EXHIBIT 4.4


                   PREFERRED SECURITIES GUARANTEE AGREEMENT

                                BY AND BETWEEN

                            SOUTHWEST BANCORP, INC.

                                      AND

                      STATE STREET BANK AND TRUST COMPANY

                                 JUNE 4, 1997

 
                               TABLE OF CONTENTS



                                                                        Page No.
                                                                     
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



                                       i

 

                                                                     
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



                                      ii

 
                             CROSS-REFERENCE TABLE




Section of
Trust Indenture Act                                     Section of
of 1939, as amended                                     Indenture
- -------------------                                 ------------------
                                                 
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)
                               
                                       
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

 
                   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

 
     (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

 
     "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

 
                                  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

 
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

 
     (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;

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     (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.

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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

 
     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;

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     (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.

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                                 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

 
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



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(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



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