Document:

<PAGE>

                                                                    EXHIBIT 10.8

                           FIFTH AMENDED AND RESTATED
                             STOCK PLEDGE AGREEMENT

      This FIFTH AMENDED AND RESTATED STOCK PLEDGE AGREEMENT ("Pledge
Agreement"), dated as of October 4, 2004, is made by and between SAI Holdings,
Inc., formerly known as Service Asset Investments, Inc., a Texas corporation
("Pledger"), and Guaranty Bank, successor by merger to Guaranty Federal Bank,
F.S.B., a federal savings bank ("Pledgee").

                                   WITNESSETH:

      WHEREAS, Pledgor and Pledgee have entered into an Amended and Restated
Loan Agreement dated as of April 30, 2001, as amended as of even date herewith
(such agreement, together with all amendments, restatements, modifications and
supplements thereto, being hereinafter referred to as the "Loan Agreement"); and

      WHEREAS, in connection with the transactions contemplated by the Loan
Agreement, the Pledgor executed that certain Fourth Amended and Restated Pledge
Agreement dated as of December 29, 2001 (as amended, the "Original Pledge
Agreement"), which the Pledgor hereby acknowledges and ratifies; and

      WHEREAS, Pledgor has requested Pledgee to make certain modifications to
the Loan Agreement pursuant to the terms of a Ninth Amendment to Loan Agreement,
dated of even date herewith, between Pledgor and Pledgee (the "Ninth
Amendment"); and

      WHEREAS, Pledgee has conditioned its acceptance of the Ninth Amendment
upon the execution and delivery of this Pledge Agreement by Pledgor, which
amends and restates the Original Pledge Agreement; and

      WHEREAS, capitalized terms used herein shall have the meanings assigned to
them in the Loan Agreement.

      NOW, THEREFORE, to induce Pledgee to enter into the Ninth Amendment and
for good and valuable considerations, the receipt and sufficiency of which are
hereby acknowledged, the parties hereto agree as follows, intending to be
legally bound:

      1.    Grant of Security Interest and Pledge.

            (a) As security for the payment and performance of the Notes and the
      Obligations, including, without limitation, the due and punctual payment
      of the principal of, and accrued and unpaid interest on, the Notes,
      whether at maturity, by acceleration or otherwise, and all renewals,
      extensions, rearrangements, amendments, modifications and increases
      thereof, Pledgor hereby pledges and grants to Pledgee a first priority
      security interest in and to, and assigns and transfers to Pledgee, (i) all
      of the capital stock of each entity listed on the attached Schedule 1, as
      evidenced on the date hereof by the certificates described on Schedule 1
      attached hereto; (ii) all proceeds and products of the stock described in
      item (i) above; and (iii) all income, stock dividends and other
      distributions from items (i) and (ii) above (such shares, proceeds,
      products, income, stock

<PAGE>

      dividends and distributions being referred to collectively as the
      "Collateral"). The Collateral shall be held by Pledgee, but shall continue
      to be registered in the name of the Pledgor unless and until the
      occurrence of an Event of Default.

            (b) Pledgor hereby designates and appoints Pledgee as its
      attorney-in-fact and proxy, with full power of substitution, which
      designation and appointment is irrevocable and coupled with an interest,
      exercisable upon the occurrence of an Event of Default for the purpose of
      voting the Collateral and performing any and all acts, in the name, place
      and stead of Pledgor, that are authorized by the provisions of this Pledge
      Agreement. Accordingly, Pledgor irrevocably constitutes and appoints
      Pledgee as Pledgor's proxy and attorney-in-fact, effective only after
      notice to Pledgor after an Event of Default has occurred and so long as it
      is continuing, but with full power of substitution, to vote, and to act
      with respect to, the Collateral, standing in the name of Pledgor or with
      respect to which Pledgor is entitled to vote and act.

            (c) Concurrently with the execution and delivery of this Pledge
      Agreement, Pledgor shall deliver to Pledgee all certificates identified in
      Schedule 1 accompanied by undated stock powers duly executed in blank.

      2.    Voting.

      During the term of this Pledge Agreement and for so long as no Event of
Default shall have occurred, Pledgor shall have the sole and absolute right to
vote the Collateral. After an Event of Default has occurred and so long as it is
continuing, the right to vote the Collateral is vested exclusively in Pledgee.
Such proxy is coupled with an interest, is irrevocable, and continues until the
Obligations are fully paid and performed.

      3.    Cash Dividends and Distributions.

      During the term of this Pledge Agreement and for so long as no Event of
Default shall have occurred, cash dividends and cash distribution payments may
be paid to Pledgor. All non-cash dividends and other non-cash distributions
shall be immediately delivered to Pledgee (together with appropriate stock
powers signed by Pledgor).

      4.    Transfer, Dividends, Etc. After Default.

      If an Event of Default shall have occurred, then upon written notice to
Pledgor, Pledgee may take any of the following actions:

            (a) Pledgee may, in its absolute discretion, cause all or any of the
      Collateral then held by it under this Pledge Agreement to be transferred
      into the name of Pledgee, or the name or names of the nominee or nominees
      of Pledgee;

            (b) Pledgee may receive, and Pledgor upon request shall assign to
      the order of Pledgee, all dividends, interest or principal and payments or
      other distributions in respect of the Collateral, all of which shall
      thereafter be held by Pledgee as part of the Collateral or shall be
      applied to the Notes and the Obligations in such manner and order as
      Pledgee determines in its absolute discretion;

                                        2
<PAGE>

            (c) Pledgee, as Pledgor's attorney-in-fact and proxy, shall have and
      may exercise on behalf of Pledgor all rights of an owner in respect of any
      of the Collateral hereunder or may, in any respect not contrary to the
      provisions of this Pledge Agreement, permit such rights to be exercised by
      Pledgor; and, without limiting the generality of the foregoing, in its
      discretion:

                  (i) Pledgee may join in and become a party to any plan of
            reorganization and readjustment, whether voluntary or involuntary,
            may deposit any of the Collateral under such plan or make any
            exchange or surrender or permit any substitution of or cancellation
            of the Collateral as required by such plan and may take all such
            action as may be required by such plan; provided, however, that all
            securities issued or created under such plan and exchanged for the
            Collateral or any portion thereof, and all securities, monies or
            property received pursuant to such plan shall thereafter be subject
            to the terms of this Pledge Agreement and become part of the
            Collateral or shall be applied to the Notes and Obligations in such
            manner and order as Pledgee determines in its absolute discretion;
            and

                  (ii) Pledgee may receive, endorse and collect all checks,
            whether or not made payable to the order of Pledgor, representing
            any dividend, interest or principal payments or other distributions
            at any time paid or made on or with respect to the Collateral all of
            which shall be held by Pledgee pursuant to the terms of this Pledge
            Agreement as part of the Collateral or shall be applied to the Notes
            and Obligations in such manner and order as Pledgee determines in
            its absolute discretion.

      5.    Representations and Warranties of Pledgor. Pledgor represents and
warrants to Pledgee as follows:

            (a) Financing Statements. Except for financing statements in favor
      of Pledgee, no financing statement covering the Collateral or any portion
      thereof, or any proceeds thereof, is on file in any public office.

            (b) Ownership Free of Encumbrances. All shares of capital stock that
      are Collateral are duly issued, fully paid and non-assessable, and except
      for the security interest granted hereby to Pledgee, Pledgor now owns the
      Collateral free from any lien, security interest, claim or encumbrance.

            (c) Benefit. Pledgor will benefit, directly or indirectly, from the
      loans to Pledgor evidenced by the Notes.

            (d) All Outstanding Stock; No Warrants; Etc. The shares of common
      stock of the entity(ies) pledged hereunder represent all of the
      outstanding capital stock of such entity(ies). There are no warrants,
      options or other rights to acquire capital stock of such entity(ies)
      outstanding.

            (e) Organization and Authority. Pledgor is a corporation duly
      organized, validly existing, and in good standing under the laws of its
      state of incorporation.

                                        3
<PAGE>

      Pledgor has the corporate power and authority to execute, deliver, and
      perform this Agreement, and the execution, delivery, and performance of
      this Agreement by Pledgor have been duly authorized by all necessary
      corporate action on the part of Pledgor and do not and will not violate or
      conflict with the articles of incorporation or bylaws of Pledgor or any
      law, rule, or regulation or any order, writ, injunction, or decree of any
      court, governmental authority, or arbitrator and do not and will not
      conflict with, result in a breach of, or constitute a default under the
      provisions of any indenture, mortgage, deed of trust, security agreement,
      or other instrument or agreement binding on Pledgor or any of its
      property.

      6.    Covenants.

            (a) Encumbrances. Pledgor shall not create, permit, or suffer to
      exist, and shall defend the Collateral against, any Lien, security
      interest, or other encumbrance on the Collateral except the pledge and
      security interest of Pledgee hereunder, and shall defend Pledgor's rights
      in the Collateral and Pledgee's security interest in the Collateral
      against the claims of all Persons.

            (b) Sale of Collateral. Pledgor shall not sell, assign, or otherwise
      dispose of the Collateral or any part thereof without the prior written
      consent of Pledgee.

