Period, provided that such Extended Interest Payment Period, together with all
such further extensions thereof, shall not exceed 20 consecutive quarters. At
the termination of any such Extended Interest Payment Period and upon the
payment of all accrued and unpaid interest and any additional amounts then due,
the Company may commence a new Extended Interest Payment Period.

     As provided in the Indenture and subject to certain limitations therein set
forth, this Debenture is transferable by the registered holder hereof on the
Debenture Register of the Company, upon surrender of this Debenture for
registration of transfer at the office or agency of the Trustee accompanied by a
written instrument or instruments of transfer in form satisfactory to the
Company or the Trustee duly executed by the registered holder hereof or his
attorney duly authorized in writing, and thereupon one or more new Debentures of
authorized denominations and for the same aggregate principal amount shall be
issued to the designated transferee or transferees. No service charge shall be
made for any such transfer, but the Company may require payment of a sum
sufficient to cover any tax or other governmental charge payable in relation
thereto.

     Prior to due presentment for registration of transfer of this Debenture,
the Company, the Trustee, any paying agent and the Debenture Registrar may deem
and treat the registered holder hereof as the absolute owner hereof (whether or
not this Debenture shall be overdue and notwithstanding any notice of ownership
or writing hereon made by anyone other than the Debenture Registrar) for the
purpose of receiving payment of or on account of the principal hereof and
interest due hereon and for all other purposes, and neither the Company nor the
Trustee, nor any paying agent, nor any Debenture Registrar shall be affected by
any notice to the contrary.

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

     The Debentures are issuable only in registered form without coupons in
denominations of $25 and any integral multiple thereof.

     All terms used in this Debenture that are defined in the Indenture shall
have the meanings assigned to them in the Indenture.



<PAGE>
 
                                                                     EXHIBIT 4.3



                   AGREEMENT AS TO EXPENSES AND LIABILITIES

     AGREEMENT AS TO EXPENSES AND LIABILITIES (this "Agreement") dated as of
June 4, 1997, between SOUTHWEST BANCORP, INC. an Oklahoma corporation (the
"Company"), and SBI CAPITAL TRUST, a Delaware business trust (the "Trust").

                                   RECITALS

     WHEREAS, the Trust intends to issue its common securities (the "Common
Securities") to, and receive Debentures from, the Company and to issue and sell
one million five hundred (1,000,500) of its 9.30% Cumulative Trust Preferred
Securities (the "Preferred Securities") with such powers, preferences and
special rights and restrictions as are set forth in the Amended and Restated
Trust Agreement of the Trust dated as of June 4, 1997, as the same may be
amended from time to time (the "Trust Agreement");

     WHEREAS, the Company shall directly or indirectly own all of the Common
Securities of the Trust and shall issue the Debentures;

     NOW, THEREFORE, in consideration of the purchase by each holder of the
Preferred Securities, which purchase the Company hereby agrees shall benefit the
Company and which purchase the Company acknowledges shall be made in reliance
upon the execution and delivery of this Agreement, the Company, including in its
capacity as holder of the Common Securities, and the Trust hereby agree as
follows:

                                   ARTICLE I

     SECTION 1.1.     GUARANTEE BY THE COMPANY.

     Subject to the terms and conditions hereof, the Company, including in its
capacity as holder of the Common Securities, hereby irrevocably and
unconditionally guarantees to each person or entity to whom the Trust is now or
hereafter becomes indebted or liable (the "Beneficiaries") the full payment when
and as due, of any and all Obligations (as hereinafter defined) to such
Beneficiaries. As used herein, "Obligations" means any costs, expenses or
liabilities of the Trust other than obligations of the Trust to pay to holders
of any Preferred Securities or other similar interests in the Trust the amounts
due such holders pursuant to the terms of the Preferred Securities or such other
similar interests, as the case may be. This Agreement is intended to be for the
benefit of, and to be enforceable by, all such Beneficiaries, whether or not
such Beneficiaries have received notice hereof.

     SECTION 1.2.     TERM OF AGREEMENT.

     This Agreement shall terminate and be of no further force and effect upon
the later of (a) the date on which full payment has been made of all amounts
payable to all holders of all the Preferred Securities (whether upon redemption,
liquidation, exchange or otherwise); and (b) the date on which there are no
Beneficiaries remaining; provided, however, that this Agreement shall continue
to be effective or shall be reinstated, as the case may be, if at any time any
holder of Preferred Securities or any Beneficiary must restore payment of any
sums paid under the Preferred Securities, under any obligation, under the
Preferred Securities Guarantee Agreement dated the date hereof by the Company
and State Street Bank and Trust Company as guarantee trustee, or under this
Agreement for any reason whatsoever. This Agreement is continuing, irrevocable,
unconditional and absolute.

     SECTION 1.3.     WAIVER OF NOTICE.

     The Company hereby waives notice of acceptance of this Agreement and of any
obligation to which it applies or may apply, and the Company hereby waives
presentment, demand for payment, protest, notice of nonpayment, notice of
dishonor, notice of redemption and all other notices and demands.
<PAGE>
 
     SECTION 1.4.     NO IMPAIRMENT.

     The obligations, covenants, agreements and duties of the Company under this
Agreement shall in no way be affected or impaired by reason of the happening
from time to time of any of the following:

        (a) the extension of time for the payment by the Trust of all or any
portion of the obligations or for the performance of any other obligation under,
arising out of, or in connection with, the obligations;

        (b) any failure, omission, delay or lack of diligence on the part of the
Beneficiaries to enforce, assert or exercise any right, privilege, power or
remedy conferred on the Beneficiaries with respect to the obligations or any
action on the part of the Trust granting indulgence or extension of any kind; or

        (c) the voluntary or involuntary liquidation, dissolution, sale of any
collateral, receivership, insolvency, bankruptcy, assignment for the benefit of
creditors, reorganization, arrangement composition or readjustment of debt of,
or other similar proceedings affecting, the Trust or any of the assets of the
Trust.

     There shall be no obligation of the Beneficiaries to give notice to, or
obtain the consent of, the Company with respect to the happening of any of the
foregoing.

     SECTION 1.5.     ENFORCEMENT.

     A Beneficiary may enforce this Agreement directly against the Company, and
the Company waives any right or remedy to require that any action be brought
against the Trust or any other person or entity before proceeding against the
Company.

                                  ARTICLE II

     SECTION 2.1.     BINDING EFFECT.

     All guarantees and agreements contained in this Agreement shall bind the
successors, assigns, receivers, trustees and representatives of the Company and
shall inure to the benefit of the Beneficiaries.

     SECTION 2.2.     AMENDMENT.

     So long as there remains any Beneficiary or any Preferred Securities of any
series are outstanding, this Agreement shall not be modified or amended in any
manner adverse to such Beneficiary or to the holders of the Preferred
Securities.

     SECTION 2.3.     NOTICES.

     Any notice, request or other communication required or permitted to be
given hereunder shall be given in writing by delivering the same by facsimile
transmission (confirmed by mail), telex, or by registered or certified mail,
addressed as follows (and if so given, shall be deemed given when mailed or upon
receipt of an answer back, if sent by telex):

     SBI Capital Trust, 608 South Main Street, Stillwater, Oklahoma,  74074.
     Facsimile No.: 405-742-4799 Attention: Kerby E. Crowell

     Southwest Bancorp, Inc., 608 South Main Street, Stillwater, Oklahoma
     74074. Facsimile No.: 405-742-4799 Attention: Kerby E. Crowell
<PAGE>
 
     SECTION 2.4     This agreement shall be governed by and construed and
interpreted in accordance with the laws of the State of Oklahoma (without regard
to conflict of laws principles).

     THIS AGREEMENT is executed as of the day and year first above written.

                              SOUTHWEST BANCORP, INC.



                         By:  /s/ Robert L. McCormick, Jr.
                              ------------------------------------------------
                              Robert L. McCormick, Jr., President

 
                              SBI CAPITAL TRUST




                         By:  /s/ Robert L. McCormick, Jr.
                              ------------------------------------------------
                              Robert L. McCormick, Jr., Administrative Trustee

<PAGE>
 
                                                                     EXHIBIT 4.4


                   PREFERRED SECURITIES GUARANTEE AGREEMENT

                                BY AND BETWEEN

                            SOUTHWEST BANCORP, INC.

                                      AND

                      STATE STREET BANK AND TRUST COMPANY

                                 JUNE 4, 1997
<PAGE>
 
                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                        Page No.
<S>                                                                     <C>
ARTICLE I. DEFINITIONS AND INTERPRETATION.............................     1
     SECTION 1.1. DEFINITIONS AND INTERPRETATION......................     1

ARTICLE II. TRUST INDENTURE ACT.......................................     4
     SECTION 2.1. TRUST INDENTURE ACT; APPLICATION....................     4
     SECTION 2.2. LISTS OF HOLDERS OF SECURITIES......................     4
     SECTION 2.3. REPORTS BY THE PREFERRED GUARANTEE TRUSTEE..........     4
     SECTION 2.4. PERIODIC REPORTS TO PREFERRED GUARANTEE TRUSTEE.....     4
     SECTION 2.5. EVIDENCE OF COMPLIANCE WITH CONDITIONS PRECEDENT....     4
     SECTION 2.6. EVENTS OF DEFAULT; WAIVER...........................     4
     SECTION 2.7. EVENT OF DEFAULT; NOTICE............................     4
     SECTION 2.8. CONFLICTING INTERESTS...............................     5

ARTICLE III POWERS, DUTIES AND RIGHTS OF PREFERRED GUARANTEE TRUSTEE..     5
     SECTION 3.1. POWERS AND DUTIES OF THE PREFERRED GUARANTEE
                  TRUSTEE.............................................     5
     SECTION 3.2. CERTAIN RIGHTS OF PREFERRED GUARANTEE TRUSTEE.......     6
     SECTION 3.3. NOT RESPONSIBLE FOR RECITALS OR ISSUANCE OF 
                  GUARANTEE...........................................     8

ARTICLE IV PREFERRED GUARANTEE TRUSTEE................................     8
     SECTION 4.1. PREFERRED GUARANTEE TRUSTEE; ELIGIBILITY............     8
     SECTION 4.2. APPOINTMENT, REMOVAL AND RESIGNATION OF PREFERRED
                  GUARANTEE TRUSTEE...................................     8
ARTICLE V GUARANTEE...................................................     9
     SECTION 5.1. GUARANTEE...........................................     9
     SECTION 5.2. WAIVER OF NOTICE AND DEMAND.........................     9
     SECTION 5.3. OBLIGATIONS NOT AFFECTED............................     9
     SECTION 5.4. RIGHTS OF HOLDERS...................................    10
     SECTION 5.5. GUARANTEE OF PAYMENT................................    10
     SECTION 5.6. SUBROGATION.........................................    10
     SECTION 5.7. INDEPENDENT OBLIGATIONS.............................    10

ARTICLE VI LIMITATION OF TRANSACTIONS; SUBORDINATION..................    11
     SECTION 6.1. LIMITATION ON TRANSACTIONS..........................    11
     SECTION 6.2 RANKING..............................................    11

ARTICLE VII TERMINATION...............................................    11
     SECTION 7.1. TERMINATION.........................................    11

ARTICLE VIII INDEMNIFICATION..........................................    11
     SECTION 8.1. EXCULPATION.........................................    11
     SECTION 8.2. INDEMNIFICATION.....................................    12
</TABLE>


                                       i
<PAGE>
 
<TABLE>
<S>                                                                     <C>
ARTICLE IX MISCELLANEOUS..............................................    13
     SECTION 9.1. SUCCESSORS AND ASSIGNS..............................    13
     SECTION 9.2. AMENDMENTS..........................................    13
     SECTION 9.3. NOTICES.............................................    13
     SECTION 9.4. BENEFIT.............................................    14
     SECTION 9.5. GOVERNING LAW.......................................    14
</TABLE>


                                      ii
<PAGE>
 
                             CROSS-REFERENCE TABLE


<TABLE>
<CAPTION>
Section of
Trust Indenture Act                                     Section of
of 1939, as amended                                     Indenture
- -------------------                                 ------------------
<S>                                                 <C>
310(a).............................................            4.1(a)
310(b).............................................            4.1(c), 2.8
310(c)............................................. Not Applicable
311(a).............................................            2.2(b)
311(b).............................................            2.2(b)
311(c)............................................. Not Applicable
312(a).............................................            2.2(a)
312(b).............................................            2.2(b)
313................................................            2.3
314(a).............................................            2.4
314(b)............................................. Not Applicable
314(c).............................................            2.5
314(d)............................................. Not Applicable
314(e).............................................   1.1, 2.5,3.2
314(f).............................................       2.1, 3.2
315(a).............................................            3.1(d)
315(b).............................................            2.7
315(c).............................................            3.1
315(d).............................................            3.1(d)
316(a).............................................  1.1, 2.6, 5.4
316(b).............................................            5.3
317(a).............................................            3.1
317(b)............................................. Not Applicable
318(a).............................................            2.1
318(b).............................................            2.1
318(c).............................................            2.1(b)
</TABLE>                               
                                       
Note: This Cross-Reference Table does not constitute part of this Agreement and
shall not affect the interpretation of any of its terms or provisions.

  
                                      iii
<PAGE>
 
                   PREFERRED SECURITIES GUARANTEE AGREEMENT

     THIS PREFERRED SECURITIES GUARANTEE AGREEMENT (this "Preferred Securities
Guarantee"), dated as of June 4, 1997, is executed and delivered by Southwest
Bancorp, Inc., an Oklahoma corporation (the "Guarantor"), and STATE STREET BANK
AND TRUST COMPANY, a trust company organized and existing under the laws of the
Commonwealth of Massachusetts, as trustee (the "Preferred Guarantee Trustee"),
for the benefit of the Holders (as defined herein) from time to time of the
Preferred Securities (as defined herein) of SBI Capital Trust, a Delaware
statutory business trust (the "Trust").

                                   RECITALS

     WHEREAS, pursuant to an Amended and Restated Trust Agreement (the "Trust
Agreement"), dated as of June 4, 1997, among the trustees of the Trust named
therein, the Guarantor, as depositor, and the holders from time to time of
undivided beneficial interests in the assets of the Trust, the Trust is issuing
on the date hereof one million five hundred (1,000,500) preferred securities,
having an aggregate liquidation amount of $25,012,500, designated the 9.30%
Cumulative Trust Preferred Securities (the "Preferred Securities");

     WHEREAS, as incentive for the Holders to purchase the Preferred Securities,
the Guarantor desires irrevocably and unconditionally to agree, to the extent
set forth in this Preferred Securities Guarantee, to pay to the Holders of the
Preferred Securities the Guarantee Payments (as defined herein) and to make
certain other payments on the terms and conditions set forth herein.

     NOW, THEREFORE, in consideration of the purchase by each Holder of 
Preferred Securities, which purchase the Guarantor hereby agrees shall benefit
the Guarantor, the Guarantor executes and delivers this Preferred Securities
Guarantee for the benefit of the Holders.

                                   ARTICLE I
                        DEFINITIONS AND INTERPRETATION

SECTION 1.1. DEFINITIONS AND INTERPRETATION

     In this Preferred Securities Guarantee, unless the context
otherwise requires:

     (a)  capitalized terms used in this Preferred Securities Guarantee but not
defined in the preamble above have the respective meanings assigned to them
in this Section 1.1;

     (b)  terms defined in the Trust Agreement as at the date of execution of 
this Preferred Securities Guarantee have the same meaning when used in this
Preferred Securities Guarantee;

     (c)  a term defined anywhere in this Preferred Securities Guarantee has 
the same meaning throughout;

     (d) all references to "the Preferred Securities Guarantee" or "this
Preferred Securities Guarantee" are to this Preferred Securities Guarantee
as modified, supplemented or amended from time to time;

     (e) all references in this Preferred Securities Guarantee to Articles and
Sections are to Articles and Sections of this Preferred Securities Guarantee,
unless otherwise specified;

     (f) a term defined in the Trust Indenture Act has the same meaning when
used in this Preferred Securities Guarantee, unless otherwise defined in this
Preferred Securities Guarantee or unless the context otherwise requires; and



                                       1
<PAGE>
 
     (g)  a reference to the singular includes the plural and vice versa.

     "Affiliate" has the same meaning as given to that term in Rule 405 of the
Securities Act of 1933, as amended, or any successor rule thereunder.

     "Business Day" means any day other than a day on which federal or state 
banking institutions in New York, New York are authorized or required by law, 
executive order or regulation to close or a day on which the Corporate Trust 
Office of the Preferred Guarantee Trustee is closed for business.

     "Corporate Trust Office" means the office of the Preferred Guarantee
Trustee at which the corporate trust business of the Preferred Guarantee Trustee
shall, at any particular time, be principally administered, which office at the
date of execution of this Preferred Securities Guarantee is located at Two
International Place, 4th Floor, Boston, Massachusetts 02110, Attention:
Corporate Trust Department.

     "Covered Person" means any Holder or beneficial owner of Preferred
Securities.

     "Debentures" means the 9.30% Subordinated Debentures due July 31, 2027, of
the Debenture Issuer held by the Property Trustee of the Trust.

     "Debenture Issuer" means the Guarantor.

     "Event of Default" means a default by the Guarantor on any of its payment
or other obligations under this Preferred Securities Guarantee.

     "Guarantor" means Southwest Bancorp, Inc., an Oklahoma corporation.

     "Guarantee Payments" means the following payments or distributions, without
duplication, with respect to the Preferred Securities, to the extent not paid or
made by the Trust: (i) any accrued and unpaid Distributions that are required to
be paid on such Preferred Securities, to the extent the Trust shall have funds
available therefor, (ii) the redemption price, including all accrued and unpaid
Distributions to the date of redemption (the "Redemption Price"), to the extent
the Trust has funds available therefor, with respect to any Preferred Securities
called for redemption by the Trust, and (iii) upon a voluntary or involuntary
dissolution, winding-up or termination of the Trust (other than in connection
with the distribution of Debentures to the Holders in exchange for Preferred
Securities as provided in the Trust Agreement), the lesser of (a) the aggregate
of the Liquidation Amount and all accrued and unpaid Distributions on the
Preferred Securities to the date of payment, to the extent the Trust shall have
funds available therefor (the "Liquidation Distribution"), and (b) the amount of
assets of the Trust remaining available for distribution to Holders in
liquidation of the Trust.

     "Holder" shall mean any holder, as registered on the books and records of
the Trust, of any Preferred Securities; provided, however, that, in determining
whether the holders of the requisite percentage of Preferred Securities have
given any request, notice, consent or waiver hereunder, "Holder" shall not
include the Guarantor or any Affiliate of the Guarantor.

     "Indemnified Person" means the Preferred Guarantee Trustee, any Affiliate
of the Preferred Guarantee Trustee, or any officers, directors, shareholders,
members, partners, employees, representatives, nominees, custodians or agents of
the Preferred Guarantee Trustee.

     "Indenture" means the Indenture dated as of June 4, 1997, among the
Debenture Issuer and State Street Bank and Trust Company, as trustee, and any
indenture supplemental thereto pursuant to which Subordinated Debentures of the
Debenture Issuer are to be issued to the Property Trustee of the Trust.

     "Liquidation Distribution" has the meaning provided therefor in the
definition of Guarantee Payments.



                                       2
<PAGE>
 
     "Majority in Liquidation Amount of the Preferred Securities" means the
holders of more than 50% of the Liquidation Amount (including the stated amount
that would be paid on redemption, liquidation or otherwise, plus accrued and
unpaid Distributions to the date upon which the voting percentages are
determined) of all of the Preferred Securities.

     "Officers' Certificate" means, with respect to any Person, a certificate
signed by two authorized officers of such Person. Any Officers' Certificate
delivered with respect to compliance with a condition or covenant provided for
in this Preferred Securities Guarantee shall include:

     (a) a statement that each officer signing the Officers' Certificate has
read the covenant or condition and the definition relating thereto;

     (b)  a brief statement of the nature and scope of the examination or
investigation undertaken by each officer in rendering the Officers'
Certificate;

     (c)  a statement that each such officer has made such examination or
investigation as, in such officer's opinion, is necessary to enable such
officer to express an informed opinion as to whether or not such covenant
or condition has been complied with; and

     (d)  a statement as to whether, in the opinion of each such officer, such
condition or covenant has been complied with.

     "Person" means a legal person, including any individual, corporation,
estate, partnership, joint venture, association, joint stock company, limited
liability company, trust, unincorporated association, or government or any
agency or political subdivision thereof, or any other entity of whatever nature.

     "Preferred Guarantee Trustee" means State Street Bank and Trust Company,
until a Successor Preferred Guarantee Trustee has been appointed and has
accepted such appointment pursuant to the terms of this Preferred Securities
Guarantee and thereafter means each such Successor Preferred Guarantee Trustee.

     "Redemption Price" has the meaning provided therefor in the definition of
Guarantee Payments.

     "Responsible Officer" means, with respect to the Preferred Guarantee
Trustee, any officer within the Corporate Trust Office of the Preferred
Guarantee Trustee, including any vice-president, any assistant vice-president,
any assistant secretary, the treasurer, any assistant treasurer or other officer
of the Corporate Trust Office of the Preferred Guarantee Trustee customarily
performing functions similar to those performed by any of the above designated
officers and also means, with respect to a particular corporate trust matter,
any other officer to whom such matter is referred because of that officer's
knowledge of and familiarity with the particular subject.

     "Successor Preferred Guarantee Trustee" means a successor Preferred
Guarantee Trustee possessing the qualifications to act as Preferred Guarantee
Trustee under Section 4.1.

     "Trust Indenture Act" means the Trust Indenture Act of 1939, as amended, as
in force at the date of which this instrument was executed; provided, however,
that in the event the Trust Indenture Act of 1939, as amended, is amended after
such date, "Trust Indenture Act" means, to the extent required by any such
amendment, the Trust Indenture Act of 1939, as so amended.



                                       3
<PAGE>
 
                                  ARTICLE II
                              TRUST INDENTURE ACT

SECTION 2.1. TRUST INDENTURE ACT; APPLICATION

     (a) This Preferred Securities Guarantee is subject to the provisions of the
Trust Indenture Act that are required to be part of this Preferred Securities
Guarantee and shall, to the extent applicable, be governed by such provisions.


     (b) If and to the extent that any provision of this Preferred Securities
Guarantee limits, qualifies or conflicts with the duties imposed by Section 310
to 317, inclusive, of the Trust Indenture Act, such imposed duties shall
control.

SECTION 2.2. LISTS OF HOLDERS OF SECURITIES

     (a) In the event the Preferred Guarantee Trustee is not also the Securities
Registrar, the Guarantor shall provide the Preferred Guarantee Trustee with a
list, in such form as the Preferred Guarantee Trustee may reasonably require, of
the names and addresses of the Holders of the Preferred Securities (the "List of
Holders") as of such date, (i) within 1 Business Day after January 1 and June 30
of each year, and (ii) at any other time within 30 days of receipt by the
Guarantor of a written request for a List of Holders as of a date no more than
15 days before such List of Holders is given to the Preferred Guarantee Trustee;
provided, that the Guarantor shall not be obligated to provide such List of
Holders at any time the List of Holders does not differ from the most recent
List of Holders given to the Preferred Guarantee Trustee by the Guarantor. The
Preferred Guarantee Trustee may destroy any List of Holders previously given to
it on receipt of a new List of Holders.

     (b) The Preferred Guarantee Trustee shall comply with its obligations under
Sections 311(a), 311(b) and Section 312(b) of the Trust Indenture Act.

SECTION 2.3. REPORTS BY THE PREFERRED GUARANTEE TRUSTEE

     On or before July 15 of each year, the Preferred Guarantee Trustee shall
provide to the Holders of the Preferred Securities such reports as are required
by Section 313 of the Trust Indenture Act, if any, in the form and in the manner
provided by Section 313 of the Trust Indenture Act. The Preferred Guarantee
Trustee shall also comply with the requirements of Section 313(d) of the Trust
Indenture Act.

SECTION 2.4. PERIODIC REPORTS TO PREFERRED GUARANTEE TRUSTEE

     The Guarantor shall provide to the Preferred Guarantee Trustee such
documents, reports and information as required by Section 314 (if any) and the
compliance certificate required by Section 314 of the Trust Indenture Act in the
form, in the manner and at the times required by Section 314 of the Trust
Indenture Act.

SECTION 2.5. EVIDENCE OF COMPLIANCE WITH CONDITIONS PRECEDENT

     The Guarantor shall provide to the Preferred Guarantee Trustee such
evidence of compliance with any conditions precedent, if any, provided for in
this Preferred Securities Guarantee that relate to any of the matters set forth
in Section 314(c) of the Trust Indenture Act. Any certificate or opinion
required to be given by an officer pursuant to Section 314(c)(1) may be given in
the form of an Officers' Certificate.

SECTION 2.6. EVENTS OF DEFAULT; WAIVER

     The Holders of a Majority in Liquidation Amount of Preferred Securities
may, by vote, on behalf of the Holders of all of the Preferred Securities, waive
any past Event of Default and its consequences. Upon such waiver, any such Event
of Default shall cease to exist, and any Event of Default arising therefrom
shall be deemed to have been cured,


                                       4
<PAGE>
 
for every purpose of this Preferred Securities Guarantee, but no such waiver
shall extend to any subsequent or other default or Event of Default or impair
any right consequent thereon.

SECTION 2.7. EVENT OF DEFAULT; NOTICE

     (a) The Preferred Guarantee Trustee shall, within 90 days after the
occurrence of an Event of Default, transmit by mail, first class postage
prepaid, to the Holders of the Preferred Securities, notices of all Events of
Default actually known to a Responsible Officer of the Preferred Guarantee
Trustee, unless such defaults have been cured before the giving of such notice;
provided, that the Preferred Guarantee Trustee shall be protected in withholding
such notice if and so long as a Responsible Officer of the Preferred Guarantee
Trustee in good faith determines that the withholding of such notice is in the
interests of the Holders of the Preferred Securities.

     (b) The Preferred Guarantee Trustee shall not be deemed to have knowledge
of any Event of Default unless the Preferred Guarantee Trustee shall have
received written notice, or of which a Responsible Officer of the Preferred
Guarantee Trustee charged with the administration of the Trust Agreement shall
have obtained actual knowledge.

SECTION 2.8. CONFLICTING INTERESTS

     The Trust Agreement shall be deemed to be specifically described in this
Preferred Securities Guarantee for the purposes of clause (i) of the first
proviso contained in Section 310(b) of the Trust Indenture Act.

                                 ARTICLE III 
           POWERS, DUTIES AND RIGHTS OF PREFERRED GUARANTEE TRUSTEE

SECTION 3.1. POWERS AND DUTIES OF THE PREFERRED GUARANTEE TRUSTEE

     (a) This Preferred Securities Guarantee shall be held by the Preferred
Guarantee Trustee for the benefit of the Holders of the Preferred Securities,
and the Preferred Guarantee Trustee shall not transfer this Preferred Securities
Guarantee to any Person except a Holder of Preferred Securities exercising his
or her rights pursuant to Section 5.4(b) or to a Successor Preferred Guarantee
Trustee on acceptance by such Successor Preferred Guarantee Trustee of its
appointment to act as Successor Preferred Guarantee Trustee. The right, title
and interest of the Preferred Guarantee Trustee shall automatically vest in any
Successor Preferred Guarantee Trustee, and such vesting and cessation of title
shall be effective whether or not conveyancing documents have been executed and
delivered pursuant to the appointment of such Successor Preferred Guarantee
Trustee.

     (b) If an Event of Default actually known to a Responsible Officer of the
Preferred Guarantee Trustee has occurred and is continuing, the Preferred
Guarantee Trustee shall enforce this Preferred Securities Guarantee for the
benefit of the Holders of the Preferred Securities.

     (c) The Preferred Guarantee Trustee, before the occurrence of any Event of
Default and after the curing of all Events of Default that may have occurred,
shall undertake to perform only such duties as are specifically set forth in
this Preferred Securities Guarantee, and no implied covenants shall be read into
this Preferred Securities Guarantee against the Preferred Guarantee Trustee. In
case an Event of Default has occurred (that has not been cured or waived
pursuant to Section 2.6) and is actually known to a Responsible Officer of the
Preferred Guarantee Trustee, the Preferred Guarantee Trustee shall exercise such
of the rights and powers vested in it by this Preferred Securities Guarantee,
and use the same degree of care and skill in its exercise thereof, as a prudent
person would exercise or use under the circumstances in the conduct of his or
her own affairs.

     (d) No provision of this Preferred Securities Guarantee shall be construed
to relieve the Preferred Guarantee Trustee from liability for its own negligent
action, its own negligent failure to act, or its own willful misconduct, except
that:

                                       5
<PAGE>
 
     (i) prior to the occurrence of any Event of Default and after the curing or
waiving of all such Events of Default that may have occurred:

         (A) the duties and obligations of the Preferred Guarantee Trustee shall
be determined solely by the express provisions of this Preferred Securities
Guarantee, and the Preferred Guarantee Trustee shall not be liable except for
the performance of such duties and obligations as are specifically set forth in
this Preferred Securities Guarantee, and no implied covenants or obligations
shall be read into this Preferred Securities Guarantee against the Preferred
Guarantee Trustee; and

         (B) in the absence of bad faith on the part of the Preferred Guarantee
Trustee, the Preferred Guarantee Trustee may conclusively rely, as to the truth
of the statements and the correctness of the opinions expressed therein, upon
any certificates or opinions furnished to the Preferred Guarantee Trustee and
conforming to the requirements of this Preferred Securities Guarantee; but in
the case of any such certificates or opinions that by any provision hereof are
specifically required to be furnished to the Preferred Guarantee Trustee, the
Preferred Guarantee Trustee shall be under a duty to examine the same to
determine whether or not they conform to the requirements of this Preferred
Securities Guarantee;

     (ii) the Preferred Guarantee Trustee shall not be liable for any error of
judgment made in good faith by a Responsible Officer of the Preferred Guarantee
Trustee, unless it shall be proved that the Preferred Guarantee Trustee was
negligent in ascertaining the pertinent facts upon which such judgment was made;

     (iii) the Preferred Guarantee Trustee shall not be liable with respect to
any action taken or omitted to be taken by it in good faith in accordance with
the direction of the Holders of not less than a Majority in Liquidation Amount
of the Preferred Securities relating to the time, method and place of conducting
any proceeding for any remedy available to the Preferred Guarantee Trustee, or
exercising any trust or power conferred upon the Preferred Guarantee Trustee
under this Preferred Securities Guarantee; and

     (iv) no provision of this Preferred Securities Guarantee shall require the
Preferred Guarantee Trustee to expend or risk its own funds or otherwise incur
personal financial liability in the performance of any of its duties or in the
exercise of any of its rights or powers, if the Preferred Guarantee Trustee
shall have reasonable grounds for believing that the repayment of such funds or
liability is not reasonably assured to it under the terms of this Preferred
Securities Guarantee or indemnity, reasonably satisfactory to the Preferred
Guarantee Trustee, against such risk or liability is not reasonably assured to
it.

SECTION 3.2. CERTAIN RIGHTS OF PREFERRED GUARANTEE TRUSTEE

(a)  Subject to the provisions of Section 3.1:

     (i) the Preferred Guarantee Trustee may conclusively rely, and shall be
fully protected in acting or refraining from acting upon, any resolution,
certificate, statement, instrument, opinion, report, notice, request, direction,
consent, order, bond, debenture, note, other evidence of indebtedness or other
paper or document believed by it to be genuine and to have been signed, sent or
presented by the proper party or parties;

     (ii) any direction or act of the Guarantor contemplated by this Preferred
Securities Guarantee shall be sufficiently evidenced by an Officers'
Certificate;

     (iii) whenever, in the administration of this Preferred Securities
Guarantee, the Preferred Guarantee Trustee shall deem it desirable that a matter
be proved or established before taking, suffering or omitting any action
hereunder, the Preferred Guarantee Trustee (unless other evidence is herein
specifically prescribed) may, in the absence of bad faith on its part, request
and conclusively rely upon an Officers' Certificate which, upon receipt of such
request, shall be promptly delivered by the Guarantor;

                                       6
<PAGE>
 
     (iv) the Preferred Guarantee Trustee shall have no duty to see to any
recording, filing or registration of any instrument (or any rerecording,
refiling or registration thereof);

     (v) the Preferred Guarantee Trustee may consult with counsel, and the
written advice or opinion of such counsel with respect to legal matters shall be
full and complete authorization and protection in respect of any action taken,
suffered or omitted by it hereunder in good faith and in accordance with such
advice or opinion. Such counsel may be counsel to the Guarantor or any of its
Affiliates and may include any of its employees. The Preferred Guarantee Trustee
shall have the right at any time to seek instructions concerning the
administration of this Preferred Securities Guarantee from any court of
competent jurisdiction;

     (vi) the Preferred Guarantee Trustee shall be under no obligation to
exercise any of the rights or powers vested in it by this Preferred Securities
Guarantee at the request or direction of any Holder, unless such Holder shall
have provided to the Preferred Guarantee Trustee such security and indemnity,
reasonably satisfactory to the Preferred Guarantee Trustee, against the costs,
expenses (including attorneys' fees and expenses and the expenses of the
Preferred Guarantee Trustee's agents, nominees or custodians) and liabilities
that might be incurred by it in complying with such request or direction,
including such reasonable advances as may be requested by the Preferred
Guarantee Trustee; provided that, nothing contained in this Section 3.2(a)(vi)
shall be taken to relieve the Preferred Guarantee Trustee, upon the occurrence
of an Event of Default, of its obligation to exercise the rights and powers
vested in it by this Preferred Securities Guarantee;

     (vii) the Preferred Guarantee Trustee shall not be bound to make any
investigation into the facts or matters stated in any resolution, certificate,
statement, instrument, opinion, report, notice, request, direction, consent,
order, bond, debenture, note, other evidence of indebtedness or other paper or
document, but the Preferred Guarantee Trustee, in its discretion, may make such
further inquiry or investigation into such facts or matters as it may see fit;

     (viii) the Preferred Guarantee Trustee may execute any of the trusts or
powers hereunder or perform any duties hereunder either directly or by or
through agents, nominees, custodians or attorneys, and the Preferred Guarantee
Trustee shall not be responsible for any misconduct or negligence on the part of
any agent or attorney appointed with due care by it hereunder;

     (ix) any action taken by the Preferred Guarantee Trustee or its agents
hereunder shall bind the Holders of the Preferred Securities, and the signature
of the Preferred Guarantee Trustee or its agents alone shall be sufficient and
effective to perform any such action. No third party shall be required to
inquire as to the authority of the Preferred Guarantee Trustee to so act or as
to its compliance with any of the terms and provisions of this Preferred
Securities Guarantee, both of which shall be conclusively evidenced by the
Preferred Guarantee Trustee's or its agent's taking such action;

     (x) whenever in the administration of this Preferred Securities Guarantee
the Preferred Guarantee Trustee shall deem it desirable to receive instructions
with respect to enforcing any remedy or right or taking any other action
hereunder, the Preferred Guarantee Trustee (i) may request instructions from the
Holders of a Majority in Liquidation Amount of the Preferred Securities, (ii)
may refrain from enforcing such remedy or right or taking such other action
until such instructions are received, and (iii) shall be protected in
conclusively relying on or acting in accordance with such instructions.

  (b) No provision of this Preferred Securities Guarantee shall be deemed to
impose any duty or obligation on the Preferred Guarantee Trustee to perform any
act or acts or exercise any right, power, duty or obligation conferred or
imposed on it in any jurisdiction in which it shall be illegal, or in which the
Preferred Guarantee Trustee shall be unqualified or incompetent in accordance
with applicable law, to perform any such act or acts or to exercise any such
right, power, duty or obligation. No permissive power or authority available to
the Preferred Guarantee Trustee shall be construed to be a duty.

                                      7
<PAGE>
 
SECTION 3.3. NOT RESPONSIBLE FOR RECITALS OR ISSUANCE OF GUARANTEE

     The Recitals contained in this Guarantee shall be taken as the statements
of the Guarantor, and the Preferred Guarantee Trustee does not assume any
responsibility for their correctness. The Preferred Guarantee Trustee makes no
representation as to the validity or sufficiency of this Preferred Securities
Guarantee.

                                  ARTICLE IV 
                          PREFERRED GUARANTEE TRUSTEE

SECTION 4.1. PREFERRED GUARANTEE TRUSTEE; ELIGIBILITY

  (a) There shall at all times be a Preferred Guarantee Trustee which shall:

     (i) not be an Affiliate of the Guarantor; and

     (ii) be a corporation organized and doing business under the laws of the
United States of America or any State or Territory thereof or of the District of
Columbia, or a corporation or Person permitted by the Securities and Exchange
Commission to act as an institutional trustee under the Trust Indenture Act,
authorized under such laws to exercise corporate trust powers, having a combined
capital and surplus of at least $50,000,000, and subject to supervision or
examination by Federal, State, Territorial or District of Columbia authority. If
such corporation publishes reports of condition at least annually, pursuant to
law or to the requirements of the supervising or examining authority referred to
above, then, for the purposes of this Section 4.1(a)(ii), the combined capital
and surplus of such corporation shall be deemed to be its combined capital and
surplus as set forth in its most recent report of condition so published.

  (b) If at any time the Preferred Guarantee Trustee shall cease to be eligible
to so act under Section 4.1(a), the Preferred Guarantee Trustee shall
immediately resign in the manner and with the effect set out in Section 4.2(c).

  (c) If the Preferred Guarantee Trustee has or shall acquire any "conflicting
interest" within the meaning of Section 310(b) of the Trust Indenture Act, the
Preferred Guarantee Trustee and Guarantor shall in all respects comply with the
provisions of Section 310(b) of the Trust Indenture Act.

SECTION 4.2. APPOINTMENT, REMOVAL AND RESIGNATION OF PREFERRED GUARANTEE 
TRUSTEE

  (a) Subject to Section 4.2(b), the Preferred Guarantee Trustee may be
appointed or removed without cause at any time by the Guarantor.

  (b) The Preferred Guarantee Trustee shall not be removed in accordance with
Section 4.2(a) until a Successor Preferred Guarantee Trustee has been appointed
and has accepted such appointment by written instrument executed by such
Successor Preferred Guarantee Trustee and delivered to the Guarantor.

  (c) The Preferred Guarantee Trustee appointed to office shall hold office
until a Successor Preferred Guarantee Trustee shall have been appointed or until
its removal or resignation. The Preferred Guarantee Trustee may resign from
office (without need for prior or subsequent accounting) by an instrument in
writing executed by the Preferred Guarantee Trustee and delivered to the
Guarantor, which resignation shall not take effect until a Successor Preferred
Guarantee Trustee has been appointed and has accepted such appointment by
instrument in writing executed by such Successor Preferred Guarantee Trustee and
delivered to the Guarantor and the resigning Preferred Guarantee Trustee.

  (d) If no Successor Preferred Guarantee Trustee shall have been appointed and
accepted appointment as provided in this Section 4.2 within 60 days after
delivery to the Guarantor of an instrument of resignation, the resigning
Preferred Guarantee Trustee may petition any court of competent jurisdiction for
appointment of a Successor


                                       8
<PAGE>
 
     Preferred Guarantee Trustee. Such court may thereupon, after prescribing
such notice, if any, as it may deem proper, appoint a Successor Preferred
Guarantee Trustee.

     (e) No Preferred Guarantee Trustee shall be liable for the acts or
omissions to act of any Successor Preferred Guarantee Trustee.

     (f) Upon termination of this Preferred Securities Guarantee or removal or
resignation of the Preferred Guarantee Trustee pursuant to this Section 4.2, the
Guarantor shall pay to the Preferred Guarantee Trustee all amounts accrued to
the date of such termination, removal or resignation.

                                  ARTICLE V 
                                  GUARANTEE

SECTION 5.1. GUARANTEE

     The Guarantor irrevocably and unconditionally agrees to pay in full to the
Holders the Guarantee Payments (without duplication of amounts theretofore paid
by the Trust), as and when due, regardless of any defense, right of set-off or
counterclaim that the Trust may have or assert. The Guarantor's obligation to
make a Guarantee Payment may be satisfied by direct payment of the required
amounts by the Guarantor to the Holders or by causing the Trust to pay such
amounts to the Holders.

SECTION 5.2. WAIVER OF NOTICE AND DEMAND

     The Guarantor hereby waives notice of acceptance of this Preferred
Securities Guarantee and of any liability to which it applies or may apply,
presentment, demand for payment, any right to require a proceeding first against
the Trust or any other Person before proceeding against the Guarantor, protest,
notice of nonpayment, notice of dishonor, notice of redemption and all other
notices and demands.

SECTION 5.3. OBLIGATIONS NOT AFFECTED

     The obligations, covenants, agreements and duties of the Guarantor under
this Preferred Securities Guarantee shall in no way be affected or impaired by
reason of the happening from time to time of any of the following:

     (a) the release or waiver, by operation of law or otherwise, of the
performance or observance by the Trust of any express or implied agreement,
covenant, term or condition relating to the Preferred Securities to be performed
or observed by the Trust;

     (b) the extension of time for the payment by the Trust of all or any
portion of the Distributions, Redemption Price, Liquidation Distribution or any
other sums payable under the terms of the Preferred Securities or the extension
of time for the performance of any other obligation under, arising out of, or in
connection with, the Preferred Securities (other than an extension of time for
payment of Distributions, Redemption Price, Liquidation Distribution or other
sum payable that results from the extension of any interest payment period on
the Debentures or any extension of the maturity date of the Debentures permitted
by the Indenture);

     (c) any failure, omission, delay or lack of diligence on the part of the
Holders to enforce, assert or exercise any right, privilege, power or remedy
conferred on the Holders pursuant to the terms of the Preferred Securities, or
any action on the part of the Trust granting indulgence or extension of any
kind;

     (d) the voluntary or involuntary liquidation, dissolution, sale of any
collateral, receivership, insolvency, bankruptcy, assignment for the benefit of
creditors, reorganization, arrangement, composition or readjustment of debt of,
or other similar proceedings affecting, the Trust or any of the assets of the
Trust;

                                       9
<PAGE>
 
     (e) any invalidity of, or defect or deficiency in, the Preferred
Securities;

     (f) any failure or omission to receive any regulatory approval or consent
required in connection with the Preferred Securities (or the common equity
securities issued by the Trust), including the failure to receive any approval
of the Board of Governors of the Federal Reserve System required for the
redemption of the Preferred Securities;

     (g) the settlement or compromise of any obligation guaranteed hereby or
hereby incurred; or

     (h) any other circumstance whatsoever that might otherwise constitute a
legal or equitable discharge or defense of a guarantor, it being the intent of
this Section 5.3 that the obligations of the Guarantor hereunder shall be
absolute and unconditional under any and all circumstances.

     There shall be no obligation of the Holders to give notice to, or obtain
consent of, the Guarantor with respect to the happening of any of the foregoing.

SECTION 5.4. RIGHTS OF HOLDERS

     (a) The Holders of a Majority in Liquidation Amount of the Preferred
Securities have the right to direct the time, method and place of conducting of
any proceeding for any remedy available to the Preferred Guarantee Trustee in
respect of this Preferred Securities Guarantee or exercising any trust or power
conferred upon the Preferred Guarantee Trustee under this Preferred Securities
Guarantee.

     (b) Any Holder of Preferred Securities may institute a legal proceeding
directly against the Guarantor to enforce its rights under this Preferred
Securities Guarantee, without first instituting a legal proceeding against the
Trust, the Preferred Guarantee Trustee or any other Person.

SECTION 5.5. GUARANTEE OF PAYMENT

     This Preferred Securities Guarantee creates a guarantee of payment and not
of collection.

SECTION 5.6. SUBROGATION

     The Guarantor shall be subrogated to all (if any) rights of the Holders of
Preferred Securities against the Trust in respect of any amounts paid to such
Holders by the Guarantor under this Preferred Securities Guarantee; provided,
however, that the Guarantor shall not (except to the extent required by
mandatory provisions of law) be entitled to enforce or exercise any right that
it may acquire by way of subrogation or any indemnity, reimbursement or other
agreement, in all cases as a result of payment under this Preferred Securities
Guarantee, if, at the time of any such payment, any amounts are due and unpaid
under this Preferred Securities Guarantee. If any amount shall be paid to the
Guarantor in violation of the preceding sentence, the Guarantor agrees to hold
such amount in trust for the Holders and to pay over such amount to the Holders.

SECTION 5.7. INDEPENDENT OBLIGATIONS

     The Guarantor acknowledges that its obligations hereunder are independent
of the obligations of the Trust with respect to the Preferred Securities, and
that the Guarantor shall be liable as principal and as debtor hereunder to make
Guarantee Payments pursuant to the terms of this Preferred Securities Guarantee
notwithstanding the occurrence of any event referred to in subsections (a)
through (h), inclusive, of Section 5.3 hereof.

                                      10
<PAGE>
 
                                 ARTICLE VI   
                   LIMITATION OF TRANSACTIONS; SUBORDINATION

SECTION 6.1. LIMITATION ON TRANSACTIONS

     So long as any Preferred Securities remain outstanding, if there shall have
occurred an Event of Default under this Preferred Securities Guarantee, an Event
of Default under the Trust Agreement or during an Extended Interest Payment
Period (as defined in the Indenture), then (a) the Guarantor shall not declare
or pay any dividend on, make any distributions with respect to, or redeem,
purchase, acquire or make a liquidation payment with respect to, any of its
capital stock and (b) the Guarantor shall not make any payment of interest or
principal on or repay, repurchase or redeem any debt securities issued by the
Guarantor which rank pari passu with or junior to the Debentures other than
payments under this Preferred Securities Guarantee and (c) the Guarantor shall
not redeem, purchase or acquire less than all of the Outstanding Debentures or
any of the Preferred Securities.

SECTION 6.2 RANKING

     This Preferred Securities Guarantee will constitute an unsecured obligation
of the Guarantor and will rank (i) subordinate and junior in right of payment to
all other liabilities of the Guarantor, (ii) pari passu with the most senior
preferred securities or preference stock now or hereafter issued by the
Guarantor and with any guarantee now or hereafter entered into by the Guarantor
in respect of any preferred securities or preference stock of any Affiliate of
the Guarantor, and (iii) senior to the Guarantor's common stock.

                                 ARTICLE VII 
                                 TERMINATION

SECTION 7.1. TERMINATION

     This Preferred Securities Guarantee shall terminate upon (i) full payment
of the Redemption Price of all Preferred Securities, (ii) upon full payment of
the amounts payable in accordance with the Trust Agreement upon liquidation of
the Trust, or (iii) upon distribution of the Debentures to the Holders of the
Preferred Securities. Notwithstanding the foregoing, this Preferred Securities
Guarantee shall continue to be effective or shall be reinstated, as the case may
be, if at any time any Holder of Preferred Securities must restore payment of
any sums paid under the Preferred Securities or under this Preferred Securities
Guarantee.

                                 ARTICLE VIII 
                                INDEMNIFICATION

SECTION 8.1. EXCULPATION

     (a) No Indemnified Person shall be liable, responsible or accountable in
damages or otherwise to the Guarantor or any Covered Person for any loss, damage
or claim incurred by reason of any act or omission performed or omitted by such
Indemnified Person in good faith in accordance with this Preferred Securities
Guarantee and in a manner that such Indemnified Person reasonably believed to be
within the scope of the authority conferred on such Indemnified Person by this
Preferred Securities Guarantee or by law, except that an Indemnified Person
shall be liable for any such loss, damage or claim incurred by reason of such
Indemnified Person's negligence or willful misconduct with respect to such acts
or omissions.

     (b) An Indemnified Person shall be fully protected in relying in good faith
upon the records of the Guarantor and upon such information, opinions, reports
or statements presented to the Guarantor by any Person as to matters the
Indemnified Person reasonably believes are within such other Person's
professional or expert competence and who has been selected with reasonable care
by or on behalf of the Guarantor, including information, opinions, reports

                                      11
<PAGE>
 
or statements as to the value and amount of the assets, liabilities, profits,
losses, or any other facts pertinent to the existence and amount of assets from
which Distributions to Holders of Preferred Securities might properly be paid.

SECTION 8.2. INDEMNIFICATION

     The Guarantor agrees to indemnify each Indemnified Person for, and to hold
each Indemnified Person harmless against, any loss, liability or expense
incurred without negligence or bad faith on its part, arising out of or in
connection with the acceptance or administration of the trust or trusts
hereunder, including the costs and expenses (including reasonable legal fees and
expenses) of defending itself against, or investigating, any claim or liability
in connection with the exercise or performance of any of its powers or duties
hereunder. The obligation to indemnify as set forth in this Section 8.2 shall
survive the termination of this Preferred Securities Guarantee.

                                  ARTICLE IX 
                                 MISCELLANEOUS

SECTION 9.1. SUCCESSORS AND ASSIGNS

     All guarantees and agreements contained in this Preferred Securities
Guarantee shall bind the successors, assigns, receivers, trustees and
representatives of the Guarantor and shall inure to the benefit of the Holders
of the Preferred Securities then outstanding.

SECTION 9.2. AMENDMENTS

     Except with respect to any changes that do not materially adversely affect
the rights of Holders (in which case no consent of Holders will be required),
this Preferred Securities Guarantee may only be amended with the prior approval
of the Holders of at least a Majority in Liquidation Amount of the Preferred
Securities. The provisions of Article VI of the Trust Agreement with respect to
meetings of Holders of the Preferred Securities apply to the giving of such
approval.

SECTION 9.3. NOTICES

     All notices provided for in this Preferred Securities Guarantee shall be in
writing, duly signed by the party giving such notice, and shall be delivered,
telecopied or mailed by registered or certified mail, as follows:

     (a) If given to the Preferred Guarantee Trustee, at the Preferred Guarantee
Trustee's mailing address set forth below (or such other address as the
Preferred Guarantee Trustee may give notice of to the Holders of the Preferred
Securities):

                State Street Bank and Trust Company
                Two International Place, 4th Floor
                Boston, Massachusetts 02110
                Attention: Corporate Trust Department

     (b) If given to the Guarantor, at the Guarantor's mailing address set forth
below (or such other address as the Guarantor may give notice of to the Holders
of the Preferred Securities):

                Southwest Bancorp, Inc.
                608 South Main Street
                Stillwater, Oklahoma  74074
                Attention: Kerby E. Crowell



                                      12
<PAGE>
 
(c) If given to any Holder of Preferred Securities, at the address set forth on
the books and records of the Trust.

     All such notices shall be deemed to have been given when received in
person, telecopied with receipt confirmed, or mailed by first class mail,
postage prepaid except that if a notice or other document is refused delivery or
cannot be delivered because of a changed address of which no notice was given,
such notice or other document shall be deemed to have been delivered on the date
of such refusal or inability to deliver.

SECTION 9.4. BENEFIT

     This Preferred Securities Guarantee is solely for the benefit of the
Holders of the Preferred Securities and, subject to Section 3.1(a), is not
separately transferable from the Preferred Securities.

SECTION 9.5. GOVERNING LAW

     THIS PREFERRED SECURITIES GUARANTEE SHALL BE GOVERNED BY, AND CONSTRUED AND
INTERPRETED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF OKLAHOMA.

     This Preferred Securities Guarantee is executed as of the day and year
first above written.

                              SOUTHWEST BANCORP, INC.
                              as Guarantor

                              By  /s/ Robert L. MCCormick, Jr.
                                 ----------------------------------------
                                      Robert L. McCormick, Jr., President

                              STATE STREET BANK AND TRUST COMPANY,
                              as Preferred Guarantee Trustee

                              By  /s/ Paul D. Allen
                                 ----------------------------------------
                                      Paul D. Allen, Vice President



                                      13

<PAGE>
 
                                                                     EXHIBIT 4.5


                            SOUTHWEST BANCORP, INC.

                                      AND

                     STATE STREET BANK AND TRUST COMPANY,
                                  AS TRUSTEE

                                   INDENTURE

                    9.30% SUBORDINATED DEBENTURES DUE 2027

                           DATED AS OF JUNE 4, 1997.
<PAGE>
 
                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                           PAGE
<S>                      <C>                                                                                <C>
ARTICLE I.                 DEFINITIONS....................................................................  1
      SECTION 1.1          DEFINITIONS OF TERMS...........................................................  1
ARTICLE II.                ISSUE, DESCRIPTION, TERMS, CONDITIONS REGISTRATION AND
                                EXCHANGE OF THE DEBENTURES................................................. 7
      SECTION 2.1          DESIGNATION AND PRINCIPAL AMOUNT...............................................  7
      SECTION 2.2          MATURITY.......................................................................  7
      SECTION 2.3          FORM AND PAYMENT...............................................................  8
      SECTION 2.4          [Intentionally Omitted.........................................................  8
      SECTION 2.5          INTEREST.......................................................................  8
      SECTION 2.6          EXECUTION AND AUTHENTICATIONS..................................................  9
      SECTION 2.7          REGISTRATION OF TRANSFER AND EXCHANGE.......................................... 10
      SECTION 2.8          TEMPORARY DEBENTURES........................................................... 10
      SECTION 2.9          MUTILATED, DESTROYED, LOST OR STOLEN DEBENTURES................................ 11
      SECTION 2.10         CANCELLATION................................................................... 11
      SECTION 2.11         BENEFIT OF INDENTURE........................................................... 11
      SECTION 2.12         AUTHENTICATION AGENT........................................................... 12
ARTICLE III.               REDEMPTION OF DEBENTURES....................................................... 12
      SECTION 3.1          REDEMPTION..................................................................... 12
      SECTION 3.2          SPECIAL EVENT REDEMPTION....................................................... 12
      SECTION 3.3          OPTIONAL REDEMPTION BY COMPANY................................................. 13
      SECTION 3.4          NOTICE OF REDEMPTION........................................................... 13
      SECTION 3.5          PAYMENT UPON REDEMPTION........................................................ 14
      SECTION 3.6          NO SINKING FUND................................................................ 14
ARTICLE IV.                EXTENSION OF INTEREST PAYMENT PERIOD........................................... 14
      SECTION 4.1          EXTENSION OF INTEREST PAYMENT PERIOD........................................... 14
      SECTION 4.2          NOTICE OF EXTENSION............................................................ 15
      SECTION 4.3          LIMITATION ON TRANSACTIONS..................................................... 15
ARTICLE V.                 PARTICULAR COVENANTS OF THE COMPANY............................................ 15
      SECTION 5.1          PAYMENT OF PRINCIPAL AND INTEREST.............................................. 15
      SECTION 5.2          MAINTENANCE OF AGENCY.......................................................... 15
      SECTION 5.3          PAYING AGENTS.................................................................. 16
      SECTION 5.4          APPOINTMENT TO FILL VACANCY IN OFFICE OF TRUSTEE............................... 16
      SECTION 5.5          COMPLIANCE WITH CONSOLIDATION PROVISIONS....................................... 17
      SECTION 5.6          LIMITATION ON TRANSACTIONS..................................................... 17
      SECTION 5.7          COVENANTS AS TO THE TRUST...................................................... 17
      SECTION 5.8          COVENANTS AS TO PURCHASES...................................................... 17
  ARTICLE VI.              DEBENTUREHOLDERS' LISTS AND REPORTS BY THE COMPANY AND THE TRUSTEE............. 17
        SECTION 6.1        COMPANY TO FURNISH TRUSTEE NAMES AND ADDRESSES OF DEBENTUREHOLDERS............. 17
  </TABLE>
  
                                        -i-
<PAGE>
 
<TABLE> 
<CAPTION> 
<S>                      <C>                                                                                 <C>
     SECTION 6.2         PRESERVATION OF INFORMATION COMMUNICATIONS WITH DEBENTUREHOLDERS................... 18
     SECTION 6.3         REPORTS BY THE COMPANY............................................................. 18
     SECTION 6.4         REPORTS BY THE TRUSTEE............................................................. 18

ARTICLE VII.             REMEDIES OF THE TRUSTEE AND DEBENTUREHOLDERS ON EVENT OF DEFAULT................... 19
     SECTION 7.1         EVENTS OF DEFAULT.................................................................. 19
     SECTION 7.2         COLLECTION OF INDEBTEDNESS AND SUITS FOR ENFORCEMENT BY TRUSTEE.................... 20
     SECTION 7.3         APPLICATION OF MONEYS COLLECTED.................................................... 21
     SECTION 7.4         LIMITATION ON SUITS................................................................ 21
     SECTION 7.5         RIGHTS AND REMEDIES CUMULATIVE; DELAY OR OMISSION NOT WAIVER....................... 22
     SECTION 7.6         CONTROL BY DEBENTUREHOLDERS........................................................ 22
     SECTION 7.7         UNDERTAKING TO PAY COSTS........................................................... 23

ARTICLE VIII.            FORM OF DEBENTURE AND ORIGINAL ISSUE............................................... 23
     SECTION 8.1         FORM OF DEBENTURE.................................................................. 23
     SECTION 8.2         ORIGINAL ISSUE OF DEBENTURES....................................................... 23

ARTICLE IX.              CONCERNING THE TRUSTEE............................................................. 23
     SECTION 9.1         CERTAIN DUTIES AND RESPONSIBILITIES TRUSTEE........................................ 23
     SECTION 9.2         NOTICE OF DEFAULTS................................................................. 24
     SECTION 9.3         CERTAIN RIGHTS OF TRUSTEE.......................................................... 24
     SECTION 9.4         TRUSTEE NOT RESPONSIBLE FOR RECITALS, ETC.......................................... 25
     SECTION 9.5         MAY HOLD DEBENTURES................................................................ 26
     SECTION 9.6         MONEYS HELD IN TRUST............................................................... 26
     SECTION 9.7         COMPENSATION AND REIMBURSEMENT..................................................... 26
     SECTION 9.8         RELIANCE ON OFFICERS' CERTIFICATE.................................................. 26
     SECTION 9.9         DISQUALIFICATION; CONFLICTING INTERESTS............................................ 26
     SECTION 9.10        CORPORATE TRUSTEE REQUIRED; ELIGIBILITY............................................ 26
     SECTION 9.11        RESIGNATION AND REMOVAL; APPOINTMENT OF SUCCESSOR.................................. 27
     SECTION 9.12        ACCEPTANCE OF APPOINTMENT BY SUCCESSOR............................................. 28
     SECTION 9.13        MERGER, CONVERSION, CONSOLIDATION OR SUCCESSION TO BUSINESS........................ 28
     SECTION 9.14        PREFERENTIAL COLLECTION OF CLAIMS AGAINST THE COMPANY.............................. 28

ARTICLE X.               CONCERNING THE DEBENTUREHOLDERS.................................................... 29
     SECTION 10.1        EVIDENCE OF ACTION BY HOLDERS...................................................... 29
     SECTION 10.2        PROOF OF EXECUTION BY DEBENTUREHOLDERS............................................. 29
     SECTION 10.3        WHO MAY BE DEEMED OWNERS........................................................... 29
     SECTION 10.4        CERTAIN DEBENTURES OWNED BY COMPANY DISREGARDED.................................... 30
     SECTION 10.5        ACTIONS BINDING ON FUTURE DEBENTUREHOLDERS......................................... 30

ARTICLE XI.              SUPPLEMENTAL INDENTURES............................................................ 30
     SECTION 11.1        SUPPLEMENTAL INDENTURES WITHOUT THE CONSENT OF DEBENTUREHOLDERS.................... 30
     SECTION 11.2        SUPPLEMENTAL INDENTURES WITH CONSENT OF DEBENTUREHOLDERS........................... 31
     SECTION 11.3        EFFECT OF SUPPLEMENTAL INDENTURES.................................................. 31
     SECTION 11.4        DEBENTURES AFFECTED BY SUPPLEMENTAL INDENTURES..................................... 31
 
</TABLE>



                                     -ii-
<PAGE>
 
<TABLE> 
<S>                                                                                                         <C>
     SECTION 11.5        EXECUTION OF SUPPLEMENTAL INDENTURES............................................... 32
                                                                                                            
ARTICLE XII.             SUCCESSOR CORPORATION.............................................................. 32
     SECTION 12.1        COMPANY MAY CONSOLIDATE, ETC....................................................... 32
     SECTION 12.2        SUCCESSOR CORPORATION SUBSTITUTED.................................................. 32
     SECTION 12.3        EVIDENCE OF CONSOLIDATION, ETC. TO TRUSTEE......................................... 33
                                                                                                            
ARTICLE XIII.            SATISFACTION AND DISCHARGE......................................................... 33
     SECTION 13.1        SATISFACTION AND DISCHARGE OF INDENTURE............................................ 33
     SECTION 13.2        DISCHARGE OF OBLIGATIONS........................................................... 33
     SECTION 13.3        DEPOSITED MONEYS TO BE HELD IN TRUST............................................... 34
     SECTION 13.4        PAYMENT OF MONIES HELD BY PAYING AGENTS............................................ 34
     SECTION 13.5        REPAYMENT TO COMPANY............................................................... 34
                                                                                                            
ARTICLE XIV.             IMMUNITY OF INCORPORATORS, STOCKHOLDERS, OFFICERS AND DIRECTORS.................... 34
     SECTION 14.1        NO RECOURSE........................................................................ 34
                                                                                                            
ARTICLE XV.              MISCELLANEOUS PROVISIONS........................................................... 35
     SECTION 15.1        EFFECT ON SUCCESSORS AND ASSIGNS................................................... 35
     SECTION 15.2        ACTIONS BY SUCCESSOR............................................................... 35
     SECTION 15.3        SURRENDER OF COMPANY POWERS........................................................ 35
     SECTION 15.4        NOTICES............................................................................ 35
     SECTION 15.5        GOVERNING LAW...................................................................... 35
     SECTION 15.6        TREATMENT OF DEBENTURES AS DEBT.................................................... 35
     SECTION 15.7        COMPLIANCE CERTIFICATES AND OPINIONS............................................... 35
     SECTION 15.8        PAYMENTS ON BUSINESS DAYS.......................................................... 36
     SECTION 15.9        CONFLICT WITH TRUST INDENTURE ACT.................................................. 36
     SECTION 15.10       COUNTERPARTS....................................................................... 36
     SECTION 15.11       SEPARABILITY....................................................................... 36
     SECTION 15.12       ASSIGNMENT......................................................................... 36
     SECTION 15.13       ACKNOWLEDGMENT OF RIGHTS; RIGHT OF SET-OFF......................................... 36
                                                                                                            
ARTICLE XVI.             SUBORDINATION OF DEBENTURES........................................................ 37
     SECTION 16.1        AGREEMENT TO SUBORDINATE........................................................... 37
     SECTION 16.2        DEFAULT ON SENIOR DEBT, SUBORDINATED DEBT ADDITIONAL SENIOR OBLIGATIONS............ 37 
     SECTION 16.3        LIQUIDATION; DISSOLUTION; BANKRUPTCY............................................... 37
     SECTION 16.4        SUBROGATION........................................................................ 38
     SECTION 16.5        TRUSTEE TO EFFECTUATE SUBORDINATION................................................ 39
     SECTION 16.6        NOTICE BY THE COMPANY.............................................................. 39
     SECTION 16.7        RIGHTS OF THE TRUSTEE; HOLDERS OF SENIOR INDEBTEDNESS.............................. 40
     SECTION 16.8        SUBORDINATION MAY NOT BE IMPAIRED.................................................. 40
</TABLE>
 



                                     -iii-
<PAGE>
 
                             CROSS-REFERENCE TABLE

<TABLE>
<CAPTION>
Section of
Trust Indenture Act                                       Section of      
of 1939, as amended                                        Indenture    
- -------------------                                    ----------------- 

<S>                                                    <C>
310(a)................................................              9.10
310(b)................................................         9.9, 9.11
310(c)................................................    Not Applicable
311(a)................................................              9.14
311(b)................................................              9.14
311(c)................................................    Not Applicable
312(a)................................................       6.1, 6.2(a)
312(b)................................................            6.2(c)
312(c)................................................            6.2(c)
313(a)................................................            6.4(a)
313(b)................................................            6.4(b)
313(c)................................................    6.4(a), 6.4(b)
313(d)................................................            6.4(c)
314(a)................................................            6.3(a)
314(b)................................................    Not Applicable
314(c)................................................              15.7
314(d)................................................    Not Applicable
314(e)................................................              15.7
314(f)................................................    Not Applicable
315(a)................................................       9.1(a), 9.3
315(b)................................................               9.2
315(c)................................................            9.1(a)
315(d)................................................            9.1(b)
315(e)................................................               7.7
316(a)................................................          1.1, 7.6
316(b)................................................            7.4(b)
316(c)................................................           10.1(b)
317(a)................................................               7.2
317(b)................................................               5.3
318(a)................................................              15.9
</TABLE>

Note: This Cross-Reference Table does not constitute part of this Indenture and
shall not affect the interpretation of any of its terms or provisions.

                                     -iv-
<PAGE>
 
                                   INDENTURE

  INDENTURE, dated as of June 4, 1997, between SOUTHWEST BANCORP, INC., an
Oklahoma corporation (the "Company") and STATE STREET BANK AND TRUST COMPANY, a
trust company duly organized and existing under the laws of the Commonwealth of
Massachusetts, as trustee (the "Trustee");

                                   RECITALS

  WHEREAS, for its lawful corporate purposes, the Company has duly authorized
the execution and delivery of this Indenture to provide for the issuance of
securities to be known as its 9.30% Subordinated Debentures due 2027
(hereinafter referred to as the "Debentures"), the form and substance of such
Debentures and the terms, provisions and conditions thereof to be set forth as
provided in this Indenture;

  WHEREAS, SBI Capital Trust, a Delaware statutory business trust (the "Trust"),
has offered to the public Twenty Five Million Twelve Thousand Five Hundred
Dollars ($25,012,500) aggregate liquidation amount of its Preferred Securities
(as defined herein) and proposes to invest the proceeds from such offering,
together with the proceeds of the issuance and sale by the Trust to the Company
of Seven Hundred Seventy Four Thousand Dollars ($774,000) aggregate liquidation
amount of its Common Securities (as defined herein), in Twenty Five Million
Seven Hundred Eighty Six Thousand Five Hundred Dollars ($25,786,500) aggregate
principal amount of the Debentures; and

  WHEREAS, the Company has requested that the Trustee execute and deliver this
Indenture; and

  WHEREAS, all requirements necessary to make this Indenture a valid instrument
in accordance with its terms, and to make the Debentures, when executed by the
Company and authenticated and delivered by the Trustee, the valid obligations of
the Company, have been performed, and the execution and delivery of this
Indenture have been duly authorized in all respects:

  WHEREAS, to provide the terms and conditions upon which the Debentures are to
be authenticated, issued and delivered, the Company has duly authorized the
execution of this Indenture; and

  WHEREAS, all things necessary to make this Indenture a valid agreement of the
Company, in accordance with its terms, have been done.

  NOW, THEREFORE, in consideration of the premises and the purchase of the
Debentures by the holders thereof, it is mutually covenanted and agreed as
follows for the equal and ratable benefit of the holders of the Debentures:

                                  ARTICLE I.

                                  DEFINITIONS
                                        
SECTION 1.1. DEFINITIONS OF TERMS

  The terms defined in this Section 1.1 (except as in this Indenture otherwise
expressly provided or unless the context otherwise requires) for all purposes of
this Indenture and of any indenture supplemental hereto shall have the
respective meanings specified in this Section 1.1 and shall include the plural
as well as the singular. All other terms used in this Indenture that are defined
in the Trust Indenture Act, or that are by reference in the Trust Indenture Act
defined in the Securities Act (except as herein otherwise expressly provided or
unless the context otherwise requires), shall have the meanings assigned to such
terms in the Trust Indenture Act and in the Securities Act as in force at the
date of the execution of this instrument. All accounting terms used herein and
not expressly defined shall have the meanings assigned to such terms in
accordance with Generally Accepted Accounting Principles.


                                      -1-
<PAGE>
 
  "Accelerated Maturity Date" means if the Company elects to accelerate the
Maturity Date in accordance with Section 2.2(c), the date selected by the
Company which is prior to the Scheduled Maturity Date, but is after July 31,
2002.

  "Additional Interest" shall have the meaning set forth in Section 2.5.

  "Additional Senior Obligations" means all indebtedness of the Company whether
incurred on or prior to the date of this Indenture or thereafter incurred, for
claims in respect of derivative products such as interest and foreign exchange
rate contracts, commodity contracts and similar arrangements; provided, however,
that Additional Senior Obligations does not include claims in respect of Senior
Debt or Subordinated Debt or obligations which, by their terms, are expressly
stated to be not superior in right of payment to the Debentures or to rank pari
passu in right of payment with the Debentures. For purposes of this definition,
"claim" shall have the meaning assigned thereto in Section 101(4) of the United
States Bankruptcy Code of 1978, as amended.

  "Administrative Trustees" shall have the meaning set forth in the Trust
Agreement.

  "Affiliate" means, with respect to a specified Person, (a) any Person directly
or indirectly owning, controlling or holding with power to vote 10% or more of
the outstanding voting securities or other ownership interests of the specified
Person; (b) any Person 10% or more of whose outstanding voting securities or
other ownership interests are directly or indirectly owned, controlled or held
with power to vote by the specified Person; (c) any Person directly or
indirectly controlling, controlled by, or under common control with the
specified Person; (d) a partnership in which the specified Person is a general
partner; (e) any officer or director of the specified Person; and (f) if the
specified Person is an individual, any entity of which the specified Person is
an officer, director or general partner.

  "Authenticating Agent" means an authenticating agent with respect to the
Debentures appointed by the Trustee pursuant to Section 2.12.

  "Bankruptcy Law" means Title 11, U.S. Code, or any similar federal or state
law for the relief of debtors.

  "Board of Directors" means the Board of Directors of the Company or any duly
authorized committee of such Board.

  "Board Resolution" means a copy of a resolution certified by the Secretary or
an Assistant Secretary of the Company to have been duly adopted by the Board of
Directors and to be in full force and effect on the date of such certification.

  "Business Day" means, with respect to the Debentures, any day other than a
Saturday or a Sunday or a day on which federal or state banking institutions in
the City of New York, are authorized or required by law, executive order or
regulation to close, or a day on which the Corporate Trust Office of the Trustee
or the Property Trustee is closed for business.

  "Capital Treatment Event" means the receipt by the Trust of an Opinion of
Counsel, rendered by a law firm experienced in such matters to the effect that,
as a result of any amendment to or any change (including any announced
prospective change) in the laws (or any regulations thereunder) of the United
States or any political subdivision thereof or therein, or as a result of any
official administrative pronouncement or judicial decision interpreting or
applying such laws or regulations, which amendment or change is effective or
such proposed change, pronouncement or decision is announced on or after the
date of issuance of the Preferred Securities under the Trust Agreement, there is
more than an insubstantial risk of impairment of the Company's ability to treat
the aggregate Liquidation Amount of the Preferred Securities (or any substantial
portion thereof) as "Tier 1 Capital" (or the then equivalent thereof) for
purposes of the capital adequacy guidelines of the Federal Reserve, as then
applicable to the Company, provided, however, that the inability of the Company
to treat all or any portion of the Liquidation Amount of the Preferred
Securities as Tier 1 Capital shall not constitute the basis of a Capital


                                      -2-
<PAGE>
 
Treatment Event if such inability results from the Company having cumulative
preferred capital in excess of the amount which may qualify for treatment as
Tier 1 Capital under applicable capital adequacy guidelines of the Federal
Reserve.

  "Certificate" means a certificate signed by the principal executive officer,
the principal financial officer, the principal accounting officer, the treasurer
or any vice president of the Company. The Certificate need not comply with the
provisions of Section 15.7.

  "Change in 1940 Act Law" shall have the meaning set forth in the definition of
"Investment Company Event."

  "Commission" means the Securities and Exchange Commission, as from time to
time constituted, created under the Exchange Act, or, if at any time after the
execution of this instrument such Commission is not existing and performing the
duties now assigned to it under the Trust Indenture Act, then the body
performing such duties at such time.

  "Common Securities" means undivided beneficial interests in the assets of the
Trust which rank pari passu with the Preferred Securities; provided, however,
that upon the occurrence of an Event of Default, the rights of holders of Common
Securities to payment in respect of (i) distributions, and (ii) payments upon
liquidation, redemption and otherwise, are subordinated to the rights of holders
of Preferred Securities.

  "Company" means Southwest Bancorp, Inc., a corporation duly organized and
existing under the laws of the State of Oklahoma, and, subject to the provisions
of Article XII, shall also include its successors and assigns.

  "Compounded Interest" shall have the meaning set forth in Section 4.1.

  "Corporate Trust Office" means the office of the Trustee at which, at any
particular time, its corporate trust business shall be principally administered,
which office at the date hereof is located at Two International Place, 4th
Floor, Boston, Massachusetts 02110, Attention: Corporate Trust Department.

  "Coupon Rate" shall have the meaning set forth in Section 2.5.

  "Custodian" means any receiver, trustee, assignee, liquidator, or similar
official under any Bankruptcy Law.

  "Debentures" shall have the meaning set forth in the Recitals hereto.

  "Debentureholder," "holder of Debentures," "registered holder," or other
similar term, means the Person or Persons in whose name or names a particular
Debenture shall be registered on the books of the Company or the Trustee kept
for that purpose in accordance with the terms of this Indenture.

  "Debenture Register" shall have the meaning set forth in Section 2.7(b).

  "Debenture Registrar" shall have the meaning set forth in Section 2.7(b).

  "Debt" means with respect to any Person, whether recourse is to all or a
portion of the assets of such Person and whether or not contingent, (i) every
obligation of such Person for money borrowed; (ii) every obligation of such
Person evidenced by bonds, debentures, notes or other similar instruments,
including obligations incurred in connection with the acquisition of property,
assets or businesses; (iii) every reimbursement obligation of such Person with
respect to letters of credit, bankers' acceptances or similar facilities issued
for the account of such Person; (iv) every obligation of such Person issued or
assumed as the deferred purchase price of property or services (but excluding
trade accounts payable or accrued liabilities arising in the ordinary course of
business); (v) every capital lease obligation of such Person; and (vi) and every
obligation of the type referred to in clauses (i) through (v) of another Person
and all dividends of another Person the payment of which, in either case, such
Person has guaranteed or is responsible or liable, directly or indirectly, as
obligor or otherwise.

                                      -3-
<PAGE>
 
  "Default" means any event, act or condition that with notice or lapse of time,
or both, would constitute an Event of Default.

  "Deferred Interest" shall have the meaning set forth in Section 4.1.

  "Dissolution Event" means that as a result of the occurrence and continuation
of a Special Event, the Trust is to be dissolved in accordance with the Trust
Agreement and the Debentures held by the Property Trustee are to be distributed
to the holders of the Trust Securities issued by the Trust pro rata in
accordance with the Trust Agreement.

  "Distribution" shall have the meaning set forth in the Trust Agreement.

  "Event of Default" means, with respect to the Debentures, any event specified
in Section 7.1, which has continued for the period of time, if any, and after
the giving of the notice, if any, therein designated.

  "Exchange Act," means the Securities Exchange Act of 1934, as amended, as in
effect at the date of execution of this instrument.

  "Extended Interest Payment Period" shall have the meaning set forth in Section
4.1.

  "Extended Maturity Date" means if the Company elects to extend the Maturity
Date in accordance with Section 2.2(b), the date selected by the Company which
is after the Scheduled Maturity Date but before July 31, 2036.

  "Federal Reserve" means the Board of Governors of the Federal Reserve System.

  "Generally Accepted Accounting Principles" means such accounting principles as
are generally accepted at the time of any computation required hereunder.

  "Governmental Obligations" means securities that are (i) direct obligations of
the United States of America for the payment of which its full faith and credit
is pledged; or (ii) obligations of a Person controlled or supervised by and
acting as an agency or instrumentality of the United States of America, the
payment of which is unconditionally guaranteed as a full faith and credit
obligation by the United States of America that, in either case, are not
callable or redeemable at the option of the issuer thereof, and shall also
include a depositary receipt issued by a bank (as defined in Section 3(a)(2) of
the Securities Act) as custodian with respect to any such Governmental
Obligation or a specific payment of principal of or interest on any such
Governmental Obligation held by such custodian for the account of the holder of
such depositary receipt; provided, however, that (except as required by law)
such custodian is not authorized to make any deduction from the amount payable
to the holder of such depositary receipt from any amount received by the
custodian in respect of the Governmental Obligation or the specific payment of
principal of or interest on the Governmental Obligation evidenced by such
depositary receipt.

  "Herein," "hereof," and "hereunder," and other words of similar import, refer
to this Indenture as a whole and not to any particular Article, Section or other
subdivision.

  "Indenture" means this instrument as originally executed or as it may from
time to time be supplemented or amended by one or more indentures supplemental
hereto entered into in accordance with the terms hereof.

  "Interest Payment Date" shall have the meaning set forth in Section 2.5.

  "Investment Company Act," means the Investment Company Act of 1940, as
amended, as in effect at the date of execution of this instrument.

  "Investment Company Event" means the receipt by the Trust of an Opinion of
Counsel, rendered by a law firm experienced in such matters, to the effect that,
as a result of the occurrence of a change in law or regulation or a

                                      -4-
<PAGE>
 
change in interpretation or application of law or regulation by any legislative
body, court, governmental agency or regulatory authority (a "Change in 1940 Act
Law"), the Trust is or shall be considered an "investment company" that is
required to be registered under the Investment Company Act, which Change in 1940
Act Law becomes effective on or after the date of original issuance of the
Preferred Securities under the Trust Agreement.

  "Maturity Date" means the date on which the Debentures mature and on which the
principal shall be due and payable together with all accrued and unpaid interest
thereon including Compounded Interest and Additional Interest, if any.

  "Ministerial Action" shall have the meaning set forth in Section 3.2.

  "Officers' Certificate" means a certificate signed by the President or a Vice
President and by the Treasurer or an Assistant Treasurer or the Controller or an
Assistant Controller or the Secretary or an Assistant Secretary of the Company
that is delivered to the Trustee in accordance with the terms hereof. Each such
certificate shall include the statements provided for in Section 15.7, if and to
the extent required by the provisions thereof.

  "Opinion of Counsel" means an opinion in writing of legal counsel, who may be
an employee of or counsel for the Company, that is delivered to the Trustee in
accordance with the terms hereof. Each such opinion shall include the statements
provided for in Section 15.7, if and to the extent required by the provisions
thereof.

  "Outstanding," when used with reference to the Debentures, means, subject to
the provisions of Section 10.4, as of any particular time, all Debentures
theretofore authenticated and delivered by the Trustee under this Indenture,
except (a) Debentures theretofore canceled by the Trustee or any paying agent,
or delivered to the Trustee or any paying agent for cancellation or that have
previously been canceled; (b) Debentures or portions thereof for the payment or
redemption of which moneys or Governmental Obligations in the necessary amount
shall have been deposited in trust with the Trustee or with any paying agent
(other than the Company) or shall have been set aside and segregated in trust by
the Company (if the Company shall act as its own paying agent); provided,
however, that if such Debentures or portions of such Debentures are to be
redeemed prior to the maturity thereof, notice of such redemption shall have
been given as in Article III provided, or provision satisfactory to the Trustee
shall have been made for giving such notice; and (c) Debentures in lieu of or in
substitution for which other Debentures shall have been authenticated and
delivered pursuant to the terms of Section 2.7.

  "Paying Agent" means any paying agent or co-paying agent appointed pursuant to
Section 5.3.

  "Person" means any individual, corporation, partnership, joint-venture, joint-
stock company, unincorporated organization or government or any agency or
political subdivision thereof.

  "Predecessor Debenture" means every previous Debenture evidencing all or a
portion of the same debt as that evidenced by such particular Debenture; and,
for the purposes of this definition, any Debenture authenticated and delivered
under Section 2.9 in lieu of a lost, destroyed or stolen Debenture shall be
deemed to evidence the same debt as the lost, destroyed or stolen Debenture.

  "Preferred Securities" means undivided beneficial interests in the assets of
the Trust which rank pari passu with Common Securities issued by the Trust;
provided, however, that upon the occurrence of an Event of Default, the rights
of holders of Common Securities to payment in respect of (i) distributions, and
(ii) payments upon liquidation, redemption and otherwise, are subordinated to
the rights of holders of Preferred Securities.

  "Preferred Securities Guarantee" means any guarantee that the Company may
enter into with the Trustee or other Persons that operate directly or indirectly
for the benefit of holders of Preferred Securities.

  "Property Trustee" has the meaning set forth in the Trust Agreement.

                                      -5-
<PAGE>
 
  "Responsible Officer" when used with respect to the Trustee means the Chairman
of the Board of Directors, the President, any Vice President, the Secretary, the
Treasurer, any trust officer, any corporate trust officer or any other officer
or assistant officer of the Trustee customarily performing functions similar to
those performed by the Persons who at the time shall be such officers,
respectively, or to whom any corporate trust matter is referred because of his
or her knowledge of and familiarity with the particular subject.

  "Scheduled Maturity Date" means July 31, 2027.

  "Securities Act," means the Securities Act of 1933, as amended, as in effect
at the date of execution of this instrument.

  "Senior Debt" means the principal of (and premium, if any) and interest, if
any (including interest accruing on or after the filing of any petition in
bankruptcy or for reorganization relating to the Company whether or not such
claim for post-petition interest is allowed in such proceeding), on Debt,
whether incurred on or prior to the date of this Indenture or thereafter
incurred, unless, in the instrument creating or evidencing the same or pursuant
to which the same is outstanding, it is provided that such obligations are not
superior in right of payment to the Debentures or to other Debt which is pari
passu with, or subordinated to, the Debentures; provided, however, that Senior
Debt shall not be deemed to include (i) any Debt of the Company which, when
incurred and without respect to any election under section 1111(b) of the United
States Bankruptcy Code of 1978, as amended, was without recourse to the Company;
(ii) any Debt of the Company to any of its subsidiaries; (iii) Debt to any
employee of the Company; (iv) Debt which by its terms is subordinated to trade
accounts payable or accrued liabilities arising in the ordinary course of
business to the extent that payments made to the holders of such Debt by the
holders of the Debentures as a result of the subordination provisions of this
Indenture would be greater than they otherwise would have been as a result of
any obligation of such holders to pay amounts over to the obligees on such trade
accounts payable or accrued liabilities arising in the ordinary course of
business as a result of subordination provisions to which such Debt is subject;
and (v) Debt which constitutes Subordinated Debt.

  "Senior Indebtedness" shall have the meaning set forth in Section 16.1.

  "Special Event" means a Tax Event, a Capital Treatment Event or an Investment
Company Event.

  "Subordinated Debt" means the principal of (and premium, if any) and interest,
if any (including interest accruing on or after the filing of any petition in
bankruptcy or for reorganization relating to the Company whether or not such
claim for post-petition interest is allowed in such proceeding), on Debt,
whether incurred on or prior to the date of this Indenture or thereafter
incurred, which is by its terms expressly provided to be junior and subordinate
to other Debt of the Company (other than the Debentures).

  "Subsidiary" means, with respect to any Person, (i) any corporation at least a
majority of whose outstanding Voting Stock shall at the time be owned, directly
or indirectly, by such Person or by one or more of its Subsidiaries or by such
Person and one or more of its Subsidiaries; (ii) any general partnership, joint
venture, trust or similar entity, at least a majority of whose outstanding
partnership or similar interests shall at the time be owned by such Person, or
by one or more of its Subsidiaries, or by such Person and one or more of its
Subsidiaries; and (iii) any limited partnership of which such Person or any of
its Subsidiaries is a general partner.

  "Tax Event" means the receipt by the Trust of an Opinion of Counsel, rendered
by a law firm experienced in such matters, to the effect that, as a result of
any amendment to, or change (including any announced prospective change) in, the
laws (or any regulations thereunder) of the United States or any political
subdivision or taxing authority thereof or therein, or as a result of any
official administrative pronouncement or judicial decision interpreting or
applying such laws or regulations, which amendment or change is effective or
which pronouncement or decision is announced on or after the date of issuance of
the Preferred Securities under the Trust Agreement, there is more than an
insubstantial risk that (i) the Trust is, or shall be within 90 days after the
date of such Opinion of Counsel, subject to United States federal income tax
with respect to income received or accrued on the Debentures; (ii) interest

                                      -6-
<PAGE>
 
payable by the Company on the Debentures is not, or within 90 days after the
date of such Opinion of Counsel, shall not be, deductible by the Company, in
whole or in part, for United States federal income tax purposes; or (iii) the
Trust is, or shall be within 90 days after the date of such Opinion of Counsel,
subject to more than a de minimis amount of other taxes, duties, assessments or
other governmental charges. The Trust or the Company shall request and receive
such Opinion of Counsel with regard to such matters within a reasonable period
of time after the Trust or the Company shall have become aware of the possible
occurrence of any of the events described in clauses (i) through (iii) above.

  "Trust" means SBI Capital Trust, a Delaware statutory business trust.

  "Trust Agreement" means the Amended and Restated Trust Agreement, dated June
4, 1997, of the Trust.