            (c) Distributions. If Pledgor shall become entitled to receive or
      shall receive any stock certificate (including, without limitation, any
      certificate representing a stock dividend or a distribution in connection
      with any reclassification, increase, or reduction of capital or issued in
      connection with any reorganization), option or rights, whether as an
      addition to, in substitution of, or in exchange for any Collateral or
      otherwise, Pledgor agrees to accept the same as Pledgee's agent and to
      hold the same in trust for Pledgee, and to deliver the same forthwith to
      Pledgee in the exact form received, with the appropriate endorsement of
      Pledgor when necessary and/or appropriate undated stock powers duly
      executed in blank, to be held by Pledgee as additional Collateral for the
      Obligations, subject to the terms hereof. Any sums paid upon or in respect
      of the Collateral upon the liquidation or dissolution of the issuer
      thereof shall be paid over to Pledgee to be held by it as additional
      Collateral for the Obligations subject to the terms hereof; and in case
      any distribution of capital shall be made on or in respect of the
      Collateral or any property shall be distributed upon or with respect to
      the Collateral pursuant to any recapitalization or reclassification of the
      capital of the issuer thereof or pursuant to any reorganization of the
      issuer thereof, the property so distributed shall be delivered to the
      Pledgee to be held by it, as additional Collateral for the Obligations,
      subject to the terms hereof. All sums of money and property so paid or
      distributed in respect of the Collateral that are received by Pledgor
      shall, until paid or delivered to Pledgee, be held by Pledgor in trust as
      additional security for the Obligations.

            (d) Further Assurances. At any time and from time to time, upon the
      request of Pledgee, and at the sole expense of Pledgor, Pledgor shall
      promptly execute and deliver all such further instruments and documents
      and take such further action as Pledgee may deem necessary or desirable to
      preserve and perfect its security interest in the Collateral and carry out
      the provisions and purposes of this Agreement, including,

                                        4
<PAGE>

      without limitation, the execution and filing of such financing statements
      as Pledgee may require. A carbon, photographic, or other reproduction of
      this Agreement or of any financing statement covering the Collateral or
      any part thereof shall be sufficient as a financing statement and may be
      filed as a financing statement. Subject to the right of Pledgor to receive
      cash dividends under Section 3 hereof, in the event any Collateral is ever
      received by Pledgor, Pledgor shall promptly transfer and deliver to
      Pledgee such Collateral so received by Pledgor (together with any
      necessary endorsements in blank or undated stock powers duly executed in
      blank), which Collateral shall thereafter be held by Pledgee pursuant to
      the terms of this Agreement. Pledgee shall at all times have the right to
      exchange any certificates representing Collateral for certificates of
      smaller or larger denominations for any purpose consistent with this
      Agreement.

            (e) Inspection Rights. Pledgor shall permit Pledgee and its
      representatives to examine, inspect, and copy Pledgor's books and records
      at any reasonable time and as often as Pledgee may reasonably desire.

            (f) Taxes. Pledgor agrees to pay or discharge prior to delinquency
      all taxes, assessments, levies, and other governmental charges imposed on
      it or its property, except Pledgor shall not be required to pay or
      discharge any tax, assessment, levy, or other governmental charge if (i)
      the amount or validity thereof is being contested by Pledgor in good faith
      by appropriate proceedings diligently pursued, (ii) such proceedings do
      not involve any risk of sale, forfeiture, or loss of the Collateral or any
      interest therein, and (iii) adequate reserves therefor have been
      established in conformity with GAAP.

            (g) Notification. Pledgor shall promptly notify Pledgee of (i) any
      Lien, security interest, encumbrance, or claim made or threatened against
      the Collateral, (ii) any material change in the Collateral, including,
      without limitation, any material decrease in the value of the Collateral,
      and (iii) the occurrence or existence of any Event of Default or the
      occurrence or existence of any condition or event that, with the giving of
      notice or lapse of time or both, would be an Event of Default.

            (h) Additional Securities. Pledgor shall not consent to or approve
      the issuance of any additional shares of any class of capital stock of any
      issuer of Collateral, or any securities convertible into, or exchangeable
      for, any such shares or any warrants, options, rights, or other
      commitments entitling any Person to purchase or otherwise acquire any such
      shares.

      7.    Rights of Pledgee Upon Event of Default.

      Upon the occurrence of an Event of Default, Pledgee may, at its option,
but subject to the provisions of this Section 7, have and exercise all rights of
a secured party under the Texas Business and Commerce Code, including, without
limitation, the following specific rights:

            (a) to take and assume immediate possession of the Collateral
      without further notice to Pledgor or prior resort to legal process;

                                        5
<PAGE>

            (b) to sell or otherwise dispose of all or any portion of the
      Collateral judicially or at public or private sale or any combination
      thereof, and to bid and become a purchaser at any public (including
      judicial) sale;

            (c) written notice shall be given to Pledgor as provided for in
      Section 13 hereof 10 days prior to the date of any public sale of all or
      any portion of the Collateral, or 10 days prior to the date after which a
      private sale of all or any portion of Collateral will be made, and Pledgor
      agrees that such notice shall constitute reasonable commercial notice of
      such public or private sale;

            (d) to apply the proceeds of disposition of the Collateral in
      satisfaction of the Notes and the Obligations; and

            (e) to apply any cash or other proceeds received by Pledgee pursuant
      to Section 4(c)(ii) hereof in fall or partial satisfaction of the Notes
      and the Obligations.

      Pledgee, pursuant to paragraph (b) of Section 1 of this Pledge Agreement,
may make and execute all conveyances, assignments and transfers of the
Collateral sold pursuant to this Section 7 that Pledgee shall reasonably deem
advisable, and the Pledgor hereby ratifies and confirms all that Pledgee, as
Pledgor's attorney-in-fact, shall reasonably do by virtue thereof. Nevertheless,
Pledgor shall, if so requested by Pledgee, ratify and confirm any sale or sales
by executing and delivering or causing to be executed and delivered to Pledgee
or to such purchaser or purchasers all such instruments as may, in the sole
judgment of Pledgee, be advisable for the purpose.

      The receipt of Pledgee for the purchase money paid at any such sale made
by it shall be sufficient discharge therefor to any purchaser of any of the
Collateral, or any portion thereof, sold as aforesaid; and no such purchaser (or
his, her or its representatives or assigns), after paying such purchase money
and receiving such receipt, shall be bound to see to the application of such
purchase money or any part thereof or in any manner whatsoever be answerable for
any loss, misapplication or non-application of any such purchase money, or any
part thereof, or be bound to inquire as to the authorization, necessity,
expediency or regularity of any such sale.

      8.    No Waiver.

      No failure on the part of the Pledgee to exercise, and no delay on the
part of Pledgee in exercising, any right, power or remedy hereunder shall
operate as a waiver hereof, nor shall any single or partial exercise by Pledgee
of any right, power or remedy hereunder serve to in any way limit Pledgee in the
further exercise of all or any portion of its rights, powers and remedies
hereunder. The remedies herein provided are cumulative and are not exclusive of
any remedies provided by law.

      9.    Termination of Pledge.

      When the Notes and Obligations (and all renewals, extensions,
modifications and increases thereof) have been fully and indefeasibly paid and
performed and all commitments to lend under the Loan Agreement have terminated,
this Pledge Agreement shall terminate and be of no further force or effect. Upon
termination of this Pledge Agreement, Pledgee hereby

                                        6
<PAGE>

covenants and agrees to forthwith assign, transfer and deliver the Collateral,
or to cause such Collateral to be assigned, transferred and delivered, to
Pledgor or its designees.

      10.   Governing Law, Severability.

      This Pledge Agreement shall in all respects be construed and interpreted
in accordance with and governed by the laws of the State of Texas. Any
provisions of this Pledge Agreement which are found to be invalid shall be
severable and shall not invalidate the remainder of this Pledge Agreement.

      11.   Successors and Assigns.

      This Pledge Agreement shall be binding upon and inure to the benefit of
the respective successors and assigns of Pledgor and Pledgee and each subsequent
holder of the Notes and the Obligations; provided, however, Pledgor may not
assign any of its rights or obligations under this Pledge Agreement.

      12.   Additional Instruments and Assurances.

      Pledgor hereby agrees, at its own expense, to execute and deliver or cause
to be executed and delivered, from time to time, any and all other instruments
and to perform such other acts as Pledgee may reasonably request to effect the
purpose of this Pledge Agreement. Pledgor agrees to pay all transfer taxes, if
any, that may be payable or determined to be payable in connection with any
transfer of all or any portion of the Collateral pursuant to the terms hereof.

      13.   Notices.

      All notices, demands and other communications required or permitted to be
given shall be in writing and must be personally delivered or mailed by prepaid
certified or registered mail to the party to whom such notice or communication
is directed at the address of such party shown on the signature page hereof. Any
such notice or other communication shall be deemed to have been given (whether
actually received or not) on the day it is personally delivered as aforesaid or,
if mailed, on the second business day it is mailed as aforesaid.

      14.   Amendment.

      Neither this Pledge Agreement nor any term or provision hereof may be
amended, except by an instrument in writing executed by Pledgor and Pledgee.