  "Trustee" means State Street Bank and Trust Company and, subject to the
provisions of Article IX, shall also include its successors and assigns, and, if
at any time there is more than one Person acting in such capacity hereunder,
"Trustee" shall mean each such Person.

  "Trust Indenture Act," means the Trust Indenture Act of 1939, as amended,
subject to the provisions of Sections 11.1, 11.2, and 12.1, as in effect at the
date of execution of this instrument.

  "Trust Securities" means the Common Securities and Preferred Securities,
collectively.

  "Voting Stock," as applied to stock of any Person, means shares, interests,
participations or other equivalents in the equity interest (however designated)
in such Person having ordinary voting power for the election of a majority of
the directors (or the equivalent) of such Person, other than shares, interests,
participations or other equivalents having such power only by reason of the
occurrence of a contingency.

                                  ARTICLE II

                     ISSUE, DESCRIPTION, TERMS, CONDITIONS
                  REGISTRATION AND EXCHANGE OF THE DEBENTURES

SECTION 2.1 DESIGNATION AND PRINCIPAL AMOUNT

  There is hereby authorized Debentures designated the "9.30% Subordinated
Debentures due 2027," limited in aggregate principal amount up to Twenty Five
Million Seven Hundred Eighty Six Thousand Five Hundred Dollars ($25,786,500)
which amount shall be as set forth in any written order of the Company for the
authentication and delivery of Debentures pursuant to Section 2.6.

SECTION 2.2. MATURITY

 (a) The Maturity Date shall be either:

     (i)    the Scheduled Maturity Date; or

     (ii)   if the Company elects to extend the Maturity Date beyond the
            Scheduled Maturity Date in accordance with Section 2.2(b), the
            Extended Maturity Date; or

     (iii)  if the Company elects to accelerate the Maturity Date to be a date
            prior to the Scheduled Maturity Date in accordance with Section
            2.2(c), the Accelerated Maturity Date.

 (b) The Company may at any time before the day which is 90 days before the
     Scheduled Maturity Date, elect to extend the Maturity Date to the Extended
     Maturity Date, provided that the Company has received the prior approval
     of the Federal Reserve, if then required under applicable capital


                                      -7-
<PAGE>
 
            guidelines or policies of the Federal Reserve, and further provided
            that the following conditions in this Section 2.2(b) are satisfied
            both at the date the Company gives notice in accordance with Section
            2.2(d) of its election to extend the Maturity Date and at the
            Scheduled Maturity Date:

     (i)    the Company is not in bankruptcy, otherwise insolvent or in
            liquidation;

     (ii)   the Company is not in default in the payment of interest or
            principal on the Debentures;

     (iii)  the Trust is not in arrears on payments of Distributions on the
            Trust Securities issued by it and no deferred Distributions are
            accumulated; and

     (iv)   the Company has a rating on its Senior Debt of investment grade.

  (c) The Company may, on one occasion, at any time before the day which is 90
      days before the Scheduled Maturity Date and after July 31, 2002, elect to
      shorten the Maturity Date to the Accelerated Maturity Date, provided that
      the Company has received the prior approval of the Federal Reserve, if
      then required under applicable capital guidelines or policies of the
      Federal Reserve.

  (d) If the Company elects to extend the Maturity Date in accordance with
      Section 2.2(b), the Company shall give notice to the registered holders of
      the Debentures, the Property Trustee and the Trust of the extension of the
      Maturity Date and the Extended Maturity Date at least 90 days and no more
      than 180 days before the Scheduled Maturity Date.

  (e) If the Company elects to accelerate the Maturity Date in accordance with
      Section 2.2(c), the Company shall give notice to the registered holders of
      the Debentures, the Property Trustee and the Trust of the acceleration of
      the Maturity Date and the Accelerated Maturity Date at least 90 days and
      no more than 180 days before the Accelerated. Maturity Date.

SECTION 2.3. FORM AND PAYMENT

  The Debentures shall be issued in fully registered certificated form without
interest coupons. Principal and interest on the Debentures issued in
certificated form shall be payable, the transfer of such Debentures shall be
registrable and such Debentures shall be exchangeable for Debentures bearing
identical terms and provisions at the office or agency of the Trustee; provided,
however, that payment of interest may be made at the option of the Company by
check mailed to the holder at such address as shall appear in the Debenture
Register or by wire transfer to an account maintained by the holder as specified
in the Debenture Register, provided that the holder provides proper transfer
instructions by the regular record date. Notwithstanding the foregoing, so long
as the holder of any Debentures is the Property Trustee, the payment of the
principal of and interest (including Compounded Interest and Additional
Interest, if any) on such Debentures held by the Property Trustee shall be made
at such place and to such account as may be designated by the Property Trustee.

SECTION 2.4. [Intentionally Omitted]

SECTION 2.5. INTEREST

  (a) Each Debenture shall bear interest at the rate of 9.30% per annum (the
"Coupon Rate") from the original date of issuance until the principal thereof
becomes due and payable, and on any overdue principal and (to the extent that
payment of such interest is enforceable under applicable law) on any overdue
installment of interest at the Coupon Rate, compounded quarterly, payable
(subject to the provisions of Article IV) quarterly in arrears on January 31,
April 30, July 31, and October 31 of each year (each, an "Interest Payment
Date," commencing on July 31, 1997), to the Person in whose name such Debenture
or any Predecessor Debenture is registered, at the close of business on

                                      -8-
<PAGE>
 
the regular record date for such interest installment, which shall be the
fifteenth day of the last month of the calendar quarter.

  (b) The amount of interest payable for any period shall be computed on the
basis of a 360-day year of twelve 30-day months. The amount of interest payable
for any period shorter than a full quarterly period for which interest is
computed shall be computed on the basis of the number of days elapsed in a 360-
day year of twelve 30-day months. In the event that any date on which interest
is payable on the Debentures is not a Business Day, then payment of interest
payable on such date shall be made on the next succeeding day which is a
Business Day (and without any interest or other payment in respect of any such
delay) with the same force and effect as if made on the date such payment was
originally payable.

  (c) If, at any time while the Property Trustee is the holder of any
Debentures, the Trust or the Property Trustee is required to pay any taxes,
duties, assessments or governmental charges of whatever nature (other than
withholding taxes) imposed by the United States, or any other taxing authority,
then, in any case, the Company shall pay as additional interest ("Additional
Interest") on the Debentures held by the Property Trustee, such additional
amounts as shall be required so that the net amounts received and retained by
the Trust and the Property Trustee after paying such taxes, duties, assessments
or other governmental charges shall be equal to the amounts the Trust and the
Property Trustee would have received had no such taxes, duties, assessments or
other government charges been imposed.

SECTION 2.6. EXECUTION AND AUTHENTICATIONS

  (a) The Debentures shall be signed on behalf of the Company by its Chief
Executive Officer, President or one of its Vice Presidents, under its corporate
seal attested by its Secretary or one of its Assistant Secretaries. Signatures
may be in the form of a manual or facsimile signature. The Company may use the
facsimile signature of any Person who shall have been a Chief Executive Officer,
President or Vice President thereof, or of any Person who shall have been a
Secretary or Assistant Secretary thereof, notwithstanding the fact that at the
time the Debentures shall be authenticated and delivered or disposed of such
Person shall have ceased to be the Chief Executive Officer, President or a Vice
President, or the Secretary or an Assistant Secretary, of the Company. The seal
of the Company may be in the form of a facsimile of such seal and may be
impressed, affixed, imprinted or otherwise reproduced on the Debentures. The
Debentures may contain such notations, legends or endorsements required by law,
stock exchange rule or usage. Each Debenture shall be dated the date of its
authentication by the Trustee.

  (b) A Debenture shall not be valid until manually authenticated by an
authorized signatory of the Trustee, or by an Authenticating Agent. Such
signature shall be conclusive evidence that the Debenture so authenticated has
been duly authenticated and delivered hereunder and that the holder is entitled
to the benefits of this Indenture.

  (c) At any time and from time to time after the execution and delivery of this
Indenture, the Company may deliver Debentures executed by the Company to the
Trustee for authentication, together with a written order of the Company for the
authentication and delivery of such Debentures signed by its Chief Executive
Officer, President or any Vice President and its Treasurer or any Assistant
Treasurer, and the Trustee in accordance with such written order shall
authenticate and deliver such Debentures.

  (d) In authenticating such Debentures and accepting the additional
responsibilities under this Indenture in relation to such Debentures, the
Trustee shall be entitled to receive, and (subject to Section 9.1) shall be
fully protected in relying upon, an Opinion of Counsel stating that the form and
terms thereof have been established in conformity with the provisions of this
Indenture.

  (e) The Trustee shall not be required to authenticate such Debentures if the
issue of such Debentures pursuant to this Indenture shall affect the Trustee's
own rights, duties or immunities under the Debentures and this Indenture or
otherwise in a manner that is not reasonably acceptable to the Trustee.

                                      -9-
<PAGE>
 
SECTION 2.7. REGISTRATION OF TRANSFER AND EXCHANGE

  (a) Debentures may be exchanged upon presentation thereof at the office or
agency of the Company designated for such purpose in the Borough of Manhattan,
the City of New York, or at the office of the Debenture Registrar, for other
Debentures and for a like aggregate principal amount, upon payment of a sum
sufficient to cover any tax or other governmental charge in relation thereto,
all as provided in this Section 2.7. In respect of any Debentures so surrendered
for exchange, the Company shall execute, the Trustee shall authenticate and such
office or agency shall deliver in exchange therefor the Debenture or Debentures
that the Debentureholder making the exchange shall be entitled to receive,
bearing numbers not contemporaneously outstanding.

  (b) The Company shall keep, or cause to be kept, at its office or agency
designated for such purpose in the Borough of Manhattan, the City of New York,
or at the office of the Debenture Registrar, or such other location designated
by the Company a register or registers (herein referred to as the "Debenture
Register") in which, subject to such reasonable regulations as it may prescribe,
the Company shall register the Debentures and the transfers of Debentures as in
this Article II provided and which at all reasonable times shall be open for
inspection by the Trustee. The registrar for the purpose of registering
Debentures and transfer of Debentures as herein provided shall initially be the
Trustee and thereafter as may be appointed by the Company as authorized by Board
Resolution (the "Debenture Registrar"). Upon surrender for transfer of any
Debenture at the office or agency of the Company designated for such purpose,
the Company shall execute, the Trustee shall authenticate and such office or
agency shall deliver in the name of the transferee or transferees a new
Debenture or Debentures for a like aggregate principal amount. All Debentures
presented or surrendered for exchange or registration of transfer, as provided
in this Section 2.7, shall be accompanied (if so required by the Company or the
Debenture Registrar) by a written instrument or instruments of transfer, in form
satisfactory to the Company or the Debenture Registrar, duly executed by the
registered holder or by such holder's duly authorized attorney in writing.

  (c) No service charge shall be made for any exchange or registration of
transfer of Debentures, or issue of new Debentures in case of partial
redemption, but the Company may require payment of a sum sufficient to cover any
tax or other governmental charge in relation thereto, other than exchanges
pursuant to Section 2.8, Section 3.5(b) and Section 11.4 not involving any
transfer.

  (d) The Company shall not be required (i) to issue, exchange or register the
transfer of any Debentures during a period beginning at the opening of business
15 days before the day of the mailing of a notice of redemption of less than all
the Outstanding Debentures and ending at the close of business on the day of
such mailing; nor (ii) to register the transfer of or exchange any Debentures or
portions thereof called for redemption.

SECTION 2.8. TEMPORARY DEBENTURES

  Pending the preparation of definitive Debentures, the Company may execute, and
the Trustee shall authenticate and deliver, temporary Debentures (printed,
lithographed, or typewritten). Such temporary Debentures shall be substantially
in the form of the definitive Debentures in lieu of which they are issued, but
with such omissions, insertions and variations as may be appropriate for
temporary Debentures, all as may be determined by the Company. Every temporary
Debenture shall be executed by the Company and be authenticated by the Trustee
upon the same conditions and in substantially the same manner, and with like
effect, as the definitive Debentures. Without unnecessary delay the Company
shall execute and shall furnish definitive Debentures and thereupon any or all
temporary Debentures may be surrendered in exchange therefor (without charge to
the holders), at the office or agency of the Company designated for the purpose
in the Borough of Manhattan, the City of New York, and the Trustee shall
authenticate and such office or agency shall deliver in exchange for such
temporary Debentures an equal aggregate principal amount of definitive
Debentures, unless the Company advises the Trustee to the effect that definitive
Debentures need not be executed and furnished until further notice from the
Company. Until so exchanged, the temporary Debentures shall be entitled to the
same benefits under this Indenture as definitive Debentures authenticated and
delivered hereunder.

                                     -10-
<PAGE>
 
SECTION 2.9. MUTILATED, DESTROYED, LOST OR STOLEN DEBENTURES

  (a) In case any temporary or definitive Debenture shall become mutilated or be
destroyed, lost or stolen, the Company (subject to the next succeeding sentence)
shall execute, and upon the Company's request the Trustee (subject as aforesaid)
shall authenticate and deliver, a new Debenture bearing a number not
contemporaneously outstanding, in exchange and substitution for the mutilated
Debenture, or in lieu of and in substitution for the Debenture so destroyed,
lost or stolen. In every case the applicant for a substituted Debenture shall
furnish to the Company and the Trustee such security or indemnity as may be
required by them to save each of them harmless, and, in every case of
destruction, loss or theft, the applicant shall also furnish to the Company and
the Trustee evidence to their satisfaction of the destruction, loss or theft of
the applicant's Debenture and of the ownership thereof. The Trustee may
authenticate any such substituted Debenture and deliver the same upon the
written request or authorization of the Chairman, President or any Vice
President and the Treasurer or any Assistant Treasurer of the Company. Upon the
issuance of any substituted Debenture, the Company may require the payment of a
sum sufficient to cover any tax or other governmental charge that may be imposed
in relation thereto and any other expenses (including the fees and expenses of
the Trustee) connected therewith. In case any Debenture that has matured or is
about to mature shall become mutilated or be destroyed, lost or stolen, the
Company may, instead of issuing a substitute Debenture, pay or authorize the
payment of the same (without surrender thereof except in the case of a mutilated
Debenture) if the applicant for such payment shall furnish to the Company and
the Trustee such security or indemnity as they may require to save them
harmless, and, in case of destruction, loss or theft, evidence to the
satisfaction of the Company and the Trustee of the destruction, loss or theft of
such Debenture and of the ownership thereof.

  (b) Every replacement Debenture issued pursuant to the provisions of this
Section 2.9 shall constitute an additional contractual obligation of the Company
whether or not the mutilated, destroyed, lost or stolen Debenture shall be found
at any time, or be enforceable by anyone, and shall be entitled to all the
benefits of this Indenture equally and proportionately with any and all other
Debentures duly issued hereunder. All Debentures shall be held and owned upon
the express condition that the foregoing provisions are exclusive with respect
to the replacement or payment of mutilated, destroyed, lost or stolen
Debentures, and shall preclude (to the extent lawful) any and all other rights
or remedies, notwithstanding any law or statute existing or hereafter enacted to
the contrary with respect to the replacement or payment of negotiable
instruments or other securities without their surrender.

SECTION 2.10. CANCELLATION

  All Debentures surrendered for the purpose of payment, redemption, exchange or
registration of transfer shall, if surrendered to the Company or any paying
agent, be delivered to the Trustee for cancellation, or, if surrendered to the
Trustee, shall be canceled by it, and no Debentures shall be issued in lieu
thereof except as expressly required or permitted by any of the provisions of
this Indenture. On request of the Company at the time of such surrender, the
Trustee shall deliver to the Company canceled Debentures held by the Trustee. In
the absence of such request the Trustee may dispose of canceled Debentures in
accordance with its standard procedures and deliver a certificate of disposition
to the Company. If the Company shall otherwise acquire any of the Debentures,
however, such acquisition shall not operate as a redemption or satisfaction of
the indebtedness represented by such Debentures unless and until the same are
delivered to the Trustee for cancellation.

SECTION 2.11. BENEFIT OF INDENTURE

  Nothing in this Indenture or in the Debentures, express or implied, shall give
or be construed to give to any Person, other than the parties hereto and the
holders of the Debentures (and, with respect to the provisions of Article XVI,
the holders of Senior Indebtedness) any legal or equitable right, remedy or
claim under or in respect of this Indenture, or under any covenant, condition or
provision herein contained; all such covenants, conditions and provisions being
for the sole benefit of the parties hereto and of the holders of the Debentures
(and, with respect to the provisions of Article XVI, the holders of Senior
Indebtedness).

                                     -11-
<PAGE>
 
SECTION 2.12. AUTHENTICATION AGENT

  (a) So long as any of the Debentures remain Outstanding there may be an
Authenticating Agent for any or all such Debentures, which the Trustee shall
have the right to appoint. Said Authenticating Agent shall be authorized to act
on behalf of the Trustee to authenticate Debentures issued upon exchange,
transfer or partial redemption thereof, and Debentures so authenticated shall be
entitled to the benefits of this Indenture and shall be valid and obligatory for
all purposes as if authenticated by the Trustee hereunder. All references in
this Indenture to the authentication of Debentures by the Trustee shall be
deemed to include authentication by an Authenticating Agent. Each Authenticating
Agent shall be acceptable to the Company and shall be a corporation that has a
combined capital and surplus, as most recently reported or determined by it,
sufficient under the laws of any jurisdiction under which it is organized or in
which it is doing business to conduct a trust business, and that is otherwise
authorized under such laws to conduct such business and is subject to
supervision or examination by federal or state authorities. If at any time any
Authenticating Agent shall cease to be eligible in accordance with these
provisions, it shall resign immediately.

  (b) Any Authenticating Agent may at any time resign by giving written notice
of resignation to the Trustee and to the Company. The Trustee may at any time
(and upon request by the Company shall) terminate the agency of any
Authenticating Agent by giving written notice of termination to such
Authenticating Agent and to the Company. Upon resignation, termination or
cessation of eligibility of any Authenticating Agent, the Trustee may appoint an
eligible successor Authenticating Agent acceptable to the Company. Any successor
Authenticating Agent, upon acceptance of its appointment hereunder, shall become
vested with all the rights, powers and duties of its predecessor hereunder as if
originally named as an Authenticating Agent pursuant hereto.

                                 ARTICLE III.

                           REDEMPTION OF DEBENTURES


SECTION 3.1. REDEMPTION

  Subject to the Company having received prior approval of the Federal Reserve,
if then required under the applicable capital guidelines or policies of the
Federal Reserve, the Company may redeem the Debentures issued hereunder on and
after the dates set forth in and in accordance with the terms of this Article
III.

SECTION 3.2. SPECIAL EVENT REDEMPTION

  Subject to the Company having received the prior approval of the Federal
Reserve, if then required under the applicable capital guidelines or policies of
the Federal Reserve, if a Special Event has occurred and is continuing, then,
notwithstanding Section 3.3(a) but subject to Section 3.3(b), the Company shall
have the right upon not less than 30 days nor more than 60 days notice to the
holders of the Debentures to redeem the Debentures, in whole but not in part,
for cash within 180 days following the occurrence of such Special Event (the
"180-Day Period") at a redemption price equal to 100% of the principal amount to
be redeemed plus any accrued and unpaid interest thereon to the date of such
redemption (the "Redemption Price"), provided that if at the time there is
available to the Company the opportunity to eliminate, within the 180-Day
Period, a Tax Event by taking some ministerial action (a "Ministerial Action"),
such as filing a form or making an election, or pursuing some other similar
reasonable measure which has no adverse effect on the Company, the Trust or the
holders of the Trust Securities issued by the Trust, the Company shall pursue
such Ministerial Action in lieu of redemption, and, provided further, that the
Company shall have no right to redeem the Debentures while the Trust is pursuing
any Ministerial Action pursuant to its obligations under the Trust Agreement.
The Redemption Price shall be paid prior to 12:00 noon, New York time, on the
date of such redemption or such earlier time as the Company determines, provided
that the Company shall deposit with the Trustee an amount sufficient to pay the
Redemption Price by 10:00 a.m., New York time, on the date such Redemption Price
is to be paid.

                                     -12-
<PAGE>
 
SECTION 3.3. OPTIONAL REDEMPTION BY COMPANY

  (a) Subject to the provisions of Section 3.3(b), except as otherwise may be
specified in this Indenture, the Company shall have the right to redeem the
Debentures, in whole or in part, from time to time, on or after July 31, 2002,
at a Redemption Price equal to 100% of the principal amount to be redeemed plus
any accrued and unpaid interest thereon to the date of such redemption. Any
redemption pursuant to this Section 3.3(a) shall be made upon not less than 30
days nor more than 60 days notice to the holder of the Debentures, at the
Redemption Price. If the Debentures are only partially redeemed pursuant to this
Section 3.3, the Debentures shall be redeemed pro rata or by lot or in such
other manner as the Trustee shall deem appropriate and fair in its discretion.
The Redemption Price shall be paid prior to 12:00 noon, New York time, on the
date of such redemption or at such earlier time as the Company determines
provided that the Company shall deposit with the Trustee an amount sufficient to
pay the Redemption Price by 10:00 a.m., New York time, on the date such
Redemption Price is to be paid.

  (b) If a partial redemption of the Debentures would result in the delisting of
the Preferred Securities issued by the Trust from The Nasdaq Stock Market's
National Market or any national securities exchange or other organization on
which the Preferred Securities are then listed, the Company shall not be
permitted to effect such partial redemption and may only redeem the Debentures
in whole.

SECTION 3.4. NOTICE OF REDEMPTION

  (a) In case the Company shall desire to exercise such right to redeem all or,
as the case may be, a portion of the Debentures in accordance with the right
reserved so to do, the Company shall, or shall cause the Trustee to, upon
receipt of 45 days' written notice from the Company (which notice shall, in the
event of a partial redemption, include a representation to the effect that such
partial redemption shall not result in the delisting of the Preferred Securities
as described in Section 3.3(b) above), give notice of such redemption to holders
of the Debentures to be redeemed by mailing, first class postage prepaid, a
notice of such redemption, not less than 30 days and not more than 60 days
before the date fixed for redemption to such holders at their last addresses as
they shall appear upon the Debenture Register unless a shorter period is
specified in the Debentures to be redeemed. Any notice that is mailed in the
manner herein provided shall be conclusively presumed to have been duly given,
whether or not the registered holder receives the notice. In any case, failure
duly to give such notice to the holder of any Debenture designated for
redemption in whole or in part, or any defect in the notice, shall not affect
the validity of the proceedings for the redemption of any other Debentures. In
the case of any redemption of Debentures prior to the expiration of any
restriction on such redemption provided in the terms of such Debentures or
elsewhere in this Indenture, the Company shall furnish the Trustee with an
Officers' Certificate evidencing compliance with any such restriction. Each such
notice of redemption shall specify the date fixed for redemption and the
Redemption Price and shall state that payment of the Redemption Price shall be
made at the office or agency of the Company in the Borough of Manhattan, the
City of New York or at the Corporate Trust Office, upon presentation and
surrender of such Debentures, that interest accrued to the date fixed for
redemption shall be paid as specified in said notice and that from and after
said date interest shall cease to accrue. If less than all the Debentures are to
be redeemed, the notice to the holders of the Debentures shall specify the
particular Debentures to be redeemed. If the Debentures are to be redeemed in
part only, the notice shall state the portion of the principal amount thereof to
be redeemed and shall state that on and after the redemption date, upon
surrender of such Debenture, a new Debenture or Debentures in principal amount
equal to the unredeemed portion thereof shall be issued.

  (b) If less than all the Debentures are to be redeemed, the Company shall give
the Trustee at least 45 days' notice in advance of the date fixed for redemption
as to the aggregate principal amount of Debentures to be redeemed, and thereupon
the Trustee shall select, by lot or in such other manner as it shall deem
appropriate and fair in its discretion, the portion or portions (equal to $25 or
any integral multiple thereof) of the Debentures to be redeemed and shall
thereafter promptly notify the Company in writing of the numbers of the
Debentures to be redeemed, in whole or in part. The Company may, if and whenever
it shall so elect pursuant to the terms hereof, by delivery of instructions
signed on its behalf by its President or any Vice President, instruct the
Trustee or any paying agent to call all or any part of the Debentures for
redemption and to give notice of redemption in the manner set forth in this

                                     -13-
<PAGE>
 
Section 3.4, such notice to be in the name of the Company or its own name as the
Trustee or such paying agent may deem advisable. In any case in which notice of
redemption is to be given by the Trustee or any such paying agent, the Company
shall deliver or cause to be delivered to, or permit to remain with, the Trustee
or such paying agent, as the case may be, such Debenture Register, transfer
books or other records, or suitable copies or extracts therefrom, sufficient to
enable the Trustee or such paying agent to give any notice by mail that may be
required under the provisions of this Section 3.4.

SECTION 3.5. PAYMENT UPON REDEMPTION

  (a) If the giving of notice of redemption shall have been completed as above
provided, the Debentures or portions of Debentures to be redeemed specified in
such notice shall become due and payable on the date and at the place stated in
such notice at the applicable Redemption Price, and interest on such Debentures
or portions of Debentures shall cease to accrue on and after the date fixed for
redemption, unless the Company shall default in the payment of such Redemption
Price with respect to any such Debenture or portion thereof. On presentation and
surrender of such Debentures on or after the date fixed for redemption at the
place of payment specified in the notice, said Debentures shall be paid and
redeemed at the Redemption Price (but if the date fixed for redemption is an
interest payment date, the interest installment payable on such date shall be
payable to the registered holder at the close of business on the applicable
record date pursuant to Section 3.3).

  (b) Upon presentation of any Debenture that is to be redeemed in part only,
the Company shall execute and the Trustee shall authenticate and the office or
agency where the Debenture is presented shall deliver to the holder thereof, at
the expense of the Company, a new Debenture of authorized denomination in
principal amount equal to the unredeemed portion of the Debenture so presented.

SECTION 3.6. NO SINKING FUND

 The Debentures are not entitled to the benefit of any sinking fund.

                                  ARTICLE IV.

                     EXTENSION OF INTEREST PAYMENT PERIOD

SECTION 4.1. EXTENSION OF INTEREST PAYMENT PERIOD

  So long as no Event of Default has occurred and is continuing, the Company
shall have the right, at any time and from time to time during the term of the
Debentures, to defer payments of interest by extending the interest payment
period of such Debentures for a period not exceeding 20 consecutive quarters
(the "Extended Interest Payment Period"), during which Extended Interest Payment
Period no interest shall be due and payable; provided that no Extended Interest
Payment Period may extend beyond the Maturity Date. Interest, the payment of
which has been deferred because of the extension of the interest payment period
pursuant to this Section 4.1, shall bear interest thereon at the Coupon Rate
compounded quarterly for each quarter of the Extended Interest Payment Period
("Compounded Interest"). At the end of the Extended Interest Payment Period, the
Company shall calculate (and deliver such calculation to the Trustee) and pay
all interest accrued and unpaid on the Debentures, including any Additional
Interest and Compounded Interest (together, "Deferred Interest") that shall be
payable to the holders of the Debentures in whose names the Debentures are
registered in the Debenture Register on the first record date after the end of
the Extended Interest Payment Period. Before the termination of any Extended
Interest Payment Period, the Company may further extend such period, provided
that such period together with all such further extensions thereof shall not
exceed 20 consecutive quarters, or extend beyond the Maturity Date of the
Debentures. Upon the termination of any Extended Interest Payment Period and
upon the payment of all Deferred Interest then due, the Company may commence a
new Extended Interest Payment Period, subject to the foregoing requirements. No
interest shall be due and payable during an Extended Interest Payment Period,
except at the end thereof, but the Company may prepay at any time all or any
portion of the interest accrued during an Extended Interest Payment Period.

                                     -14-
<PAGE>
 
SECTION 4.2. NOTICE OF EXTENSION

  (a) If the Property Trustee is the only registered holder of the Debentures at
the time the Company elects an Extended Interest Payment Period, the Company
shall give written notice to the Administrative Trustees, the Property Trustee
and the Trustee of its election of such Extended Interest Payment Period two
Business Days before the earlier of (i) the next succeeding date on which
Distributions on the Trust Securities issued by the Trust are payable; or (ii)
the date the Trust is required to give notice of the record date, or the date
such Distributions are payable, to The Nasdaq Stock Market's National Market or
other applicable self-regulatory organization or to holders of the Preferred
Securities issued by the Trust, but in any event at least one Business Day
before such record date.

  (b) If the Property Trustee is not the only holder of the Debentures at the
time the Company elects an Extended Interest Payment Period, the Company shall
give the holders of the Debentures and the Trustee written notice of its
election of such Extended Interest Payment Period at least two Business Days
before the earlier of (i) the next succeeding Interest Payment Date; or (ii) the
date the Company is required to give notice of the record or payment date of
such interest payment to The Nasdaq Stock Market's National Market or other
applicable self-regulatory organization or to holders of the Debentures.

  (c) The quarter in which any notice is given pursuant to paragraphs (a) or (b)
of this Section 4.2 shall be counted as one of the 20 quarters permitted in the
maximum Extended Interest Payment Period permitted under Section 4.1.

SECTION 4.3. LIMITATION ON TRANSACTIONS

  If (i) the Company shall exercise its right to defer payment of interest as
provided in Section 4.1; or (ii) there shall have occurred any Event of Default,
then (a) the Company shall not declare or pay any dividend on, make any
distributions with respect to, or redeem, purchase, acquire or make a
liquidation payment with respect to, any of its capital stock; (b) the Company
shall not make any payment of interest, principal or premium, if any, or repay,
repurchase or redeem any debt securities issued by the Company which rank pari
passu with or junior to the Debentures; provided, however, that notwithstanding
the foregoing the Company may make payments pursuant to its obligations under
the Preferred Securities Guarantee; and (c) the Company shall not redeem,
purchase or acquire less than all of the Outstanding Debentures or any of the
Preferred Securities.

                                  ARTICLE V.

                      PARTICULAR COVENANTS OF THE COMPANY

SECTION 5.1. PAYMENT OF PRINCIPAL AND INTEREST

  The Company shall duly and punctually pay or cause to be paid the principal of
and interest on the Debentures at the time and place and in the manner provided
herein.

SECTION 5.2. MAINTENANCE OF AGENCY

  So long as any of the Debentures remain Outstanding, the Company shall
maintain an office or agency in the Borough of Manhattan, the City of New York,
and at such other location or locations as may be designated as provided in this
Section 5.2, where (i) Debentures may be presented for payment; (ii) Debentures
may be presented as hereinabove authorized for registration of transfer and
exchange; and (iii) notices and demands to or upon the Company in respect of the
Debentures and this Indenture may be given or served, such designation to
continue with respect to such office or agency until the Company shall, by
written notice signed by its President or a Vice President and delivered to the
Trustee, designate some other office or agency for such purposes or any of them.
If at any time the Company shall fail to maintain any such required office or
agency or shall fail to furnish the Trustee with the address thereof, such
presentations, notices and demands may be made or served at the Corporate Trust
Office of the Trustee, and the Company hereby appoints the Trustee as its agent
to receive all such presentations, notices and demands. In addition to any such
office or agency, the Company may from time to time designate one or more

                                     -15-
<PAGE>
 
offices or agencies outside of the Borough of Manhattan, the City of New York,
where the Debentures may be presented for registration or transfer and for
exchange in the manner provided herein, and the Company may from time to time
rescind such designation as the Company may deem desirable or expedient;
provided, however, that no such designation or rescission shall in any manner
relieve the Company of its obligation to maintain any such office or agency in
the Borough of Manhattan, the City of New York, for the purposes above
mentioned. The Company shall give the Trustee prompt written notice of any such
designation or rescission thereof.

SECTION 5.3. PAYING AGENTS

  (a) The Trustee shall act as the Paying Agent.  If the Company shall appoint
one or more paying agents for the Debentures, other than the Trustee, the
Company shall cause each such paying agent to execute and deliver to the Trustee
an instrument in which such agent shall agree with the Trustee, subject to the
provisions of this Section 5.3:

  (i) that it shall hold all sums held by it as such agent for the payment of
the principal of or interest on the Debentures (whether such sums have been paid
to it by the Company or by any other obligor of such Debentures) in trust for
the benefit of the Persons entitled thereto;

  (ii) that it shall give the Trustee notice of any failure by the Company (or
by any other obligor of such Debentures) to make any payment of the principal of
or interest on the Debentures when the same shall be due and payable;

  (iii) that it shall, at any time during the continuance of any failure
referred to in the preceding paragraph (a)(ii) above, upon the written request
of the Trustee, forthwith pay to the Trustee all sums so held in trust by such
Paying Agent; and

  (iv) that it shall perform all other duties of Paying Agent as set forth in
this Indenture.

  (b) If the Company shall act as its own Paying Agent with respect to the
Debentures, it shall on or before each due date of the principal of or interest
on such Debentures, set aside, segregate and hold in trust for the benefit of
the Persons entitled thereto a sum sufficient to pay such principal or interest
so becoming due on Debentures until such sums shall be paid to such Persons or
otherwise disposed of as herein provided and shall promptly notify the Trustee
of such action, or any failure (by it or any other obligor on such Debentures)
to take such action. Whenever the Company shall have one or more Paying Agents
for the Debentures, it shall, prior to each due date of the principal of or
interest on any Debentures, deposit with the Paying Agent a sum sufficient to
pay the principal or interest so becoming due, such sum to be held in trust for
the benefit of the Persons entitled to such principal or interest, and (unless
such Paying Agent is the Trustee) the Company shall promptly notify the Trustee
of this action or failure so to act.

  (c) Notwithstanding anything in this Section 5.3 to the contrary, (i) the
agreement to hold sums in trust as provided in this Section 5.3 is subject to
the provisions of Section 13.3 and 13.4; and (ii) the Company may at any time,
for the purpose of obtaining the satisfaction and discharge of this Indenture or
for any other purpose, pay, or direct any Paying Agent to pay, to the Trustee
all sums held in trust by the Company or such Paying Agent, such sums to be held
by the Trustee upon the same terms and conditions as those upon which such sums
were held by the Company or such Paying Agent; and, upon such payment by any
Paying Agent to the Trustee, such Paying Agent shall be released from all
further liability with respect to such money.

SECTION 5.4. APPOINTMENT TO FILL VACANCY IN OFFICE OF TRUSTEE

  The Company, whenever necessary to avoid or fill a vacancy in the office of
Trustee, shall appoint, in the manner provided in Section 9.10, a Trustee, so
that there shall at all times be a Trustee hereunder.

                                     -16-
<PAGE>
 
SECTION 5.5. COMPLIANCE WITH CONSOLIDATION PROVISIONS

  The Company shall not, while any of the Debentures remain outstanding,
consolidate with, or merge into, or merge into itself, or sell or convey all or
substantially all of its property to, any other company, unless the provisions
of Article XII hereof are complied with.

SECTION 5.6. LIMITATION ON TRANSACTIONS

  If Debentures are issued to the Trust or a trustee of the Trust in connection
with the issuance of Trust Securities by the Trust and (i) there shall have
occurred any event that would constitute an Event of Default; (ii) the Company
shall be in default with respect to its payment of any obligations under the
Preferred Securities Guarantee relating to the Trust; or (iii) the Company shall
have given notice of its election to defer payments of interest on such
Debentures by extending the interest payment period as provided in this
Indenture and such period, or any extension thereof, shall be continuing, then
(a) the Company shall not declare or pay any dividend on, make any distributions
with respect to, or redeem, purchase, acquire or make a liquidation payment with
respect to, any of its capital stock; (b) the Company shall not make any payment
of interest, principal or premium, if any, or repay, repurchase or redeem any
debt securities issued by the Company which rank pari passu with or junior to
the Debentures; provided, however, that the Company may make payments pursuant
to its obligations under the Preferred Securities Guarantee; and (c) the Company
shall not redeem, purchase or acquire less than all of the Outstanding
Debentures or any of the Preferred Securities.

SECTION 5.7. COVENANTS AS TO THE TRUST

  For so long as the Trust Securities of the Trust remain outstanding, the
Company shall (i) maintain 100% direct or indirect ownership of the Common
Securities of the Trust; provided, however, that any permitted successor of the
Company under this Indenture may succeed to the Company's ownership of the
Common Securities; (ii) not voluntarily terminate, wind up or liquidate the
Trust, except upon prior approval of the Federal Reserve, if then so required
under applicable capital guidelines or policies of the Federal Reserve, and use
its reasonable efforts to cause the Trust (a) to remain a business trust, except
in connection with a distribution of Debentures, the redemption of all of the
Trust Securities of the Trust or certain mergers, consolidations or
amalgamations, each as permitted by the Trust Agreement; and (b) to otherwise
continue not to be treated as an association taxable as a corporation for United
States federal income tax purposes; and (iii) use its reasonable efforts to
cause each holder of Trust Securities to be treated as owning an individual
beneficial interest in the Debentures. In connection with the distribution of
the Debentures to the holders of the Preferred Securities issued by the Trust
upon a Dissolution Event, the Company shall use its best efforts to list such
Debentures on The Nasdaq Stock Market's National Market or on such other
exchange as the Preferred Securities are then listed.

SECTION 5.8. COVENANTS AS TO PURCHASES

  Except upon the exercise by the Company of its right to redeem the Debentures
pursuant to Section 3.2 upon the occurrence and continuation of a Special Event,
the Company shall not purchase any Debentures, in whole or in part, from the
Trust prior to July 31, 2002.

                                  ARTICLE VI

                      DEBENTUREHOLDERS' LISTS AND REPORTS
                        BY THE COMPANY AND THE TRUSTEE

SECTION 6.1. COMPANY TO FURNISH TRUSTEE NAMES AND ADDRESSES OF DEBENTUREHOLDERS.

  The Company shall furnish or cause to be furnished to the Trustee (a) on a
quarterly basis on each regular record date (as described in Section 2.5) a
list, in such form as the Trustee may reasonably require, of the names and
addresses of the holders of the Debentures as of such regular record date,


                                     -17-
<PAGE>
 
provided that the Company shall not be obligated to furnish or cause to furnish
such list at any time that the list shall not differ in any respect from the
most recent list furnished to the Trustee by the Company (in the event the
Company fails to provide such list on a monthly basis, the Trustee shall be
entitled to rely on the most recent list provided by the Company); and (b) at
such other times as the Trustee may request in writing within 30 days after the
receipt by the Company of any such request, a list of similar form and content
as of a date not more than 15 days prior to the time such list is furnished;
provided, however, that, in either case, no such list need be furnished if the
Trustee shall be the Debenture Registrar .

SECTION 6.2. PRESERVATION OF INFORMATION; COMMUNICATIONS WITH DEBENTUREHOLDERS

  (a) The Trustee shall preserve, in as current a form as is reasonably
practicable, all information as to the names and addresses of the holders of
Debentures contained in the most recent list furnished to it as provided in
Section 6.1 and as to the names and addresses of holders of Debentures received
by the Trustee in its capacity as Debenture Registrar for the Debentures (if
acting in such capacity).

  (b) The Trustee may destroy any list furnished to it as provided in Section
6.1 upon receipt of a new list so furnished.

  (c) Debentureholders may communicate as provided in Section 312(b) of the
Trust Indenture Act with other Debentureholders with respect to their rights
under this Indenture or under the Debentures.

SECTION 6.3. REPORTS BY THE COMPANY

  (a) The Company covenants and agrees to file with the Trustee, within 15 days
after the Company is required to file the same with the Commission, copies of
the annual reports and of the information, documents and other reports (or
copies of such portions of any of the foregoing as the Commission may from time
to time by rules and regulations prescribe) that the Company may be required to
file with the Commission pursuant to Section 13 or Section 15(d) of the Exchange
Act; or, if the Company is not required to file information, documents or
reports pursuant to either of such sections, then to file with the Trustee and
the Commission, in accordance with the rules and regulations prescribed from
time to time by the Commission, such of the supplementary and periodic
information, documents and reports that may be required pursuant to Section 13
of the Exchange Act in respect of a security listed and registered on a national
securities exchange as may be prescribed from time to time in such rules and
regulations.

  (b) The Company covenants and agrees to file with the Trustee and the
Commission, in accordance with the rules and regulations prescribed from to time
by the Commission, such additional information, documents and reports with
respect to compliance by the Company with the conditions and covenants provided
for in this Indenture as may be required from time to time by such rules and
regulations.

  (c) The Company covenants and agrees to transmit by mail, first class postage
prepaid, or reputable overnight delivery service that provides for evidence of
receipt, to the Debentureholders, as their names and addresses appear upon the
Debenture Register, within 30 days after the filing thereof with the Trustee,
such summaries of any information, documents and reports required to be filed by
the Company pursuant to subsections (a) and (b) of this Section 6.3 as may be
required by rules and regulations prescribed from time to time by the
Commission.

SECTION 6.4. REPORTS BY THE TRUSTEE

  (a) On or before July 15 in each year in which any of the Debentures are
Outstanding, the Trustee shall transmit by mail, first class postage prepaid, to
the Debentureholders, as their names and addresses appear upon the Debenture
Register, a brief report dated as of the preceding May 15, if and to the extent
required under Section 313(a) of the Trust Indenture Act.

  (b) The Trustee shall comply with Section 313(b) and 313(c) of the Trust
Indenture Act.

                                     -18-
<PAGE>
 
  (c) A copy of each such report shall, at the time of such transmission to
Debentureholders, be filed by the Trustee with the Company, with each stock
exchange upon which any Debentures are listed (if so listed) and also with the
Commission. The Company agrees to notify the Trustee when any Debentures become
listed on any stock exchange.


                                  ARTICLE VII

                 REMEDIES OF THE TRUSTEE AND DEBENTUREHOLDERS
                              ON EVENT OF DEFAULT

SECTION 7.1. EVENTS OF DEFAULT

  (a) Whenever used herein with respect to the Debentures, "Event of Default"
means any one or more of the following events that has occurred and is
continuing:

     (i) the Company defaults in the payment of any installment of interest upon
  any of the Debentures, as and when the same shall become due and payable, and
  continuance of such default for a period of 30 days; provided, however, that a
  valid extension of an interest payment period by the Company in accordance
  with the terms of this Indenture shall not constitute a default in the payment
  of interest for this purpose;

     (ii) the Company defaults in the payment of the principal on the Debentures
  as and when the same shall become due and payable whether at maturity, upon
  redemption, by declaration or otherwise; provided, however, that a valid
  extension of the maturity of such Debentures in accordance with the terms of
  this Indenture shall not constitute a default in the payment of principal;

     (iii) the Company fails to observe or perform any other of its covenants or
  agreements with respect to the Debentures for a period of 90 days after the
  date on which written notice of such failure, requiring the same to be
  remedied and stating that such notice is a "Notice of Default" hereunder,
  shall have been given to the Company by the Trustee, by registered or
  certified mail, or to the Company and the Trustee by the holders of at least
  25% in principal amount of the Debentures at the time Outstanding;

     (iv) the Company pursuant to or within the meaning of any Bankruptcy Law
  (i) commences a voluntary case; (ii) consents to the entry of an order for
  relief against it in an involuntary case; (iii) consents to the appointment of
  a Custodian of it or for all or substantially all of its property; or (iv)
  makes a general assignment for the benefit of its creditors;

     (v) a court of competent jurisdiction enters an order under any Bankruptcy
  Law that (i) is for relief against the Company in an involuntary case; (ii)
  appoints a Custodian of the Company for all or substantially all of its
  property; or (iii) orders the liquidation of the Company, and the order or
  decree remains unstayed and in effect for 90 days; or

     (vi) the Trust shall have voluntarily or involuntarily dissolved, wound-up
  its business or otherwise terminated its existence except in connection with
  (i) the distribution of Debentures to holders of Trust Securities in
  liquidation of their interests in the Trust; (ii) the redemption of all of the
  outstanding Trust Securities of the Trust; or (iii) certain mergers,
  consolidations or amalgamations, each as permitted by the Trust Agreement.

  (b) In each and every such case, unless the principal of all the Debentures
shall have already become due and payable, either the Trustee or the holders of
not less than 25% in aggregate principal amount of the Debentures then
Outstanding hereunder, by notice in writing to the Company (and to the Trustee
if given by such Debentureholders) may declare the principal of all the
Debentures to be due and payable immediately, and upon any such declaration the
same shall become and shall be immediately due and payable, notwithstanding
anything contained in this Indenture or in the Debentures.

  (c) At any time after the principal of the Debentures shall have been so
declared due and payable, and before any judgment or decree for the payment of
the moneys due shall have been obtained or entered as hereinafter provided,

                                     -19-
<PAGE>
 
the holders of a majority in aggregate principal amount of the Debentures then
Outstanding hereunder, by written notice to the Company and the Trustee, may
rescind and annul such declaration and its consequences if: (i) the Company has
paid or deposited with the Trustee a sum sufficient to pay all matured
installments of interest upon all the Debentures and the principal of any and
all Debentures that shall have become due otherwise than by acceleration (with
interest upon such principal, and upon overdue installments of interest, at the
rate per annum expressed in the Debentures to the date of such payment or
deposit) and the amount payable to the Trustee under Section 9.7; and (ii) any
and all Events of Default under this Indenture, other than the nonpayment of
principal on Debentures that shall not have become due by their terms, shall
have been remedied or waived as provided in Section 7.6. No such rescission and
annulment shall extend to or shall affect any subsequent default or impair any
right consequent thereon.

  (d) In case the Trustee shall have proceeded to enforce any right with respect
to Debentures under this Indenture and such proceedings shall have been
discontinued or abandoned because of such rescission or annulment or for any
other reason or shall have been determined adversely to the Trustee, then, and
in every such case, the Company and the Trustee shall be restored to their
respective former positions and rights hereunder, and all rights, remedies and
powers of the Company and the Trustee shall continue as though no such
proceedings had been taken.

SECTION 7.2. COLLECTION OF INDEBTEDNESS AND SUITS FOR ENFORCEMENT BY TRUSTEE

  (a) The Company covenants that (1) in case it shall default in the payment of
any installment of interest on any of the Debentures, and such default shall
have continued for a period of 90 Business Days; or (2) in case it shall default
in the payment of the principal of any of the Debentures when the same shall
have become due and payable, whether upon maturity of the Debentures or upon
redemption or upon declaration or otherwise, then, upon demand of the Trustee,
the Company shall pay to the Trustee, for the benefit of the holders of the
Debentures, the whole amount that then shall have been become due and payable on
all such Debentures for principal or interest, or both, as the case may be, with
interest upon the overdue principal and upon overdue installments of interest at
the rate per annum expressed in the Debentures; and (if the Debentures are held
by the Trust or a trustee of the Trust, without duplication of any other amounts
paid by the Trust or trustee in respect thereof) in addition thereto, such
further amount as shall be sufficient to cover the costs and expenses of
collection, and the amount payable to the Trustee under Section 9.7.

  (b) If the Company shall fail to pay such amounts set forth in Section 7.2(a)
forthwith upon such demand, the Trustee, in its own name and as trustee of an
express trust, shall be entitled and empowered to institute any action or
proceedings at law or in equity for the collection of the sums so due and
unpaid, and may prosecute any such action or proceeding to judgment or final
decree, and may enforce any such judgment or final decree against the Company or
other obligor upon the Debentures and collect the moneys adjudged or decreed to
be payable in the manner provided by law out of the property of the Company or
other obligor upon the Debentures, wherever situated.

  (c) In case of any receivership, insolvency, liquidation, bankruptcy,
reorganization, readjustment, arrangement, composition or judicial proceedings
affecting the Company or the creditors or property thereof, the Trustee shall
have power to intervene in such proceedings and take any action therein that may
be permitted by the court and shall (except as may be otherwise provided by law)
be entitled to file such proofs of claim and other papers and documents as may
be necessary or advisable in order to have the claims of the Trustee and of the
holders of the Debentures allowed for the entire amount due and payable by the
Company under this Indenture at the date of institution of such proceedings and
for any additional amount that may become due and payable by the Company after
such date, and to collect and receive any moneys or other property payable or
deliverable on any such claim, and to distribute the same after the deduction of
the amount payable to the Trustee under Section 9.7; and any receiver, assignee
or trustee in bankruptcy or reorganization is hereby authorized by each of the
holders of the Debentures to make such payments to the Trustee, and, in the
event that the Trustee shall consent to the making of such payments directly to
such Debentureholders, to pay to the Trustee any amount due it under Section
9.7.

                                     -20-
<PAGE>
 
  (d) All rights of action and of asserting claims under this Indenture, or
under any of the terms established with respect to Debentures, may be enforced
by the Trustee without the possession of any of such Debentures, or the
production thereof at any trial or other proceeding relative thereto, and any
such suit or proceeding instituted by the Trustee shall be brought in its own
name as trustee of an express trust, and any recovery of judgment shall, after
provision for payment to the Trustee of any amounts due under Section 9.7, be
for the ratable benefit of the holders of the Debentures. In case of an Event of
Default hereunder, the Trustee may in its discretion proceed to protect and
enforce the rights vested in it by this Indenture by such appropriate judicial
proceedings as the Trustee shall deem most effectual to protect and enforce any
of such rights, either at law or in equity or in bankruptcy or otherwise,
whether for the specific enforcement of any covenant or agreement contained in
this Indenture or in aid of the exercise of any power granted in this Indenture,
or to enforce any other legal or equitable right vested in the Trustee by this
Indenture or by law. Nothing contained herein shall be deemed to authorize the
Trustee to authorize or consent to or accept or adopt on behalf of any
Debentureholder any plan of reorganization, arrangement, adjustment or
composition affecting the Debentures or the rights of any holder thereof or to
authorize the Trustee to vote in respect of the claim of any Debentureholder in
any such proceeding.

SECTION 7.3. APPLICATION OF MONEYS COLLECTED

  Any moneys collected by the Trustee pursuant to this Article VII with respect
to the Debentures shall be applied in the following order, at the date or dates
fixed by the Trustee and, in case of the distribution of such moneys on account
of principal or interest, upon presentation of the Debentures, and notation
thereon of the payment, if only partially paid, and upon surrender thereof if
fully paid:

     FIRST: To the payment of costs and expenses of collection and of all
  amounts payable to the Trustee under Section 9.7;

     SECOND: To the payment of all Senior Indebtedness of the Company if and to
  the extent required by Article XVI; and

     THIRD: To the payment of the amounts then due and unpaid upon the
  Debentures for principal and interest, in respect of which or for the benefit
  of which such money has been collected, ratably, without preference or
  priority of any kind, according to the amounts due and payable on such
  Debentures for principal and interest, respectively.

SECTION 7.4. LIMITATION ON SUITS

  (a) Except as provided in Section 15.13 hereof, no holder of any Debenture
shall have any right by virtue or by availing of any provision of this Indenture
to institute any suit, action or proceeding in equity or at law upon or under or
with respect to this Indenture or for the appointment of a receiver or trustee,
or for any other remedy hereunder, unless (i) such holder previously shall have
given to the Trustee written notice of an Event of Default and of the
continuance thereof with respect to the Debentures specifying such Event of
Default, as hereinbefore provided; (ii) the holders of not less than 25% in
aggregate principal amount of the Debentures then Outstanding shall have made
written request upon the Trustee to institute such action, suit or proceeding in
its own name as trustee hereunder; (iii) such holder or holders shall have
offered to the Trustee such reasonable indemnity as it may require against the
costs, expenses and liabilities to be incurred therein or thereby; and (iv) the
Trustee for 60 days after its receipt of such notice, request and offer of
indemnity, shall have failed to institute any such action, suit or proceeding;
and (v) during such 60 day period, the holders of a majority in principal amount
of the Debentures do not give the Trustee a direction inconsistent with the
request.

  (b) Notwithstanding anything contained herein to the contrary or any other
provisions of this Indenture, the right of any holder of the Debentures to
receive payment of the principal of and interest on the Debentures, as therein
provided, on or after the respective due dates expressed in such Debenture (or
in the case of redemption, on the redemption date), or to institute suit for the
enforcement of any such payment on or after such respective dates or

                                     -21-
<PAGE>
 
redemption date, shall not be impaired or affected without the consent of such
holder and by accepting a Debenture hereunder it is expressly understood,
intended and covenanted by the taker and holder of every Debenture with every
other such taker and holder and the Trustee, that no one or more holders of
Debentures shall have any right in any manner whatsoever by virtue or by
availing of any provision of this Indenture to affect, disturb or prejudice the
rights of the holders of any other of such Debentures, or to obtain or seek to
obtain priority over or preference to any other such holder, or to enforce any
right under this Indenture, except in the manner herein provided and for the
equal, ratable and common benefit of all holders of Debentures. For the
protection and enforcement of the provisions of this Section 7.4, each and every
Debentureholder and the Trustee shall be entitled to such relief as can be given
either at law or in equity.

SECTION 7.5. RIGHTS AND REMEDIES CUMULATIVE; DELAY OR OMISSION NOT WAIVER

  (a) All powers and remedies given by this Article VII to the Trustee or to the
Debentureholders shall, to the extent permitted by law, be deemed cumulative and
not exclusive of any other powers and remedies available to the Trustee or the
holders of the Debentures, by judicial proceedings or otherwise, to enforce the
performance or observance of the covenants and agreements contained in this
Indenture or otherwise established with respect to such Debentures.

  (b) No delay or omission of the Trustee or of any holder of any of the
Debentures to exercise any right or power accruing upon any Event of Default
occurring and continuing as aforesaid shall impair any such right or power, or
shall be construed to be a waiver of any such default or an acquiescence
therein; and, subject to the provisions of Section 7.4, every power and remedy
given by this Article VII or by law to the Trustee or the Debentureholders may
be exercised from time to time, and as often as shall be deemed expedient, by
the Trustee or by the Debentureholders.

SECTION 7.6. CONTROL BY DEBENTUREHOLDERS

  The holders of a majority in aggregate principal amount of the Debentures at
the time Outstanding, determined in accordance with Section 10.4, shall have the
right to direct the time, method and place of conducting any proceeding for any
remedy available to the Trustee, or exercising any trust or power conferred on
the Trustee; provided, however, that such direction shall not be in conflict
with any rule of law or with this Indenture. Subject to the provisions of
Section 9.1, the Trustee shall have the right to decline to follow any such
direction if the Trustee in good faith shall, by a Responsible Officer or
Officers of the Trustee, determine that the proceeding so directed would involve
the Trustee in personal liability. The holders of a majority in aggregate
principal amount of the Debentures at the time Outstanding affected thereby,
determined in accordance with Section 10.4, may on behalf of the holders of all
of the Debentures waive any past default in the performance of any of the
covenants contained herein and its consequences, except (i) a default in the
payment of the principal of or interest on, any of the Debentures as and when
the same shall become due by the terms of such Debentures otherwise than by
acceleration (unless such default has been cured and a sum sufficient to pay all
matured installments of interest and principal has been deposited with the
Trustee (in accordance with Section 7.1(c)); (ii) a default in the covenants
contained in Section 5.6; or (iii) in respect of a covenant or provision hereof
which cannot be modified or amended without the consent of the holder of each
Outstanding Debenture affected; provided, however, that if the Debentures are
held by the Trust or a trustee of the Trust, such waiver or modification to such
waiver shall not be effective until the holders of a majority in liquidation
preference of Trust Securities of the Trust shall have consented to such waiver
or modification to such waiver; provided further, that if the consent of the
holder of each Outstanding Debenture is required, such waiver shall not be
effective until each holder of the Trust Securities of the Trust shall have
consented to such waiver. Upon any such waiver, the default covered thereby
shall be deemed to be cured for all purposes of this Indenture and the Company,
the Trustee and the holders of the Debentures shall be restored to their
respective former positions and rights hereunder; but no such waiver shall
extend to any subsequent or other default or impair any right consequent
thereon.

                                     -22-
<PAGE>
 
SECTION 7.7. UNDERTAKING TO PAY COSTS

  All parties to this Indenture agree, and each holder of any Debentures by such
holder's acceptance thereof shall be deemed to have agreed, that any court may
in its discretion require, in any suit for the enforcement of any right or
remedy under this Indenture, or in any suit against the Trustee for any action
taken or omitted by it as Trustee, the filing by any party litigant in such suit
of an undertaking to pay the costs of such suit, and that such court may in its
discretion assess reasonable costs, including reasonable attorneys' fees,
against any party litigant in such suit, having due regard to the merits and
good faith of the claims or defenses made by such party litigant; but the
provisions of this Section 7.8 shall not apply to any suit instituted by the
Trustee, to any suit instituted by any Debentureholder, or group of
Debentureholders holding more than 10% in aggregate principal amount of the
Outstanding Debentures, or to any suit instituted by any Debentureholder for the
enforcement of the payment of the principal of or interest on the Debentures, on
or after the respective due dates expressed in such Debenture or established
pursuant to this Indenture.

                                 ARTICLE VIII

                     FORM OF DEBENTURE AND ORIGINAL ISSUE

SECTION 8.1. FORM OF DEBENTURE

  The Debenture and the Trustee's Certificate of Authentication to be endorsed
thereon are to be substantially in the forms contained as Exhibit A attached
hereto and incorporated herein by reference.

SECTION 8.2. ORIGINAL ISSUE OF DEBENTURES.

  Debentures in the aggregate principal amount of Twenty Five Million Seven
Hundred Eighty Six Thousand Five Hundred Dollars ($25,786,500) (reflecting the
exercise in full of the Underwriter's Option (as such terms are defined in
Underwriting Agreement, dated May 29, 1997, by and among the Company, the Trust
and Stifel Nicolaus & Company, Incorporated)) may, upon execution of this
Indenture, be executed by the Company and delivered to the Trustee for
authentication.  The Trustee shall thereupon authenticate and deliver said
Debentures to or upon the written order of the Company, signed by its Chairman,
its Vice Chairman, its President, or any Vice President and its Treasurer or an
Assistant Treasurer, without any further action by the Company.

                                  ARTICLE IX 

                            CONCERNING THE TRUSTEE

SECTION 9.1. CERTAIN DUTIES AND RESPONSIBILITIES TRUSTEE

  (a) The Trustee, prior to the occurrence of an Event of Default and after the
curing of all Events of Default that may have occurred, shall undertake to
perform with respect to the Debentures such duties and only such duties as are
specifically set forth in this Indenture, and no implied covenants shall be read
into this Indenture against the Trustee. In case an Event of Default has
occurred that has not been cured or waived, the Trustee shall exercise such of
the rights and powers vested in it by this Indenture, and use the same degree of
care and skill in their exercise, as a prudent man would exercise or use under
the circumstances in the conduct of his own affairs.

  (b) No provision of this Indenture shall be construed to relieve the Trustee
from liability for its own negligent action, its own negligent failure to act,
or its own willful misconduct, except that:

     (1) prior to the occurrence of an Event of Default and after the curing or
  waiving of all such Events of Default that may have occurred:

                                     -23-
<PAGE>
 
          (i) the duties and obligations of the Trustee shall with respect to
     the Debentures be determined solely by the express provisions of this
     Indenture, and the Trustee shall not be liable with respect to the
     Debentures except for the performance of such duties and obligations as are
     specifically set forth in this Indenture, and no implied covenants or
     obligations shall be read into this Indenture against the Trustee; and

          (ii) in the absence of bad faith on the part of the Trustee, the
     Trustee may with respect to the Debentures conclusively rely, as to the
     truth of the statements and the correctness of the opinions expressed
     therein, upon any certificates or opinions furnished to the Trustee and
     conforming to the requirements of this Indenture; but in the case of any
     such certificates or opinions that by any provision hereof are specifically
     required to be furnished to the Trustee, the Trustee shall be under a duty
     to examine the same to determine whether or not they conform to the
     requirements of this Indenture;

     (2) the Trustee shall not be liable for any error of judgment made in good
  faith by a Responsible Officer or Responsible Officers of the Trustee, unless
  it shall be proved that the Trustee was negligent in ascertaining the
  pertinent facts;

     (3) the Trustee shall not be liable with respect to any action taken or
  omitted to be taken by it in good faith in accordance with the direction of
  the holders of not less than a majority in principal amount of the Debentures
  at the time Outstanding relating to the time, method and place of conducting
  any proceeding for any remedy available to the Trustee, or exercising any
  trust or power conferred upon the Trustee under this Indenture with respect to
  the Debentures; and

     (4) none of the provisions contained in this Indenture shall require the
  Trustee to expend or risk its own funds or otherwise incur personal financial
  liability in the performance of any of its duties or in the exercise of any of
  its rights or powers, if there is reasonable ground for believing that the
  repayment of such funds or liability is not reasonably assured to it under the
  terms of this Indenture or adequate indemnity against such risk is not
  reasonably assured to it.

SECTION 9.2. NOTICE OF DEFAULTS

  Within 90 days after actual knowledge by a Responsible Officer of the Trustee
of the occurrence of any default hereunder with respect to the Debentures, the
Trustee shall transmit by mail to all holders of the Debentures, as their names
and addresses appear in the Debenture Register, notice of such default, unless
such default shall have been cured or waived; provided, however, that, except in
the case of a default in the payment of the principal or interest (including any
Additional Interest) on any Debenture, the Trustee shall be protected in
withholding such notice if and so long as the board of directors, the executive
committee or a trust committee of the directors and/or Responsible Officers of
the Trustee determines in good faith that the withholding of such notice is in
the interests of the holders of such Debentures; and provided, further, that in
the case of any default of the character specified in section 7.1(a)(iii), no
such notice to holders of Debentures need be sent until at least 30 days after
the occurrence thereof. For the purposes of this Section 9.2, the term "default"
means any event which is, or after notice or lapse of time or both, would
become, an Event of Default with respect to the Debentures.

SECTION 9.3. CERTAIN RIGHTS OF TRUSTEE

 Except as otherwise provided in Section 9.1:

  (a) The Trustee may rely and shall be protected in acting or refraining from
acting upon any resolution, certificate, statement, instrument, opinion, report,
notice, request, consent, order, approval, bond, security or other paper or
document believed by it to be genuine and to have been signed or presented by
the proper party or parties;

  (b) Any request, direction, order or demand of the Company mentioned herein
shall be sufficiently evidenced by a Board Resolution or an instrument signed in
the name of the Company by the President or any Vice President and

                                     -24-
<PAGE>
 
by the Secretary or an Assistant Secretary or the Treasurer or an Assistant
Treasurer thereof (unless other evidence in respect thereof is specifically
prescribed herein);

  (c) The Trustee shall not be deemed to have knowledge of a default or an Event
of Default, other than an Event of Default specified in Section 7.1(a)(i); or
(ii), unless and until it receives written notification of such Event of Default
from the Company or by holders of at least 25% of the aggregate principal amount
of the Debentures at the time Outstanding;

  (d) The Trustee may consult with counsel, and the written advice of such
counsel or any Opinion of Counsel shall be full and complete authorization and
protection in respect of any action taken or suffered or omitted hereunder in
good faith and in reliance thereon;

  (e) The Trustee shall be under no obligation to exercise any of the rights or
powers vested in it by this Indenture at the request, order or direction of any
of the Debentureholders, pursuant to the provisions of this Indenture, unless
such Debentureholders shall have offered to the Trustee reasonable security or
indemnity against the costs, expenses and liabilities that may be incurred
therein or thereby; nothing contained herein shall, however, relieve the Trustee
of the obligation, upon the occurrence of an Event of Default (that has not been
cured or waived) to exercise with respect to the Debentures such of the rights
and powers vested in it by this Indenture, and to use the same degree of care
and skill in their exercise, as a prudent man would exercise or use under the
circumstances in the conduct of his own affairs;

  (f) The Trustee shall not be liable for any action taken or omitted to be
taken by it in good faith and believed by it to be authorized or within the
discretion or rights or powers conferred upon it by this Indenture;

  (g) The Trustee shall not be bound to make any investigation into the facts or
matters stated in any resolution, certificate, statement, instrument, opinion,
report, notice, request, consent, order, approval, bond, security, or other
papers or documents, unless requested in writing so to do by the holders of not
less than a majority in principal amount of the Outstanding Debentures
(determined as provided in Section 10.4); provided, however, that if the payment
within a reasonable time to the Trustee of the costs, expenses or liabilities
likely to be incurred by it in the making of such investigation is, in the
opinion of the Trustee, not reasonably assured to the Trustee by the security
afforded to it by the terms of this Indenture, the Trustee may require
reasonable indemnity against such costs, expenses or liabilities as a condition
to so proceeding. The reasonable expense of every such examination shall be paid
by the Company or, if paid by the Trustee, shall be repaid by the Company upon
demand; and

  (h) The Trustee may execute any of the trusts or powers hereunder or perform
any duties hereunder either directly or by or through agents or attorneys, and
the Trustee shall not be responsible for any misconduct or negligence on the
part of any agent or attorney appointed with due care by it hereunder.

SECTION 9.4. TRUSTEE NOT RESPONSIBLE FOR RECITALS, ETC

  (a) The Recitals contained herein and in the Debentures shall be taken as the
statements of the Company, and the Trustee assumes no responsibility for the
correctness of the same.

  (b) The Trustee makes no representations as to the validity or sufficiency of
this Indenture or of the Debentures.

  (c) The Trustee shall not be accountable for the use or application by the
Company of any of the Debentures or of the proceeds of such Debentures, or for
the use or application of any moneys paid over by the Trustee in accordance with
any provision of this Indenture, or for the use or application of any moneys
received by any paying agent other than the Trustee.

                                     -25-
<PAGE>
 
SECTION 9.5. MAY HOLD DEBENTURES

  The Trustee or any Paying Agent or Debenture Registrar for the Debentures, in
its individual or any other capacity, may become the owner or pledgee of
Debentures with the same rights it would have if it were not Trustee, Paying
Agent or Debenture Registrar.

SECTION 9.6. MONEYS HELD IN TRUST

  Subject to the provisions of Section 13.5, all moneys received by the Trustee
shall, until used or applied as herein provided, be held in trust for the
purposes for which they were received, but need not be segregated from other
funds except to the extent required by law. The Trustee shall be under no
liability for interest on any moneys received by it hereunder except such as it
may agree with the Company to pay thereon.

SECTION 9.7. COMPENSATION AND REIMBURSEMENT

  (a) The Company covenants and agrees to pay to the Trustee, and the Trustee
shall be entitled to, such reasonable compensation (which shall not be limited
by any provision of law in regard to the compensation of a trustee of an express
trust), as the Company and the Trustee may from time to time agree in writing,
for all services rendered by it in the execution of the trusts hereby created
and in the exercise and performance of any of the powers and duties hereunder of
the Trustee, and, except as otherwise expressly provided herein, the Company
shall pay or reimburse the Trustee upon its request for all reasonable expenses,
disbursements and advances incurred or made by the Trustee in accordance with
any of the provisions of this Indenture (including the reasonable compensation
and the expenses and disbursements of its counsel and of all Persons not
regularly in its employ) except any such expense, disbursement or advance as may
arise from its negligence or bad faith. The Company also covenants to indemnify
the Trustee (and its officers, agents, directors and employees) for, and to hold
it harmless against, any loss, liability or expense incurred without negligence
or bad faith on the part of the Trustee and arising out of or in connection with
the acceptance or administration of this trust, including the costs and expenses
of defending itself against any claim of liability in the premises.

  (b) The obligations of the Company under this Section 9.7 to compensate and
indemnify the Trustee and to pay or reimburse the Trustee for expenses,
disbursements and advances shall constitute additional indebtedness hereunder.

SECTION 9.8. RELIANCE ON OFFICERS' CERTIFICATE

  Except as otherwise provided in Section 9.1, whenever in the administration of
the provisions of this Indenture the Trustee shall deem it necessary or
desirable that a matter be proved or established prior to taking or suffering or
omitting to take any action hereunder, such matter (unless other evidence in
respect thereof be herein specifically prescribed) may, in the absence of
negligence or bad faith on the part of the Trustee, be deemed to be conclusively
proved and established by an Officers' Certificate delivered to the Trustee and
such certificate, in the absence of negligence or bad faith on the part of the
Trustee, shall be full warrant to the Trustee for any action taken, suffered or
omitted to be taken by it under the provisions of this Indenture upon the faith
thereof.

SECTION 9.9. DISQUALIFICATION; CONFLICTING INTERESTS

  If the Trustee has or shall acquire any "conflicting interest" within the
meaning of Section 310(b) of the Trust Indenture Act, the Trustee and the
Company shall in all respects comply with the provisions of Section 310(b) of
the Trust Indenture Act.

SECTION 9.10. CORPORATE TRUSTEE REQUIRED; ELIGIBILITY

  There shall at all times be a Trustee with respect to the Debentures issued
hereunder which shall at all times be a corporation organized and doing business
under the laws of the United States of America or any State or Territory

                                     -26-
<PAGE>
 
thereof or of the District of Columbia, or a corporation or other Person
permitted to act as trustee by the Commission, authorized under such laws to
exercise corporate trust powers, having a combined capital and surplus of at
least $50,000,000, and subject to supervision or examination by federal, state,
territorial, or District of Columbia authority. If such corporation publishes
reports of condition at least annually, pursuant to law or to the requirements
of the aforesaid supervising or examining authority, then for the purposes of
this Section 9.10, the combined capital and surplus of such corporation shall be
deemed to be its combined capital and surplus as set forth in its most recent
report of condition so published. The Company may not, nor may any Person
directly or indirectly controlling, controlled by, or under common control with
the Company, serve as Trustee. In case at any time the Trustee shall cease to be
eligible in accordance with the provisions of this Section 9.10, the Trustee
shall resign immediately in the manner and with the effect specified in Section
9.11.

SECTION 9.11. RESIGNATION AND REMOVAL; APPOINTMENT OF SUCCESSOR

  (a) The Trustee or any successor hereafter appointed, may at any time resign
by giving written notice thereof to the Company and by transmitting notice of
resignation by mail, first class postage prepaid, to the Debentureholders, as
their names and addresses appear upon the Debenture Register. Upon receiving
such notice of resignation, the Company shall promptly appoint a successor
trustee with respect to Debentures by written instrument, in duplicate, executed
by order of the Board of Directors, one copy of which instrument shall be
delivered to the resigning Trustee and one copy to the successor trustee. If no
successor trustee shall have been so appointed and have accepted appointment
within 30 days after the mailing of such notice of resignation, the resigning
Trustee may petition any court of competent jurisdiction for the appointment of
a successor trustee with respect to Debentures, or any Debentureholder who has
been a bona fide holder of a Debenture or Debentures for at least six months
may, subject to the provisions of Section 9.9, on behalf of himself and all
others similarly situated, petition any such court for the appointment of a
successor trustee. Such court may thereupon after such notice, if any, as it may
deem proper and prescribe, appoint a successor trustee.

  (b) In case at any time any one of the following shall occur:

      (i) the Trustee shall fail to comply with the provisions of Section 9.9
    after written request therefor by the Company or by any Debentureholder who
    has been a bona fide holder of a Debenture or Debentures for at least six
    months; or

      (ii) the Trustee shall cease to be eligible in accordance with the
    provisions of Section 9.10 and shall fail to resign after written request
    therefor by the Company or by any such Debentureholder; or

      (iii) the Trustee shall become incapable of acting, or shall be adjudged a
    bankrupt or insolvent, or commence a voluntary bankruptcy proceeding, or a
    receiver of the Trustee or of its property shall be appointed or consented
    to, or any public officer shall take charge or control of the Trustee or of
    its property or affairs for the purpose of rehabilitation, conservation or
    liquidation, then, in any such case, the Company may remove the Trustee with
    respect to all Debentures and appoint a successor trustee by written
    instrument, in duplicate, executed by order of the Board of Directors, one
    copy of which instrument shall be delivered to the Trustee so removed and
    one copy to the successor trustee, or, subject to the provisions of Section
    9.9, unless the Trustee's duty to resign is stayed as provided herein, any
    Debentureholder who has been a bona fide holder of a Debenture or Debentures
    for at least six months may, on behalf of that holder and all others
    similarly situated, petition any court of competent jurisdiction for the
    removal of the Trustee and the appointment of a successor trustee. Such
    court may thereupon after such notice, if any, as it may deem proper and
    prescribe, remove the Trustee and appoint a successor trustee.

  (c) The holders of a majority in aggregate principal amount of the Debentures
at the time Outstanding may at any time remove the Trustee by so notifying the
Trustee and the Company and may appoint a successor Trustee with the consent of
the Company.

                                     -27-
<PAGE>
 
  (d) Any resignation or removal of the Trustee and appointment of a successor
trustee with respect to the Debentures pursuant to any of the provisions of this
Section 9.11 shall become effective upon acceptance of appointment by the
successor trustee as provided in Section 9.12.

  (e) Any successor trustee appointed pursuant to this Section 9.11 may be
appointed with respect to the Debentures, and at any time there shall be only
one Trustee with respect to the Debentures.

SECTION 9.12. ACCEPTANCE OF APPOINTMENT BY SUCCESSOR

  (a) In case of the appointment hereunder of a successor trustee with respect
to the Debentures, every successor trustee so appointed shall execute,
acknowledge and deliver to the Company and to the retiring Trustee an instrument
accepting such appointment, and thereupon the resignation or removal of the
retiring Trustee shall become effective and such successor trustee, without any
further act, deed or conveyance, shall become vested with all the rights,
powers, trusts and duties of the retiring Trustee; but, on the request of the
Company or the successor trustee, such retiring Trustee shall, upon payment of
its charges, execute and deliver an instrument transferring to such successor
trustee all the rights, powers, and trusts of the retiring Trustee and shall
duly assign, transfer and deliver to such successor trustee all property and
money held by such retiring Trustee hereunder.

  (b) Upon request of any successor trustee, the Company shall execute any and
all instruments for more fully and certainly vesting in and confirming to such
successor trustee all such rights, powers and trusts referred to in paragraph
(a) of this Section 9.12.

  (c) No successor trustee shall accept its appointment unless at the time of
such acceptance such successor trustee shall be qualified and eligible under
this Article IX.

  (d) Upon acceptance of appointment by a successor trustee as provided in this
Section 9.12, the Company shall transmit notice of the succession of such
trustee hereunder by mail, first class postage prepaid, to the Debentureholders,
as their names and addresses appear upon the Debenture Register. If the Company
fails to transmit such notice within ten days after acceptance of appointment by
the successor trustee, the successor trustee shall cause such notice to be
transmitted at the expense of the Company.

SECTION 9.13. MERGER, CONVERSION, CONSOLIDATION OR SUCCESSION TO BUSINESS

  Any corporation into which the Trustee may be merged or converted or with
which it may be consolidated, or any corporation resulting from any merger,
conversion or consolidation to which the Trustee shall be a party, or any
corporation succeeding to the corporate trust business of the Trustee, shall be
the successor of the Trustee hereunder, provided that such corporation shall be
qualified under the provisions of Section 9.9 and eligible under the provisions
of Section 9.10, without the execution or filing of any paper or any further act
on the part of any of the parties hereto, anything herein to the contrary
notwithstanding. In case any Debentures shall have been authenticated, but not
delivered, by the Trustee then in office, any successor by merger, conversion or
consolidation to such authenticating Trustee may adopt such authentication and
deliver the Debentures so authenticated with the same effect as if such
successor Trustee had itself authenticated such Debentures.

SECTION 9.14. PREFERENTIAL COLLECTION OF CLAIMS AGAINST THE COMPANY

  The Trustee shall comply with Section 311(a) of the Trust Indenture Act,
excluding any creditor relationship described in Section 311(b) of the Trust
Indenture Act. A Trustee who has resigned or been removed shall be subject to
Section 311(a) of the Trust Indenture Act to the extent included therein.

                                     -28-
<PAGE>
 
                                   ARTICLE X

                        CONCERNING THE DEBENTUREHOLDERS

SECTION 10.1. EVIDENCE OF ACTION BY HOLDERS

  (a) Whenever in this Indenture it is provided that the holders of a majority
or specified percentage in aggregate principal amount of the Debentures may take
any action (including the making of any demand or request, the giving of any
notice, consent or waiver or the taking of any other action), the fact that at
the time of taking any such action the holders of such majority or specified
percentage have joined therein may be evidenced by any instrument or any number
of instruments of similar tenor executed by such holders of Debentures in Person
or by agent or proxy appointed in writing.

  (b) If the Company shall solicit from the Debentureholders any request,
demand, authorization, direction, notice, consent, waiver or other action, the
Company may, at its option, as evidenced by an Officers' Certificate, fix in
advance a record date for the determination of Debentureholders entitled to give
such request, demand, authorization, direction, notice, consent, waiver or other
action, but the Company shall have no obligation to do so. If such a record date
is fixed, such request, demand, authorization, direction, notice, consent,
waiver or other action may be given before or after the record date, but only
the Debentureholders of record at the close of business on the record date shall
be deemed to be Debentureholders for the purposes of determining whether
Debentureholders of the requisite proportion of Outstanding Debentures have
authorized or agreed or consented to such request, demand, authorization,
direction, notice, consent, waiver or other action, and for that purpose the
Outstanding Debentures shall be computed as of the record date; provided,
however, that no such authorization, agreement or consent by such
Debentureholders on the record date shall be deemed effective unless it shall
become effective pursuant to the provisions of this Indenture not later than six
months after the record date.

SECTION 10.2. PROOF OF EXECUTION BY DEBENTUREHOLDERS

  Subject to the provisions of Section 9.1, proof of the execution of any
instrument by a Debentureholder (such proof shall not require notarization) or
his agent or proxy and proof of the holding by any Person of any of the
Debentures shall be sufficient if made in the following manner:

  (a) The fact and date of the execution by any such Person of any instrument
may be proved in any reasonable manner acceptable to the Trustee.

  (b) The ownership of Debentures shall be proved by the Debenture Register of
such Debentures or by a certificate of the Debenture Registrar thereof.

  (c) The Trustee may require such additional proof of any matter referred to in
this Section 10.2 as it shall deem necessary.

SECTION 10.3. WHO MAY BE DEEMED OWNERS

  Prior to the due presentment for registration of transfer of any Debenture,
the Company, the Trustee, any Paying Agent, any Authenticating Agent and any
Debenture Registrar may deem and treat the Person in whose name such Debenture
shall be registered upon the books of the Company as the absolute owner of such
Debenture (whether or not such Debenture shall be overdue and notwithstanding
any notice of ownership or writing thereon made by anyone other than the
Debenture Registrar) for the purpose of receiving payment of or on account of
the principal of and interest on such Debenture (subject to Section 2.3) and for
all other purposes; and neither the Company nor the Trustee nor any Paying Agent
nor any Authenticating Agent nor any Debenture Registrar shall be affected by
any notice to the contrary.

                                     -29-
<PAGE>
 
SECTION 10.4. CERTAIN DEBENTURES OWNED BY COMPANY DISREGARDED

  In determining whether the holders of the requisite aggregate principal amount
of Debentures have concurred in any direction, consent or waiver under this
Indenture, the Debentures that are owned by the Company or any other obligor on
the Debentures or by any Person directly or indirectly controlling or controlled
by or under common control with the Company or any other obligor on the
Debentures shall be disregarded and deemed not to be Outstanding for the purpose
of any such determination, except that for the purpose of determining whether
the Trustee shall be protected in relying on any such direction, consent or
waiver, only Debentures that the Trustee actually knows are so owned shall be so
disregarded. The Debentures so owned that have been pledged in good faith may be
regarded as Outstanding for the purposes of this Section 10.4, if the pledgee
shall establish to the satisfaction of the Trustee the pledgee's right so to act
with respect to such Debentures and that the pledgee is not a Person directly or
indirectly controlling or controlled by or under direct or indirect common
control with the Company or any such other obligor. In case of a dispute as to
such right, any decision by the Trustee taken upon the advice of counsel shall
be full protection to the Trustee.

SECTION 10.5. ACTIONS BINDING ON FUTURE DEBENTUREHOLDERS

  At any time prior to (but not after) the evidencing to the Trustee, as
provided in Section 10.1, of the taking of any action by the holders of the
majority or percentage in aggregate principal amount of the Debentures specified
in this Indenture in connection with such action, any holder of a Debenture that
is shown by the evidence to be included in the Debentures the holders of which
have consented to such action may, by filing written notice with the Trustee,
and upon proof of holding as provided in Section 10.2, revoke such action so far
as concerns such Debenture. Except as aforesaid any such action taken by the
holder of any Debenture shall be conclusive and binding upon such holder and
upon all future holders and owners of such Debenture, and of any Debenture
issued in exchange therefor, on registration of transfer thereof or in place
thereof, irrespective of whether or not any notation in regard thereto is made
upon such Debenture. Any action taken by the holders of the majority or
percentage in aggregate principal amount of the Debentures specified in this
Indenture in connection with such action shall be conclusively binding upon the
Company, the Trustee and the holders of all the Debentures.

                                  ARTICLE XI

                            SUPPLEMENTAL INDENTURES

SECTION 11.1. SUPPLEMENTAL INDENTURES WITHOUT THE CONSENT OF DEBENTUREHOLDERS

  In addition to any supplemental indenture otherwise authorized by this
Indenture, the Company and the Trustee may from time to time and at any time
enter into an indenture or indentures supplemental hereto (which shall conform
to the provisions of the Trust Indenture Act as then in effect), without the
consent of the Debentureholders, for one or more of the following purposes:

  (a) to cure any ambiguity, defect, or inconsistency herein, or in the
Debentures;

  (b) to comply with Article X;

  (c) to provide for uncertificated Debentures in addition to or in place of
certificated Debentures;

  (d) to add to the covenants of the Company for the benefit of the holders of
all or any of the Debentures or to surrender any right or power herein conferred
upon the Company;

  (e) to add to, delete from, or revise the conditions, limitations, and
restrictions on the authorized amount, terms, or purposes of issue,
authentication, and delivery of Debentures, as herein set forth;

  (f) to make any change that does not adversely affect the rights of any
Debentureholder in any material respect;

                                     -30-
<PAGE>
 
  (g) to provide for the issuance of and establish the form and terms and
conditions of the Debentures, to establish the form of any certifications
required to be furnished pursuant to the terms of this Indenture or of the
Debentures, or to add to the rights of the holders of the Debentures;

  (h) to qualify or maintain the qualification of this Indenture under the Trust
Indenture Act; or

  (i) to evidence a consolidation or merger involving the Company as permitted
under Section 12.1.

  The Trustee is hereby authorized to join with the Company in the execution of
any such supplemental indenture, and to make any further appropriate agreements
and stipulations that may be therein contained, but the Trustee shall not be
obligated to enter into any such supplemental indenture that affects the
Trustee's own rights, duties or immunities under this Indenture or otherwise.
Any supplemental indenture authorized by the provisions of this Section 11.1 may
be executed by the Company and the Trustee without the consent of the holders of
any of the Debentures at the time Outstanding, notwithstanding any of the
provisions of Section 11.2.

SECTION 11.2. SUPPLEMENTAL INDENTURES WITH CONSENT OF DEBENTUREHOLDERS

  With the consent (evidenced as provided in Section 10.1) of the holders of not
less than a majority in aggregate principal amount of the Debentures at the time
Outstanding, the Company, when authorized by Board Resolutions, and the Trustee
may from time to time and at any time enter into an indenture or indentures
supplemental hereto (which shall conform to the provisions of the Trust
Indenture Act as then in effect), for the purpose of adding any provisions to or
changing in any manner or eliminating any of the provisions of this Indenture or
of any supplemental indenture or of modifying in any manner not covered by
Section 11.1, the rights of the holders of the Debentures under this Indenture;
provided, however, that no such supplemental indenture shall without the consent
of the holders of each Debenture then Outstanding and affected thereby, (i)
extend the fixed maturity of any Debentures, reduce the principal amount
thereof, or reduce the rate or extend the time of payment of interest thereon,
without the consent of the holder of each Debenture so affected; or (ii) reduce
the aforesaid percentage of Debentures, the holders of which are required to
consent to any such supplemental indenture; provided further, that if the
Debentures are held by the Trust or a trustee of the Trust, such supplemental
indenture shall not be effective until the holders of a majority in liquidation
preference of Trust Securities of the Trust shall have consented to such
supplemental indenture; provided further, that if the consent of the holder of
each Outstanding Debenture is required, such supplemental indenture shall not be
effective until each holder of the Trust Securities of the Trust shall have
consented to such supplemental indenture. It shall not be necessary for the
consent of the Debentureholders affected thereby under this Section 11.2 to
approve the particular form of any proposed supplemental indenture, but it shall
be sufficient if such consent shall approve the substance thereof.

SECTION 11.3. EFFECT OF SUPPLEMENTAL INDENTURES

  Upon the execution of any supplemental indenture pursuant to the provisions of
this Article XI, this Indenture shall be and be deemed to be modified and
amended in accordance therewith and the respective rights, limitations of
rights, obligations, duties and immunities under this Indenture of the Trustee,
the Company and the holders of Debentures shall thereafter be determined,
exercised and enforced hereunder subject in all respects to such modifications
and amendments, and all the terms and conditions of any such supplemental
indenture shall be and be deemed to be part of the terms and conditions of this
Indenture for any and all purposes.