      15.   Compliance and Securities Laws.

      The securities initially pledged to Pledgee hereunder have not been
registered under the Securities Act of 1933 or any other securities statute.
Pledgor agrees that, because of the Securities Act of 1933, as amended, or any
other laws or regulations, and for other reasons, there may be legal and/or
practical restrictions or limitations affecting Pledgee in any attempts to
dispose of certain portions of the Collateral and to enforce its rights,
privileges and remedies granted pursuant to this Pledge Agreement. For these
reasons, Pledgee is hereby authorized by Pledgor, but not obligated, in the
event of the occurrence of an Event of Default, to sell all or any

                                        7
<PAGE>

part of the Collateral at private sale, subject to investment letter or in any
other manner that will not require the Collateral, or any part thereof, to be
registered in accordance with the Securities Act of 1933, as amended, or the
rules and regulations promulgated thereunder, or any other similar law or
regulation, at the best price reasonably obtainable by Pledgee at any such
private sale or other disposition in the manner mentioned above. Pledgee is also
hereby authorized by Pledgor, but not obligated, to take such actions, give such
notices, obtain such consents, and do such other things as Pledgee reasonably
may deem to be required or appropriate in the event of sale or disposition of
any of the Collateral. Pledgor understands that Pledgee may in its discretion
approach a restricted number of potential purchasers and that a sale under such
circumstances may yield a lower price for the Collateral, or any part or parts
thereof, than would otherwise be obtainable if same were either offered to a
large number of potential purchasers, or registered and sold in the open market.
Pledgor agrees (a) that in the event Pledgee shall, upon the occurrence of an
Event of Default, sell the Collateral, or any portion thereof, at such private
sale or sales, Pledgee shall have the right, but not the obligation, to obtain
or rely upon the advice and opinion of any member or firm of a national
securities exchange as to the best price reasonably obtainable upon such a
private sale thereof, and (b) that such reliance shall be conclusive evidence
that Pledgee handled such matter in a commercially reasonable manner under the
applicable provisions of the Texas Business and Commerce Code.

      16.   Liens Carried Forward.

      This Pledge Agreement is an amendment and restatement of the Original
Pledge Agreement and does not constitute a novation or discharge thereof. All of
the security interests and liens granted in the Original Pledge Agreement are
renewed, extended, carried forward, ratified and confirmed in this Pledge
Agreement.

      17.   Final Agreement. THIS WRITTEN AGREEMENT REPRESENTS THE FINAL
AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR,
CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE ARE NO
UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]

                                        8
<PAGE>

Executed to be effective as of the date first written above.

                                    PLEDGOR:

                                    SAI HOLDINGS, INC., formerly known as
                                    SERVICE ASSET INVESTMENTS, INC.

                                    By: /s/ Roger J. Engemoen, Jr.
                                        ----------------------------------------
                                    Name: Roger J. Engemoen, Jr.
                                    Title: CHAIRMAN

                                    Address: 1700 Pacific Avenue
                                             Suite 1400
                                             Dallas, Texas 75201

                                    PLEDGEE:

                                    GUARANTY BANK

                                    By: ________________________________________
                                        Name:___________________________________
                                        Title:__________________________________

                                    Address: 8333 Douglas Avenue
                                             Dallas, Texas 75225

                           FIFTH AMENDED AND RESTATED
                             STOCK PLEDGE AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                   SAI HOLDINGS, INC. STOCK PLEDGE AGREEMENT

                                   SCHEDULE 1

<TABLE>
<CAPTION>
                                           STATE OF     NUMBER OF  CERTIFICATE
                ENTITY                   ORGANIZATION    SHARES     NUMBER(s)
--------------------------------------  --------------  ---------  -----------
<S>                                     <C>             <C>        <C>
Penson Holdings, Inc. ("Holdings")         Delaware        1000         003

Nexa Technologies, Inc. (formerly          Delaware        1000         001
Integrated Technology Solutions, Inc.)

Penson Financial Futures, Inc.             Delaware        1000           1

SAH, Inc.                                  Delaware        1000           1

SAMCO Financial Services, Inc.             Arizona          100           1

Penson Financial Services, Inc.         North Carolina     1000           1

SAMCO Financial Advisors, Inc.             Texas         10,000         003
</TABLE>

<PAGE>

                    REAFFIRMATION OF STOCK PLEDGE AGREEMENTS

            Each of the undersigned (each a "Pledgor") hereby (i) consents to
the execution and delivery of that certain Eleventh Amendment to Amended and
Restated Loan Agreement (the "Amendment") dated as of March 24, 2005 by and
between SAI HOLDINGS, INC., formerly known as SERVICE ASSET INVESTMENTS, INC., a
Texas corporation ("Borrower"), and GUARANTY BANK, a federal savings bank
("Bank") by which Bank advances an additional $10,000,000.00 to Borrower; (ii)
agrees that the Amendment shall not limit or diminish the obligations of any
Pledgor under its respective stock pledge agreement described on Schedule A
attached hereto (each, a "Stock Pledge Agreement" and collectively, the "Stock
Pledge Agreements"); (iii) reaffirms its obligations under its respective Stock
Pledge Agreement; (iv) agrees that the Schedule 1 to its respective Stock Pledge
Agreement remains true and correct in all material respect without modification
except as attached hereto as Schedule B; (v) represents and warrants (a) the
shares of stock of each entity pledged under the Stock Pledge Agreements
represent all of the outstanding capital stock of such entities (b) such shares
of stock of each entity pledged under the Stock Pledge Agreements have been
delivered to Bank and no other capital stock has been issued or reissued, and
(c) there are no warrants, options or other rights to acquire capital stock of
such entities outstanding; and (vi) agrees that its Stock Pledge Agreement
remains in full force and effect and is hereby ratified and confirmed.

Dated as of March 24, 2005.

                                    PLEDGORS:

                                    SAI HOLDINGS, INC., formerly known as
                                    SERVICE ASSET INVESTMENTS, INC.

                                    By: /s/ Roger J. Engemoen, Jr
                                        ----------------------------------------
                                        Name: Roger J. Engemoen, Jr
                                        Title: Chairman

                                    PENSON WORLDWIDE, INC.

                                    By: /s/ Roger J. Engemoen, Jr
                                        ----------------------------------------
                                        Name: Roger J. Engemoen, Jr
                                        Title: Chairman

                                    PENSON FINANCIAL SERVICES VENTURE, INC.

                                    By: /s/ Roger J. Engemoen, Jr
                                        ----------------------------------------
                                        Name: Roger J. Engemoen, Jr
                                        Title: Chairman

<PAGE>

                                    PENSON HOLDINGS, INC.

                                    By: /s/ Roger J. Engemoen, Jr
                                        ----------------------------------------
                                        Name: Roger J. Engemoen, Jr
                                        Title: Chairman

<PAGE>

                                   SCHEDULE A

                             Stock Pledge Agreements

1.    That certain Fifth Amended and Restated Stock Pledge Agreement dated as of
      October 4, 2004 by and between SAI Holdings, Inc., formerly known as
      Service Asset Investments, Inc., a Texas corporation, and Guaranty Bank, a
      federal savings bank.

2.    That certain Amended and Restated Penson Worldwide Stock Pledge Agreement
      dated as of October 4, 2004 by and between Penson Worldwide, Inc., a
      Delaware corporation, and Guaranty Bank, a federal savings bank.

3.    That certain Penson Financial Services Venture, Inc. Stock Pledge
      Agreement dated as of October 4, 2004 by and between Penson Financial
      Services, Inc., a Canadian entity, and Guaranty Bank, a federal savings
      bank.

4.    That certain Fourth Amended and Restated Penson Stock Pledge Agreement
      dated as of October 4, 2004 by and between Penson Holdings, Inc., a
      Delaware corporation, and Guaranty Bank, a federal savings bank.

<PAGE>

                                   SCHEDULE B

             Modifications to Schedule 1 to Stock Pledge Agreements
<PAGE>

                    SAI HOLDINGS, INC. STOCK PLEDGE AGREEMENT

                                   SCHEDULE 1

<TABLE>
<CAPTION>
                                           STATE OF     NUMBER OF  CERTIFICATE
               ENTITY                    ORGANIZATION    SHARES      NUMBER(S)
--------------------------------------  --------------  ---------  ------------
<S>                                     <C>             <C>        <C>
Penson Holdings, Inc. ("Holdings")         Delaware         1000       003

Nexa Technologies, Inc. (formerly          Delaware         1000       001
Integrated Technology Solutions, Inc.)

Penson Financial Futures, Inc.             Delaware         1000         1

SAH, Inc.                                  Delaware         1000         1

SAMCO Financial Services, Inc.             Arizona           100         1

Penson Financial Services, Inc.         North Carolina      1000         1

SAMCO Financial Advisors, Inc.              Texas         10,000       003
</TABLE>

<PAGE>

                  PENSON WORLDWIDE, INC. STOCK PLEDGE AGREEMENT

                                   SCHEDULE 1

<TABLE>
<CAPTION>
                      STATE OF    NUMBER OF  CERTIFICATE
    ENTITY          ORGANIZATION   SHARES     NUMBER(S)
------------------  ------------  ---------  -----------
<S>                 <C>           <C>        <C>
SAMCO BD LLC          Delaware      1000         1

SAI Holdings, Inc.     Texas        1000         1
</TABLE>

<PAGE>

     PENSON FINANCIAL SERVICES VENTURE INC. (FORMERLY 3812359 CANADA, INC.)
                             STOCK PLEDGE AGREEMENT

                                   SCHEDULE 1

<TABLE>
<CAPTION>
                      STATE OF    NUMBER OF  CERTIFICATE
    ENTITY          ORGANIZATION   SHARES     NUMBER(S)
------------------  ------------  ---------  -----------
<S>                 <C>           <C>        <C>
Turnpike Trading
Systems, Inc.         Canada         51          C-3
</TABLE>

<PAGE>

                  PENSON HOLDINGS, INC. STOCK PLEDGE AGREEMENT

                                   SCHEDULE 1

<TABLE>
<CAPTION>
                                           STATE OF    NUMBER OF  CERTIFICATE
               ENTITY                    ORGANIZATION   SHARES     NUMBER(S)
---------------------------------------  ------------  ---------  -----------
<S>                                      <C>           <C>        <C>
Penson Financial Services Venture, Inc.    Canada           100        001
(formerly 3812359 Canada, Inc.)