SECTION 11.4. DEBENTURES AFFECTED BY SUPPLEMENTAL INDENTURES

  Debentures affected by a supplemental indenture, authenticated and delivered
after the execution of such supplemental indenture pursuant to the provisions of
this Article XI, may bear a notation in form approved by the Company, provided
such form meets the requirements of any exchange upon which the Debentures may
be listed, as to any matter provided for in such supplemental indenture. If the
Company shall so determine, new Debentures so modified as to conform, in the
opinion of the Board of Directors of the Company, to any modification of this

                                     -31-
<PAGE>
 
Indenture contained in any such supplemental indenture may be prepared by the
Company, authenticated by the Trustee and delivered in exchange for the
Debentures then Outstanding.

SECTION 11.5. EXECUTION OF SUPPLEMENTAL INDENTURES

  (a) Upon the request of the Company, accompanied by its Board Resolutions
authorizing the execution of any such supplemental indenture, and upon the
filing with the Trustee of evidence of the consent of Debentureholders required
to consent thereto as aforesaid, the Trustee shall join with the Company in the
execution of such supplemental indenture unless such supplemental indenture
affects the Trustee's own rights, duties or immunities under this Indenture or
otherwise, in which case the Trustee may in its discretion, but shall not be
obligated, to enter into such supplemental indenture. The Trustee, subject to
the provisions of Sections 9.1, may receive an Opinion of Counsel as conclusive
evidence that any supplemental indenture executed pursuant to this Article XI is
authorized or permitted by, and conforms to, the terms of this Article XI and
that it is proper for the Trustee under the provisions of this Article XI to
join in the execution thereof.

  (b) Promptly after the execution by the Company and the Trustee of any
supplemental indenture pursuant to the provisions of this Section 11.5, the
Trustee shall transmit by mail, first class postage prepaid, a notice, setting
forth in general terms the substance of such supplemental indenture, to the
Debentureholders as their names and addresses appear upon the Debenture
Register. Any failure of the Trustee to mail such notice, or any defect therein,
shall not, however, in any way impair or affect the validity of any such
supplemental indenture.

                                  ARTICLE XII

                             SUCCESSOR CORPORATION

SECTION 12.1. COMPANY MAY CONSOLIDATE, ETC.

  Nothing contained in this Indenture or in any of the Debentures shall prevent
any consolidation or merger of the Company with or into any other corporation or
corporations (whether or not affiliated with the Company, as the case may be),
or successive consolidations or mergers in which the Company, as the case may
be, or its successor or successors shall be a party or parties, or shall prevent
any sale, conveyance, transfer or other disposition of the property of the
Company, as the case may be, or its successor or successors as an entirety, or
substantially as an entirety, to any other corporation (whether or not
affiliated with the Company, as the case may be, or its successor or successors)
authorized to acquire and operate the same; provided, however, that the Company
hereby covenants and agrees that, (i) upon any such consolidation, merger, sale,
conveyance, transfer or other disposition, the due and punctual payment, in the
case of the Company, of the principal of and interest on all of the Debentures,
according to their tenor and the due and punctual performance and observance of
all the covenants and conditions of this Indenture to be kept or performed by
the Company as the case may be, shall be expressly assumed, by supplemental
indenture (which shall conform to the provisions of the Trust Indenture Act, as
then in effect) satisfactory in form to the Trustee executed and delivered to
the Trustee by the entity formed by such consolidation, or into which the
Company, as the case may be, shall have been merged, or by the entity which
shall have acquired such property; (ii) in case the Company consolidates with or
merges into another Person or conveys or transfers its properties and assets
substantially then as an entirety to any Person, the successor Person is
organized under the laws of the United States or any state or the District of
Columbia; and (iii) immediately after giving effect thereto, an Event of
Default, and no event which, after notice or lapse of time or both, would become
an Event of Default, shall have occurred and be continuing.

SECTION 12.2. SUCCESSOR CORPORATION SUBSTITUTED

  (a) In case of any such consolidation, merger, sale, conveyance, transfer or
other disposition and upon the assumption by the successor corporation, by
supplemental indenture, executed and delivered to the Trustee and satisfactory
in form to the Trustee, of the due and punctual payment of the principal of and
interest on all of the Debentures Outstanding and the due and punctual
performance of all of the covenants and conditions of this

                                     -32-
<PAGE>
 
Indenture to be performed by the Company such successor corporation shall
succeed to and be substituted for the Company, with the same effect as if it had
been named as the Company herein, and thereupon the predecessor corporation
shall be relieved of all obligations and covenants under this Indenture and the
Debentures.

  (b) In case of any such consolidation, merger, sale, conveyance, transfer or
other disposition such changes in phraseology and form (but not in substance)
may be made in the Debentures thereafter to be issued as may be appropriate.

  (c) Nothing contained in this Indenture or in any of the Debentures shall
prevent the Company from merging into itself or acquiring by purchase or
otherwise all or any part of the property of any other Person (whether or not
affiliated with the Company).

SECTION 12.3. EVIDENCE OF CONSOLIDATION, ETC. TO TRUSTEE

  The Trustee, subject to the provisions of Section 9.1, may receive an Opinion
of Counsel as conclusive evidence that any such consolidation, merger, sale,
conveyance, transfer or other disposition, and any such assumption, comply with
the provisions of this Article XII.

                                 ARTICLE XIII

                          SATISFACTION AND DISCHARGE

SECTION 13.1. SATISFACTION AND DISCHARGE OF INDENTURE

  If at any time: (a) the Company shall have delivered to the Trustee for
cancellation all Debentures theretofore authenticated (other than any Debentures
that shall have been destroyed, lost or stolen and that shall have been replaced
or paid as provided in Section 2.9) and Debentures for whose payment money or
Governmental Obligations have theretofore been deposited in trust or segregated
and held in trust by the Company (and thereupon repaid to the Company or
discharged from such trust, as provided in Section 13.5); or (b) all such
Debentures not theretofore delivered to the Trustee for cancellation shall have
become due and payable, or are by their terms to become due and payable within
one year or are to be called for redemption within one year under arrangements
satisfactory to the Trustee for the giving of notice of redemption, and the
Company shall deposit or cause to be deposited with the Trustee as trust funds
the entire amount in moneys or Governmental Obligations sufficient or a
combination thereof, sufficient in the opinion of a nationally recognized firm
of independent public accountants expressed in a written certification thereof
delivered to the Trustee, to pay at maturity or upon redemption all Debentures
not theretofore delivered to the Trustee for cancellation, including principal
and interest due or to become due to such date of maturity or date fixed for
redemption, as the case may be, and if the Company shall also pay or cause to be
paid all other sums payable hereunder by the Company; then this Indenture shall
thereupon cease to be of further effect except for the provisions of Sections
2.3, 2.7, 2.9, 5.1, 5.2, 5.3, 9.7 and 9.10, that shall survive until the date of
maturity or redemption date, as the case may be, and Sections 9.6 and 13.5, that
shall survive to such date and thereafter, and the Trustee, on demand of the
Company and at the cost and expense of the Company, shall execute proper
instruments acknowledging satisfaction of and discharging this Indenture.

SECTION 13.2. DISCHARGE OF OBLIGATIONS

  If at any time all Debentures not heretofore delivered to the Trustee for
cancellation or that have not become due and payable as described in Section
13.1 shall have been paid by the Company by depositing irrevocably with the
Trustee as trust funds, an amount of moneys or Governmental Obligations, or a
combination thereof, sufficient in the opinion of a nationally recognized
certified public accounting firm to pay at maturity or upon redemption all
Debentures not theretofore delivered to the Trustee for cancellation, including
principal and interest due or to become due to such date of maturity or date
fixed for redemption, as the case may be, and if the Company shall also pay or
cause to be paid all other sums payable hereunder by the Company, then after the
date such moneys or Governmental Obligations, as the case may be, are deposited


                                     -33-
<PAGE>
 
with the Trustee, the obligations of the Company under this Indenture shall
cease to be of further effect except for the provisions of Sections 2.3, 2.7,
2.9, 5.1, 5.2, 5.3, 9.6, 9.10 and 13.5 hereof that shall survive until such
Debentures shall mature and be paid. Thereafter, Sections 9.6 and 13.5 shall
survive.

SECTION 13.3. DEPOSITED MONEYS TO BE HELD IN TRUST

  All monies or Governmental Obligations deposited with the Trustee pursuant to
Sections 13.1 or 13.2 shall be held in trust and shall be available for payment
as due, either directly or through any Paying Agent (including the Company
acting as its own Paying Agent), to the holders of the Debentures for the
payment or redemption of which such moneys or Governmental Obligations have been
deposited with the Trustee.

SECTION 13.4. PAYMENT OF MONIES HELD BY PAYING AGENTS

  In connection with the satisfaction and discharge of this Indenture, all
moneys or Governmental Obligations then held by any Paying Agent under the
provisions of this Indenture shall, upon demand of the Company, be paid to the
Trustee and thereupon such Paying Agent shall be released from all further
liability with respect to such moneys or Governmental Obligations.

SECTION 13.5. REPAYMENT TO COMPANY

  Any monies or Governmental Obligations deposited with any Paying Agent or the
Trustee, or then held by the Company in trust, for payment of principal of or
interest on the Debentures that are not applied but remain unclaimed by the
holders of such Debentures for at least two years after the date upon which the
principal of or interest on such Debentures shall have respectively become due
and payable, shall be repaid to the Company, as the case may be, on May 31 of
each year or (if then held by the Company) shall be discharged from such trust;
and thereupon the Paying Agent and the Trustee shall be released from all
further liability with respect to such moneys or Governmental Obligations, and
the holder of any of the Debentures entitled to receive such payment shall
thereafter, as an unsecured general creditor, look only to the Company for the
payment thereof.

                                  ARTICLE XIV

        IMMUNITY OF INCORPORATORS, STOCKHOLDERS, OFFICERS AND DIRECTORS

SECTION 14.1. NO RECOURSE

  No recourse under or upon any obligation, covenant or agreement of this
Indenture, or of the Debentures, or for any claim based thereon or otherwise in
respect thereof, shall be had against any incorporator, stockholder, officer or
director, past, present or future as such, of the Company or of any predecessor
or successor corporation, either directly or through the Company or any such
predecessor or successor corporation, whether by virtue of any constitution,
statute or rule of law, or by the enforcement of any assessment or penalty or
otherwise; it being expressly understood that this Indenture and the obligations
issued hereunder are solely corporate obligations, and that no such personal
liability whatever shall attach to, or is or shall be incurred by, the
incorporators, stockholders, officers or directors as such, of the Company or of
any predecessor or successor corporation, or any of them, because of the
creation of the indebtedness hereby authorized, or under or by reason of the
obligations, covenants or agreements contained in this Indenture or in any of
the Debentures or implied therefrom; and that any and all such personal
liability of every name and nature, either at common law or in equity or by
constitution or statute, of, and any and all such rights and claims against,
every such incorporator, stockholder, officer or director as such, because of
the creation of the indebtedness hereby authorized, or under or by reason of the
obligations, covenants or agreements contained in this Indenture or in any of
the Debentures or implied therefrom, are hereby expressly waived and released as
a condition of, and as a consideration for, the execution of this Indenture and
the issuance of such Debentures.

                                     -34-
<PAGE>
 
                                  ARTICLE XV

                           MISCELLANEOUS PROVISIONS

SECTION 15.1. EFFECT ON SUCCESSORS AND ASSIGNS

  All the covenants, stipulations, promises and agreements in this Indenture
contained by or on behalf of the Company shall bind their respective successors
and assigns, whether so expressed or not.

SECTION 15.2. ACTIONS BY SUCCESSOR

  Any act or proceeding by any provision of this Indenture authorized or
required to be done or performed by any board, committee or officer of the
Company shall and may be done and performed with like force and effect by the
corresponding board, committee or officer of any corporation that shall at the
time be the lawful sole successor of the Company.

SECTION 15.3. SURRENDER OF COMPANY POWERS

  The Company by instrument in writing executed by appropriate authority of its
Board of Directors and delivered to the Trustee may surrender any of the powers
reserved to the Company, and thereupon such power so surrendered shall terminate
both as to the Company, as the case may be, and as to any successor corporation.

SECTION 15.4. NOTICES

  Except as otherwise expressly provided herein any notice or demand that by any
provision of this Indenture is required or permitted to be given or served by
the Trustee or by the holders of Debentures to or on the Company may be given or
served by being deposited first class postage prepaid in a post-office letterbox
addressed (until another address is filed in writing by the Company with the
Trustee), as follows: Southwest Bancorp, Inc., 608 South Main Street,
Stillwater, Oklahoma 74074, Attention: Kerby E. Crowell. Any notice, election,
request or demand by the Company or any Debentureholder to or upon the Trustee
shall be deemed to have been sufficiently given or made, for all purposes, if
given or made in writing at the Corporate Trust Office of the Trustee.

SECTION 15.5. GOVERNING LAW

  This Indenture and each Debenture shall be deemed to be a contract made under
the internal laws of the State of Oklahoma, and for all purposes shall be
construed in accordance with the laws of said State.

SECTION 15.6. TREATMENT OF DEBENTURES AS DEBT

  It is intended that the Debentures shall be treated as indebtedness and not as
equity for federal income tax purposes. The provisions of this Indenture shall
be interpreted to further this intention.

SECTION 15.7. COMPLIANCE CERTIFICATES AND OPINIONS

  (a) Upon any application or demand by the Company to the Trustee to take any
action under any of the provisions of this Indenture, the Company shall furnish
to the Trustee an Officers' Certificate stating that all conditions precedent
provided for in this Indenture relating to the proposed action have been
complied with and an Opinion of Counsel stating that in the opinion of such
counsel all such conditions precedent have been complied with, except that in
the case of any such application or demand as to which the furnishing of such
documents is specifically required by any provision of this Indenture relating
to such particular application or demand, no additional certificate or opinion
need be furnished.

                                     -35-
<PAGE>
 
  (b) Each certificate or opinion of the Company provided for in this Indenture
and delivered to the Trustee with respect to compliance with a condition or
covenant in this Indenture shall include (i) a statement that the Person making
such certificate or opinion has read such covenant or condition; (ii) a brief
statement as to the nature and scope of the examination or investigation upon
which the statements or opinions contained in such certificate or opinion are
based; (iii) a statement that, in the opinion of such Person, he has made such
examination or investigation as, in the opinion of such Person, is necessary to
enable him to express an informed opinion as to whether or not such covenant or
condition has been complied with; and (iv) a statement as to whether or not, in
the opinion of such Person, such condition or covenant has been complied with.

SECTION 15.8. PAYMENTS ON BUSINESS DAYS

  In any case where the date of maturity of interest or principal of any
Debenture or the date of redemption of any Debenture shall not be a Business
Day, then payment of interest or principal may (subject to Section 2.5) be made
on the next succeeding Business Day with the same force and effect as if made on
the nominal date of maturity or redemption, and no interest shall accrue for the
period after such nominal date.

SECTION 15.9. CONFLICT WITH TRUST INDENTURE ACT

  If and to the extent that any provision of this Indenture limits, qualifies or
conflicts with the duties imposed by Sections 310 to 317, inclusive, of the
Trust Indenture Act, such imposed duties shall control.

SECTION 15.10. COUNTERPARTS

  This Indenture may be executed in any number of counterparts, each of which
shall be an original, but such counterparts shall together constitute but one
and the same instrument.

SECTION 15.11. SEPARABILITY

  In case any one or more of the provisions contained in this Indenture or in
the Debentures shall for any reason be held to be invalid, illegal or
unenforceable in any respect, such invalidity, illegality or unenforceability
shall not affect any other provisions of this Indenture or of the Debentures,
but this Indenture and the Debentures shall be construed as if such invalid or
illegal or unenforceable provision had never been contained herein or therein.

SECTION 15.12. ASSIGNMENT

  The Company shall have the right at all times to assign any of its respective
rights or obligations under this Indenture to a direct or indirect wholly owned
Subsidiary of the Company, provided that, in the event of any such assignment,
the Company shall remain liable for all such obligations. Subject to the
foregoing, this Indenture is binding upon and inures to the benefit of the
parties thereto and their respective successors and assigns. This Indenture may
not otherwise be assigned by the parties thereto.

SECTION 15.13. ACKNOWLEDGMENT OF RIGHTS; RIGHT OF SET-OFF

  (a) The Company acknowledges that, with respect to any Debentures held by the
Trust or a trustee of the Trust, if the Property Trustee fails to enforce its
rights under this Indenture as the holder of the Debentures held as the assets
of the Trust, any holder of Preferred Securities may institute legal proceedings
directly against the Company to enforce such Property Trustee's rights under
this Indenture without first instituting any legal proceedings against such
Property Trustee or any other person or entity. Notwithstanding the foregoing,
and notwithstanding the provisions of Section 7.4(a) hereof,if an Event of
Default has occurred and is continuing and such event is attributable to the
failure of the Company to pay interest or principal on the Debentures on the
date such interest or principal is otherwise payable (or in the case of
redemption, on the redemption date), the Company acknowledges that a holder of
Preferred Securities may directly institute a proceeding for enforcement of


                                     -36-
<PAGE>
 
payment to such holder of the principal of or interest on the Debentures having
a principal amount equal to the aggregate liquidation amount of the Preferred
Securities of such holder on or after the respective due date specified in the
Debentures.

  (b) Notwithstanding anything to the contrary contained in this Indenture, the
Company shall have the right to set-off any payment it is otherwise required to
make hereunder in respect of any Trust Securities to the extent that the Company
has previously made, or is concurrently making, a payment to the holder of such
Trust Securities under the Guarantee or in connection with a proceeding for
enforcement of payment of the principal of or interest on the Debentures
directly brought by holders of any Trust Securities.

                                  ARTICLE XVI

                          SUBORDINATION OF DEBENTURES

SECTION 16.1. AGREEMENT TO SUBORDINATE

  The Company covenants and agrees, and each holder of Debentures issued
hereunder by such holder's acceptance thereof likewise covenants and agrees,
that all Debentures shall be issued subject to the provisions of this Article
XVI; and each holder of a Debenture, whether upon original issue or upon
transfer or assignment thereof, accepts and agrees to be bound by such
provisions. The payment by the Company of the principal of and interest on all
Debentures issued hereunder shall, to the extent and in the manner hereinafter
set forth, be subordinated and junior in right of payment to the prior payment
in full of all Senior Debt, Subordinated Debt and Additional Senior Obligations
(collectively, "Senior Indebtedness") to the extent provided herein, whether
outstanding at the date of this Indenture or thereafter incurred. No provision
of this Article XVI shall prevent the occurrence of any default or Event of
Default hereunder.

SECTION 16.2. DEFAULT ON SENIOR DEBT, SUBORDINATED DEBT OR ADDITIONAL SENIOR
OBLIGATIONS

  In the event and during the continuation of any default by the Company in the
payment of principal, premium, interest or any other payment due on any Senior
Indebtedness of the Company, or in the event that the maturity of any Senior
Indebtedness of the Company has been accelerated because of a default, then, in
either case, no payment shall be made by the Company with respect to the
principal (including redemption payments) of or interest on the Debentures. In
the event that, notwithstanding the foregoing, any payment shall be received by
the Trustee when such payment is prohibited by the preceding sentence of this
Section 16.2, such payment shall be held in trust for the benefit of, and shall
be paid over or delivered to, the holders of Senior Indebtedness or their
respective representatives, or to the trustee or trustees under any indenture
pursuant to which any of such Senior Indebtedness may have been issued, as their
respective interests may appear, but only to the extent that the holders of the
Senior Indebtedness (or their representative or representatives or a trustee)
notify the Trustee in writing within 90 days of such payment of the amounts then
due and owing on the Senior Indebtedness, and only the amounts specified in such
notice to the Trustee shall be paid to the holders of Senior Indebtedness.

SECTION 16.3. LIQUIDATION; DISSOLUTION; BANKRUPTCY

  (a) Upon any payment by the Company or distribution of assets of the Company
of any kind or character, whether in cash, property or securities, to creditors
upon any dissolution or winding-up or liquidation or reorganization of the
Company, whether voluntary or involuntary or in bankruptcy, insolvency,
receivership or other proceedings, all amounts due upon all Senior Indebtedness
of the Company shall first be paid in full, or payment thereof provided for in
money in accordance with its terms, before any payment or distribution is made
by the Company on account of the principal or interest on the Debentures; and
upon any such dissolution or winding-up or liquidation or reorganization, any
payment by the Company, or distribution of assets of the Company of any kind or
character, whether in cash, property or securities, to which the holders of the
Debentures or the Trustee would be entitled to receive from the Company, except
for the provisions of this Article XVI, shall be paid by the Company or by any
receiver, trustee in bankruptcy, liquidating trustee, agent or other Person


                                     -37-
<PAGE>
 
making such payment or distribution, or by the holders of the Debentures or by
the Trustee under this Indenture if received by them or it, directly to the
holders of Senior Indebtedness of the Company (pro rata to such holders on the
basis of the respective amounts of Senior Indebtedness held by such holders, as
calculated by the Company) or their representative or representatives, or to the
trustee or trustees under any indenture pursuant to which any instruments
evidencing such Senior Indebtedness may have been issued, as their respective
interests may appear, to the extent necessary to pay such Senior Indebtedness in
full, in money or money's worth, after giving effect to any concurrent payment
or distribution to or for the holders of such Senior Indebtedness, before any
payment or distribution is made to the holders of Debentures or to the Trustee.

  (b) In the event that, notwithstanding the foregoing, any payment or
distribution of assets of the Company of any kind or character, whether in cash,
property or securities, prohibited by the foregoing, shall be received by the
Trustee before all Senior Indebtedness of the Company is paid in full, or
provision is made for such payment in money in accordance with its terms, such
payment or distribution shall be held in trust for the benefit of and shall be
paid over or delivered to the holders of such Senior Indebtedness or their
representative or representatives, or to the trustee or trustees under any
indenture pursuant to which any instruments evidencing such Senior Indebtedness
may have been issued, as their respective interests may appear, as calculated by
the Company, for application to the payment of all Senior Indebtedness of the
Company, as the case may be, remaining unpaid to the extent necessary to pay
such Senior Indebtedness in full in money or money's worth in accordance with
its terms, after giving effect to any concurrent payment or distribution to or
for the benefit of the holders of such Senior Indebtedness.

  (c) For purposes of this Article XVI, the words "cash, property or securities"
shall not be deemed to include shares of stock of the Company as reorganized or
readjusted, or securities of the Company or any other corporation provided for
by a plan of reorganization or readjustment, the payment of which is
subordinated, at least to the extent provided in this Article XVI with respect
to the Debentures, to the payment of all Senior Indebtedness of the Company, as
the case may be, that may at the time be outstanding, provided that (i) such
Senior Indebtedness is assumed by the new corporation, if any, resulting from
any such reorganization or readjustment; and (ii) the rights of the holders of
such Senior Indebtedness are not, without the consent of such holders, altered
by such reorganization or readjustment. The consolidation of the Company with,
or the merger of the Company into, another corporation, or the liquidation or
dissolution of the Company following the conveyance or transfer of its property
as an entirety, or substantially as an entirety, to another corporation upon the
terms and conditions provided for in Article XII shall not be deemed a
dissolution, winding-up, liquidation or reorganization for the purposes of this
Section 16.3 if such other corporation shall, as a part of such consolidation,
merger, conveyance or transfer, comply with the conditions stated in Article
XII. Nothing in Section 16.2 or in this Section 16.3 shall apply to claims of,
or payments to, the Trustee under or pursuant to Section 9.7.

SECTION 16.4. SUBROGATION

  (a) Subject to the payment in full of all Senior Indebtedness of the Company,
the rights of the holders of the Debentures shall be subrogated to the rights of
the holders of such Senior Indebtedness to receive payments or distributions of
cash, property or securities of the Company, as the case may be, applicable to
such Senior Indebtedness until the principal of and interest on the Debentures
shall be paid in full; and, for the purposes of such subrogation, no payments or
distributions to the holders of such Senior Indebtedness of any cash, property
or securities to which the holders of the Debentures or the Trustee would be
entitled except for the provisions of this Article XVI, and no payment pursuant
to the provisions of this Article XVI to or for the benefit of the holders of
such Senior Indebtedness by holders of the Debentures or the Trustee, shall, as
between the Company, its creditors other than holders of Senior Indebtedness of
the Company, and the holders of the Debentures, be deemed to be a payment by the
Company to or on account of such Senior Indebtedness. It is understood that the
provisions of this Article XVI are and are intended solely for the purposes of
defining the relative rights of the holders of the Debentures, on the one hand,
and the holders of such Senior Indebtedness on the other hand.

  (b) Nothing contained in this Article XVI or elsewhere in this Indenture or in
the Debentures is intended to or shall impair, as between the Company, its
creditors (other than the holders of Senior Indebtedness of the Company),

                                     -38-
<PAGE>
 
and the holders of the Debentures, the obligation of the Company, which is
absolute and unconditional, to pay to the holders of the Debentures the
principal of and interest on the Debentures as and when the same shall become
due and payable in accordance with their terms, or is intended to or shall
affect the relative rights of the holders of the Debentures and creditors of the
Company, as the case may be, other than the holders of Senior Indebtedness of
the Company, as the case may be, nor shall anything herein or therein prevent
the Trustee or the holder of any Debenture from exercising all remedies
otherwise permitted by applicable law upon default under this Indenture, subject
to the rights, if any, under this Article XVI of the holders of such Senior
Indebtedness in respect of cash, property or securities of the Company, as the
case may be, received upon the exercise of any such remedy.

  (c) Upon any payment or distribution of assets of the Company referred to in
this Article XVI, the Trustee, subject to the provisions of Article IX, and the
holders of the Debentures shall be entitled to conclusively rely upon any order
or decree made by any court of competent jurisdiction in which such dissolution,
winding-up, liquidation or reorganization proceedings are pending, or a
certificate of the receiver, trustee in bankruptcy, liquidation trustee, agent
or other Person making such payment or distribution, delivered to the Trustee or
to the holders of the Debentures, for the purposes of ascertaining the Persons
entitled to participate in such distribution, the holders of Senior Indebtedness
and other indebtedness of the Company, as the case may be, the amount thereof or
payable thereon, the amount or amounts paid or distributed thereon and all other
facts pertinent thereto or to this Article XVI.

SECTION 16.5. TRUSTEE TO EFFECTUATE SUBORDINATION

  Each holder of Debentures by such holder's acceptance thereof authorizes and
directs the Trustee on such holder's behalf to take such action as may be
necessary or appropriate to effectuate the subordination provided in this
Article XVI and appoints the Trustee such holder's attorney-in-fact for any and
all such purposes.

SECTION 16.6. NOTICE BY THE COMPANY

  (a) The Company shall give prompt written notice to a Responsible Officer of
the Trustee of any fact known to the Company that would prohibit the making of
any payment of monies to or by the Trustee in respect of the Debentures pursuant
to the provisions of this Article XVI. Notwithstanding the provisions of this
Article XVI or any other provision of this Indenture, the Trustee shall not be
charged with knowledge of the existence of any facts that would prohibit the
making of any payment of monies to or by the Trustee in respect of the
Debentures pursuant to the provisions of this Article XVI, unless and until a
Responsible Officer of the Trustee shall have received written notice thereof
from the Company or a holder or holders of Senior Indebtedness or from any
trustee therefor; and before the receipt of any such written notice, the
Trustee, subject to the provisions of Section 9.1, shall be entitled in all
respects to assume that no such facts exist; provided, however, that if the
Trustee shall not have received the notice provided for in this Section 16.6 at
least two Business Days prior to the date upon which by the terms hereof any
money may become payable for any purpose (including, without limitation, the
payment of the principal of or interest on any Debenture), then, anything herein
contained to the contrary notwithstanding, the Trustee shall have full power and
authority to receive such money and to apply the same to the purposes for which
they were received, and shall not be affected by any notice to the contrary that
may be received by it within two Business Days prior to such date.

  (b) The Trustee, subject to the provisions of Section 9.1, shall be entitled
to conclusively rely on the delivery to it of a written notice by a Person
representing himself to be a holder of Senior Indebtedness of the Company (or a
trustee on behalf of such holder) to establish that such notice has been given
by a holder of such Senior Indebtedness or a trustee on behalf of any such
holder or holders. In the event that the Trustee determines in good faith that
further evidence is required with respect to the right of any Person as a holder
of such Senior Indebtedness to participate in any payment or distribution
pursuant to this Article XVI, the Trustee may request such Person to furnish
evidence to the reasonable satisfaction of the Trustee as to the amount of such
Senior Indebtedness held by such Person, the extent to which such Person is
entitled to participate in such payment or distribution and any other facts
pertinent to the rights of such Person under this Article XVI, and, if such

                                     -39-
<PAGE>
 
evidence is not furnished, the Trustee may defer any payment to such Person
pending judicial determination as to the right of such Person to receive such
payment.

SECTION 16.7. RIGHTS OF THE TRUSTEE; HOLDERS OF SENIOR INDEBTEDNESS

  (a) The Trustee in its individual capacity shall be entitled to all the rights
set forth in this Article XVI in respect of any Senior Indebtedness at any time
held by it, to the same extent as any other holder of Senior Indebtedness, and
nothing in this Indenture shall deprive the Trustee of any of its rights as such
holder. The Trustee's right to compensation and reimbursement of expenses as set
forth in Section 9.7 shall not be subject to the subordination provisions of the
Article XVI.

  (b) With respect to the holders of Senior Indebtedness of the Company, the
Trustee undertakes to perform or to observe only such of its covenants and
obligations as are specifically set forth in this Article XVI, and no implied
covenants or obligations with respect to the holders of such Senior Indebtedness
shall be read into this Indenture against the Trustee. The Trustee shall not be
deemed to owe any fiduciary duty to the holders of such Senior Indebtedness and,
subject to the provisions of Section 9.1, the Trustee shall not be liable to any
holder of such Senior Indebtedness if it shall pay over or deliver to holders of
Debentures, the Company or any other Person money or assets to which any holder
of such Senior Indebtedness shall be entitled by virtue of this Article XVI or
otherwise.

SECTION 16.8. SUBORDINATION MAY NOT BE IMPAIRED

  (a) No right of any present or future holder of any Senior Indebtedness of the
Company to enforce subordination as herein provided shall at any time in any way
be prejudiced or impaired by any act or failure to act on the part of the
Company or by any act or failure to act, in good faith, by any such holder, or
by any noncompliance by the Company with the terms, provisions and covenants of
this Indenture, regardless of any knowledge thereof that any such holder may
have or otherwise be charged with.

                                     -40-
<PAGE>
 
  (b) Without in any way limiting the generality of Section 16.8(a), the holders
of Senior Indebtedness of the Company may, at any time and from time to time,
without the consent of or notice to the Trustee or the holders of the
Debentures, without incurring responsibility to the holders of the Debentures
and without impairing or releasing the subordination provided in this Article
XVI or the obligations hereunder of the holders of the Debentures to the holders
of such Senior Indebtedness, do any one or more of the following: (i) change the
manner, place or terms of payment or extend the time of payment of, or renew or
alter, such Senior Indebtedness, or otherwise amend or supplement in any manner
such Senior Indebtedness or any instrument evidencing the same or any agreement
under which such Senior Indebtedness is outstanding; (ii) sell, exchange,
release or otherwise deal with any property pledged, mortgaged or otherwise
securing such Senior Indebtedness; (iii) release any Person liable in any manner
for the collection of such Senior Indebtedness; and (iv) exercise or refrain
from exercising any rights against the Company and any other Person.

  IN WITNESS WHEREOF, the parties hereto have caused this Indenture to be duly
executed, and their respective corporate seals to be hereunto affixed and
attested, all as of the day and year first above written.

                              SOUTHWEST BANCORP, INC.

                              By: /s/Robert L. McCormick, Jr.
                                  --------------------------------------- 
                                  Robert L. McCormick, Jr., President

Attest:

/s/ Deborah T. Bradley
- -----------------------------
Deborah T. Bradley, Secretary

                              STATE STREET BANK AND TRUST COMPANY, as trustee

                              By: /s/ Paul D. Allen
                                  -----------------------------
                                  Paul D. Allen, Vice President

Attest:

/s/ [Attested]
- -----------------------------

                                     -41-
<PAGE>
 
STATE OF OKLAHOMA   )
                    ) ss
COUNTY OF PAYNE     )

  On this 4th day of June 1997, before me appeared Robert L. McCormick, Jr., to
me personally known, who, being by me duly sworn, did say that he is the
President of Southwest Bancorp, Inc. and that the seal affixed to said
instrument is the corporate seal of said corporation, and that said instrument
was signed and sealed in behalf of said corporation by authority of its board of
directors and said Robert L. McCormick, Jr. acknowledged said instrument to be
the free act and deed of said corporation.

  In testimony whereof I have hereunto set my hand and affixed my official seal
at my office in said county and state the day and year last above written.

                              [Notarized]
                              ---------------------------------
                              Notary Public
 
                              My term expires: 
                                              -----------------
[seal]

COMMONWEALTH OF MASSACHUSETTS )
                              ) ss
COUNTY OF SUFFOLK             )

  On this 4th day of June 1997, before me appeared Paul D. Allen, to me
personally known, who, being by me duly sworn, did say that he is the Vice
President of STATE STREET BANK AND TRUST, and that the seal affixed to said
instrument is the corporate seal of said corporation, and that said instrument
was signed and sealed in behalf of said corporation by authority of its board of
directors and said Paul D. Allen acknowledged said instrument to be the free act
and deed of said corporation.

  In testimony whereof I have hereunto set my hand and affixed my official seal
at my office in said county and commonwealth the day and year last above
written.

                              [Notarized]
                              ---------------------------------
                              Notary Public
 
                              My term expires: 
                                               ---------------- 
[seal]

                                     -42-

<PAGE>
 
     =====================================================================
                         _____________________________
                              AMENDED AND RESTATED

                                TRUST AGREEMENT

                                     AMONG

                     SOUTHWEST BANCORP, INC., AS DEPOSITOR

            STATE STREET BANK AND TRUST COMPANY, AS PROPERTY TRUSTEE

                 WILMINGTON TRUST COMPANY, AS DELAWARE TRUSTEE,

                                      AND

                    THE ADMINISTRATIVE TRUSTEES NAMED HEREIN

                            DATED AS OF JUNE 4, 1997

       ================================================================== 
<PAGE>
 
                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                            PAGE
                                                                                                            ----    
<S>                      <C>                                                                                <C>
ARTICLE I.               DEFINED TERMS...................................................................... 1
     SECTION 101.        DEFINITIONS........................................................................ 1

ARTICLE II.              ESTABLISHMENT OF THE TRUST......................................................... 7
     SECTION 201.        NAME............................................................................... 7
     SECTION 202.        OFFICE OF THE DELAWARE TRUSTEE; PRINCIPAL PLACE OF BUSINESS........................ 8
     SECTION 203.        INITIAL CONTRIBUTION OF TRUST PROPERTY; ORGANIZATIONAL EXPENSES.................... 8
     SECTION 204.        ISSUANCE OF THE PREFERRED SECURITIES............................................... 8
     SECTION 205.        ISSUANCE OF THE COMMON SECURITIES; SUBSCRIPTION AND PURCHASE OF DEBENTURES......... 8
     SECTION 206.        DECLARATION OF TRUST............................................................... 8
     SECTION 207.        AUTHORIZATION TO ENTER INTO CERTAIN TRANSACTIONS................................... 9
     SECTION 208.        ASSETS OF TRUST....................................................................11
     SECTION 209.        TITLE TO TRUST PROPERTY............................................................11

ARTICLE III.             PAYMENT ACCOUNT....................................................................11
     SECTION 301.        PAYMENT ACCOUNT....................................................................11

ARTICLE IV.              DISTRIBUTIONS; REDEMPTION..........................................................12
     SECTION 401.        DISTRIBUTIONS......................................................................12
     SECTION 402.        REDEMPTION.........................................................................12
     SECTION 403.        SUBORDINATION OF COMMON SECURITIES.................................................13
     SECTION 404.        PAYMENT PROCEDURES.................................................................14
     SECTION 405.        TAX RETURNS AND REPORTS............................................................14
     SECTION 406.        PAYMENT OF TAXES, DUTIES, ETC. OF THE TRUST........................................14
     SECTION 407.        PAYMENTS UNDER INDENTURE...........................................................14

ARTICLE V.               TRUST SECURITIES CERTIFICATES......................................................15
     SECTION 501.        INITIAL OWNERSHIP..................................................................15
     SECTION 502.        THE TRUST SECURITIES CERTIFICATES..................................................15
     SECTION 503.        EXECUTION, AUTHENTICATION AND DELIVERY OF TRUST SECURITIES CERTIFICATES............15
     SECTION 504.        REGISTRATION OF TRANSFER AND EXCHANGE OF PREFERRED SECURITIES CERTIFICATES.........15
     SECTION 505.        MUTILATED, DESTROYED, LOST OR STOLEN TRUST SECURITIES CERTIFICATES.................16
     SECTION 506.        PERSONS DEEMED SECURITYHOLDERS.....................................................16
     SECTION 507.        ACCESS TO LIST OF SECURITYHOLDERS' NAMES AND ADDRESSES.............................17
     SECTION 508.        MAINTENANCE OF OFFICE OR AGENCY....................................................17
     SECTION 509.        APPOINTMENT OF PAYING AGENT........................................................17
     SECTION 510.        OWNERSHIP OF COMMON SECURITIES BY DEPOSITOR........................................18
     SECTION 511.        PREFERRED SECURITIES CERTIFICATES..................................................18
 
</TABLE>
                                      i
<PAGE>
 
<TABLE>
<CAPTION>
                                                                                                            PAGE
                                                                                                            ----    
<S>                      <C>                                                                                <C>
     SECTION 512.        [Intentionally Omitted]............................................................18
     SECTION 513.        [Intentionally Omitted]............................................................18
     SECTION 514.        RIGHTS OF SECURITYHOLDERS..........................................................18

ARTICLE VI.              ACTS OF SECURITYHOLDERS; MEETINGS; VOTING..........................................19
     SECTION 601.        LIMITATIONS ON VOTING RIGHTS.......................................................19
     SECTION 602.        NOTICE OF MEETINGS.................................................................19
     SECTION 603.        MEETINGS OF PREFERRED SECURITYHOLDERS..............................................19
     SECTION 604.        VOTING RIGHTS......................................................................20
     SECTION 605.        PROXIES, ETC.......................................................................20
     SECTION 606.        SECURITYHOLDER ACTION BY WRITTEN CONSENT...........................................20
     SECTION 607.        RECORD DATE FOR VOTING AND OTHER PURPOSES..........................................20
     SECTION 608.        ACTS OF SECURITYHOLDERS............................................................21
     SECTION 609.        INSPECTION OF RECORDS..............................................................21

ARTICLE VII.             REPRESENTATIONS AND WARRANTIES.....................................................22
     SECTION 701.        REPRESENTATIONS AND WARRANTIES OF THE BANK AND THE PROPERTY TRUSTEE................22
     SECTION 702.        REPRESENTATIONS AND WARRANTIES OF THE DELAWARE BANK AND THE DELAWARE TRUSTEE.......22
     SECTION 703.        REPRESENTATIONS AND WARRANTIES OF DEPOSITOR........................................23

ARTICLE VIII.            TRUSTEES...........................................................................24
     SECTION 801.        CERTAIN DUTIES AND RESPONSIBILITIES................................................24
     SECTION 802.        CERTAIN NOTICES....................................................................25
     SECTION 803.        CERTAIN RIGHTS OF PROPERTY TRUSTEE.................................................25
     SECTION 804.        NOT RESPONSIBLE FOR RECITALS OR ISSUANCE OF SECURITIES.............................27
     SECTION 805.        MAY HOLD SECURITIES................................................................27
     SECTION 806.        COMPENSATION; INDEMNITY; FEES......................................................27
     SECTION 807.        CORPORATE PROPERTY TRUSTEE REQUIRED; ELIGIBILITY OF TRUSTEES.......................27
     SECTION 808.        CONFLICTING INTERESTS..............................................................28
     SECTION 809.        CO-TRUSTEES AND SEPARATE TRUSTEE...................................................28
     SECTION 810.        RESIGNATION AND REMOVAL; APPOINTMENT OF SUCCESSOR..................................29
     SECTION 811.        ACCEPTANCE OF APPOINTMENT BY SUCCESSOR.............................................30
     SECTION 812.        MERGER, CONVERSION, CONSOLIDATION OR SUCCESSION TO BUSINESS........................30
     SECTION 813.        PREFERENTIAL COLLECTION OF CLAIMS AGAINST DEPOSITOR OR TRUST.......................30
     SECTION 814.        REPORTS BY PROPERTY TRUSTEE........................................................31
     SECTION 815.        REPORTS TO THE PROPERTY TRUSTEE....................................................31
     SECTION 816.        EVIDENCE OF COMPLIANCE WITH CONDITIONS PRECEDENT...................................31
     SECTION 817.        NUMBER OF TRUSTEES.................................................................31
     SECTION 818.        DELEGATION OF POWER................................................................31
     SECTION 819.        VOTING.............................................................................32

ARTICLE IX.              TERMINATION, LIQUIDATION AND MERGER................................................32
     SECTION 901         TERMINATION UPON EXPIRATION DATE...................................................32
     SECTION 902.        EARLY TERMINATION..................................................................32
 
</TABLE>
                                      ii
<PAGE>
 
<TABLE>
<CAPTION>
                                                                                                            PAGE
                                                                                                            ----     
<S>                      <C>                                                                                <C>
     SECTION 903.        TERMINATION........................................................................32
     SECTION 904.        LIQUIDATION........................................................................33
     SECTION 905.        MERGERS, CONSOLIDATIONS, AMALGAMATIONS OR REPLACEMENTS OF THE TRUST................34

ARTICLE X.               MISCELLANEOUS PROVISIONS...........................................................34
     SECTION 1001.       LIMITATION OF RIGHTS OF SECURITYHOLDERS............................................34
     SECTION 1002.       AMENDMENT..........................................................................34
     SECTION 1003.       SEPARABILITY.......................................................................35
     SECTION 1004.       GOVERNING LAW......................................................................36
     SECTION 1005.       PAYMENTS DUE ON NON-BUSINESS DAY...................................................36
     SECTION 1006.       SUCCESSORS.........................................................................36
     SECTION 1007.       HEADINGS...........................................................................36
     SECTION 1008.       REPORTS, NOTICES AND DEMANDS.......................................................36
     SECTION 1009.       AGREEMENT NOT TO PETITION..........................................................37
     SECTION 1010.       TRUST INDENTURE ACT; CONFLICT WITH TRUST INDENTURE ACT.............................37
     SECTION 1011.       ACCEPTANCE OF TERMS OF TRUST AGREEMENT, GUARANTEE AND INDENTURE....................38
</TABLE>
                                     iii
<PAGE>
 
                             CROSS-REFERENCE TABLE

<TABLE>
<CAPTION>
Section of                                      Section of Amended
Trust Indenture Act                                   and Restated
of 1939, as amended                                Trust Agreement
- -------------------                                ---------------
 
<S>                                          <C>                
310(a)(1)....................................                  807
310(a)(2)....................................                  807
310(a)(3)....................................                  807
310(a)(4)....................................           207(a)(ii)
310(b).......................................                  808
311(a).......................................                  813
311(b).......................................                  813
312(a).......................................                  507
312(b).......................................                  507
312(c).......................................                  507
313(a).......................................               814(a)
313(a)(4)....................................               814(b)
313(b).......................................               814(b)
313(c).......................................                 1008
313(d).......................................               814(c)
314(a).......................................                  815
314(b).......................................       Not Applicable
314(c)(1)....................................                  816
314(c)(2)....................................                  816
314(c)(3)....................................       Not Applicable
314(d).......................................       Not Applicable
314(e).......................................             101, 816
315(a).......................................       801(a), 803(a)
315(b).......................................            802, 1008
315(c).......................................               801(a)
315(d).......................................             801, 803
316(a)(2)....................................       Not Applicable
316(b).......................................       Not Applicable
316(c).......................................                  607
317(a)(1)....................................       Not Applicable
317(a)(2)....................................       Not Applicable
317(b).......................................                  509
318(a).......................................                 1010
</TABLE>
Note: This Cross-Reference Table does not constitute part of this Agreement and
      shall not affect any interpretation of any of its terms or provisions.

                                      iv
<PAGE>
 
                      AMENDED AND RESTATED TRUST AGREEMENT

  AMENDED AND RESTATED TRUST AGREEMENT, dated as of June 4, 1997, among (i)
SOUTHWEST BANCORP, INC., an Oklahoma corporation (including any successors or
assigns, the "Depositor"), (ii) STATE STREET BANK AND TRUST COMPANY, a trust
company duly organized and existing under the laws of the Commonwealth of
Massachusetts, as property trustee (the "Property Trustee" and, in its separate
corporate capacity and not in its capacity as Property Trustee, the "Bank"),
(iii) WILMINGTON TRUST COMPANY, a Delaware banking corporation duly organized
and existing under the laws of the State of Delaware, as Delaware trustee (the
"Delaware Trustee," and, in its separate corporate capacity and not in its
capacity as Delaware Trustee, the "Delaware Bank") (iv) Robert L. McCormick,
Jr., an individual, Kerby E. Crowell, an individual, and Deborah T. Bradley, an
individual, each of whose address is c/o Southwest Bancorp, Inc., 608 South Main
Street, Stillwater, Oklahoma 74074 (each an "Administrative Trustee" and
collectively the "Administrative Trustees") (the Property Trustee, the Delaware
Trustee and the Administrative Trustees referred to collectively as the
"Trustees"), and (v) the several Holders (as hereinafter defined).

                                    RECITALS

  WHEREAS, the Depositor, the Delaware Trustee, and Robert L. McCormick, Jr.,
Kerby E. Crowell and Deborah T. Bradley, each as an Administrative Trustee, have
heretofore duly declared and established a business trust pursuant to the
Delaware Business Trust Act (as hereinafter defined) by the entering into of
that certain Trust Agreement, dated as of May 8, 1997 (the "Original Trust
Agreement"), and by the execution and filing by the Delaware Trustee, the
Depositor and the Administrative Trustees with the Secretary of State of the
State of Delaware of the Certificate of Trust, filed on May 9, 1997, the form of
which is attached as Exhibit A; and

  WHEREAS, the Depositor, the Delaware Trustee, the Property Trustee and the
Administrative Trustees desire to amend and restate the Original Trust Agreement
in its entirety as set forth herein to provide for, among other things, (i) the
issuance of the Common Securities (as defined herein) by the Trust (as defined
herein) to the Depositor; (ii) the issuance and sale of the Preferred Securities
(as defined herein) by the Trust pursuant to the Underwriting Agreement (as
defined herein); (iii) the acquisition by the Trust from the Depositor of all of
the right, title and interest in the Debentures (as defined herein); and (iv)
the appointment of the Trustees;

  NOW THEREFORE, in consideration of the agreements and obligations set forth
herein and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, each party, for the benefit of the
other parties and for the benefit of the Securityholders (as defined herein),
hereby amends and restates the Original Trust Agreement in its entirety and
agrees as follows:

                                   ARTICLE I

                                 DEFINED TERMS

 SECTION 101.  DEFINITIONS.

  For all purposes of this Trust Agreement, except as otherwise expressly
provided or unless the context otherwise requires:

  (a) the terms defined in this Article I have the meanings assigned to them in
this Article I and include the plural as well as the singular;

  (b) all other terms used herein that are defined in the Trust Indenture Act,
either directly or by reference therein, have the meanings assigned to them
therein;

                                      1
<PAGE>
 
  (c) unless the context otherwise requires, any reference to an "Article" or a
"Section" refers to an Article or a Section, as the case may be, of this Trust
Agreement; and

  (d) the words "herein", "hereof" and "hereunder" and other words of similar
import refer to this Trust Agreement as a whole and not to any particular
Article, Section or other subdivision.

  "Act" has the meaning specified in Section 608.

  "Additional Amount" means, with respect to Trust Securities of a given
Liquidation Amount and/or a given period, the amount of additional interest
accrued on interest in arrears and paid by the Depositor on a Like Amount of
Debentures for such period.

  "Additional Interest" has the meaning specified in Section 1.1 of the
Indenture.

  "Administrative Trustee" means each of Robert L. McCormick, Jr., Kerby E.
Crowell and Deborah T. Bradley, solely in his capacity as Administrative Trustee
of the Trust formed and continued hereunder and not in his individual capacity,
or such Administrative Trustee's successor in interest in such capacity, or any
successor trustee appointed as herein provided.

  "Affiliate" means, with respect to a specified Person, (a) any Person directly
or indirectly owning, controlling or holding with power to vote 10% or more of
the outstanding voting securities or other ownership interests of the specified
Person, any Person 10% or more of whose outstanding voting securities or other
ownership interests are directly or indirectly owned, controlled or held with
power to vote by the specified Person; (c) any Person directly or indirectly
controlling, controlled by, or under common control with the specified Person;
(d) a partnership in which the specified Person is a general partner; (e) any
officer or director of the specified Person; and (f) if the specified Person is
an individual, any entity of which the specified Person is an officer, director
or general partner.

  "Authenticating Agent" means an authenticating agent with respect to the
Preferred Securities appointed by the Property Trustee pursuant to Section 503.

  "Bank" has the meaning specified in the Preamble to this Trust Agreement.

  "Bankruptcy Event" means, with respect to any Person:

  (a) the entry of a decree or order by a court having jurisdiction in the
premises adjudging such Person a bankrupt or insolvent, or approving as properly
filed a petition seeking liquidation or reorganization of or in respect of such
Person under the United States Bankruptcy Code of 1978, as amended, or any other
similar applicable federal or state law, and the continuance of any such decree
or order unvacated and unstayed for a period of 90 days; or the commencement of
an involuntary case under the United States Bankruptcy Code of 1978, as amended,
in respect of such Person, which shall continue undismissed for a period of 90
days or entry of an order for relief in such case; or the entry of a decree or
order of a court having jurisdiction in the premises for the appointment on the
ground of insolvency or bankruptcy of a receiver, custodian, liquidator, trustee
or assignee in bankruptcy or insolvency of such Person or of its property, or
for the winding up or liquidation of its affairs, and such decree or order shall
have remained in force unvacated and unstayed for a period of 90 days; or

  (b) the institution by such Person of proceedings to be adjudicated a
voluntary bankrupt, or the consent by such Person to the filing of a bankruptcy
proceeding against it, or the filing by such Person of a petition or answer or
consent seeking liquidation or reorganization under the United States Bankruptcy
Code of 1978, as amended, or other similar applicable Federal or State law, or
the consent by such Person to the filing of any such petition or to the
appointment on the ground of insolvency or bankruptcy of a receiver or custodian
or liquidator or trustee or assignee in bankruptcy or insolvency of such Person
or of its property, or shall make a general assignment for the benefit of
creditors.

                                      2
<PAGE>
 
  "Bankruptcy Laws" has the meaning specified in Section 1009.

  "Board Resolution" means a copy of a resolution certified by the Secretary or
an Assistant Secretary of the Depositor to have been duly adopted by the
Depositor's Board of Directors, or such committee of the Board of Directors or
officers of the Depositor to which authority to act on behalf of the Board of
Directors has been delegated, and to be in full force and effect on the date of
such certification, and delivered to the appropriate Trustee.

  "Business Day" means a day other than a Saturday or Sunday, a day on which
banking institutions in the City of New York are authorized or required by law,
executive order or regulation to remain closed, or a day on which the Property
Trustee's Corporate Trust Office or the Corporate Trust Office of the Debenture
Trustee is closed for business.

  "Certificate of Trust" means the certificate of trust filed with the Secretary
of State of the State of Delaware with respect to the Trust, as amended or
restated from time to time.

  "Closing Date" means the date of execution and delivery of this Trust
Agreement.

  "Code" means the Internal Revenue Code of 1986, as amended.

  "Commission" means the Securities and Exchange Commission, as from time to
time constituted, created under the Exchange Act, or, if at any time after the
execution of this instrument such Commission is not existing and performing the
duties now assigned to it under the Trust Indenture Act, then the body
performing such duties at such time.

  "Common Security" means an undivided beneficial interest in the assets of the
Trust, having a Liquidation Amount of $25 and having the rights provided
therefor in this Trust Agreement, including the right to receive Distributions
and a Liquidation Distribution as provided herein.

  "Common Securities Certificate" means a certificate evidencing ownership of
Common Securities, substantially in the form attached as Exhibit C.

  "Corporate Trust Office" means the office at which, at any particular time,
the corporate trust business of the Property Trustee or the Debenture Trustee,
as the case may be, shall be principally administered, which office at the date
hereof, in each such case, is located at Two International Place, 4th Floor,
Boston, Massachusetts 02110, Attention: Corporate Trust Department.

  "Debenture Event of Default" means an "Event of Default" as defined in Section
7.1 of the Indenture.

  "Debenture Redemption Date" means, with respect to any Debentures to be
redeemed under the Indenture, the date fixed for redemption under the Indenture.

  "Debenture Trustee" means State Street Bank and Trust Company, a banking
corporation company organized under the laws of the Commonwealth of
Massachusetts and any successor thereto, as trustee under the Indenture.

  "Debentures" means the $25,786,500 aggregate principal amount of the
Depositor's 9.30% Subordinated Debentures due 2027, issued pursuant to the
Indenture.

  "Delaware Bank" has the meaning specified in the Preamble to this Trust
Agreement.

  "Delaware Business Trust Act" means Chapter 38 of Title 12 of the Delaware
Code, 12 Delaware Code Sections 3801 et seq. as it may be amended from time to
time.

                                      3
<PAGE>
 
  "Delaware Trustee" means the commercial bank or trust company identified as
the "Delaware Trustee" in the Preamble to this Trust Agreement solely in its
capacity as Delaware Trustee of the Trust formed and continued hereunder and not
in its individual capacity, or its successor in interest in such capacity, or
any successor trustee appointed as herein provided.

  "Depositor" has the meaning specified in the Preamble to this Trust Agreement.

  "Distribution Date" has the meaning specified in Section 401(a).

  "Distributions" means amounts payable in respect of the Trust Securities as
provided in Section 401.

  "Early Termination Event" has the meaning specified in Section 902.

  "Event of Default" means any one of the following events (whatever the reason
for such Event of Default and whether it shall be voluntary or involuntary or be
effected by operation of law or pursuant to any judgment, decree or order of any
court or any order, rule or regulation of any administrative or governmental
body):

  (a) the occurrence of a Debenture Event of Default; or

  (b) default by the Trust or the Property Trustee in the payment of any
Distribution when it becomes due and payable, and continuation of such default
for a period of 30 days; or

  (c) default by the Trust or the Property Trustee in the payment of any
Redemption Price of any Trust Security when it becomes due and payable; or

  (d) default in the performance, or breach, in any material respect, of any
covenant or warranty of the Trustees in this Trust Agreement (other than a
covenant or warranty a default in the performance of which or the breach of
which is dealt with in clause (b) or (c), above) and continuation of such
default or breach for a period of 60 days after there has been given, by
registered or certified mail, to the defaulting Trustee or Trustees by the
Holders of at least 25% in aggregate Liquidation Amount of the Outstanding
Preferred Securities a written notice specifying such default or breach and
requiring it to be remedied and stating that such notice is a "Notice of
Default" hereunder; or

  (e) the occurrence of a Bankruptcy Event with respect to the Property Trustee
and the failure by the Depositor to appoint a successor Property Trustee within
60 days thereof.

  "Exchange Act" means the Securities Exchange Act of 1934, as amended.

  "Expense Agreement" means the Agreement as to Expenses and Liabilities between
the Depositor and the Trust, substantially in the form attached as Exhibit D, as
amended from time to time.

  "Expiration Date" has the meaning specified in Section 901.

  "Extended Interest Payment Period" has the meaning specified in Section 4.1 of
the Indenture.

  "Guarantee" means the Preferred Securities Guarantee Agreement executed and
delivered by the Depositor and State Street Bank and Trust Company, as trustee,
contemporaneously with the execution and delivery of this Trust Agreement, for
the benefit of the holders of the Preferred Securities, as amended from time to
time.

  "Indenture" means the Indenture, dated as of June 4, 1997, between the
Depositor and the Debenture Trustee, as trustee, as amended or supplemented from
time to time pertaining to the Debentures of the Depositor.

                                      4
<PAGE>
 
  "Investment Company Act," means the Investment Company Act of 1940, as
amended, as in effect at the date of execution of this instrument.

  "Lien" means any lien, pledge, charge, encumbrance, mortgage, deed of trust,
adverse ownership interest, hypothecation, assignment, security interest or
preference, priority or other security agreement or preferential arrangement of
any kind or nature whatsoever.

  "Like Amount" means (a) with respect to a redemption of Trust Securities,
Trust Securities having a Liquidation Amount equal to the principal amount of
Debentures to be contemporaneously redeemed in accordance with the Indenture and
the proceeds of which shall be used to pay the Redemption Price of such Trust
Securities; and (b) with respect to a distribution of Debentures to Holders of
Trust Securities in connection with a termination or liquidation of the Trust,
Debentures having a principal amount equal to the Liquidation Amount of the
Trust Securities of the Holder to whom such Debentures are distributed. Each
Debenture distributed pursuant to clause (b) above shall carry with it
accumulated interest in an amount equal to the accumulated and unpaid interest
then due on such Debenture.

  "Liquidation Amount" means the stated amount of $25 per Trust Security.

  "Liquidation Date" means the date on which Debentures are to be distributed to
Holders of Trust Securities in connection with a termination and liquidation of
the Trust pursuant to Section 904(a).

  "Liquidation Distribution" has the meaning specified in Section 904(d).

  "Officers' Certificate" means a certificate signed by the President or a Vice
President and by the Treasurer or an Assistant Treasurer or the Controller or an
Assistant Controller or the Secretary or an Assistant Secretary, of the
Depositor, and delivered to the appropriate Trustee. One of the officers signing
an Officers' Certificate given pursuant to Section 816 shall be the principal
executive, financial or accounting officer of the Depositor. Any Officers'
Certificate delivered with respect to compliance with a condition or covenant
provided for in this Trust Agreement shall include:

  (a) a statement that each officer signing the Officers' Certificate has read
the covenant or condition and the definitions relating thereto;

  (b) a brief statement of the nature and scope of the examination or
investigation undertaken by each officer in rendering the Officers' Certificate;

  (c) a statement that each such officer has made such examination or
investigation as, in such officer's opinion, is necessary to enable such officer
to express an informed opinion as to whether or not such covenant or condition
has been complied with; and

  (d) a statement as to whether, in the opinion of each such officer, such
condition or covenant has been complied with.

  "Opinion of Counsel" means an opinion in writing of legal counsel, who may be
counsel for the Trust, the Property Trustee, the Delaware Trustee or the
Depositor, but not an employee of any thereof, and who shall be reasonably
acceptable to the Property Trustee.

  "Original Trust Agreement" has the meaning specified in the Recitals to this
Trust Agreement.

  "Outstanding", when used with respect to Preferred Securities, means, as of
the date of determination, all Preferred Securities theretofore executed and
delivered under this Trust Agreement, except:

                                      5
<PAGE>
 
  (a) Preferred Securities theretofore canceled by the Property Trustee or
delivered to the Property Trustee for cancellation;

  (b) Preferred Securities for whose payment or redemption money in the
necessary amount has been theretofore deposited with the Property Trustee or any
Paying Agent for the Holders of such Preferred Securities; provided that, if
such Preferred Securities are to be redeemed, notice of such redemption has been
duly given pursuant to this Trust Agreement; and

  (c) Preferred Securities which have been paid or in exchange for or in lieu of
which other Preferred Securities have been executed and delivered pursuant to
Sections 504, 505 and 511; provided, however, that in determining whether the
Holders of the requisite Liquidation Amount of the Outstanding Preferred
Securities have given any request, demand, authorization, direction, notice,
consent or waiver hereunder, Preferred Securities owned by the Depositor, any
Trustee or any Affiliate of the Depositor or any Trustee shall be disregarded
and deemed not to be Outstanding, except that (a) in determining whether any
Trustee shall be protected in relying upon any such request, demand,
authorization, direction, notice, consent or waiver, only Preferred Securities
that such Trustee knows to be so owned shall be so disregarded; and (b) the
foregoing shall not apply at any time when all of the outstanding Preferred
Securities are owned by the Depositor, one or more of the Trustees and/or any
such Affiliate. Preferred Securities so owned which have been pledged in good
faith may be regarded as Outstanding if the pledgee establishes to the
satisfaction of the Administrative Trustees the pledgee's right so to act with
respect to such Preferred Securities and the Pledgee is not the Depositor or any
other Obligor upon the Preferred Securities or a Person directly or indirectly
controlling or controlled by or under direct or indirect common control with the
Depositor or any Affiliate of the Depositor.

  "Paying Agent" means any paying agent or co-paying agent appointed pursuant to
Section 509 and shall initially be the Bank.

  "Payment Account" means a segregated non-interest-bearing corporate trust
account maintained by the Property Trustee with the Bank in its trust department
for the benefit of the Securityholders in which all amounts paid in respect of
the Debentures shall be held and from which the Property Trustee shall make
payments to the Securityholders in accordance with Sections 401 and 402.

  "Person" means any individual, corporation, partnership, joint venture, trust,
limited liability company or corporation, unincorporated organization or
government or any agency or political subdivision thereof.

  "Preferred Security" means an undivided beneficial interest in the assets of
the Trust, having a Liquidation Amount of $25 and having the rights provided
therefor in this Trust Agreement, including the right to receive Distributions
and a Liquidation Distribution as provided herein.

  "Preferred Securities Certificate", means a certificate evidencing ownership
of Preferred Securities, substantially in the form attached as Exhibit E.

  "Property Trustee" means the commercial bank or trust company identified as
the "Property Trustee," in the Preamble to this Trust Agreement solely in its
capacity as Property Trustee of the Trust heretofore formed and continued
hereunder and not in its individual capacity, or its successor in interest in
such capacity, or any successor property trustee appointed as herein provided.

  "Redemption Date" means, with respect to any Trust Security to be redeemed,
the date fixed for such redemption by or pursuant to this Trust Agreement;
provided that each Debenture Redemption Date and the stated maturity of the
Debentures shall be a Redemption Date for a Like Amount of Trust Securities.

  "Redemption Price" means, with respect to any Trust Security, the Liquidation
Amount of such Trust Security, plus accumulated and unpaid Distributions to the
Redemption Date, paid by the Depositor upon the concurrent

                                      6
<PAGE>
 
redemption of a Like Amount of Debentures, allocated on a pro rata basis (based
on Liquidation Amounts) among the Trust Securities.

  "Relevant Trustee" shall have the meaning specified in Section 810.

  "Securities Register" and "Securities Registrar" have the respective meanings
specified in Section 504.

  "Securityholder" or "Holder" means a Person in whose name a Trust Security or
Securities is registered in the Securities Register; any such Person is a
beneficial owner within the meaning of the Delaware Business Trust Act.

  "Trust" means the Delaware business trust created and continued hereby and
identified on the cover page to this Trust Agreement.

  "Trust Agreement" means this Amended and Restated Trust Agreement, as the same
may be modified, amended or supplemented in accordance with the applicable
provisions hereof, including all exhibits hereto, including, for all purposes of
this Trust Agreement and any such modification, amendment or supplement, the
provisions of the Trust Indenture Act that are deemed to be a part of and govern
this Trust Agreement and any such modification, amendment or supplement,
respectively.

  "Trust Indenture Act" means the Trust Indenture Act of 1939, as amended, as in
force at the date as of which this instrument was executed; provided, however,
that in the event the Trust Indenture Act of 1939, as amended, is amended after
such date, "Trust Indenture Act" means, to the extent required by any such
amendment, the Trust Indenture Act of 1939 as so amended.

  "Trust Property" means (a) the Debentures; (b) the rights of the Property
Trustee under the Guarantee; (c) any cash on deposit in, or owing to, the
Payment Account; and (d) all proceeds and rights in respect of the foregoing and
any other property and assets for the time being held or deemed to be held by
the Property Trustee pursuant to the trusts of this Trust Agreement.

  "Trust Security" means any one of the Common Securities or the Preferred
Securities.

  "Trust Securities Certificate" means any one of the Common Securities
Certificates or the Preferred Securities Certificates.

  "Trustees" means, collectively, the Property Trustee, the Delaware Trustee and
the Administrative Trustees.

  "Underwriting Agreement" means the Underwriting Agreement, dated as of May 29,
1997, among the Trust, the Depositor and the Underwriters named therein.

                                   ARTICLE II

                           ESTABLISHMENT OF THE TRUST

 SECTION 201. NAME.

  The Trust created and continued hereby shall be known as "SBI Capital Trust,"
as such name may be modified from time to time by the Administrative Trustees
following written notice to the Holders of Trust Securities and the other
Trustees, in which name the Trustees may engage in the transactions contemplated
hereby, make and execute contracts and other instruments on behalf of the Trust
and sue and be sued.

                                      7
<PAGE>
 
 SECTION 202.  OFFICE OF THE DELAWARE TRUSTEE; PRINCIPAL PLACE OF BUSINESS.

  The address of the Delaware Trustee in the State of Delaware is c/o Wilmington
Trust Company, Rodney Square North, 1100 North Market Street, Wilmington,
Delaware 19890-0001, Attention: Corporate Trust Administration, or such other
address in the State of Delaware as the Delaware Trustee may designate by
written notice to the Securityholders and the Depositor. The principal executive
office of the Trust is 608 South Main Street, Stillwater, Oklahoma, 74074.

 SECTION 203.  INITIAL CONTRIBUTION OF TRUST PROPERTY; ORGANIZATIONAL EXPENSES.

  The Trustees acknowledge receipt in trust from the Depositor in connection
with the Original Trust Agreement of the sum of $10, which constituted the
initial Trust Property. The Depositor shall pay organizational expenses of the
Trust as they arise or shall, upon request of any Trustee, promptly reimburse
such Trustee for any such expenses paid by such Trustee. The Depositor shall
make no claim upon the Trust Property for the payment of such expenses.

 SECTION 204.  ISSUANCE OF THE PREFERRED SECURITIES.

  On May 29, 1997, the Depositor and an Administrative Trustee, on behalf of the
Trust and pursuant to the Original Trust Agreement, executed and delivered the
Underwriting Agreement. Contemporaneously with the execution and delivery of
this Trust Agreement, an Administrative Trustee, on behalf of the Trust, shall
execute in accordance with Section 502 and deliver in accordance with the
Underwriting Agreement, Preferred Securities Certificates, registered in the
name of the Persons entitled thereto, in an aggregate amount of 1,000,500
Preferred Securities (including exercise of the underwriter's Option) having an
aggregate Liquidation Amount of $25,012,500 against receipt of the aggregate
purchase price of such Preferred Securities of $25,012,500, which amount such
Administrative Trustee shall promptly deliver to the Property Trustee.

 SECTION 205. ISSUANCE OF THE COMMON SECURITIES; SUBSCRIPTION AND PURCHASE OF
DEBENTURES.

     Contemporaneously with the execution and delivery of this Trust Agreement,
an Administrative Trustee, on behalf of the Trust, shall execute in accordance
with Section 502 and deliver to the Depositor, Common Securities Certificates,
registered in the name of the Depositor, in an aggregate amount of 30,960 Common
Securities having an aggregate Liquidation Amount of $774,000 against payment by
the Depositor of such amount. Contemporaneously therewith, an Administrative
Trustee, on behalf of the Trust, shall subscribe to and purchase from the
Depositor Debentures, registered in the name of the Property Trustee on behalf
of the Trust and having an aggregate principal amount equal to $774,000, and, in
satisfaction of the purchase price for such Debentures, the Property Trustee, on
behalf of the Trust, shall deliver to the Depositor the sum of $774,000.

 SECTION 206.  DECLARATION OF TRUST.

  The exclusive purposes and functions of the Trust are (a) to issue and sell
Trust Securities and use the proceeds from such sale to acquire the Debentures;
and (b) to engage in those activities necessary, convenient or incidental
thereto. The Depositor hereby appoints the Trustees as trustees of the Trust, to
have all the rights, powers and duties to the extent set forth herein, and the
Trustees hereby accept such appointment. The Property Trustee hereby declares
that it shall hold the Trust Property in trust upon and subject to the
conditions set forth herein for the benefit of the Securityholders. The
Administrative Trustees shall have all rights, powers and duties set forth
herein and in accordance with applicable law with respect to accomplishing the
purposes of the Trust. The Delaware Trustee shall not be entitled to exercise
any powers, nor shall the Delaware Trustee have any of the duties and
responsibilities, of the Property Trustee or the Administrative Trustees set
forth herein. The Delaware Trustee shall be one of the Trustees of the Trust for
the sole and limited purpose of fulfilling the requirements of Section 3807 of
the Delaware Business Trust Act.

                                      8
<PAGE>
 
 SECTION 207.  AUTHORIZATION TO ENTER INTO CERTAIN TRANSACTIONS.

  (a) The Trustees shall conduct the affairs of the Trust in accordance with the
terms of this Trust Agreement. Subject to the limitations set forth in paragraph
(b) of this Section 207 and Article VIII, and in accordance with the following
provisions (i) and (ii), the Administrative Trustees shall have the authority to
enter into all transactions and agreements determined by the Administrative
Trustees to be appropriate in exercising the authority, express or implied,
otherwise granted to the Administrative Trustees under this Trust Agreement, and
to perform all acts in furtherance thereof, including without limitation, the
following:

     (i) As among the Trustees, each Administrative Trustee, acting singly or
jointly, shall have the power and authority to act on behalf of the Trust with
respect to the following matters:

      (A) the issuance and sale of the Trust Securities;

      (B) to cause the Trust to enter into, and to execute, deliver and perform
on behalf of the Trust, the Expense Agreement and such other agreements or
documents as may be necessary or desirable in connection with the purposes and
function of the Trust;

      (C) assisting in the registration of the Preferred Securities under the
Securities Act of 1933, as amended, and under state securities or blue sky laws,
and the qualification of this Trust Agreement as a trust indenture under the
Trust Indenture Act;

      (D) assisting in the listing of the Preferred Securities upon The Nasdaq
Stock Market's National Market or such securities exchange or exchanges as shall
be determined by the Depositor and the registration of the Preferred Securities
under the Exchange Act, and the preparation and filing of all periodic and other
reports and other documents pursuant to the foregoing;

      (E) the sending of notices (other than notices of default) and other
information regarding the Trust Securities and the Debentures to the
Securityholders in accordance with this Trust Agreement;

      (F) the appointment of a Paying Agent, Authenticating Agent and Securities
Registrar in accordance with this Trust Agreement;

      (G) to the extent provided in this Trust Agreement, the winding up of the
affairs of and liquidation of the Trust and the preparation, execution and
filing of the certificate of cancellation with the Secretary of State of the
State of Delaware;

      (H) to take all action that may be necessary or appropriate for the
preservation and the continuation of the Trust's valid existence, rights,
franchises and privileges as a statutory business trust under the laws of the
State of Delaware and of each other jurisdiction in which such existence is
necessary to protect the limited liability of the Holders of the Preferred
Securities or to enable the Trust to effect the purposes for which the Trust was
created; and

      (I) the taking of any action incidental to the foregoing as the
Administrative Trustees may from time to time determine is necessary or
advisable to give effect to the terms of this Trust Agreement for the benefit of
the Securityholders (without consideration of the effect of any such action on
any particular Securityholder).

     (ii) As among the Trustees, the Property Trustee shall have the power, duty
and authority to act on behalf of the Trust with respect to the following
matters:

      (A) the establishment of the Payment Account;

      (B) the receipt of the Debentures;

                                      9
<PAGE>
 
      (C) the collection of interest, principal and any other payments made in
respect of the Debentures in the Payment Account;

      (D) the distribution of amounts owed to the Securityholders in respect of
the Trust Securities in accordance with the terms of this Trust Agreement;

      (E) the exercise of all of the rights, powers and privileges of a holder
of the Debentures;

      (F) the sending of notices of default and other information regarding the
Trust Securities and the Debentures to the Securityholders in accordance with
this Trust Agreement;

      (G) the distribution of the Trust Property in accordance with the terms of
this Trust Agreement;

      (H) to the extent provided in this Trust Agreement, the winding up of the
affairs of and liquidation of the Trust;

      (I) after an Event of Default, the taking of any action incidental to the
foregoing as the Property Trustee may from time to time determine is necessary
or advisable to give effect to the terms of this Trust Agreement and protect and
conserve the Trust Property for the benefit of the Securityholders (without
consideration of the effect of any such action on any particular
Securityholder);

      (J) registering transfers of the Trust Securities in accordance with this
Trust Agreement; and

      (K) except as otherwise provided in this Section 207(a)(ii), the Property
Trustee shall have none of the duties, liabilities, powers or the authority of
the Administrative Trustees set forth in Section 207(a)(i).

  (b) So long as this Trust Agreement remains in effect, the Trust (or the
Trustees acting on behalf of the Trust) shall not undertake any business,
activities or transaction except as expressly provided herein or contemplated
hereby. In particular, the Trustees shall not (i) acquire any investments or
engage in any activities not authorized by this Trust Agreement; (ii) sell,
assign, transfer, exchange, mortgage, pledge, set-off or otherwise dispose of
any of the Trust Property or interests therein, including to Securityholders,
except as expressly provided herein; (iii) take any action that would cause the
Trust to fail or cease to qualify as a "grantor trust" for United States federal
income tax purposes; (iv) incur any indebtedness for borrowed money or issue any
other debt; or (v) take or consent to any action that would result in the
placement of a Lien on any of the Trust Property. The Administrative Trustees
shall defend all claims and demands of all Persons at any time claiming any Lien
on any of the Trust Property adverse to the interest of the Trust or the
Securityholders in their capacity as Securityholders.

  (c) In connection with the issue and sale of the Preferred Securities, the
Depositor shall have the right and responsibility to assist the Trust with
respect to, or effect on behalf of the Trust, the following (and any actions
taken by the Depositor in furtherance of the following prior to the date of this
Trust Agreement are hereby ratified and confirmed in all respects):

     (i) the preparation and filing by the Trust with the Commission and the
execution on behalf of the Trust of a registration statement on the appropriate
form in relation to the Preferred Securities and the Debentures, including any
amendments thereto;

     (ii) the determination of the States in which to take appropriate action to
qualify or, register for sale all or part of the Preferred Securities and to do
any and all such acts, other than actions which must be taken by or on behalf of
the Trust, and advise the Trustees of actions they must take on behalf of the
Trust, and prepare for execution and filing any documents to be executed and
filed by the Trust or on behalf of the Trust, as the Depositor deems necessary
or advisable in order to comply with the applicable laws of any such States;

                                      10
<PAGE>
 
     (iii) the preparation for filing by the Trust and execution on behalf of
the Trust of an application to The Nasdaq Stock Market's National Market or a
national stock exchange or other organizations for listing upon notice of
issuance of any Preferred Securities and to file or cause an Administrative
Trustee to file thereafter with such exchange or organization such notifications
and documents as may be necessary from time to time;

     (iv)  the preparation for filing by the Trust with the Commission and the
execution on behalf of the Trust of a registration statement on Form 8-A
relating to the registration of the Preferred Securities under Section 12(b) or
12(g) of the Exchange Act, including any amendments thereto;

     (v)   the negotiation of the terms of, and the execution and delivery of,
the Underwriting Agreement providing for the sale of the Preferred Securities;
and

     (vi)  the taking of any other actions necessary or desirable to carry out
any of the foregoing activities.

  (d) Notwithstanding anything herein to the contrary, the Administrative
Trustees are authorized and directed to conduct the affairs of the Trust and to
operate the Trust so that the Trust shall not be deemed to be an "investment
company" required to be registered under the Investment Company Act, shall be
classified as a "grantor trust" and not as an association taxable as a
corporation for United States federal income tax purposes and so that the
Debentures shall be treated as indebtedness of the Depositor for United States
federal income tax purposes. In this connection, subject to Section 1002, the
Depositor and the Administrative Trustees are authorized to take any action, not
inconsistent with applicable law or this Trust Agreement, that each of the
Depositor and the Administrative Trustees determines in their discretion to be
necessary or desirable for such purposes.

 SECTION 208. ASSETS OF TRUST.

 The assets of the Trust shall consist of the Trust Property.

 SECTION 209. TITLE TO TRUST PROPERTY.

  Legal title to all Trust Property shall be vested at all times in the Property
Trustee (in its capacity as such) and shall be held and administered by the
Property Trustee for the benefit of the Securityholders in accordance with this
Trust Agreement.

                                  ARTICLE III

                                PAYMENT ACCOUNT

 SECTION 301.  PAYMENT ACCOUNT.

  (a) On or prior to the Closing Date, the Property Trustee shall establish the
Payment Account. The Property Trustee and any agent of the Property Trustee
shall have exclusive control and sole right of withdrawal with respect to the
Payment Account for the purpose of making deposits and withdrawals from the
Payment Account in accordance with this Trust Agreement. All monies and other
property deposited or held from time to time in the Payment Account shall be
held by the Property Trustee in the Payment Account for the exclusive benefit of
the Securityholders and for distribution as herein provided, including (and
subject to) any priority of payments provided for herein.

  (b) The Property Trustee shall deposit in the Payment Account, promptly upon
receipt, all payments of principal of or interest on, and any other payments or
proceeds with respect to, the Debentures. Amounts held in the Payment Account
shall not be invested by the Property Trustee pending distribution thereof.

                                      11
<PAGE>
 
                                 ARTICLE IV

                           DISTRIBUTIONS; REDEMPTION

 SECTION 401.  DISTRIBUTIONS.

  (a) Distributions on the Trust Securities shall be cumulative, and shall
accumulate whether or not there are funds of the Trust available for the payment
of Distributions. Distributions shall accumulate from June 4, 1997, and, except
during any Extended Interest Payment Period with respect to the Debentures,
shall be payable quarterly in arrears on January 31, April 30, July 31 and
October 31 of each year, commencing on July 31, 1997. If any date on which a
Distribution is otherwise payable on the Trust Securities is not a Business Day,
then the payment of such Distribution shall be made on the next succeeding day
that is a Business Day (and without any interest or other payment in respect of
any such delay) with the same force and effect as if made on such date (each
date on which distributions are payable in accordance with this Section 401(a),
a "Distribution Date").

  (b) The Trust Securities represent undivided beneficial interests in the Trust
Property.  Distributions on the Trust Securities shall be payable at a rate of
9.30% per annum of the Liquidation Amount of the Trust Securities. The amount of
Distributions payable for any full period shall be computed on the basis of a
360-day year of twelve 30-day months. The amount of Distributions for any
partial period shall be computed on the basis of the number of days elapsed in a
360-day year of twelve 30 day months. During any Extended Interest Payment
Period with respect to the Debentures, Distributions on the Preferred Securities
shall be deferred for a period equal to the Extended Interest Payment Period.
The amount of Distributions payable for any period shall include the Additional
Amounts, if any.

  (c) Distributions on the Trust Securities shall be made by the Property
Trustee solely from the Payment Account and shall be payable on each
Distribution Date only to the extent that the Trust has funds then on hand and
immediately available by 12:30 p.m. on each Distribution Date in the Payment
Account for the payment of such Distributions.

  (d) Distributions on the Trust Securities with respect to a Distribution Date
shall be payable to the Holders thereof as they appear on the Securities
Register for the Trust Securities on the relevant record date, which shall be
the 15th day of the month in which the Distribution is payable.

 SECTION 402.  REDEMPTION.

  (a) On each Debenture Redemption Date and on the stated maturity of the
Debentures, the Trust shall be required to redeem a Like Amount of Trust
Securities at the Redemption Price.

  (b) Notice of redemption shall be given by the Property Trustee by first-class
mail, postage prepaid, mailed not less than 30 nor more than 60 days prior to
the Redemption Date to each Holder of Trust Securities to be redeemed, at such
Holder's address appearing in the Securities Register. The Property Trustee
shall have no responsibility for the accuracy of any CUSIP number contained in
such notice. All notices of redemption shall state:

     (i)   the Redemption Date;

     (ii)  the Redemption Price;

     (iii) the CUSIP number;

     (iv)  if less than all the Outstanding Trust Securities are to be redeemed,
the identification and the aggregate Liquidation Amount of the particular Trust
Securities to be redeemed; and

     (v)   that, on the Redemption Date, the Redemption Price shall become due
and payable upon each such Trust Security to be redeemed and that Distributions
thereon shall cease to accumulate on and after said date.

                                      12
<PAGE>
 
  (c) The Trust Securities redeemed on each Redemption Date shall be redeemed at
the Redemption Price with the proceeds from the contemporaneous redemption of
Debentures. Redemptions of the Trust Securities shall be made and the Redemption
Price shall be payable on each Redemption Date only to the extent that the Trust
has immediately available funds then on hand and available in the Payment
Account for the payment of such Redemption Price.

  (d) If the Property Trustee gives a notice of redemption in respect of any
Preferred Securities, then, by 12:00 noon, New York City time, on the Redemption
Date, subject to Section 402(c), the Property Trustee shall deposit with the
Paying Agent funds sufficient to pay the applicable Redemption Price and shall
give the Paying Agent irrevocable instructions and authority to pay the
Redemption Price to the Holders thereof upon surrender of their Preferred
Securities Certificates. Notwithstanding the foregoing, Distributions payable on
or prior to the Redemption Date for any Trust Securities called for redemption
shall be payable to the Holders of such Trust Securities as they appear on the
Securities Register for the Trust Securities on the relevant record dates for
the related Distribution Dates. If notice of redemption shall have been given
and funds deposited as required, then upon the date of such deposit, all rights
of Securityholders holding Trust Securities so called for redemption shall
cease, except the right of such Securityholders to receive the Redemption Price
and any Distribution payable on or prior to the Redemption Date, but without
interest, and such Trust Securities shall cease to be Outstanding. In the event
that any date on which any Redemption Price is payable is not a Business Day,
then payment of the Redemption Price payable on such date shall be made on the
next succeeding day that is a Business Day (and without any interest or other
payment in respect of any such delay) with the same force and effect as if made
on such date. In the event that payment of the Redemption Price in respect of
any Trust Securities called for redemption is improperly withheld or refused and
not paid either by the Trust or by the Depositor pursuant to the Guarantee,
Distributions on such Trust Securities shall continue to accumulate, at the then
applicable rate, from the Redemption Date originally established by the Trust
for such Trust Securities to the date such Redemption Price is actually paid, in
which case the actual payment date shall be the date fixed for redemption for
purposes of calculating the Redemption Price.

  (e) Payment of the Redemption Price on the Trust Securities shall be made to
the record holders thereof as they appear on the Securities Register for the
Trust Securities on the relevant record date, which shall be the date 15 days
prior to the relevant Redemption Date.

  (f) Subject to Section 403(a), if less than all the Outstanding Trust
Securities are to be redeemed on a Redemption Date, then the aggregate
Liquidation Amount of Trust Securities to be redeemed shall be allocated on a
pro rata basis (based on Liquidation Amounts) among the Common Securities and
the Preferred Securities. The particular Preferred Securities to be redeemed
shall be selected not more than 60 days prior to the Redemption Date by the
Property Trustee from the Outstanding Preferred Securities not previously called
for redemption, by such method (including, without limitation, by lot) as the
Property Trustee shall deem fair and appropriate and which may provide for the
selection for redemption of portions (equal to $25 or an integral multiple of
$25 in excess thereof) of the Liquidation Amount of Preferred Securities of a
denomination larger than $25. The Property Trustee shall promptly notify the
Securities Registrar in writing of the Preferred Securities selected for
redemption and, in the case of any Preferred Securities selected for partial
redemption, the Liquidation Amount thereof to be redeemed. For all purposes of
this Trust Agreement, unless the context otherwise requires, all provisions
relating to the redemption of Preferred Securities shall relate, in the case of
any Preferred Securities redeemed or to be redeemed only in part, to the portion
of the Liquidation Amount of Preferred Securities which has been or is to be
redeemed.

 SECTION 403.  SUBORDINATION OF COMMON SECURITIES.

  (a) Payment of Distributions (including Additional Amounts, if applicable) on,
and the Redemption Price of, the Trust Securities, as applicable, shall be made,
subject to Section 402(f), pro rata among the Common Securities and the
Preferred Securities based on the Liquidation Amount of the Trust Securities;
provided, however, that if on any Distribution Date or Redemption Date any Event
of Default resulting from a Debenture Event of Default shall have occurred and
be continuing, no payment of any Distribution (including Additional Amounts, if
applicable) on, or Redemption Price of, any Common Security, and no other
payment on account of the redemption, liquidation or

                                      13
<PAGE>
 
other acquisition of Common Securities, shall be made unless payment in full in
cash of all accumulated and unpaid Distributions (including Additional Amounts,
if applicable) on all Outstanding Preferred Securities for all Distribution
periods terminating on or prior thereto, or in the case of payment of the
Redemption Price the full amount of such Redemption Price on all Outstanding
Preferred Securities then called for redemption, shall have been made or
provided for, and all funds immediately available to the Property Trustee shall
first be applied to the payment in full in cash of all Distributions (including
Additional Amounts, if applicable) on, or the Redemption Price of, Preferred
Securities then due and payable.