Penson Financial Services Canada, Inc.     Canada       200,000       CO-6
</TABLE>

            FOURTH AMENDED AND RESTATED PENSON STOCK PLEDGE AGREEMENT
                                 SIGNATURE PAGE<PAGE>

                                                                   EXHIBIT 10.9

                  FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT
                                    (LIMITED)

      WHEREAS, the execution of this Fifth Amended and Restated Guaranty
Agreement (this "Guaranty Agreement"), which amends and restates that certain
Fourth Amended and Restated Guaranty Agreement dated as of July 31, 2002 (the
"Prior Guaranty"), is a condition to SAI HOLDINGS, INC., formerly known as
SERVICE ASSET INVESTMENT, INC., a Texas corporation ("Borrower"), borrowing from
GUARANTY BANK, a federal savings bank, formerly known as Guaranty Federal Bank,
F.S.B. ("Lender"), a term loan pursuant to that certain Amended and Restated
Loan Agreement dated as of April 30, 2001 (such Loan Agreement, as it has been
or may hereafter be amended or modified from time to time, being hereinafter
referred to as the "Loan Agreement") between Borrower and Lender; and

      WHEREAS, Borrower and Lender have agreed to modify the Loan Agreement, and
as a condition thereto, Guarantor has agreed to amend and restate the Prior
Guaranty according to the terms hereof.

      NOW, THEREFORE, for valuable consideration, the receipt and adequacy of
which are hereby acknowledged, DANIEL P.SON, an individual residing at 9507
Meadowbrook Drive, Dallas, Texas 75220 (the "Guarantor"), hereby irrevocably and
unconditionally guarantees to Lender, subject to the terms of this Guaranty
Agreement, the full and prompt payment and performance of the Guaranteed
Indebtedness (hereinafter defined), this Guaranty Agreement being upon the
following terms:

      1. DEFINITION OF GUARANTEED INDEBTEDNESS. The term "Guaranteed
Indebtedness" as used herein means Borrower's obligations under the Term Loan
(as defined in the Loan Agreement), provided that after additional capital is
raised in an amount of no less than $6,000,000 after December 31, 2002 and
injected into Penson Financial Services, Inc. on terms and conditions
satisfactory to Lender, Guarantor's liability with respect to such obligations
shall be limited to an amount not to exceed an amount equal to $864,000.00. All
capitalized terms used and not otherwise defined herein shall have their
respective meanings as set forth in the Loan Agreement.

      2. ABSOLUTE GUARANTY; NO SET-OFF RIGHTS. This instrument shall be an
absolute, continuing, irrevocable, and unconditional guaranty of payment and
performance, and not a guaranty of collection, of the Guaranteed Indebtedness as
provided herein, and Guarantor shall remain liable on its obligations hereunder
until the payment and performance in full of the Guaranteed Indebtedness,
subject to the terms of Section 1 of this Guaranty Agreement. No set-off,
counterclaim, recoupment, reduction, or diminution of any obligation, or any
defense of any kind or nature which Borrower may have against Lender or any
other party, or Guarantor may have against Borrower, Lender, or any other party,
shall be available to, or shall be asserted by, Guarantor against Lender or any
subsequent holder of the Guaranteed Indebtedness or any part thereof or against
payment of the Guaranteed Indebtedness or any part thereof.

      3. NO IMPAIRMENT OF RIGHTS. If Guarantor becomes liable for any
indebtedness owing by Borrower to Lender by endorsement or otherwise, other than
under this

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 1
<PAGE>

Guaranty Agreement, such liability shall not be in any manner impaired or
affected hereby, and the rights of Lender hereunder shall be cumulative of any
and all other rights that Lender may ever have against Guarantor. The exercise
by Lender of any right or remedy hereunder or under any other instrument, or at
Law or in equity, shall not preclude the concurrent or subsequent exercise of
any other right or remedy.

      4. OBLIGATIONS OF GUARANTORS; NO DUTY TO EXHAUST REMEDIES; WAIVER OF
SUBROGATION. In the event of default by Borrower in payment or performance of
the Guaranteed Indebtedness, or any part thereof, when such Guaranteed
Indebtedness becomes due, whether by its terms, by acceleration, or otherwise,
Guarantor shall promptly pay the amount due thereon to Lender without notice or
demand in lawful money of the United States of America and it shall not be
necessary for Lender, in order to enforce such payment by either Guarantor,
first to institute suit or exhaust its remedies against Borrower or any other
guarantor or others liable on such Guaranteed Indebtedness, or to enforce any
rights against any collateral which shall ever have been given to secure such
Guaranteed Indebtedness. Notwithstanding anything to the contrary contained in
this Guaranty Agreement, until such time as the Guaranteed Indebtedness has been
paid in full, Guarantor hereby irrevocably waives any and all rights it may now
or hereafter have under any agreement or at law or in equity (including, without
limitation, any law subrogating Guarantor to the rights of Lender) to assert any
claim against or seek contribution, indemnification or any other form of
reimbursement from Borrower or any other guarantors or any other party liable
for payment of any or all of the Guaranteed Indebtedness for any payment made by
Guarantor under or in connection with this Guaranty Agreement or otherwise. If
acceleration of the time for payment of any amount payable by Borrower under the
Guaranteed Indebtedness is stayed upon the insolvency, bankruptcy, or
reorganization of Borrower, all such amounts otherwise subject to acceleration
under the terms of the Guaranteed Indebtedness shall nonetheless be payable by
Guarantor hereunder forthwith on demand by Lender.

      5. NO IMPAIRMENT OF GUARANTOR'S OBLIGATIONS. Guarantor hereby agrees that
its obligations under this Guaranty Agreement shall not be released, discharged,
diminished, impaired, reduced, or affected for any reason or by the occurrence
of any event, including, without limitation, one or more of the following
events, whether or not with notice to or the consent of Guarantor: (a) the
taking or accepting of collateral as security for any or all of the Guaranteed
Indebtedness or the release, surrender, exchange, or subordination of any
collateral now or hereafter securing any or all of the Guaranteed Indebtedness;
(b) any partial release of the liability of Guarantor hereunder, or the full or
partial release of any other guarantor or obligor from liability for any or all
of the Guaranteed Indebtedness; (c) any disability of Borrower, or the
dissolution, insolvency, or bankruptcy of Borrower, Guarantor, or any other
party at any time liable for the payment of any or all of the Guaranteed
Indebtedness; (d) any renewal, extension, modification, waiver, amendment, or
rearrangement of any or all of the Guaranteed Indebtedness or any instrument,
document, or agreement evidencing, securing, or otherwise relating to any or all
of the Guaranteed Indebtedness; (e) any adjustment, indulgence, forbearance,
waiver, or compromise that may be granted or given by Lender to Borrower,
Guarantor, or any other party ever liable for any or all of the Guaranteed
Indebtedness; (f) any neglect, delay, omission, failure, or refusal of Lender to
take or prosecute any action for the collection of any of the Guaranteed
Indebtedness or to foreclose or take or prosecute any action in connection with
any instrument, document, or agreement evidencing, securing, or otherwise

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 2

<PAGE>

relating to any or all of the Guaranteed Indebtedness; (g) the unenforceability
or invalidity of any or all of the Guaranteed Indebtedness or of any instrument,
document, or agreement evidencing, securing, or otherwise relating to any or all
of the Guaranteed Indebtedness; (h) any payment by Borrower or any other party
to Lender is held to constitute a preference under applicable bankruptcy or
insolvency law or if for any other reason Lender is required to refund any
payment or pay the amount thereof to someone else; (i) the settlement or
compromise of any of the Guaranteed Indebtedness; (j) the non-perfection of any
security interest or lien securing any or all of the Guaranteed Indebtedness;
(k) any impairment of any collateral securing any or all of the Guaranteed
Indebtedness; (l) the failure of Lender to sell any collateral securing any or
all of the Guaranteed Indebtedness in a commercially reasonable manner or as
otherwise required by law; (m) any change in the corporate existence, structure,
or ownership of Borrower; or (n) any other circumstance which might otherwise
constitute a defense available to, or discharge of, Borrower or Guarantor.

      6. REPRESENTATIONS AND WARRANTIES. Guarantor represents and warrants to
Lender as follows:

            (a) Guarantor has the power and authority and legal right to
      execute, deliver, and perform its obligations under this Guaranty
      Agreement and this Guaranty Agreement constitutes the legal, valid, and
      binding obligation of Guarantor, enforceable against Guarantor in
      accordance with its terms, except as limited by bankruptcy, insolvency, or
      other laws of general application relating to the enforcement of
      creditors' rights.

            (b) The execution, delivery, and performance by Guarantor of this
      Guaranty Agreement do not and will not violate or conflict with any law,
      rule, or regulation or any order, writ, injunction, or decree of any
      court, governmental authority or agency, or arbitrator and do not and will
      not conflict with, result in a breach of, or constitute a default under,
      or result in the imposition of any lien upon any assets of Guarantor
      pursuant to the provisions of any indenture, mortgage, deed of trust,
      security agreement, franchise, permit, license, or other instrument or
      agreement to which Guarantor or its properties is bound.

            (c) No authorization, approval, or consent of, and no filing or
      registration with, any court, governmental authority, or third party is
      necessary for the execution, delivery, or performance by Guarantor of this
      Guaranty Agreement or the validity or enforceability thereof.

            (d) The value of the consideration received and to be received by
      Guarantor as a result of Lender making the Term Loan to Borrower under the
      Loan Agreement and Guarantor executing and delivering this Guaranty
      Agreement is reasonably worth at least as much as the liability and
      obligation of Guarantor hereunder, and such liability and obligation and
      the Loan Agreement have benefited and may reasonably be expected to
      benefit Guarantor directly and indirectly.