  (b) In the case of the occurrence of any Event of Default resulting from a
Debenture Event of Default, the Holder of Common Securities shall be deemed to
have waived any right to act with respect to any such Event of Default under
this Trust Agreement until the effect of all such Events of Default with respect
to the Preferred Securities shall have been cured, waived or otherwise
eliminated. Until any such Event of Default under this Trust Agreement with
respect to the Preferred Securities shall have been so cured, waived or
otherwise eliminated, the Property Trustee shall act solely on behalf of the
Holders of the Preferred Securities and not the Holder of the Common Securities,
and only the Holders of the Preferred Securities shall have the right to direct
the Property Trustee to act on their behalf.

 SECTION 404.  PAYMENT PROCEDURES.

  Payments of Distributions (including Additional Amounts, if applicable) in
respect of the Preferred Securities shall be made by check mailed to the address
of the Person entitled thereto as such address shall appear on the Securities
Register. Payments in respect of the Common Securities shall be made in such
manner as shall be mutually agreed between the Property Trustee and the Common
Securityholder.

 SECTION 405.  TAX RETURNS AND REPORTS.

  The Administrative Trustees shall prepare (or cause to be prepared), at the
Depositor's expense, and file all United States federal, state and local tax and
information returns and reports required to be filed by or in respect of the
Trust. In this regard, the Administrative Trustees shall (a) prepare and file
(or cause to be prepared and filed) the appropriate Internal Revenue Service
form required to be filed in respect of the Trust in each taxable year of the
Trust; and (b) prepare and furnish (or cause to be prepared and furnished) to
each Securityholder the appropriate Internal Revenue Service form required to be
furnished to such Securityholder or the information required to be provided on
such form. The Administrative Trustees shall provide the Depositor with a copy
of all such returns and reports promptly after such filing or furnishing. The
Property Trustee shall comply with United States federal withholding and backup
withholding tax laws and information reporting requirements with respect to any
payments to Securityholders under the Trust Securities.

 SECTION 406.  PAYMENT OF TAXES, DUTIES, ETC. OF THE TRUST.

  Upon receipt under the Debentures of Additional Interest, the Property
Trustee, at the direction of an Administrative Trustee or the Depositor, shall
promptly pay any taxes, duties or governmental charges of whatsoever nature
(other than withholding taxes) imposed on the Trust by the United States or any
other taxing authority.

 SECTION 407.  PAYMENTS UNDER INDENTURE.

  Any amount payable hereunder to any Holder of Preferred Securities shall be
reduced by the amount of any corresponding payment such Holder has directly
received under the Indenture pursuant to Section 514(b) or (c) hereof.

                                      14
<PAGE>
 
                                   ARTICLE V

                         TRUST SECURITIES CERTIFICATES

 SECTION 501.  INITIAL OWNERSHIP.

  Upon the creation of the Trust and the contribution by the Depositor pursuant
to Section 203 and until the issuance of the Trust Securities, and at any time
during which no Trust Securities are outstanding, the Depositor shall be the
sole beneficial owner of the Trust.

 SECTION 502.  THE TRUST SECURITIES CERTIFICATES.

  The Preferred Securities Certificates shall be issued in minimum denominations
of $25 Liquidation Amount and integral multiples of $25 in excess thereof, and
the Common Securities Certificates shall be issued in denominations of $25
Liquidation Amount and integral multiples thereof. The Trust Securities
Certificates shall be executed on behalf of the Trust by manual or facsimile
signature of at least one Administrative Trustee. Trust Securities Certificates
bearing the manual or facsimile signatures of individuals who were, at the time
when such signatures shall have been affixed, authorized to sign on behalf of
the Trust, shall be validly issued and entitled to the benefits of this Trust
Agreement, notwithstanding that such individuals or any of them shall have
ceased to be so authorized prior to the delivery of such Trust Securities
Certificates or did not hold such offices at the date of delivery of such Trust
Securities Certificates. A transferee of a Trust Securities Certificate shall
become a Securityholder, and shall be entitled to the rights and subject to the
obligations of a Securityholder hereunder, upon due registration of such Trust
Securities Certificate in such transferee's name pursuant to Sections 504 and
511.

 SECTION 503.  EXECUTION, AUTHENTICATION AND DELIVERY OF TRUST SECURITIES
CERTIFICATES.

  (a) On the Closing Date and on the date on which the Underwriter exercises the
Option, as applicable (the "Option Closing Date"), the Administrative Trustees
shall cause Trust Securities Certificates, in an aggregate Liquidation Amount as
provided in Sections 204 and 205, to be executed on behalf of the Trust by at
least one of the Administrative Trustees and delivered to or upon the written
order of the Depositor, signed by its Chief Executive Officer, President, any
Vice President, the Treasurer or any Assistant Treasurer without further
corporate action by the Depositor, in authorized denominations.

  (b) A Preferred Securities Certificate shall not be valid until authenticated
by the manual signature of an authorized signatory of the Property Trustee.  The
signature of the Property Trustee shall be conclusive evidence that the
Preferred Securities Certificate has been authenticated under this Trust
Agreement.  Each Preferred Security Certificate shall be dated the date of its
authentication.

  (c) Upon the written order of the Trust signed by the Administrative Trustee,
the Property Trustee shall authenticate and make available for delivery the
Preferred Securities Certificates.

  (d) The Property Trustee may appoint an Authenticating Agent acceptable to the
Trust to authenticate the Preferred Securities.  An Authenticating Agent may
authenticate the Preferred Securities whenever the Property Trustee may do so.
Each reference in this Trust Agreement to authentication by the Property Trustee
includes authentication by such agent.  An Authenticating Agent has the same
rights as the Property Trustee to deal with the Depositor or the Trust.

 SECTION 504.  REGISTRATION OF TRANSFER AND EXCHANGE OF PREFERRED SECURITIES
CERTIFICATES.

  (a) The Depositor shall keep or cause to be kept, at the office or agency
maintained pursuant to Section 508, a register or registers for the purpose of
registering Trust Securities Certificates and transfers and exchanges of

                                      15
<PAGE>
 
Preferred Securities Certificates (herein referred to as the "Securities
Register") in which the registrar designated by the Depositor (the "Securities
Registrar"), subject to such reasonable regulations as it may prescribe, shall
provide for the registration of Preferred Securities Certificates and Common
Securities Certificates (subject to Section 510 in the case of the Common
Securities Certificates) and registration of transfers and exchanges of
Preferred Securities Certificates as herein provided. The Property Trustee shall
be the initial Securities Registrar.

  (b) Upon surrender for registration of transfer of any Preferred Securities
Certificate at the office or agency maintained pursuant to Section 508, the
Administrative Trustees or any one of them shall execute and deliver, in the
name of the designated transferee or transferees, one or more new Preferred
Securities Certificates in authorized denominations of a like aggregate
Liquidation Amount dated the date of execution by such Administrative Trustee or
Trustees. The Securities Registrar shall not be required to register the
transfer of any Preferred Securities that have been called for redemption. At
the option of a Holder, Preferred Securities Certificates may be exchanged for
other Preferred Securities Certificates in authorized denominations of the same
class and of a like aggregate Liquidation Amount upon surrender of the Preferred
Securities Certificates to be exchanged at the office or agency maintained
pursuant to Section 508.

  (c) Every Preferred Securities Certificate presented or surrendered for
registration of transfer or exchange shall be accompanied by a written
instrument of transfer in form satisfactory to the Property Trustee and the
Securities Registrar duly executed by the Holder or his attorney duly authorized
in writing. Each Preferred Securities Certificate surrendered for registration
of transfer or exchange shall be canceled and subsequently disposed of by the
Property Trustee in accordance with its customary practice. The Trust shall not
be required to (i) issue, register the transfer of, or exchange any Preferred
Securities during a period beginning at the opening of business 15 calendar days
before the date of mailing of a notice of redemption of any Preferred Securities
called for redemption and ending at the close of business on the day of such
mailing; or (ii) register the transfer of or exchange any Preferred Securities
so selected for redemption, in whole or in part, except the unredeemed portion
of any such Preferred Securities being redeemed in part.

  (d) No service charge shall be made for any registration of transfer or
exchange of Preferred Securities Certificates, but the Securities Registrar may
require payment of a sum sufficient to cover any tax or governmental charge that
may be imposed in connection with any transfer or exchange of Preferred
Securities Certificates.

 SECTION 505.  MUTILATED, DESTROYED, LOST OR STOLEN TRUST SECURITIES
CERTIFICATES.

  If (a) any mutilated Trust Securities Certificate shall be surrendered to the
Securities Registrar, or if the Securities Registrar shall receive evidence to
its satisfaction of the destruction, loss or theft of any Trust Securities
Certificate; and (b) there shall be delivered to the Securities Registrar, the
Property Trustee and the Administrative Trustees such security or indemnity as
may be required by them to save each of them harmless, then in the absence of
notice that such Trust Securities Certificate shall have been acquired by a bona
fide purchaser, the Administrative Trustees, or any one of them, on behalf of
the Trust shall execute and make available for delivery, in exchange for or in
lieu of any such mutilated, destroyed, lost or stolen Trust Securities
Certificate, a new Trust Securities Certificate of like class, tenor and
denomination. In connection with the issuance of any new Trust Securities
Certificate under this Section 505, the Administrative Trustees or the
Securities Registrar may require the payment of a sum sufficient to cover any
tax or other governmental charge that may be imposed in connection therewith.
Any duplicate Trust Securities Certificate issued pursuant to this Section 505
shall constitute conclusive evidence of an undivided beneficial interest in the
assets of the Trust, as if originally issued, whether or not the lost, stolen or
destroyed Trust Securities Certificate shall be found at any time.

 SECTION 506.  PERSONS DEEMED SECURITYHOLDERS.

  The Trustees, the Paying Agent and the Securities Registrar shall treat the
Person in whose name any Trust Securities Certificate shall be registered in the
Securities Register as the owner of such Trust Securities Certificate

                                      16
<PAGE>
 
for the purpose of receiving Distributions and for all other purposes
whatsoever, and neither the Trustees nor the Securities Registrar shall be bound
by any notice to the contrary.

 SECTION 507.  ACCESS TO LIST OF SECURITYHOLDERS' NAMES AND ADDRESSES.

  At any time when the Property Trustee is not also acting as the Securities
Registrar, the Administrative Trustees or the Depositor shall furnish or cause
to be furnished to the Property Trustee (a) semi-annually on or before January
15 and July 15 in each year, a list, in such form as the Property Trustee may
reasonably require, of the names and addresses of the Securityholders as of the
most recent record date; and (b) promptly after receipt by any Administrative
Trustee or the Depositor of a request therefor from the Property Trustee in
order to enable the Property Trustee to discharge its obligations under this
Trust Agreement, in each case to the extent such information is in the
possession or control of the Administrative Trustees or the Depositor and is not
identical to a previously supplied list or has not otherwise been received by
the Property Trustee in its capacity as Securities Registrar. The rights of
Securityholders to communicate with other Securityholders with respect to their
rights under this Trust Agreement or under the Trust Securities, and the
corresponding rights of the Trustee shall be as provided in the Trust Indenture
Act. Each Holder, by receiving and holding a Trust Securities Certificate, and
each owner shall be deemed to have agreed not to hold the Depositor, the
Property Trustee or the Administrative Trustees accountable by reason of the
disclosure of its name and address, regardless of the source from which such
information was derived.

 SECTION 508.  MAINTENANCE OF OFFICE OR AGENCY.

  The Administrative Trustees shall maintain in a location or locations
designated by the Administrative Trustees, an office or offices or agency or
agencies where Preferred Securities Certificates may be surrendered for
registration of transfer or exchange and where notices and demands to or upon
the Trustees in respect of the Trust Securities Certificates may be served. The
Administrative Trustees initially designate the Corporate Trust Office of the
Property Trustee, Two International Place, 4th Floor, Boston, Massachusetts
02110, as the principal corporate trust office for such purposes. The
Administrative Trustees shall give prompt written notice to the Depositor and to
the Securityholders of any change in the location of the Securities Register or
any such office or agency.

 SECTION 509.  APPOINTMENT OF PAYING AGENT.

  The Paying Agent shall initially be the Property Trustee, and any co-paying
agent chosen by the Property Trustee must be acceptable to the Administrative
Trustees and the Depositor. The Paying Agent shall make Distributions to
Securityholders from the Payment Account and shall report the amounts of such
Distributions to the Property Trustee and the Administrative Trustees. Any
Paying Agent shall have the revocable power to withdraw funds from the Payment
Account for the purpose of making the Distributions referred to above. The
Administrative Trustees may revoke such power and remove the Paying Agent if
such Trustees determine in their sole discretion that the Paying Agent shall
have failed to perform its obligations under this Trust Agreement in any
material respect. Any Person acting as Paying Agent shall be permitted to resign
as Paying Agent upon 30 days' written notice to the Administrative Trustees, the
Property Trustee and the Depositor. In the event that the Property Trustee shall
no longer be the Paying Agent or a successor Paying Agent shall resign or its
authority to act be revoked, the Administrative Trustees shall appoint a
successor that is acceptable to the Property Trustee and the Depositor to act as
Paying Agent (which shall be a bank or trust company). The Administrative
Trustees shall cause such successor Paying Agent or any additional Paying Agent
appointed by the Administrative Trustees to execute and deliver to the Trustees
an instrument in which such successor Paying Agent or additional Paying Agent
shall agree with the Trustees that as Paying Agent, such successor Paying Agent
or additional Paying Agent shall hold all sums, if any, held by it for payment
to the Securityholders in trust for the benefit of the Securityholders entitled
thereto until such sums shall be paid to such Securityholders. The Paying Agent
shall return all unclaimed funds to the Property Trustee and, upon removal of a
Paying Agent, such Paying Agent shall also return all funds in its possession to
the Property Trustee. The provisions of Sections 801, 803 and 806 shall apply to
the Property Trustee also in its role as Paying Agent, for so long as the
Property Trustee shall act as Paying Agent and, to the extent applicable, to any
other paying

                                      17
<PAGE>
 
agent appointed hereunder. Any reference in this Trust Agreement to the Paying
Agent shall include any co-paying agent unless the context requires otherwise.

 SECTION 510.  OWNERSHIP OF COMMON SECURITIES BY DEPOSITOR.

  On the Closing Date, the Depositor shall acquire and retain beneficial and
record ownership of the Common Securities. To the fullest extent permitted by
law, any attempted transfer of the Common Securities (other than a transfer in
connection with a merger or consolidation of the Depositor into another
corporation pursuant to Section 12.1 of the Indenture) shall be void. The
Administrative Trustees shall cause each Common Securities Certificate issued to
the Depositor to contain a legend stating "THIS CERTIFICATE IS NOT
TRANSFERABLE".

 SECTION 511.  PREFERRED SECURITIES CERTIFICATES.

  (a) Each owner shall receive a Preferred Securities Certificate representing
such owner's interest in such Preferred Securities. Upon the issuance of
Preferred Securities Certificates, the Trustees shall recognize the record
holders of the Preferred Securities Certificates as Securityholders. The
Preferred Securities Certificates shall be printed, lithographed or engraved or
may be produced in any other manner as is reasonably acceptable to the
Administrative Trustees, as evidenced by the execution thereof by the
Administrative Trustees or any one of them.

  (b) A single Common Securities Certificate representing the Common Securities
shall be issued to the Depositor in the form of a definitive Common Securities
Certificate.

 SECTION 512.  [Intentionally Omitted]

 SECTION 513.  [Intentionally Omitted]

 SECTION 514.  RIGHTS OF SECURITYHOLDERS.

  (a) The legal title to the Trust Property is vested exclusively in the
Property Trustee (in its capacity as such) in accordance with Section 209, and
the Securityholders shall not have any right or title therein other than the
undivided beneficial interest in the assets of the Trust conferred by their
Trust Securities and they shall have no right to call for any partition or
division of property, profits or rights of the Trust except as described below.
The Trust Securities shall be personal property giving only the rights
specifically set forth therein and in this Trust Agreement. The Trust Securities
shall have no preemptive or similar rights. When issued and delivered to Holders
of the Preferred Securities against payment of the purchase price therefor, the
Preferred Securities shall be fully paid and nonassessable interests in the
Trust. The Holders of the Preferred Securities, in their capacities as such,
shall be entitled to the same limitation of personal liability extended to
stockholders of private corporations for profit organized under the General
Corporation Law of the State of Delaware.

  (b) For so long as any Preferred Securities remain Outstanding, if, upon a
Debenture Event of Default, the Debenture Trustee fails or the holders of not
less than 25% in principal amount of the outstanding Debentures fail to declare
the principal of all of the Debentures to be immediately due and payable, the
Holders of at least 25% in Liquidation Amount of the Preferred Securities then
Outstanding shall have such right by a notice in writing to the Depositor and
the Debenture Trustee; and upon any such declaration such principal amount of
and the accrued interest on all of the Debentures shall become immediately due
and payable, provided that the payment of principal and interest on such
Debentures shall remain subordinated to the extent provided in the Indenture.

  (c) For so long as any Preferred Securities remain outstanding, if, upon a
Debenture Event of Default arising from the failure to pay interest or principal
on the Debentures, the Holders of any Preferred Securities then Outstanding
shall, to the fullest extent permitted by law, have the right to directly
institute proceedings for enforcement of payment to such Holders of principal of
or interest on the Debentures having a principal amount equal to the Liquidation
Amount of the Preferred Securities of such Holders.

                                      18
<PAGE>
 
                                 ARTICLE VI

                   ACTS OF SECURITYHOLDERS; MEETINGS; VOTING

 SECTION 601.  LIMITATIONS ON VOTING RIGHTS.

  (a) Except as provided in this Section 601, in Sections 514, 810 and 1002 and
in the Indenture and as otherwise required by law, no Holder of Preferred
Securities shall have any right to vote or in any manner otherwise control the
administration, operation and management of the Trust or the obligations of the
parties hereto, nor shall anything herein set forth, or contained in the terms
of the Trust Securities Certificates, be construed so as to constitute the
Securityholders from time to time as partners or members of an association.

  (b) So long as any Debentures are held by the Property Trustee, the Trustees
shall not (i) direct the time, method and place of conducting any proceeding for
any remedy available to the Debenture Trustee, or executing any trust or power
conferred on the Debenture Trustee with respect to such Debentures; (ii) waive
any past default which is waivable under Article VII of the Indenture; (iii)
exercise any right to rescind or annul a declaration that the principal of all
the Debentures shall be due and payable; or (iv) consent to any amendment,
modification or termination of the Indenture or the Debentures, where such
consent shall be required, without, in each case, obtaining the prior approval
of the Holders of at least a majority in Liquidation Amount of all Outstanding
Preferred Securities; provided, however, that where a consent under the
Indenture would require the consent of each Holder of outstanding Debentures
affected thereby, no such consent shall be given by the Property Trustee without
the prior written consent of each holder of Preferred Securities. The Trustees
shall not revoke any action previously authorized or approved by a vote of the
Holders of the Outstanding Preferred Securities, except by a subsequent vote of
the Holders of the Outstanding Preferred Securities. The Property Trustee shall
notify each Holder of the Outstanding Preferred Securities of any notice of
default received from the Debenture Trustee with respect to the Debentures. In
addition to obtaining the foregoing approvals of the Holders of the Preferred
Securities, prior to taking any of the foregoing actions, the Trustees shall, at
the expense of the Depositor, obtain an Opinion of Counsel experienced in such
matters to the effect that the Trust shall continue to be classified as a
grantor trust and not as an association taxable as a corporation for United
States federal income tax purposes on account of such action.

  (c) If any proposed amendment to the Trust Agreement provides for, or the
Trustees otherwise propose to effect, (i) any action that would adversely affect
in any material respect the powers, preferences or special rights of the
Preferred Securities, whether by way of amendment to the Trust Agreement or
otherwise; or (ii) the dissolution, winding-up or termination of the Trust,
other than pursuant to the terms of this Trust Agreement, then the Holders of
Outstanding Preferred Securities as a class shall be entitled to vote on such
amendment or proposal and such amendment or proposal shall not be effective
except with the approval of the Holders of at least a majority in Liquidation
Amount of the Outstanding Preferred Securities. No amendment to this Trust
Agreement may be made if, as a result of such amendment, the Trust would cease
to be classified as a grantor trust or would be classified as an association
taxable as a corporation for United States federal income tax purposes.

 SECTION 602.  NOTICE OF MEETINGS.

  Notice of all meetings of the Preferred Securityholders, stating the time,
place and purpose of the meeting, shall be given by the Property Trustee
pursuant to Section 1008 to each Preferred Securityholder of record, at his
registered address, at least 15 days and not more than 90 days before the
meeting. At any such meeting, any business properly before the meeting may be so
considered whether or not stated in the notice of the meeting. Any adjourned
meeting may be held as adjourned without further notice.

 SECTION 603.  MEETINGS OF PREFERRED SECURITYHOLDERS.

  (a) No annual meeting of Securityholders is required to be held. The
Administrative Trustees, however, shall call a meeting of Securityholders to
vote on any matter in respect of which Preferred Securityholders are entitled to
vote upon the written request of the Preferred Securityholders of 25% of the
Outstanding Preferred Securities

                                      19
<PAGE>
 
(based upon their aggregate Liquidation Amount) and the Administrative Trustees
or the Property Trustee may, at any time in their discretion, call a meeting of
Preferred Securityholders to vote on any matters as to which the Preferred
Securityholders are entitled to vote.

  (b) Preferred Securityholders of record of 50% of the Outstanding Preferred
Securities (based upon their aggregate Liquidation Amount), present in person or
by proxy, shall constitute a quorum at any meeting of Securityholders.

  (c) If a quorum is present at a meeting, an affirmative vote by the Preferred
Securityholders of record present, in person or by proxy, holding more than a
majority of the Preferred Securities (based upon their aggregate Liquidation
Amount) held by the Preferred Securityholders of record present, either in
person or by proxy, at such meeting shall constitute the action of the
Securityholders, unless this Trust Agreement requires a greater number of
affirmative votes.

 SECTION 604.  VOTING RIGHTS.

  Securityholders shall be entitled to one vote for each $25 of Liquidation
Amount represented by their Trust Securities in respect of any matter as to
which such Securityholders are entitled to vote.

 SECTION 605.  PROXIES, ETC.

  At any meeting of Securityholders, any Securityholder entitled to vote thereat
may vote by proxy, provided that no proxy shall be voted at any meeting unless
it shall have been placed on file with the Administrative Trustees, or with such
other officer or agent of the Trust as the Administrative Trustees may direct,
for verification prior to the time at which such vote shall be taken. When Trust
Securities are held jointly by several persons, any one of them may vote at any
meeting in person or by proxy in respect of such Trust Securities, but if more
than one of them shall be present at such meeting in person or by proxy, and
such joint owners or their proxies so present disagree as to any vote to be
cast, such vote shall not be received in respect of such Trust Securities. A
proxy purporting to be executed by or on behalf of a Securityholder shall be
deemed valid unless challenged at or prior to its exercise, and, the burden of
proving invalidity shall rest on the challenger. No proxy shall be valid more
than three years after its date of execution.

 SECTION 606.  SECURITYHOLDER ACTION BY WRITTEN CONSENT.

  Any action which may be taken by Securityholders at a meeting may be taken
without a meeting if Securityholders holding more than a majority of all
Outstanding Trust Securities (based upon their aggregate Liquidation Amount)
entitled to vote in respect of such action (or such larger proportion thereof as
shall be required by any express provision of this Trust Agreement) shall
consent to the action in writing (based upon their aggregate Liquidation
Amount).

 SECTION 607.  RECORD DATE FOR VOTING AND OTHER PURPOSES.

  For the purposes of determining the Securityholders who are entitled to notice
of and to vote at any meeting or by written consent, or to participate in any
Distribution on the Trust Securities in respect of which a record date is not
otherwise provided for in this Trust Agreement, or for the purpose of any other
action, the Administrative Trustees may from time to time fix a date, not more
than 90 days prior to the date of any meeting of Securityholders or the payment
of Distribution or other action, as the case may be, as a record date for the
determination of the identity of the Securityholders of record for such
purposes.

                                      20
<PAGE>
 
 SECTION 608.  ACTS OF SECURITYHOLDERS.

  (a) Any request, demand, authorization, direction, notice, consent, waiver or
other action provided or permitted by this Trust Agreement to be given, made or
taken by Securityholders may be embodied in and evidenced by one or more
instruments of substantially similar tenor signed by such Securityholders in
person or by an agent duly appointed in writing; and, except as otherwise
expressly provided herein, such action shall become effective when such
instrument or instruments are delivered to an Administrative Trustee. Such
instrument or instruments (and the action embodied therein and evidenced
thereby) are herein sometimes referred to as the "Act" of the Securityholders
signing such instrument or instruments. Proof of execution of any such
instrument or of a writing appointing any such agent shall be sufficient for any
purpose of this Trust Agreement and (subject to Section 801) conclusive in favor
of the Trustees, if made in the manner provided in this Section 608.

  (b) The fact and date of the execution by any Person of any such instrument or
writing may be proved by the affidavit of a witness of such execution or by a
certificate of a notary public or other officer authorized by law to take
acknowledgments of deeds, certifying that the individual signing such instrument
or writing acknowledged to him the execution thereof. Where such execution is by
a signer acting in a capacity other than his individual capacity, such
certificate or affidavit shall also constitute sufficient proof of his
authority. The fact and date of the execution of any such instrument or writing,
or the authority of the Person executing the same, may also be proved in any
other manner which any Trustee receiving the same deems sufficient.

  (c) The ownership of Preferred Securities shall be proved by the Securities
Register.

  (d) Any request, demand, authorization, direction, notice, consent, waiver or
other Act of the Securityholder of any Trust Security shall bind every future
Securityholder of the same Trust Security and the Securityholder of every Trust
Security issued upon the registration of transfer thereof or in exchange
therefor or in lieu thereof in respect of anything done, omitted or suffered to
be done by the Trustees or the Trust in reliance thereon, whether or not
notation of such action is made upon such Trust Security.

  (e) Without limiting the foregoing, a Securityholder entitled hereunder to
take any action hereunder with regard to any particular Trust Security may do so
with regard to all or any part of the Liquidation Amount of such Trust Security
or by one or more duly appointed agents each of which may do so pursuant to such
appointment with regard to all or any part of such Liquidation Amount.

  (f) A Securityholder may institute a legal proceeding directly against the
Depositor under the Guarantee to enforce its rights under the Guarantee without
first instituting a legal proceeding against the Guarantee Trustee (as defined
in the Guarantee), the Trust or any Person.

 SECTION 609.  INSPECTION OF RECORDS.

  Upon reasonable notice to the Administrative Trustees and the Property
Trustee, the records of the Trust shall be open to inspection and copying by
Securityholders and their authorized representatives during normal business
hours for any purpose reasonably related to such Securityholder's interest as a
Securityholder.

                                      21
<PAGE>
 
                                   ARTICLE VI

                         REPRESENTATIONS AND WARRANTIES

 SECTION 701.  REPRESENTATIONS AND WARRANTIES OF THE BANK AND THE PROPERTY
TRUSTEE.

  The Bank and the Property Trustee, each severally on behalf of and as to
itself, as of the date hereof, and each successor Property Trustee at the time
of the successor Property Trustee's acceptance of its appointment as Property
Trustee hereunder (the term "Bank" being used to refer to such successor
Property Trustee in its separate corporate capacity) hereby represents and
warrants (as applicable) for the benefit of the Depositor and the
Securityholders that:

  (a) the Bank is a trust company duly organized, validly existing and in good
standing under the laws of the Commonwealth of Massachusetts;

  (b) the Bank has full corporate power, authority and legal right to execute,
deliver and perform its obligations under this Trust Agreement and has taken all
necessary action to authorize the execution, delivery and performance by it of
this Trust Agreement;

  (c) this Trust Agreement has been duly authorized, executed and delivered by
the Property Trustee and constitutes the valid and legally binding agreement of
the Property Trustee enforceable against it in accordance with its terms,
subject to bankruptcy, insolvency, fraudulent transfer, reorganization,
moratorium and similar laws of general applicability relating to or affecting
creditors, rights and to general equity principles;

  (d) the execution, delivery and performance by the Property Trustee of this
Trust Agreement has been duly authorized by all necessary corporate or other
action on the part of the Property Trustee and does not require any approval of
stockholders of the Bank and such execution, delivery and performance shall not
(i) violate the Bank's charter or by-laws; (ii) violate any provision of, or
constitute, with or without notice or lapse of time, a default under, or result
in the creation or imposition of, any Lien on any properties included in the
Trust Property pursuant to the provisions of, any indenture, mortgage, credit
agreement, license or other agreement or instrument to which the Property
Trustee or the Bank is a party or by which it is bound; or (iii) violate any
law, governmental rule or regulation of the United States or the Commonwealth of
Massachusetts, as the case may be, governing the banking or trust powers of the
Bank or the Property Trustee (as appropriate in context) or any order, judgment
or decree applicable to the Property Trustee or the Bank;

  (e) neither the authorization, execution or delivery by the Property Trustee
of this Trust Agreement nor the consummation of any of the transactions by the
Property Trustee contemplated herein or therein requires the consent or approval
of, the giving of notice to, the registration with or the taking of any other
action with respect to any governmental authority or agency under any existing
federal law governing the banking or trust powers of the Bank or the Property
Trustee, as the case may be, under the laws of the United States or the
Commonwealth of Massachusetts; and

  (f) there are no proceedings pending or, to the best of the Property Trustee's
knowledge, threatened against or affecting the Bank or the Property Trustee in
any court or before any governmental authority, agency or arbitration board or
tribunal which, individually or in the aggregate, would materially and adversely
affect the Trust or would question the right, power and authority of the
Property Trustee to enter into or perform its obligations as one of the Trustees
under this Trust Agreement.

                                      22
<PAGE>
 
 SECTION 702.  REPRESENTATIONS AND WARRANTIES OF THE DELAWARE BANK AND THE
DELAWARE TRUSTEE.

  The Delaware Bank and the Delaware Trustee, each severally on behalf of and as
to itself, as of the date hereof, and each successor Delaware Trustee at the
time of the successor Delaware Trustee's acceptance of appointment as Delaware
Trustee hereunder (the term "Delaware Bank" being used to refer to such
successor Delaware Trustee in its separate corporate capacity), hereby
represents and warrants (as applicable) for the benefit of the Depositor and the
Securityholders that:

  (a) the Delaware Bank is a Delaware banking corporation duly organized,
validly existing and in good standing under the laws of the State of Delaware;

  (b) the Delaware Bank has full corporate power, authority and legal right to
execute, deliver and perform its obligations under this Trust Agreement and has
taken all necessary action to authorize the execution, delivery and performance
by it of this Trust Agreement;

  (c) this Trust Agreement has been duly authorized, executed and delivered by
the Delaware Trustee and constitutes the valid and legally binding agreement of
the Delaware Trustee enforceable against it in accordance with its terms,
subject to bankruptcy, insolvency, fraudulent transfer, reorganization,
moratorium and similar laws of general applicability relating to or affecting
creditors, rights and to general equity principles;

  (d) the execution, delivery and performance by the Delaware Trustee of this
Trust Agreement has been duly authorized by all necessary corporate or other
action on the part of the Delaware Trustee and does not require any approval of
stockholders of the Delaware Bank and such execution, delivery and performance
shall not (i) violate the Delaware Bank's charter or by-laws; (ii) violate any
provision of, or constitute, with or without notice or lapse of time, a default
under, or result in the creation or imposition of, any Lien on any properties
included in the Trust Property pursuant to the provisions of, any indenture,
mortgage, credit agreement, license or other agreement or instrument to which
the Delaware Bank or the Delaware Trustee is a party or by which it is bound; or
(iii) violate any law, governmental rule or regulation of the United States or
the State of Delaware, as the case may be, governing the banking or trust powers
of the Delaware Bank or the Delaware Trustee (as appropriate in context) or any
order, judgment or decree applicable to the Delaware Bank or the Delaware
Trustee;

  (e) neither the authorization, execution or delivery by the Delaware Trustee
of this Trust Agreement nor the consummation of any of the transactions by the
Delaware Trustee contemplated herein or therein requires the consent or approval
of, the giving of notice to, the registration with or the taking of any other
action with respect to any governmental authority or agency under any existing
federal law governing the banking or trust powers of the Delaware Bank or the
Delaware Trustee, as the case may be, under the laws of the United States or the
State of Delaware; and

  (f) there are no proceedings pending or, to the best of the Delaware Trustee's
knowledge, threatened against or affecting the Delaware Bank or the Delaware
Trustee in any court or before any governmental authority, agency or arbitration
board or tribunal which, individually or in the aggregate, would materially and
adversely affect the Trust or would question the right, power and authority of
the Delaware Trustee to enter into or perform its obligations as one of the
Trustees under this Trust Agreement.

 SECTION 703.  REPRESENTATIONS AND WARRANTIES OF DEPOSITOR.

 The Depositor hereby represents and warrants for the benefit of the
Securityholders that:

  (a) the Trust Securities Certificates issued on the Closing Date or the Option
Closing Date, if applicable, on behalf of the Trust have been duly authorized
and, shall be, as of such date or dates, if applicable, duly and validly
executed, issued and delivered by the Administrative Trustees pursuant to the
terms and provisions of,

                                      23
<PAGE>
 
and in accordance with the requirements of, this Trust Agreement and the
Securityholders shall be, as of such date or dates, if applicable, entitled to
the benefits of this Trust Agreement; and

  (b) there are no taxes, fees or other governmental charges payable by the
Trust (or the Trustees on behalf of the Trust) under the laws of the State of
Delaware or any political subdivision thereof in connection with the execution,
delivery and performance by the Bank, the Property Trustee or the Delaware
Trustee, as the case may be, of this Trust Agreement.

                                  ARTICLE VIII

                                    TRUSTEES

 SECTION 801.  CERTAIN DUTIES AND RESPONSIBILITIES.

  (a) The duties and responsibilities of the Trustees shall be as provided by
this Trust Agreement and, in the case of the Property Trustee, by the Trust
Indenture Act. Notwithstanding the foregoing, no provision of this Trust
Agreement shall require the Trustees to expend or risk their own funds or
otherwise incur any financial liability in the performance of any of their
duties hereunder, or in the exercise of any of their rights or powers, if they
shall have reasonable grounds for believing that repayment of such funds or
adequate indemnity against such risk or liability is not reasonably assured to
it. No Administrative Trustee nor the Delaware Trustee shall be liable for its
act or omissions hereunder except as a result of its own gross negligence or
willful misconduct. The Property Trustee's liability shall be determined under
the Trust Indenture Act. Whether or not therein expressly so provided, every
provision of this Trust Agreement relating to the conduct or affecting the
liability of or affording protection to the Trustees shall be subject to the
provisions of this Section 801. To the extent that, at law or in equity, the
Delaware Trustee or an Administrative Trustee has duties (including fiduciary
duties) and liabilities relating thereto to the Trust or to the Securityholders,
the Delaware Trustee or such Administrative Trustee shall not be liable to the
Trust or to any Securityholder for such Trustee's good faith reliance on the
provisions of this Trust Agreement. The provisions of this Trust Agreement, to
the extent that they restrict the duties and liabilities of the Delaware Trustee
or the Administrative Trustees otherwise existing at law or in equity, are
agreed by the Depositor and the Securityholders to replace such other duties and
liabilities of the Delaware Trustee and the Administrative Trustees, as the case
may be.

  (b) All payments made by the Property Trustee or a Paying Agent in respect of
the Trust Securities shall be made only from the revenue and proceeds from the
Trust Property and only to the extent that there shall be sufficient revenue or
proceeds from the Trust Property to enable the Property Trustee or a Paying
Agent to make payments in accordance with the terms hereof. With respect to the
relationship of each Securityholder and the Trustee, each Securityholder, by its
acceptance of a Trust Security, agrees that it shall look solely to the revenue
and proceeds from the Trust Property to the extent legally available for
distribution to it as herein provided and that the Trustees are not personally
liable to it for any amount distributable in respect of any Trust Security or
for any other liability in respect of any Trust Security. This Section 801(b)
does not limit the liability of the Trustees expressly set forth elsewhere in
this Trust Agreement or, in the case of the Property Trustee, in the Trust
Indenture Act.

  (c) No provision of this Trust Agreement shall be construed to relieve the
Property Trustee from liability for its own negligent action, its own negligent
failure to act, or its own willful misconduct, except that:

     (i) the Property Trustee shall not be liable for any error of judgment made
in good faith by an authorized officer of the Property Trustee, unless it shall
be proved that the Property Trustee was negligent in ascertaining the pertinent
facts;

     (ii) the Property Trustee shall not be liable with respect to any action
taken or omitted to be taken by it in good faith in accordance with the
direction of the Holders of not less than a majority in Liquidation Amount of
the Trust Securities relating to the time, method and place of conducting any
proceeding for any remedy available

                                      24
<PAGE>
 
to the Property Trustee, or exercising any trust or power conferred upon the
Property Trustee under this Trust Agreement;

     (iii)  the Property Trustee's sole duty with respect to the custody, safe
keeping and physical preservation of the Debentures and the Payment Account
shall be to deal with such property in a similar manner as the Property Trustee
deals with similar property for its own account, subject to the protections and
limitations on liability afforded to the Property Trustee under this Trust
Agreement and the Trust Indenture Act;

     (iv)   the Property Trustee shall not be liable for any interest on any
money received by it except as it may otherwise agree with the Depositor and
money held by the Property Trustee need not be segregated from other funds held
by it except in relation to the Payment Account maintained by the Property
Trustee pursuant to Section 301 and except to the extent otherwise required by
law; and

     (v)    the Property Trustee shall not be responsible for monitoring the
compliance by the Administrative Trustees or the Depositor with their respective
duties under this Trust Agreement, nor shall the Property Trustee be liable for
the negligence, default or misconduct of the Administrative Trustees or the
Depositor.

 SECTION 802.  CERTAIN NOTICES.

  (a) Within 5 Business Days after the occurrence of any Event of Default
actually known to the Property Trustee, the Property Trustee shall transmit, in
the manner and to the extent provided in Section 1008, notice of such Event of
Default to the Securityholders, the Administrative Trustees and the Depositor,
unless such Event of Default shall have been cured or waived. For purposes of
this Section 802 the term "Event of Default" means any event that is, or after
notice or lapse of time or both would become, an Event of Default.

  (b) The Administrative Trustees shall transmit, to the Securityholders in the
manner and to the extent provided in Section 1008, notice of the Depositor's
election to begin or further extend an Extended Interest Payment Period on the
Debentures (unless such election shall have been revoked) within the time
specified for transmitting such notice to the holders of the Debentures pursuant
to the Indenture as originally executed.

 SECTION 803.  CERTAIN RIGHTS OF PROPERTY TRUSTEE.

 Subject to the provisions of Section 801:

  (a) the Property Trustee may rely and shall be protected in acting or
refraining from acting in good faith upon any resolution, Opinion of Counsel,
certificate, written representation of a Holder or transferee, certificate of
auditors or any other certificate, statement, instrument, opinion, report,
notice, request, consent, order, appraisal, bond, debenture, note, other
evidence of indebtedness or other paper or document believed by it to be genuine
and to have been signed or presented by the proper party or parties;

  (b) if (i) in performing its duties under this Trust Agreement the Property
Trustee is required to decide between alternative courses of action; or (ii) in
construing any of the provisions of this Trust Agreement the Property Trustee
finds the same ambiguous or inconsistent with other provisions contained herein;
or (iii) the Property Trustee is unsure of the application of any provision of
this Trust Agreement, then, except as to any matter as to which the Preferred
Securityholders are entitled to vote under the terms of this Trust Agreement,
the Property Trustee shall deliver a notice to the Depositor requesting written
instructions of the Depositor as to the course of action to be taken and the
Property Trustee shall take such action, or refrain from taking such action, as
the Property Trustee shall be instructed in writing to take, or to refrain from
taking, by the Depositor; provided, however, that if the Property Trustee does
not receive such instructions of the Depositor within 10 Business Days after it
has delivered such notice, or such reasonably shorter period of time set forth
in such notice (which to the extent practicable shall not be less than 2
Business Days), it may, but shall be under no duty to, take or refrain from
taking such action not inconsistent

                                      25
<PAGE>
 
with this Trust Agreement as it shall deem advisable and in the best interests
of the Securityholders, in which event the Property Trustee shall have no
liability except for its own bad faith, negligence or willful misconduct;

  (c) any direction or act of the Depositor or the Administrative Trustees
contemplated by this Trust Agreement shall be sufficiently evidenced by an
Officers' Certificate;

  (d) whenever in the administration of this Trust Agreement, the Property
Trustee shall deem it desirable that a matter be established before undertaking,
suffering or omitting any action hereunder, the Property Trustee (unless other
evidence is herein specifically prescribed) may, in the absence of bad faith on
its part, request and conclusively rely upon an Officer's Certificate which,
upon receipt of such request, shall be promptly delivered by the Depositor or
the Administrative Trustees;

  (e) the Property Trustee shall have no duty to see to any recording, filing or
registration of any instrument (including any financing or continuation
statement, any filing under tax or securities laws or any filing under tax or
securities laws) or any rerecording, refiling or reregistration thereof;

  (f) the Property Trustee may consult with counsel of its choice (which counsel
may be counsel to the Depositor or any of its Affiliates) and the advice of such
counsel shall be full and complete authorization and protection in respect of
any action taken, suffered or omitted by it hereunder in good faith and in
reliance thereon and in accordance with such advice; the Property Trustee shall
have the right at any time to seek instructions concerning the administration of
this Trust Agreement from any court of competent jurisdiction;

  (g) the Property Trustee shall be under no obligation to exercise any of the
rights or powers vested in it by this Trust Agreement at the request or
direction of any of the Securityholders pursuant to this Trust Agreement, unless
such Securityholders shall have offered to the Property Trustee reasonable
security or indemnity against the costs, expenses and liabilities which might be
incurred by it in compliance with such request or direction;

  (h) the Property Trustee shall not be bound to make any investigation into the
facts or matters stated in any resolution, certificate, statement, instrument,
opinion, report, notice, request, consent, order, approval, bond, debenture,
note or other evidence of indebtedness or other paper or document, unless
requested in writing to do so by one or more Securityholders, but the Property
Trustee may make such further inquiry or investigation into such facts or
matters as it may see fit;

  (i) the Property Trustee may execute any of the trusts or powers hereunder or
perform any duties hereunder either directly or by or through its agents or
attorneys, provided that the Property Trustee shall be responsible for its own
negligence or recklessness with respect to selection of any agent or attorney
appointed by it hereunder;

  (j) whenever in the administration of this Trust Agreement the Property
Trustee shall deem it desirable to receive instructions with respect to
enforcing any remedy or right or taking any other action hereunder the Property
Trustee (i) may request instructions from the Holders of the Trust Securities
which instructions may only be given by the Holders of the same proportion in
Liquidation Amount of the Trust Securities as would be entitled to direct the
Property Trustee under the terms of the Trust Securities in respect of such
remedy, right or action; (ii) may refrain from enforcing such remedy or right or
taking such other action until such instructions are received; and (iii) shall
be protected in acting in accordance with such instructions; and

  (k) except as otherwise expressly provided by this Trust Agreement, the
Property Trustee shall not be under any obligation to take any action that is
discretionary under the provisions of this Trust Agreement. No provision of this
Trust Agreement shall be deemed to impose any duty or obligation on the Property
Trustee to perform any act or acts or exercise any right, power, duty or
obligation conferred or imposed on it, in any jurisdiction in which it shall be
illegal, or in which the Property Trustee shall be unqualified or incompetent in
accordance with applicable law, to perform any such act or acts, or to exercise
any such right, power, duty or obligation. No permissive power or authority
available to the Property Trustee shall be construed to be a duty.

                                      26
<PAGE>
 
 SECTION 804.  NOT RESPONSIBLE FOR RECITALS OR ISSUANCE OF SECURITIES.

  The Recitals contained herein and in the Trust Securities Certificates shall
be taken as the statements of the Trust, and the Trustees do not assume any
responsibility for their correctness. The Trustees shall not be accountable for
the use or application by the Depositor of the proceeds of the Debentures.

 SECTION 805.  MAY HOLD SECURITIES.

  Any Trustee or any other agent of any Trustee or the Trust, in its individual
or any other capacity, may become the owner or pledgee of Trust Securities and,
subject to Sections 808 and 813 and except as provided in the definition of the
term "Outstanding" in Article I, may otherwise deal with the Trust with the same
rights it would have if it were not a Trustee or such other agent.

 SECTION 806.  COMPENSATION; INDEMNITY; FEES.

 The Depositor agrees:

  (a) to pay to the Trustees from time to time reasonable compensation for all
services rendered by them hereunder (which compensation shall not be limited by
any provision of law in regard to the compensation of a trustee of an express
trust);

  (b) except as otherwise expressly provided herein, to reimburse the Trustees
upon request for all reasonable expenses, disbursements and advances incurred or
made by the Trustees in accordance with any provision of this Trust Agreement
(including the reasonable compensation and the expenses and disbursements of its
agents and counsel), except any such expense, disbursement or advance as may be
attributable to such Trustee's negligence, bad faith or willful misconduct (or,
in the case of the Administrative Trustees or the Delaware Trustee, any such
expense, disbursement or advance as may be attributable to its, his or her gross
negligence, bad faith or willful misconduct); and

  (c) to indemnify each of the Trustees or any predecessor Trustee for, and to
hold the Trustees harmless against, any loss, damage, claims, liability, penalty
or expense incurred without negligence or bad faith on its part, arising out of
or in connection with the acceptance or administration of this Trust Agreement,
including the costs and expenses of defending itself against any claim or
liability in connection with the exercise or performance of any of its powers or
duties hereunder, except any such expense, disbursement or advance as may be
attributable to such Trustee's negligence, bad faith or willful misconduct (or,
in the case of the Administrative Trustees or the Delaware Trustee, any such
expense, disbursement or advance as may be attributable to its, his or her gross
negligence, bad faith or willful misconduct).

  No Trustee may claim any Lien or charge on any Trust Property as a result of
any amount due pursuant to this Section 806.

 SECTION 807.  CORPORATE PROPERTY TRUSTEE REQUIRED; ELIGIBILITY OF TRUSTEES.

  (a) There shall at all times be a Property Trustee hereunder with respect to
the Trust Securities. The Property Trustee shall be a Person that is eligible
pursuant to the Trust Indenture Act to act as such and has a combined capital
and surplus of at least $50,000,000. If any such Person publishes reports of
condition at least annually, pursuant to law or to the requirements of its
supervising or examining authority, then for the purposes of this Section 807,
the combined capital and surplus of such Person shall be deemed to be its
combined capital and surplus as set forth in its most recent report of condition
so published. If at any time the Property Trustee with respect to the Trust
Securities shall cease to be eligible in accordance with the provisions of this
Section 807, it shall resign immediately in the manner and with the effect
hereinafter specified in this Article VIII.

                                      27
<PAGE>
 
  (b) There shall at all times be one or more Administrative Trustees hereunder
with respect to the Trust Securities. Each Administrative Trustee shall be
either a natural person who is at least 21 years of age or a legal entity that
shall act through one or more persons authorized to bind that entity.

  (c) There shall at all times be a Delaware Trustee with respect to the Trust
Securities. The Delaware Trustee shall either be (i) a natural person who is at
least 21 years of age and a resident of the State of Delaware; or (ii) a legal
entity with its principal place of business in the State of Delaware and that
otherwise meets the requirements of applicable Delaware law that shall act
through one or more persons authorized to bind such entity.

 SECTION 808.  CONFLICTING INTERESTS.

  If the Property Trustee has or shall acquire a conflicting interest within the
meaning of the Trust Indenture Act, the Property Trustee shall either eliminate
such interest or resign, to the extent and in the manner provided by, and
subject to the provisions of, the Trust Indenture Act and this Trust Agreement.

 SECTION 809.  CO-TRUSTEES AND SEPARATE TRUSTEE.

  (a) Unless an Event of Default shall have occurred and be continuing, at any
time or times, for the purpose of meeting the legal requirements of the Trust
Indenture Act or of any jurisdiction in which any part of the Trust Property may
at the time be located, the Depositor shall have power to appoint, and upon the
written request of the Property Trustee, the Depositor shall for such purpose
join with the Property Trustee in the execution, delivery and performance of all
instruments and agreements necessary or proper to appoint, one or more Persons
approved by the Property Trustee either to act as co-trustee, jointly with the
Property Trustee, of all or any part of such Trust Property, or to the extent
required by law to act as separate trustee of any such property, in either case
with such powers as may be provided in the instrument of appointment, and to
vest in such Person or Persons in the capacity aforesaid, any property, title,
right or power deemed necessary or desirable, subject to the other provisions of
this Section 809. If the Depositor does not join in such appointment within 15
days after the receipt by it of a request so to do, or in case a Debenture Event
of Default has occurred and is continuing, the Property Trustee alone shall have
power to make such appointment. Any co-trustee or separate trustee appointed
pursuant to this Section 809 shall either be (i) a natural person who is at
least 21 years of age and a resident of the United States; or (ii) a legal
entity with its principal place of business in the United States that shall act
through one or more persons authorized to bind such entity.

  (b) Should any written instrument from the Depositor be required by any co-
trustee or separate trustee so appointed for more fully confirming to such co-
trustee or separate trustee such property, title, right, or power, any and all
such instruments shall, on request, be executed, acknowledged, and delivered by
the Depositor.

  (c) Every co-trustee or separate trustee shall, to the extent permitted by
law, but to such extent only, be appointed subject to the following terms,
namely:

     (i) The Trust Securities shall be executed and delivered and all rights,
powers, duties and obligations hereunder in respect of the custody of
securities, cash and other personal property held by, or required to be
deposited or pledged with, the Trustees specified hereunder, shall be exercised,
solely by such Trustees and not by such co-trustee or separate trustee.

     (ii) The rights, powers, duties and obligations hereby conferred or imposed
upon the Property Trustee in respect of any property covered by such appointment
shall be conferred or imposed upon and exercised or performed by the Property
Trustee or by the Property Trustee and such co-trustee or separate trustee
jointly, as shall be provided in the instrument appointing such co-trustee or
separate trustee, except to the extent that under any law of any jurisdiction in
which any particular act is to be performed, the Property Trustee shall be
incompetent or unqualified to perform such act, in which event such rights,
powers, duties and obligations shall be exercised and performed by such co-
trustee or separate trustee.

                                      28
<PAGE>
 
     (iii) The Property Trustee at any time, by an instrument in writing
executed by it, with the written concurrence of the Depositor, may accept the
resignation of or remove any co-trustee or separate trustee appointed under this
Section 809, and, in case a Debenture Event of Default has occurred and is
continuing, the Property Trustee shall have the power to accept the resignation
of, or remove, any such co-trustee or separate trustee without the concurrence
of the Depositor. Upon the written request of the Property Trustee, the
Depositor shall join with the Property Trustee in the execution, delivery and
performance of all instruments and agreements necessary or proper to effectuate
such resignation or removal. A successor to any co-trustee or separate trustee
so resigned or removed may be appointed in the manner provided in this Section
809.

     (iv)  No co-trustee or separate trustee hereunder shall be personally 
liable by reason of any act or omission of the Property Trustee or any other
trustee hereunder.

     (v)   The Property Trustee shall not be liable by reason of any act of a 
co-trustee or separate trustee.

     (vi)  Any Act of Holders delivered to the Property Trustee shall be deemed
to have been delivered to each such co-trustee and separate trustee.

 SECTION 810.  RESIGNATION AND REMOVAL; APPOINTMENT OF SUCCESSOR.

  (a) No resignation or removal of any Trustee (the "Relevant Trustee") and no
appointment of a successor Trustee pursuant to this Article VIII shall become
effective until the acceptance of appointment by the successor Trustee in
accordance with the applicable requirements of Section 811.

  (b) Subject to the immediately preceding paragraph, the Relevant Trustee may
resign at any time with respect to the Trust Securities by giving written notice
thereof to the Securityholders. If the instrument of acceptance by the successor
Trustee required by Section 811 shall not have been delivered to the Relevant
Trustee within 30 days after the giving of such notice of resignation, the
Relevant Trustee may petition, at the expense of the Depositor, any court of
competent jurisdiction for the appointment of a successor Relevant Trustee with
respect to the Trust Securities.

  (c) Unless a Debenture Event of Default shall have occurred and be continuing,
any Trustee may be removed at any time by Act of the Common Securityholder. If a
Debenture Event of Default shall have occurred and be continuing, the Property
Trustee or the Delaware Trustee, or both of them, may be removed at such time by
Act of the Holders of a majority in Liquidation Amount of the Preferred
Securities, delivered to the Relevant Trustee (in its individual capacity and on
behalf of the Trust). An Administrative Trustee may be removed by the Common
Securityholder at any time.

  (d) If any Trustee shall resign, be removed or become incapable of acting as
Trustee, or if a vacancy shall occur in the office of any Trustee for any cause,
at a time when no Debenture Event of Default shall have occurred and be
continuing, the Common Securityholder, by Act of the Common Securityholder
delivered to the retiring Trustee, shall promptly appoint a successor Trustee or
Trustees with respect to the Trust Securities and the Trust, and the successor
Trustee shall comply with the applicable requirements of Section 811. If the
Property Trustee or the Delaware Trustee shall resign, be removed or become
incapable of continuing to act as the Property Trustee or the Delaware Trustee,
as the case may be, at a time when a Debenture Event of Default shall have
occurred and is continuing, the Preferred Securityholders, by Act of the
Securityholders of a majority in Liquidation Amount of the Preferred Securities
then Outstanding delivered to the retiring Relevant Trustee, shall promptly
appoint a successor Relevant Trustee or Trustees with respect to the Trust
Securities and the Trust, and such successor Trustee shall comply with the
applicable requirements of Section 811. If an Administrative Trustee shall
resign, be removed or become incapable of acting as Administrative Trustee, at a
time when a Debenture Event of Default shall have occurred and be continuing,
the Common Securityholder, by Act of the Common Securityholder delivered to an
Administrative Trustee, shall promptly appoint a successor Administrative
Trustee or Administrative Trustees with respect to the Trust Securities and the
Trust, and such successor Administrative Trustee or Administrative Trustees
shall comply with the applicable requirements of Section 811. If no successor
Relevant Trustee with respect to the

                                      29
<PAGE>
 
Trust Securities shall have been so appointed by the Common Securityholder or
the Preferred Securityholders and accepted appointment in the manner required by
Section 811, any Securityholder who has been a Securityholder of Trust
Securities on behalf of himself and all others similarly situated may petition a
court of competent jurisdiction for the appointment of a successor Relevant
Trustee with respect to the Trust Securities.

  (e) The Property Trustee shall give notice of each resignation and each
removal of a Trustee and each appointment of a successor Trustee to all
Securityholders in the manner provided in Section 1008 and shall give notice to
the Depositor. Each notice shall include the name of the successor Relevant
Trustee and the address of its Corporate Trust Office if it is the Property
Trustee.

  (f) Notwithstanding the foregoing or any other provision of this Trust
Agreement, in the event any Administrative Trustee or a Delaware Trustee who is
a natural person dies or becomes, in the opinion of the Depositor, incompetent
or incapacitated, the vacancy created by such death, incompetence or incapacity
may be filled by (a) the unanimous act of remaining Administrative Trustees if
there are at least two of them; or (b) otherwise by the Depositor (with the
successor in each case being a Person who satisfies the eligibility requirement
for Administrative Trustees set forth in Section 807).

 SECTION 811.  ACCEPTANCE OF APPOINTMENT BY SUCCESSOR.

  (a) In case of the appointment hereunder of a successor Relevant Trustee with
respect to the Trust Securities and the Trust, the retiring Relevant Trustee and
each successor Relevant Trustee with respect to the Trust Securities shall
execute and deliver an instrument hereto wherein each successor Relevant Trustee
shall accept such appointment and which shall contain such provisions as shall
be necessary or desirable to transfer and confirm to, and to vest in, each
successor Relevant Trustee all the rights, powers, trusts and duties of the
retiring Relevant Trustee with respect to the Trust Securities and the Trust and
upon the execution and delivery of such instrument the resignation or removal of
the retiring Relevant Trustee shall become effective to the extent provided
therein and each such successor Relevant Trustee, without any further act, deed
or conveyance, shall become vested with all the rights, powers, trusts and
duties of the retiring Relevant Trustee with respect to the Trust Securities and
the Trust; but, on request of the Trust or any successor Relevant Trustee such
retiring Relevant Trustee shall duly assign, transfer and deliver to such
successor Relevant Trustee all Trust Property, all proceeds thereof and money
held by such retiring Relevant Trustee hereunder with respect to the Trust
Securities and the Trust.

  (b) Upon request of any such successor Relevant Trustee, the Trust shall
execute any and all instruments for more fully and certainly vesting in and
confirming to such successor Relevant Trustee all such rights, powers and trusts
referred to in the immediately preceding paragraph, as the case may be.

  (c) No successor Relevant Trustee shall accept its appointment unless at the
time of such acceptance such successor Relevant Trustee shall be qualified and
eligible under this Article VIII.

 SECTION 812.  MERGER, CONVERSION, CONSOLIDATION OR SUCCESSION TO BUSINESS.

  Any Person into which the Property Trustee, the Delaware Trustee or any
Administrative Trustee may be merged or converted or with which it may be
consolidated, or any Person resulting from any merger, conversion or
consolidation to which such Relevant Trustee shall be a party, or any
corporation succeeding to all or substantially all the corporate trust business
of such Relevant Trustee, shall be the successor of such Relevant Trustee
hereunder, provided such Person shall be otherwise qualified and eligible under
this Article VIII, without the execution or filing of any paper or any further
act on the part of any of the parties hereto.

 SECTION 813.  PREFERENTIAL COLLECTION OF CLAIMS AGAINST DEPOSITOR OR TRUST.

  If and when the Property Trustee or the Delaware Trustee shall be or become a
creditor of the Depositor or the Trust (or any other obligor upon the Debentures
or the Trust Securities), the Property Trustee or the Delaware

                                      30
<PAGE>
 
Trustee, as the case may be, shall be subject to and shall take all actions
necessary in order to comply with the provisions of the Trust Indenture Act
regarding the collection of claims against the Depositor or Trust (or any such
other obligor).

 SECTION 814.  REPORTS BY PROPERTY TRUSTEE.

  (a) The Property Trustee shall transmit to Securityholders such reports
concerning the Property Trustee, its actions under this Trust Agreement, and the
property and funds in its possession as Property Trustee as may be required
pursuant to the Trust Indenture Act, at the times and in the manner provided
pursuant thereto.

  (b) A copy of each such report shall, at the time of such transmission to
Holders, be filed by the Property Trustee with The Nasdaq Stock Market's
National Market, and each national securities exchange or other organization
upon which the Trust Securities are listed, and also with the Commission and the
Depositor.

 SECTION 815.  REPORTS TO THE PROPERTY TRUSTEE.

  The Depositor and the Administrative Trustees on behalf of the Trust shall
provide to the Property Trustee such documents, reports and information as
required by Section 314 of the Trust Indenture Act (if any) and the compliance
certificate required by Section 314(a) of the Trust Indenture Act in the form,
in the manner and at the times required by Section 314 of the Trust Indenture
Act.

 SECTION 816.  EVIDENCE OF COMPLIANCE WITH CONDITIONS PRECEDENT.

  Each of the Depositor and the Administrative Trustees on behalf of the Trust
shall provide to the Property Trustee such evidence of compliance with any
conditions precedent, if any, provided for in this Trust Agreement that relate
to any of the matters set forth in Section 314(c) of the Trust Indenture Act.
Any certificate or opinion required to be given by an officer pursuant to
Section 314(c)(1) of the Trust Indenture Act shall be given in the form of an
Officers' Certificate.

 SECTION 817.  NUMBER OF TRUSTEES.

  (a) The number of Trustees shall be five, provided that the Holder of all of
the Common Securities by written instrument may increase or decrease the number
of Administrative Trustees. The Property Trustee and the Delaware Trustee may be
the same Person.

  (b) If a Trustee ceases to hold office for any reason and the number of
Administrative Trustees is not reduced pursuant to Section 817(a), or if the
number of Trustees is increased pursuant to Section 817(a), a vacancy shall
occur. The vacancy shall be filled with a Trustee appointed in accordance with
Section 810.

  (c) The death, resignation, retirement, removal, bankruptcy, incompetence or
incapacity to perform the duties of a Trustee shall not operate to annul the
Trust. Whenever a vacancy in the number of Administrative Trustees shall occur,
until such vacancy is filled by the appointment of an Administrative Trustee in
accordance with Section 810, the Administrative Trustees in office, regardless
of their number (and notwithstanding any other provision of this Agreement),
shall have all the powers granted to the Administrative Trustees and shall
discharge all the duties imposed upon the Administrative Trustees by this Trust
Agreement.

 SECTION 818.  DELEGATION OF POWER.

  (a) Any Administrative Trustee may, by power of attorney consistent with
applicable law, delegate to any other natural person over the age of 21 his or
her power for the purpose of executing any documents contemplated in Section
207(a); and

                                      31
<PAGE>
 
  (b) The Administrative Trustees shall have power to delegate from time to time
to such of their number or to the Depositor the doing of such things and the
execution of such instruments either in the name of the Trust or the names of
the Administrative Trustees or otherwise as the Administrative Trustees may deem
expedient, to the extent such delegation is not prohibited by applicable law or
contrary to the provisions of the Trust, as set forth herein.

 SECTION 819.  VOTING.

  Except as otherwise provided in this Trust Agreement, the consent or approval
of the Administrative Trustees shall require consent or approval by not less
than a majority of the Administrative Trustees, unless there are only two, in
which case both must consent.

                                   ARTICLE IX

                      TERMINATION, LIQUIDATION AND MERGER

 SECTION 901.  TERMINATION UPON EXPIRATION DATE.

  Unless earlier dissolved, the Trust shall automatically dissolve on March 31,
2051 (the "Expiration Date") subject to distribution of the Trust Property in
accordance with Section 904.

 SECTION 902.  EARLY TERMINATION.

 The first to occur of any of the following events is an "Early Termination
Event:"

  (a) the occurrence of a Bankruptcy Event in respect of, or the dissolution or
liquidation of, the Depositor;

  (b) delivery of written direction to the Property Trustee by the Depositor at
any time (which direction is wholly optional and within the discretion of the
Depositor) to dissolve the Trust and distribute the Debentures to
Securityholders in exchange for the Preferred Securities in accordance with
Section 904;

  (c) the redemption of all of the Preferred Securities in connection with the
redemption of all of the Debentures; and

  (d) the entrance of an order for dissolution of the Trust by a court of
competent jurisdiction.

 SECTION 903.  TERMINATION.

  The respective obligations and responsibilities of the Trustees and the Trust
created and continued hereby shall terminate upon the latest to occur of the
following:  (a) the distribution by the Property Trustee to Securityholders upon
the liquidation of the Trust pursuant to Section 904, or upon the redemption of
all of the Trust Securities pursuant to Section 402, of all amounts required to
be distributed hereunder upon the final payment of the Trust Securities; (b) the
payment of any expenses owed by the Trust; (c) the discharge of all
administrative duties of the Administrative Trustees, including the performance
of any tax reporting obligations with respect to the Trust or the
Securityholders; and (d) the filing of a Certificate of Cancellation by the
Administrative Trustee under the Delaware Business Trust Act.

                                      32
<PAGE>
 
 SECTION 904.  LIQUIDATION.

  (a) If an Early Termination Event specified in clause (a), (b), or (d) of
Section 902 occurs or upon the Expiration Date, the Trust shall be liquidated by
the Trustees as expeditiously as the Trustees determine to be possible by
distributing, after satisfaction of liabilities to creditors of the Trust as
provided by applicable law, to each Securityholder a Like Amount of Debentures,
subject to Section 904(d). Notice of liquidation shall be given by the Property
Trustee by first-class mail, postage prepaid, mailed not later than 30 nor more
than 60 days prior to the Liquidation Date to each Holder of Trust Securities at
such Holder's address appearing in the Securities Register. All notices of
liquidation shall:

     (i)   state the Liquidation Date;

     (ii)  state that from and after the Liquidation Date, the Trust Securities
shall no longer be deemed to be Outstanding and any Trust Securities
Certificates not surrendered for exchange shall be deemed to represent a Like
Amount of Debentures; and

     (iii) provide such information with respect to the mechanics by which
Holders may exchange Trust Securities Certificates for Debentures, or, if
Section 904(d) applies, receive a Liquidation Distribution, as the
Administrative Trustees or the Property Trustee shall deem appropriate.

  (b) Except where Section 902(c) or 904(d) applies, in order to effect the
liquidation of the Trust and distribution of the Debentures to Securityholders,
the Property Trustee shall establish a record date for such distribution (which
shall be not more than 45 days prior to the Liquidation Date) and, either itself
acting as exchange agent or through the appointment of a separate exchange
agent, shall establish such procedures as it shall deem appropriate to effect
the distribution of Debentures in exchange for the Outstanding Trust Securities
Certificates.

  (c) Except where Section 902(c) or 904(d) applies, after the Liquidation Date,
(i) the Trust Securities shall no longer be deemed to be outstanding; (ii)
certificates representing a Like Amount of Debentures shall be issued to holders
of Trust Securities Certificates upon surrender of such certificates to the
Administrative Trustees or their agent for exchange; (iii) the Depositor shall
use its reasonable efforts to have the Debentures listed on The Nasdaq Stock
Market's National Market or on such other securities exchange or other
organization as the Preferred Securities are then listed or traded; (iv) any
Trust Securities Certificates not so surrendered for exchange shall be deemed to
represent a Like Amount of Debentures, accruing interest at the rate provided
for in the Debentures from the last Distribution Date on which a Distribution
was made on such Trust Securities Certificates until such certificates are so
surrendered (and until such certificates are so surrendered, no payments of
interest or principal shall be made to holders of Trust Securities Certificates
with respect to such Debentures); and (v) all rights of Securityholders holding
Trust Securities shall cease, except the right of such Securityholders to
receive Debentures upon surrender of Trust Securities Certificates.

  (d) In the event that, notwithstanding the other provisions of this Section
904, whether because of an order for dissolution entered by a court of competent
jurisdiction or otherwise, distribution of the Debentures in the manner provided
herein is determined by the Property Trustee not to be practical, the Trust
Property shall be liquidated, and the Trust shall be dissolved, wound-up or
terminated, by the Property Trustee in such manner as the Property Trustee
determines. In such event, on the date of the dissolution, winding-up or other
termination of the Trust, Securityholders shall be entitled to receive out of
the assets of the Trust available for distribution to Securityholders, after
satisfaction of liabilities to creditors of the Trust as provided by applicable
law, an amount equal to the Liquidation Amount per Trust Security plus
accumulated and unpaid Distributions thereon to the date of payment (such amount
being the "Liquidation Distribution"). If, upon any such dissolution, winding-up
or termination, the Liquidation Distribution can be paid only in part because
the Trust has insufficient assets available to pay in full the aggregate
Liquidation Distribution, then, subject to the next succeeding sentence, the
amounts payable by the Trust on the Trust Securities shall be paid on a pro rata
basis (based upon Liquidation Amounts). The holder of the Common Securities
shall be entitled to receive Liquidation Distributions upon any such
dissolution, winding-up or

                                      33
<PAGE>
 
termination pro rata (determined as aforesaid) with Holders of Preferred
Securities, except that, if a Debenture Event of Default has occurred and is
continuing, the Preferred Securities shall have a priority over the Common
Securities.

 SECTION 905.  MERGERS, CONSOLIDATIONS, AMALGAMATIONS OR REPLACEMENTS OF THE
TRUST.

  The Trust may not merge with or into, consolidate, amalgamate, or be replaced
by, or convey, transfer or lease its properties and assets substantially as an
entirety to any corporation or other Person, except pursuant to this Section
905. At the request of the Depositor, with the consent of the Administrative
Trustees and without the consent of the holders of the Preferred Securities, the
Property Trustee or the Delaware Trustee, the Trust may merge with or into,
consolidate, amalgamate, be replaced by or convey, transfer or lease its
properties and assets substantially as an entirety to a trust organized as such
under the laws of any State; provided, that (i) such successor entity either (a)
expressly assumes all of the obligations of the Trust with respect to the
Preferred Securities; or (b) substitutes for the Preferred Securities other
securities having substantially the same terms as the Preferred Securities (the
"Successor Securities") so long as the Successor Securities rank the same as the
Preferred Securities rank in priority with respect to distributions and payments
upon liquidation, redemption and otherwise; (ii) the Depositor expressly
appoints a trustee of such successor entity possessing substantially the same
powers and duties as the Property Trustee as the holder of the Debentures; (iii)
the Successor Securities are listed or traded, or any Successor Securities shall
be listed or traded upon notification of issuance, on any national securities
exchange or other organization on which the Preferred Securities are then
listed, if any; (iv) such merger, consolidation, amalgamation, replacement,
conveyance, transfer or lease does not adversely affect the rights, preferences
and privileges of the holders of the Preferred Securities (including any
Successor Securities) in any material respect; (v) prior to such merger,
consolidation, amalgamation, replacement, conveyance, transfer or lease, the
Depositor has received an Opinion of Counsel to the effect that (a) such merger,
consolidation, amalgamation, replacement, conveyance, transfer or lease does not
adversely affect the rights, preferences and privileges of the holders of the
Preferred Securities (including any Successor Securities) in any material
respect; and (b) following such merger, consolidation, amalgamation,
replacement, conveyance, transfer or lease, neither the Trust nor such successor
entity shall be required to register as an "investment company" under the
Investment Company Act; and (vi) the Depositor owns all of the Common Securities
of such successor entity and guarantees the obligations of such successor entity
under the Successor Securities at least to the extent provided by the Guarantee,
the Debentures, the Indenture, this Trust Agreement and the Expense Agreement.
Notwithstanding the foregoing, the Trust shall not, except with the consent of
holders of 100% in Liquidation Amount of the Preferred Securities, consolidate,
amalgamate, merge with or into, or be replaced by or convey, transfer or lease
its properties and assets substantially as an entirety to any other Person or
permit any other Person to consolidate, amalgamate, merge with or into, or
replace it if such consolidation, amalgamation, merger or replacement would
cause the Trust or the successor entity to be classified as other than a grantor
trust for United States federal income tax purposes.

                                   ARTICLE X

                            MISCELLANEOUS PROVISIONS

SECTION 1001.  LIMITATION OF RIGHTS OF SECURITYHOLDERS.

  The death or incapacity of any Person having an interest, beneficial or
otherwise, in Trust Securities shall not operate to terminate this Trust
Agreement, nor entitle the legal representatives or heirs of such Person or any
Securityholder for such Person, to claim an accounting, take any action or bring
any proceeding in any court for a partition or winding-up of the arrangements
contemplated hereby, nor otherwise affect the rights, obligations and
liabilities of the parties hereto or any of them.

                                      34
<PAGE>
 
 SECTION 1002.  AMENDMENT.

  (a) This Trust Agreement may be amended from time to time by the Trustees and
the Depositor, without the consent of any Securityholders, (i) as provided in
Section 811 with respect to acceptance of appointment by a successor Trustee;
(ii) to cure any ambiguity, correct or supplement any provision herein or
therein which may be inconsistent with any other provision herein or therein, or
to make any other provisions with respect to matters or questions arising under
this Trust Agreement, that shall not be inconsistent with the other provisions
of this Trust Agreement; or (iii) to modify, eliminate or add to any provisions
of this Trust Agreement to such extent as shall be necessary to ensure that the
Trust shall be classified for United States federal income tax purposes as a
grantor trust at all times that any Trust Securities are outstanding or to
ensure that the Trust shall not be required to register as an "investment
company" under the Investment Company Act; provided, however, that in the case
of clause (ii), such action shall not adversely affect in any material respect
the interests of any Securityholder, and any amendments of this Trust Agreement
shall become effective when notice thereof is given to the Securityholders.

  (b) Except as provided in Section 601(c) or Section 1002(c) hereof, any
provision of this Trust Agreement may be amended by the Trustees and the
Depositor (i) with the consent of Trust Securityholders representing not less
than a majority (based upon Liquidation Amounts) of the Trust Securities then
Outstanding; and (ii) upon receipt by the Trustees of an Opinion of Counsel to
the effect that such amendment or the exercise of any power granted to the
Trustees in accordance with such amendment shall not affect the Trust's status
as a grantor trust for United States federal income tax purposes or the Trust's
exemption from status of an "investment company" under the Investment Company
Act.

  (c) In addition to and notwithstanding any other provision in this Trust
Agreement, without the consent of each affected Securityholder (such consent
being obtained in accordance with Section 603 or 606 hereof), this Trust
Agreement may not be amended to (i) change the amount or timing of any
Distribution on the Trust Securities or otherwise adversely affect the amount of
any Distribution required to be made in respect of the Trust Securities as of a
specified date; or (ii) restrict the right of a Securityholder to institute suit
for the enforcement of any such payment on or after such date.  Notwithstanding
any other provision herein, without the unanimous consent of the Securityholders
(such consent being obtained in accordance with Section 603 or 606 hereof), this
paragraph (c) of this Section 1002 may not be amended.

  (d) Notwithstanding any other provisions of this Trust Agreement, no Trustee
shall enter into or consent to any amendment to this Trust Agreement which would
cause the Trust to fail or cease to qualify for the exemption from status of an
"investment company" under the Investment Company Act or to fail or cease to be
classified as a grantor trust for United States federal income tax purposes.

  (e) Notwithstanding anything in this Trust Agreement to the contrary, without
the consent of the Depositor, this Trust Agreement may not be amended in a
manner which imposes any additional obligation on the Depositor.

  (f) In the event that any amendment to this Trust Agreement is made, the
Administrative Trustees shall promptly provide to the Depositor a copy of such
amendment.

  (g) Neither the Property Trustee nor the Delaware Trustee shall be required to
enter into any amendment to this Trust Agreement which affects its own rights,
duties or immunities under this Trust Agreement. The Property Trustee shall be
entitled to receive an Opinion of Counsel and an Officers' Certificate stating
that any amendment to this Trust Agreement is in compliance with this Trust
Agreement.

 SECTION 1003.  SEPARABILITY.

  In case any provision in this Trust Agreement or in the Trust Securities
Certificates shall be invalid, illegal or unenforceable, the validity, legality
and enforceability of the remaining provisions shall not in any way be affected
or impaired thereby.

                                      35
<PAGE>
 
 SECTION 1004.  GOVERNING LAW.

  THIS TRUST AGREEMENT AND THE RIGHTS AND OBLIGATIONS OF EACH OF THE
SECURITYHOLDERS, THE TRUST AND THE TRUSTEES WITH RESPECT TO THIS TRUST AGREEMENT
AND THE TRUST SECURITIES SHALL BE CONSTRUED IN ACCORDANCE WITH AND GOVERNED BY
THE LAWS OF THE STATE OF DELAWARE (WITHOUT REGARD TO CONFLICT OF LAWS
PRINCIPLES).

 SECTION 1005.  PAYMENTS DUE ON NON-BUSINESS DAY.

  If the date fixed for any payment on any Trust Security shall be a day that is
not a Business Day, then such payment need not be made on such date but may be
made on the next succeeding day which is a Business Day, with the same force and
effect as though made on the date fixed for such payment, and no distribution
shall accumulate thereon for the period after such date.

 SECTION 1006.  SUCCESSORS.

  This Trust Agreement shall be binding upon and shall inure to the benefit of
any successor to the Depositor, the Trust or the Relevant Trustee(s), including
any successor by operation of law. Except in connection with a consolidation,
merger or sale involving the Depositor that is permitted under Article XII of
the Indenture and pursuant to which the assignee agrees in writing to perform
the Depositor's obligations hereunder, the Depositor shall not assign its
obligations hereunder.

 SECTION 1007.  HEADINGS.

  The Article and Section headings are for convenience only and shall not affect
the construction of this Trust Agreement.

 SECTION 1008.  REPORTS, NOTICES AND DEMANDS.

  Any report, notice, demand or other communication  which by any provision of
this Trust Agreement is required or permitted to be given or served to or upon
any Securityholder or the Depositor may be given or served in writing by deposit
thereof, first-class postage prepaid, in the United States mail, hand delivery
or facsimile transmission, in each case, addressed, (a) in the case of a
Preferred Securityholder, to such Preferred Securityholder as such
Securityholder's name and address may appear on the Securities Register; and (b)
in the case of the Common Securityholder or the Depositor, to Southwest Bancorp,
Inc., 608 South Main Street, Stillwater, Oklahoma, Attention: Mr. Kerby Crowell,
facsimile no.: (405) 377-3808. Any notice to Preferred Securityholders shall
also be given to such owners as have, within two years preceding the giving of
such notice, filed their names and addresses with the Property Trustee for that
purpose. Such notice, demand or other communication to or upon a Securityholder
shall be deemed to have been sufficiently given or made, for all purposes, upon
hand delivery, mailing or transmission.

  Any notice, demand or other communication which by any provision of this Trust
Agreement is required or permitted to be given or served to or upon the Trust,
the Property Trustee or the Administrative Trustees shall be given in writing
addressed (until another address is published by the Trust) as follows: (a) with
respect to the Property Trustee to State Street Bank and Trust Company, Two
International Place, 4th Floor, Boston, Massachusetts 02110, Attention:
Corporate Trust Department; (b) with respect to the Delaware Trustee, to
Wilmington Trust Company, Rodney Square North, 1100 North Market Street,
Wilmington, Delaware 19890-0001, Attention: Corporate Trust Administration; and
(c) with respect to the Administrative Trustees, to them at the address above
for notices to the Depositor, marked "Attention: Administrative Trustees of SBI
Capital Trust." Such notice, demand or other communication to or upon the Trust
or the Property Trustee shall be deemed to have been sufficiently given or made
only upon actual receipt of the writing by the Trust or the Property Trustee.

                                      36
<PAGE>
 
 SECTION 1009.  AGREEMENT NOT TO PETITION.

  Each of the Trustees and the Depositor agree for the benefit of the
Securityholders that, until at least one year and 1 day after the Trust has been
terminated in accordance with Article IX, they shall not file, or join in the
filing of, a petition against the Trust under any bankruptcy, insolvency,
reorganization or other similar law (including, without limitation, the United
States Bankruptcy Code of 1978, as amended) (collectively, "Bankruptcy Laws") or
otherwise join in the commencement of any proceeding against the Trust under any
Bankruptcy Law. In the event the Depositor takes action in violation of this
Section 1009, the Property Trustee agrees, for the benefit of Securityholders,
that at the expense of the Depositor (which expense shall be paid prior to the
filing), it shall file an answer with the bankruptcy court or otherwise properly
contest the filing of such petition by the Depositor against the Trust or the
commencement of such action and raise the defense that the Depositor has agreed
in writing not to take such action and should be stopped and precluded
therefrom. The provisions of this Section 1009 shall survive the termination of
this Trust Agreement.

 SECTION 1010.  TRUST INDENTURE ACT; CONFLICT WITH TRUST INDENTURE ACT.

  (a) This Trust Agreement is subject to the provisions of the Trust Indenture
Act that are required to be part of this Trust Agreement and shall, to the
extent applicable, be governed by such provisions.

  (b) The Property Trustee shall be the only Trustee which is a trustee for the
purposes of the Trust Indenture Act.

  (c) If any provision hereof limits, qualifies or conflicts with another
provision hereof which is required to be included in this Trust Agreement by any
of the provisions of the Trust Indenture Act, such required provision shall
control. If any provision of this Trust Agreement modifies or excludes any
provision of the Trust Indenture Act which may be so modified or excluded, the
latter provision shall be deemed to apply to this Trust Agreement as so modified
or to be excluded, as the case may be.

  (d) The application of the Trust Indenture Act to this Trust Agreement shall
not affect the nature of the Trust Securities as equity securities representing
undivided beneficial interests in the assets of the Trust.

                                      37
<PAGE>
 
 SECTION 1011.  ACCEPTANCE OF TERMS OF TRUST AGREEMENT, GUARANTEE AND INDENTURE.

  THE RECEIPT AND ACCEPTANCE OF A TRUST SECURITY OR ANY INTEREST THEREIN BY OR
ON BEHALF OF A SECURITYHOLDER OR ANY BENEFICIAL OWNER, WITHOUT ANY SIGNATURE OR
FURTHER MANIFESTATION OF ASSENT, SHALL CONSTITUTE THE UNCONDITIONAL ACCEPTANCE
BY THE SECURITYHOLDER AND ALL OTHERS HAVING A BENEFICIAL INTEREST IN SUCH TRUST
SECURITY OF ALL THE TERMS AND PROVISIONS OF THIS TRUST AGREEMENT AND AGREEMENT
TO THE SUBORDINATION PROVISIONS AND OTHER TERMS OF THE GUARANTEE AND THE
INDENTURE, AND SHALL CONSTITUTE THE AGREEMENT OF THE TRUST, SUCH SECURITYHOLDER
AND SUCH OTHERS THAT THE TERMS AND PROVISIONS OF THIS TRUST AGREEMENT SHALL BE
BINDING, OPERATIVE AND EFFECTIVE AS BETWEEN THE TRUST AND SUCH SECURITYHOLDER
AND SUCH OTHERS.

 
                        SOUTHWEST BANCORP, INC.                                 
                                                                                
                        By: /s/ Robert L. McCormick                             
                            --------------------------------------------------- 
                            Robert L. McCormick, President                      
                                                                                
                        STATE STREET BANK AND TRUST COMPANY,                    
                        as Property Trustee                                     
                                                                                
                        By: /s/ Paul D. Allen                                   
                            --------------------------------------------------- 
                            Paul D. Allen, Vice President                       
                                                                                
                        WILMINGTON TRUST COMPANY,                               
                        as Delaware Trustee                                     
                                                                                
                        By: /s/ Norma P. Closs                                  
                            --------------------------------------------------- 
                            Norma P. Closs, Vice President                      
                                                                                
                                                                                
                            /s/ Robert L. McCormick, Jr.                        
                            --------------------------------------------------- 
                            Robert L. McCormick, Jr., as Administrative Trustee 
                                                                                
                            /s/ Kerby E. Crowell                                
                            --------------------------------------------------- 
                            Kerby E. Crowell, as Administrative Trustee 
                                                                                
                            /s/ Deboarh T. Bradley                              
                            --------------------------------------------------- 
                            Deborah T. Bradley, as Administrative Trustee    

                                      38

<TABLE> <S> <C>

<PAGE>
 
<ARTICLE> 9
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM SOUTHWEST
BANCORP QUARTERLY REPORT ON FORM 10-Q FOR THE QUARTER ENDED JUNE 30, 1997, AND
IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000
       
<S>                             <C>
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1997
<PERIOD-START>                             JAN-01-1997
<PERIOD-END>                               JUN-01-1997
<CASH>                                          31,127
<INT-BEARING-DEPOSITS>                               0
<FED-FUNDS-SOLD>                                 4,000
<TRADING-ASSETS>                                     0
<INVESTMENTS-HELD-FOR-SALE>                     91,903
<INVESTMENTS-CARRYING>                          86,780
<INVESTMENTS-MARKET>                            87,105
<LOANS>                                        711,894
<ALLOWANCE>                                      8,669
<TOTAL-ASSETS>                                 947,972
<DEPOSITS>                                     847,292
<SHORT-TERM>                                     1,500
<LIABILITIES-OTHER>                              7,968
<LONG-TERM>                                     25,013
                                0
                                        690  
<COMMON>                                         3,769
<OTHER-SE>                                      61,740
<TOTAL-LIABILITIES-AND-EQUITY>                 947,972
<INTEREST-LOAN>                                 31,807
<INTEREST-INVEST>                                4,777
<INTEREST-OTHER>                                   270
<INTEREST-TOTAL>                                36,854
<INTEREST-DEPOSIT>                              19,214
<INTEREST-EXPENSE>                              19,479
<INTEREST-INCOME-NET>                           17,375
<LOAN-LOSSES>                                    3,802 
<SECURITIES-GAINS>                                   0
<EXPENSE-OTHER>                                 12,943     
<INCOME-PRETAX>                                  3,606
<INCOME-PRE-EXTRAORDINARY>                       3,606
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                     2,363    
<EPS-PRIMARY>                                     0.42
<EPS-DILUTED>                                     0.42
<YIELD-ACTUAL>                                    8.76
<LOANS-NON>                                      5,942 
<LOANS-PAST>                                     3,960
<LOANS-TROUBLED>                                   560
<LOANS-PROBLEM>                                 19,682   
<ALLOWANCE-OPEN>                                 7,139
<CHARGE-OFFS>                                    2,535
<RECOVERIES>                                       263
<ALLOWANCE-CLOSE>                                8,669  
<ALLOWANCE-DOMESTIC>                             8,669
<ALLOWANCE-FOREIGN>                                  0
<ALLOWANCE-UNALLOCATED>                            425
        

</TABLE>


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