            (e) Guarantor has, independently and without reliance upon Lender
      and based upon such documents and information as Guarantor has deemed
      appropriate, made its own analysis and decision to enter into this
      Guaranty Agreement.

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 3

<PAGE>

      7. COVENANTS OF GUARANTOR. Guarantor covenants and agrees that, as long as
the Guaranteed Indebtedness or any part thereof is outstanding or Lender has any
commitment under the Loan Agreement:

            (a) Guarantor will furnish promptly to Lender written notice of the
      occurrence of any default under this Guaranty Agreement or an Event of
      Default under the Loan Agreement of which Guarantor has knowledge.

            (b) Guarantor will furnish promptly to Lender such additional
      information concerning Guarantor as Lender may request.

            (c) Guarantor will obtain at any time and from time to time all
      authorizations, licenses, consents or approvals as shall now or hereafter
      be necessary or desirable under all applicable laws or regulations or
      otherwise in connection with the execution, delivery and performance of
      this Guaranty Agreement and will promptly furnish copies thereof to
      Lender.

            (d) Guarantor will at all times own directly or indirectly and free
      and clear of all liens and encumbrances whatsoever at least the same
      percentage of voting shares of Borrower, if any, as it owns directly or
      indirectly on the date hereof.

      8. LENDER'S RIGHTS WITH RESPECT TO GUARANTOR'S PROPERTY IN LENDER'S
POSSESSION. Lender shall have the right to set off and apply against this
Guaranty Agreement or the Guaranteed Indebtedness or both, at any time and
without notice to Guarantor, any and all deposits (general or Special, time or
demand, provisional or final) or other sums at any time credited by or owing
from Lender to Guarantor whether or not the Guaranteed Indebtedness is then due
and irrespective of whether or not Lender shall have made any demand under this
Guaranty Agreement. As security for this Guaranty Agreement and the Guaranteed
Indebtedness, Guarantor hereby grants Lender a security interest in all money,
instruments, certificates of deposit, and other property of Guarantor now or
hereafter held by Lender, including, without limitation, property held in
safekeeping. In addition to Lender's right of setoff and as further security for
this Guaranty Agreement and the Guaranteed Indebtedness, Guarantor hereby grants
Lender a security interest in all deposits (general or special, time or demand,
provisional or final) and all other accounts of Guarantor now or hereafter on
deposit with or held by Lender and all other sums at any time credited by or
owing from Lender to Guarantor. The rights and remedies of Lender hereunder are
in addition to other rights and remedies (including, without limitation, other
rights of setoff) which Lender may have.

      9. SUBORDINATION. (a) Guarantor hereby agrees that the Subordinated
Indebtedness (as hereinafter defined) shall be subordinate and junior in right
of payment to the prior payment in full of all Guaranteed Indebtedness, and
Guarantor hereby assigns the Subordinated Indebtedness to Lender as security for
the Guaranteed Indebtedness. If any sums shall be paid to Guarantor by Borrower
or any other person or entity on account of the Subordinated Indebtedness, suck
sums shall be held in trust by Guarantor for the benefit of Lender and shall
forthwith be paid to Lender without affecting the liability of Guarantor under
this Guaranty Agreement and may be applied by Lender against the Guaranteed
Indebtedness in such order and manner as Lender may determine in its sole
discretion. Upon the request of

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 4

<PAGE>

Lender, Guarantor shall execute, deliver, and endorse to Lender such documents
and instruments as Lender may request to perfect, preserve, and enforce its
rights hereunder. For purposes of this Guaranty Agreement, the term
"Subordinated Indebtedness" means all indebtedness, liabilities, and obligations
of Borrower to Guarantor, whether such indebtedness, liabilities, and
obligations now exist or are hereafter incurred or arise, or whether the
obligations of Borrower thereon are direct, indirect, contingent, primary,
secondary, several, joint and several, or otherwise, and irrespective of whether
such indebtedness, liabilities, or obligations are evidenced by a note,
contract, open account, or otherwise, and irrespective of the person or persons
in whose favor such indebtedness, obligations, or liabilities may, at their
inception, have been, or may hereafter be created, or the manner in which they
have been or may hereafter be acquired by Guarantor.

            (b) Guarantor agrees that any and all liens, security interests,
      judgment liens, charges, or other encumbrances upon Borrower's assets
      securing payment of any Subordinated Indebtedness shall be and remain
      inferior and subordinate to any and all liens, security interests,
      judgment liens, charges, or other encumbrances upon Borrower's assets
      securing payment of the Guaranteed Indebtedness or any part thereof,
      regardless of whether such encumbrances in favor of Guarantor or Lender
      presently exist or are hereafter created or attached. Without the prior
      written consent of Lender, Guarantor shall not (i) file suit against
      Borrower or exercise or enforce any other creditor's right it may have
      against Borrower, or (ii) foreclose, repossess, sequester, or otherwise
      take steps or institute any action or proceedings (judicial or otherwise,
      including without limitation the commencement of, or joinder in, any
      liquidation, bankruptcy, rearrangement, debtor's relief or insolvency
      proceeding) to enforce any liens, security interests, collateral rights,
      judgments or other encumbrances held by Guarantor on assets of Borrower.

            (c) In the event of any receivership, bankruptcy, reorganization,
      rearrangement, debtor's relief, or other insolvency proceeding involving
      Borrower as debtor, Lender shall have the right to prove and vote any
      claim under the Subordinated Indebtedness and to receive directly from the
      receiver, trustee or other court custodian all dividends, distributions,
      and payments made in respect of the Subordinated Indebtedness. Lender may
      apply any such dividends, distributions, and payments against the
      Guaranteed Indebtedness in such order and manner as Lender may determine
      in its sole discretion.

      10. AMENDMENTS; CUMULATIVE REMEDIES. No amendment or waiver of any
provision of this Guaranty Agreement nor consent to any departure by Guarantor
therefrom shall in any event be effective unless the same shall be in writing
and signed by Lender. No failure on the part of Lender to exercise, and no delay
in exercising any right, power, or privilege hereunder shall operate as a waiver
thereof; nor shall any single or partial exercise of any right, power, or
privilege hereunder preclude any other or further exercise thereof or the
exercise of any other right, power, or privilege. The remedies herein provided
are cumulative and not exclusive of any remedies provided by law.

      11. SUCCESSORS AND ASSIGNS. This Guaranty Agreement is for the benefit of
Lender and its successors and assigns, and in the event of an assignment of the
Guaranteed Indebtedness, or any part thereof, the rights and benefits hereunder,
to the extent applicable to the indebtedness so assigned, may be transferred
with such indebtedness. This Guaranty

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 5

<PAGE>

Agreement is binding not only on Guarantor, but on Guarantor's heirs and
personal representatives.

      12. RELIANCE BY LENDER. Guarantor recognizes that Lender is relying upon
this Guaranty Agreement and the undertakings of Guarantor hereunder in making
extensions of credit to Borrower under the Loan Agreement and further recognizes
that the execution and delivery of this Guaranty Agreement is a material
inducement to Lender in making the Term Loan under the Loan Agreement Guarantor
hereby acknowledges that there are no conditions to the full effectiveness of
this Guaranty Agreement.

      13. GOVERNING LAW. THIS GUARANTY AGREEMENT SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS.

      14. FEES AND EXPENSES. Guarantor shall pay on demand all reasonable
attorneys' fees and all other costs and expenses incurred by Lender in
connection with the enforcement or collection of this Guaranty Agreement.

      15. WAIVERS BY GUARANTOR. Guarantor hereby waives promptness, diligence,
notice of any default under the Guaranteed Indebtedness, demand for payment,
notice of acceptance of this Guaranty Agreement, presentment, notice of protest,
notice of dishonor, notice of the incurring by Borrower of additional
indebtedness, and all other notices and demands with respect to the Guaranteed
Indebtedness and this Guaranty Agreement.

      16. VALIDITY; ENFORCEABILITY. The Loan Agreement, and all of the terms
thereof, are incorporated herein by reference, the same as if stated verbatim
herein, and Guarantor agrees that Lender may exercise any and all rights granted
to it under the Loan Agreement and the other Loan Documents (as defined in the
Loan Agreement) without affecting the validity or enforceability of this
Guaranty Agreement.

      17. NO RELIANCE ON LENDER. Guarantor hereby represents and warrants to
Lender that Guarantor has adequate means to obtain from Borrower and the
Subsidiaries on a continuing basis information concerning the financial
condition and assets of Borrower and the Subsidiaries and that Guarantor is not
relying upon Lender to provide (and Lender shall have no duty to provide) any
such information to Guarantor either now or in the future.

      18. NO ORAL AGREEMENTS. THIS GUARANTY AGREEMENT REPRESENTS THE FINAL
AGREEMENT OF GUARANTOR AND LENDER WITH RESPECT TO GUARANTOR'S GUARANTY OF THE
GUARANTEED INDEBTEDNESS AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR,
CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS. THERE ARE NO UNWRITTEN ORAL
AGREEMENTS AMONG THE PARTIES HERETO.

      [Remainder of Page Intentionally Left Blank. Signature Page Follows]

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 6

<PAGE>

      EXECUTED as of the 31 day of December, 2002.

                                          GUARANTOR:

                                          /s/ Daniel P. Son
                                          --------------------------------------
                                          Daniel P. Son

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Signature Page

<PAGE>

                  FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT
                                    (LIMITED)

      WHEREAS, the execution of this Fifth Amended and Restated Guaranty
Agreement (this "Guaranty Agreement"), which amends and restates that certain
Fourth Amended and Restated Guaranty Agreement dated as of July 31, 2002 (the
"Prior Guaranty"), is a condition to SAI HOLDINGS, INC., formerly known as
SERVICE ASSET INVESTMENT, INC., a Texas corporation ("Borrower"), borrowing from
GUARANTY BANK, a federal savings bank, formerly known as Guaranty Federal Bank,
F.S.B. ("Lender"), a term loan pursuant to that certain Amended and Restated
Loan Agreement dated as of April 30, 2001 (such Loan Agreement, as it has been
or may hereafter be amended or modified from time to time, being hereinafter
referred to as the "Loan Agreement") between Borrower and Lender; and

      WHEREAS, Borrower and Lender have agreed to modify the Loan Agreement, and
as a condition thereto, Guarantor has agreed to amend and restate the Prior
Guaranty according to the terms hereof.

      NOW, THEREFORE, for valuable consideration, the receipt and adequacy of
which are hereby acknowledged, PHILIP A. PENDERGRAFT, an individual residing at
3708 Big Bear Lake Drive, Arlington, Texas 76016 (the 'Guarantor"), hereby
irrevocably and unconditionally guarantees to Lender, subject to the terms of
this Guaranty Agreement, the full and prompt payment and performance of the
Guaranteed Indebtedness (hereinafter defined), this Guaranty Agreement being
upon the following terms:

      1. DEFINITION OF GUARANTEED INDEBTEDNESS. The term "Guaranteed
Indebtedness" as used herein means Borrower's obligations under the Term Loan
(as defined in the Loan Agreement), provided that after additional capital is
raised in an amount of no less than $6,000,000 after December 31, 2002 and
injected into Penson Financial Services, Inc. on terms and conditions
satisfactory to Lender, Guarantor's liability with respect to such obligations
shall be limited to an amount not to exceed an amount equal to $864,000.00. All
capitalized terms used and not otherwise defined herein shall have their
respective meanings as set forth in the Loan Agreement.

      2. ABSOLUTE GUARANTY; NO SET-OFF RIGHTS. This instrument shall be an
absolute, continuing, irrevocable, and unconditional guaranty of payment and
performance, and not a guaranty of collection, of the Guaranteed Indebtedness as
provided herein, and Guarantor shall remain liable on its obligations hereunder
until the payment and performance in full of the Guaranteed Indebtedness,
subject to the terms of Section 1 of this Guaranty Agreement. No set-off,
counterclaim, recoupment, reduction, or diminution of any obligation, or any
defense of any kind or nature which Borrower may have against Lender or any
other party, or Guarantor may have against Borrower, Lender, or any other party,
shall be available to, or shall be asserted by, Guarantor against Lender or any
subsequent holder of the Guaranteed Indebtedness or any part thereof or against
payment of the Guaranteed Indebtedness or any part thereof.

      3. NO IMPAIRMENT OF RIGHTS. If Guarantor becomes liable for any
indebtedness owing by Borrower to Lender by endorsement or otherwise, other than
under this

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 1

<PAGE>

Guaranty Agreement, such liability shall not be in any manner impaired or
affected hereby, and the rights of Lender hereunder shall be cumulative of any
and all other rights that Lender may ever have against Guarantor. The exercise
by Lender of any right or remedy hereunder or under any other instrument, or at
law or in equity, shall not preclude the concurrent or subsequent exercise of
any other right or remedy.

      4. OBLIGATIONS OF GUARANTORS; NO DUTY TO EXHAUST REMEDIES; WAIVER OF
SUBROGATION. In the event of default by Borrower in payment or performance of
the Guaranteed Indebtedness, or any part thereof, when such Guaranteed
Indebtedness becomes due, whether by its terms, by acceleration, or otherwise,
Guarantor shall promptly pay the amount due thereon to Lender without notice or
demand in lawful money of the United States of America and it shall not be
necessary for Lender, in order to enforce such payment by either Guarantor,
first to institute suit or exhaust its remedies against Borrower or any other
guarantor or others liable on such Guaranteed Indebtedness, or to enforce any
rights against any collateral which shall ever have been given to secure such
Guaranteed Indebtedness. Notwithstanding anything to the contrary contained in
this Guaranty Agreement, until such time as the Guaranteed Indebtedness has been
paid in full, Guarantor hereby irrevocably waives any and all rights it may now
or hereafter have under any agreement or at law or in equity (including, without
limitation, any law subrogating Guarantor to the rights of Lender) to assert any
claim against or seek contribution, indemnification or any other form of
reimbursement from Borrower or any other guarantors or any other party liable
for payment of any or all of the Guaranteed Indebtedness for any payment made by
Guarantor under or in connection with this Guaranty Agreement or otherwise. If
acceleration of the time for payment of any amount payable by Borrower under the
Guaranteed Indebtedness is stayed upon the insolvency, bankruptcy, or
reorganization of Borrower, all such amounts otherwise subject to acceleration
under the terms of the Guaranteed Indebtedness shall nonetheless be payable by
Guarantor hereunder forthwith on demand by Lender.

      5. NO IMPAIRMENT OF GUARANTOR'S OBLIGATIONS. Guarantor hereby agrees that
its obligations under this Guaranty Agreement shall not be released, discharged,
diminished, impaired, reduced, or affected for any reason or by the occurrence
of any event, including, without limitation, one or more of the following
events, whether or not with notice to or the consent of Guarantor: (a) the
taking or accepting of collateral as security for any or all of the Guaranteed
Indebtedness or the release, surrender, exchange, or subordination of any
collateral now or hereafter securing any or all of the Guaranteed Indebtedness;
(b) any partial release of the liability of Guarantor hereunder, or the full or
partial release of any other guarantor or obligor from liability for any or all
of the Guaranteed Indebtedness; (c) any disability of Borrower, or the
dissolution, insolvency, or bankruptcy of Borrower, Guarantor, or any other
party at any time liable for the payment of any or all of the Guaranteed
Indebtedness; (d) any renewal, extension, modification, waiver, amendment, or
rearrangement of any or all of the Guaranteed Indebtedness or any instrument,
document, or agreement evidencing, securing, or otherwise relating to any or all
of the Guaranteed Indebtedness; (e) any adjustment, indulgence, forbearance,
waiver, or compromise that may be granted or given by Lender to Borrower,
Guarantor, or any other party ever liable for any or all of the Guaranteed
Indebtedness; (f) any neglect, delay, omission, failure, or refusal of Lender to
take or prosecute any action for the collection of any of the Guaranteed
Indebtedness or to foreclose or take or prosecute any action in connection with
any instrument, document, or agreement evidencing, securing, or otherwise

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 2

<PAGE>

relating to any or all of the Guaranteed Indebtedness; (g) the unenforceability
or invalidity of any or all of the Guaranteed Indebtedness or of any instrument,
document, or agreement evidencing, securing, or otherwise relating to any or all
of the Guaranteed Indebtedness; (h) any payment by Borrower or any other party
to Lender is held to constitute a preference under applicable bankruptcy or
insolvency law or if for any other reason Lender is required to refund any
payment or pay the amount thereof to someone else; (i) the settlement or
compromise of any of the Guaranteed Indebtedness; (j) the non-perfection of any
security interest or lien securing any or all of the Guaranteed Indebtedness;
(k) any impairment of any collateral securing any or all of the Guaranteed
Indebtedness; (l) the failure of Lender to sell any collateral securing any or
all of the Guaranteed Indebtedness in a commercially reasonable manner or as
otherwise required by law; (m) any change in the corporate existence, structure,
or ownership of Borrower; or (n) any other circumstance which might otherwise
constitute a defense available to, or discharge of, Borrower or Guarantor.

      6. REPRESENTATIONS AND WARRANTIES. Guarantor represents and warrants to
Lender as follows:

            (a) Guarantor has the power and authority and legal right to
      execute, deliver, and perform its obligations under this Guaranty
      Agreement and this Guaranty Agreement constitutes the legal, valid, and
      binding obligation of Guarantor, enforceable against Guarantor in
      accordance with its terms, except as limited by bankruptcy, insolvency, or
      other laws of general application relating to the enforcement of
      creditors' rights.

            (b) The execution, delivery, and performance by Guarantor of this
      Guaranty Agreement do not and will not violate or conflict with any law,
      rule, or regulation or any order, writ, injunction, or decree of any
      court, governmental authority or agency, or arbitrator and do not and will
      not conflict with, result in a breach of, or constitute a default under,
      or result in the imposition of any lien upon any assets of Guarantor
      pursuant to the provisions of any indenture, mortgage, deed of trust,
      security agreement, franchise, permit, license, or other instrument or
      agreement to which Guarantor or its properties is bound.

            (c) No authorization, approval, or consent of, and no filing or
      registration with, any court, governmental authority, or third party is
      necessary for the execution, delivery, or performance by Guarantor of this
      Guaranty Agreement or the validity or enforceability thereof.

            (d) The value of the consideration received and to be received by
      Guarantor as a result of Lender making the Term Loan to Borrower under the
      Loan Agreement and Guarantor executing and delivering this Guaranty
      Agreement is reasonably worth at least as much as the liability and
      obligation of Guarantor hereunder, and such liability and obligation and
      the Loan Agreement have benefitted and may reasonably be expected to
      benefit Guarantor directly and indirectly.

            (e) Guarantor has, independently and without reliance upon Lender
      and based upon such documents and information as Guarantor has deemed
      appropriate, made its own analysis and decision to enter into this
      Guaranty Agreement.

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 3

<PAGE>

      7. COVENANTS OF GUARANTOR. Guarantor covenants and agrees that, as long as
the Guaranteed Indebtedness or any part thereof is outstanding or Lender has any
commitment under the Loan Agreement:

            (a) Guarantor will furnish promptly to Lender written notice of the
      occurrence of any default under this Guaranty Agreement or an Event of
      Default under the Loan Agreement of which Guarantor has knowledge.

            (b) Guarantor will furnish promptly to Lender such additional
      information concerning Guarantor as Lender may request.

            (c) Guarantor will obtain at any time and from time to time all
      authorizations, licenses, consents or approvals as shall now or hereafter
      be necessary or desirable under all applicable laws or regulations or
      otherwise in connection with the execution, delivery and performance of
      this Guaranty Agreement and will promptly furnish copies thereof to
      Lender.

            (d) Guarantor will at all times own directly or indirectly and free
      and clear of all liens and encumbrances whatsoever at least the same
      percentage of voting shares of Borrower, if any, as it owns directly or
      indirectly on the date hereof.

      8. LENDER'S RIGHTS WITH RESPECT TO GUARANTOR'S PROPERTY IN LENDER'S
POSSESSION. Lender shall have the right to set off and apply against this
Guaranty Agreement or the Guaranteed Indebtedness or both, at any time and
without notice to Guarantor, any and all deposits (general or special, time or
demand, provisional or final) or other sums at any time credited by or owing
from Lender to Guarantor whether or not the Guaranteed Indebtedness is then due
and irrespective of whether or not Lender shall have made any demand under this
Guaranty Agreement. As security for this Guaranty Agreement and the Guaranteed
Indebtedness, Guarantor hereby grants Lender a security interest in all money,
instruments, certificates of deposit, and other property of Guarantor now or
hereafter held by Lender, including, without limitation, property held in
safekeeping. In addition to Lender's right of setoff and as further security for
this Guaranty Agreement and the Guaranteed Indebtedness, Guarantor hereby grants
Lender a security interest in all deposits (general or special, time or demand,
provisional or final) and all other accounts of Guarantor now or hereafter on
deposit with or held by Lender and all other sums at any time credited by or
owing from Lender to Guarantor. The rights and remedies of Lender hereunder are
in addition to other rights and remedies (including, without limitation, other
rights of setoff) which Lender may have.

      9. SUBORDINATION. (a) Guarantor hereby agrees that the Subordinated
Indebtedness (as hereinafter defined) shall be subordinate and junior in right
of payment to the prior payment in full of all Guaranteed Indebtedness, and
Guarantor hereby assigns the Subordinated Indebtedness to Lender as security for
the Guaranteed Indebtedness. If any sums shall be paid to Guarantor by Borrower
or any other person or entity on account of the Subordinated Indebtedness, such
sums shall be held in trust by Guarantor for the benefit of Lender and shall
forthwith be paid to Lender without affecting the liability of Guarantor under
this Guaranty Agreement and may be applied by Lender against the Guaranteed
Indebtedness in such order and manner as Lender may determine in its sole
discretion. Upon the request of

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 4

<PAGE>

Lender, Guarantor shall execute, deliver, and endorse to Lender such documents
and instruments as Lender may request to perfect, preserve, and enforce its
rights hereunder. For purposes of this Guaranty Agreement, the term
"Subordinated Indebtedness" means all indebtedness, liabilities, and obligations
of Borrower to Guarantor, whether such indebtedness, liabilities, and
obligations now exist or are hereafter incurred or arise, or whether the
obligations of Borrower thereon are direct, indirect, contingent, primary,
secondary, several, joint and several, or otherwise, and irrespective of whether
such indebtedness, liabilities, or obligations are evidenced by a note,
contract, open account, or otherwise, and irrespective of the person or persons
in whose favor such indebtedness, obligations, or liabilities may, at their
inception, have been, or may hereafter be created, or the manner in which they
have been or may hereafter be acquired by Guarantor.

            (b) Guarantor agrees that any and all liens, security interests,
      judgment liens, charges, or other encumbrances upon Borrower's assets
      securing payment of any Subordinated Indebtedness shall be and remain
      inferior and subordinate to any and all liens, security interests,
      judgment liens, charges, or other encumbrances upon Borrower's assets
      securing payment of the Guaranteed Indebtedness or any part thereof,
      regardless of whether such encumbrances in favor of Guarantor or Lender
      presently exist or are hereafter created or attached. Without the prior
      written consent of Lender, Guarantor shall not (i) file suit against
      Borrower or exercise or enforce any other creditor's right it may have
      against Borrower, or (ii) foreclose, repossess, sequester, or otherwise
      take steps or institute any action or proceedings (judicial or otherwise,
      including without limitation the commencement of, or joinder in, any
      liquidation, bankruptcy, rearrangement, debtor's relief or insolvency
      proceeding) to enforce any liens, security interests, collateral rights,
      judgments or other encumbrances held by Guarantor on assets of Borrower.

            (c) In the event of any receivership, bankruptcy, reorganization,
      rearrangement, debtor's relief, or other insolvency proceeding involving
      Borrower as debtor, Lender shall have the right to prove and vote any
      claim under the Subordinated Indebtedness and to receive directly from the
      receiver, trustee or other court custodian all dividends, distributions,
      and payments made in respect of the Subordinated Indebtedness. Lender may
      apply any such dividends, distributions, and payments against the
      Guaranteed Indebtedness in such order and manner as Lender may determine
      in its sole discretion.

      10. AMENDMENTS; CUMULATIVE REMEDIES. No amendment or waiver of any
provision of this Guaranty Agreement nor consent to any departure by Guarantor
therefrom shall in any event be effective unless the same shall be in writing
and signed by Lender. No failure on the part of Lender to exercise, and no delay
in exercising any right, power, or privilege hereunder shall operate as a waiver
thereof; nor shall any single or partial exercise of any right, power, or
privilege hereunder preclude any other or further exercise thereof or the
exercise of any other right, power, or privilege. The remedies herein provided
are cumulative and not exclusive of any remedies provided by law.

      11. SUCCESSORS AND ASSIGNS. This Guaranty Agreement is for the benefit of
Lender and its successors and assigns, and in the event of an assignment of the
Guaranteed Indebtedness, or any part thereof, the rights and benefits hereunder,
to the extent applicable to the indebtedness so assigned, may be transferred
with such indebtedness. This Guaranty

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 5

<PAGE>

Agreement is binding not only on Guarantor, but on Guarantor's heirs and
personal representatives.

      12. RELIANCE BY LENDER. Guarantor recognizes that Lender is relying upon
this Guaranty Agreement and the undertakings of Guarantor hereunder in making
extensions of credit to Borrower under the Loan Agreement and further recognizes
that the execution and delivery of this Guaranty Agreement is a material
inducement to Lender in making the Term Loan under the Loan Agreement. Guarantor
hereby acknowledges that there are no conditions to the full effectiveness of
this Guaranty Agreement.

      13. GOVERNING LAW. THIS GUARANTY AGREEMENT SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS.

      14. FEES AND EXPENSES. Guarantor shall pay on demand all reasonable
attorneys' fees and all other costs and expenses incurred by Lender in
connection with the enforcement or collection of this Guaranty Agreement.

      15. WAIVERS BY GUARANTOR. Guarantor hereby waives promptness, diligence,
notice of any default under the Guaranteed Indebtedness, demand for payment,
notice of acceptance of this Guaranty Agreement, presentment, notice of protest,
notice of dishonor, notice of the incurring by Borrower of additional
indebtedness, and all other notices and demands with respect to the Guaranteed
Indebtedness and this Guaranty Agreement.

      16. VALIDITY; ENFORCEABILITY. The Loan Agreement, and all of the terms
thereof, are incorporated herein by reference, the same as if stated verbatim
herein, and Guarantor agrees that Lender may exercise any and all rights granted
to it under the Loan Agreement and the other Loan Documents (as defined in the
Loan Agreement) without affecting the validity or enforceability of this
Guaranty Agreement.

      17. NO RELIANCE ON LENDER. Guarantor hereby represents and warrants to
Lender that Guarantor has adequate means to obtain from Borrower and the
Subsidiaries on a continuing basis information concerning the financial
condition and assets of Borrower and the Subsidiaries and that Guarantor is not
relying upon Lender to provide (and Lender shall have no duty to provide) any
such information to Guarantor either now or in the future.

      18. NO ORAL AGREEMENTS. THIS GUARANTY AGREEMENT REPRESENTS THE FINAL
AGREEMENT OF GUARANTOR AND LENDER WITH RESPECT TO GUARANTOR'S GUARANTY OF THE
GUARANTEED INDEBTEDNESS AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR,
CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS. THERE ARE NO UNWRITTEN ORAL
AGREEMENTS AMONG THE PARTIES HERETO.

      [Remainder of Page Intentionally Left Blank. Signature Page Follows]

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 6
<PAGE>

      EXECUTED as of the 31 day of December, 2002.

                                          GUARANTOR:

                                          /s/ Philip A. Pendergraft
                                          --------------------------------------
                                          Philip A. Pendergraft

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Signature Page

<PAGE>

                  FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT
                                    (LIMITED)

      WHEREAS, the execution of this Fifth Amended and Restated Guaranty
Agreement (this "Guaranty Agreement"), which amends and restates that certain
Fourth Amended and Restated Guaranty Agreement dated as of July 31, 2002 (the
"Prior Guaranty"), is a condition to SAI HOLDINGS, INC., formerly known as
SERVICE ASSET INVESTMENT, INC., a Texas corporation ("Borrower"), borrowing from
GUARANTY BANK, a federal savings bank, formerly known as Guaranty Federal Bank,
F.S.B. ("Lender"), a term loan pursuant to that certain Amended and Restated
Loan Agreement dated as of April 30, 2001 (such Loan Agreement, as it has been
or may hereafter be amended or modified from time to time, being hereinafter
referred to as the "Loan Agreement") between Borrower and Lender; and

      WHEREAS, Borrower and Lender have agreed to modify the Loan Agreement, and
as a condition thereto, Guarantor has agreed to amend and restate the Prior
Guaranty according to the terms hereof.

      NOW, THEREFORE, for valuable consideration, the receipt and adequacy of
which are hereby acknowledged, WILLIAM D. GROSS, an individual residing at 7424
Axminster, Dallas, Texas 75214 (the "Guarantor"), hereby irrevocably and
unconditionally guarantees to Lender, subject to the terms of this Guaranty
Agreement, the full and prompt payment and performance of the Guaranteed
Indebtedness (hereinafter defined), this Guaranty Agreement being upon the
following terms:

      1. DEFINITION OF GUARANTEED INDEBTEDNESS. The term "Guaranteed
Indebtedness" as used herein means Borrower's obligations under the Term Loan
(as defined in the Loan Agreement), provided that after additional capital is
raised in an amount of no less than $6,000,000 after December 31, 2002 and
injected into Penson Financial Services, Inc. on terms and conditions
satisfactory to Lender, Guarantor's liability with respect to such obligations
shall be limited to an amount not to exceed an amount equal to $864,000.00. All
capitalized terms used and not otherwise defined herein shall have their
respective meanings as set forth in the Loan Agreement.

      2. ABSOLUTE GUARANTY; NO SET-OFF RIGHTS. This instrument shall be an
absolute, continuing, irrevocable, and unconditional guaranty of payment and
performance, and not a guaranty of collection, of the Guaranteed Indebtedness as
provided herein, and Guarantor shall remain liable on its obligations hereunder
until the payment and performance in full of the Guaranteed Indebtedness,
subject to the terms of Section 1 of this Guaranty Agreement. No set-off,
counterclaim, recoupment, reduction, or diminution of any obligation, or any
defense of any kind or nature which Borrower may have against Lender or any
other party, or Guarantor may have against Borrower, Lender, or any other party,
shall be available to, or shall be asserted by, Guarantor against Lender or any
subsequent holder of the Guaranteed Indebtedness or any part thereof or against
payment of the Guaranteed Indebtedness or any part thereof.

      3. NO IMPAIRMENT OF RIGHTS. If Guarantor becomes liable for any
indebtedness owing by Borrower to Lender by endorsement or otherwise, other than
under this

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 1

<PAGE>

Guaranty Agreement, such liability shall not be in any manner impaired or
affected hereby, and the rights of Lender hereunder shall be cumulative of any
and all other rights that Lender may ever have against Guarantor. The exercise
by Lender of any right or remedy hereunder or under any other instrument, or at
law or in equity, shall not preclude the concurrent or subsequent exercise of
any other right or remedy.

      4. OBLIGATIONS OF GUARANTORS; NO DUTY TO EXHAUST REMEDIES; WAIVER OF
SUBROGATION. In the event of default by Borrower in payment or performance of
the Guaranteed Indebtedness, or any part thereof, when such Guaranteed
Indebtedness becomes due, whether by its terms, by acceleration, or otherwise,
Guarantor shall promptly pay the amount due thereon to Lender without notice or
demand in lawful money of the United States of America and it shall not be
necessary for Lender, in order to enforce such payment by either Guarantor,
first to institute suit or exhaust its remedies against Borrower or any other
guarantor or others liable on such Guaranteed Indebtedness, or to enforce any
rights against any collateral which shall ever have been given to secure such
Guaranteed Indebtedness. Notwithstanding anything to the contrary contained in
this Guaranty Agreement, until such time as the Guaranteed Indebtedness has been
paid in full, Guarantor hereby irrevocably waives any and all rights it may now
or hereafter have under any agreement or at law or in equity (including, without
limitation, any law subrogating Guarantor to the rights of Lender) to assert any
claim against or seek contribution, indemnification or any other form of
reimbursement from Borrower or any other guarantors or any other party liable
for payment of any or all of the Guaranteed Indebtedness for any payment made by
Guarantor under or in connection with this Guaranty Agreement or otherwise. If
acceleration of the time for payment of any amount payable by Borrower under the
Guaranteed Indebtedness is stayed upon the insolvency, bankruptcy, or
reorganization of Borrower, all such amounts otherwise subject to acceleration
under the terms of the Guaranteed Indebtedness shall nonetheless be payable by
Guarantor hereunder forthwith on demand by Lender.

      5. NO IMPAIRMENT OF GUARANTOR'S OBLIGATIONS. Guarantor hereby agrees that
its obligations under this Guaranty Agreement shall not be released, discharged,
diminished, impaired, reduced, or affected for any reason or by the occurrence
of any event, including, without limitation, one or more of the following
events, whether or not with notice to or the consent of Guarantor: (a) the
taking or accepting of collateral as security for any or all of the Guaranteed
Indebtedness or the release, surrender, exchange, or subordination of any
collateral now or hereafter securing any or all of the Guaranteed Indebtedness;
(b) any partial release of the liability of Guarantor hereunder, or the full or
partial release of any other guarantor or obligor from liability for any or all
of the Guaranteed Indebtedness; (c) any disability of Borrower, or the
dissolution, insolvency, or bankruptcy of Borrower, Guarantor, or any other
party at any time liable for the payment of any or all of the Guaranteed
Indebtedness; (d) any renewal, extension, modification, waiver, amendment, or
rearrangement of any or all of the Guaranteed Indebtedness or any instrument,
document, or agreement evidencing, securing, or otherwise relating to any or all
of the Guaranteed Indebtedness; (e) any adjustment, indulgence, forbearance,
waiver, or compromise that may be granted or given by Lender to Borrower,
Guarantor, or any other party ever liable for any or all of the Guaranteed
Indebtedness; (f) any neglect, delay, omission, failure, or refusal of Lender to
take or prosecute any action for the collection of any of the Guaranteed
Indebtedness or to foreclose or take or prosecute any action in connection with
any instrument, document, or agreement evidencing, securing, or otherwise

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 2

<PAGE>

relating to any or all of the Guaranteed Indebtedness; (g) the unenforceability
or invalidity of any or all of the Guaranteed Indebtedness or of any instrument,
document, or agreement evidencing, securing, or otherwise relating to any or all
of the Guaranteed Indebtedness; (h) any payment by Borrower or any other party
to Lender is held to constitute a preference under applicable bankruptcy or
insolvency law or if for any other reason Lender is required to refund any
payment or pay the amount thereof to someone else; (i) the settlement or
compromise of any of the Guaranteed Indebtedness; (j) the non-perfection of any
security interest or lien securing any or all of the Guaranteed Indebtedness;
(k) any impairment of any collateral securing any or all of the Guaranteed
Indebtedness; (l) the failure of Lender to sell any collateral securing any or
all of the Guaranteed Indebtedness in a commercially reasonable manner or as
otherwise required by law; (m) any change in the corporate existence, structure,
or ownership of Borrower; or (n) any other circumstance which might otherwise
constitute a defense available to, or discharge of, Borrower Or Guarantor.

      6. REPRESENTATIONS AND WARRANTIES. Guarantor represents and warrants to
Lender as follows:

            (a) Guarantor has the power and authority and legal right to
      execute, deliver, and perform its obligations under this Guaranty
      Agreement and this Guaranty Agreement constitutes the legal, valid, and
      binding obligation of Guarantor, enforceable against Guarantor in
      accordance with its terms, except as limited by bankruptcy, insolvency, or
      other laws of general application relating to the enforcement of
      creditors' rights.

            (b) The execution, delivery, and performance by Guarantor of this
      Guaranty Agreement do not and will not violate or conflict with any law,
      rule, or regulation or any order, writ, injunction, or decree of any
      court, governmental authority or agency, or arbitrator and do not and will
      not conflict with, result in a breach of, or constitute a default under,
      or result in the imposition of any lien upon any assets of Guarantor
      pursuant to the provisions of any indenture, mortgage, deed of trust,
      security agreement, franchise, permit, license, or other instrument or
      agreement to which Guarantor or its properties is bound.

            (c) No authorization, approval, or consent of, and no filing or
      registration with, any court, governmental authority, or third party is
      necessary for the execution, delivery, or performance by Guarantor of this
      Guaranty Agreement or the validity or enforceability thereof.

            (d) The value of the consideration received and to be received by
      Guarantor as a result of Lender making the Term Loan to Borrower under the
      Loan Agreement and Guarantor executing and delivering this Guaranty
      Agreement is reasonably worth at least as much as the liability and
      obligation of Guarantor hereunder, and such liability and obligation and
      the Loan Agreement have benefitted and may reasonably be expected to
      benefit Guarantor directly and indirectly.

            (e) Guarantor has, independently and without reliance upon Lender
      and based upon such documents and information as Guarantor has deemed
      appropriate, made its own analysis and decision to enter into this
      Guaranty Agreement.

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 3

<PAGE>

      7. COVENANTS OF GUARANTOR. Guarantor covenants and agrees that, as long as
the Guaranteed Indebtedness or any part thereof is outstanding or Lender has any
commitment under the Loan Agreement:

            (a) Guarantor will furnish promptly to Lender written notice of the
      occurrence of any default under this Guaranty Agreement or an Event of
      Default under the Loan Agreement of which Guarantor has knowledge.

            (b) Guarantor will furnish promptly to Lender such additional
      information concerning Guarantor as Lender may request.

            (c) Guarantor will obtain at any time and from time to time all
      authorizations, licenses, consents or approvals as shall now or hereafter
      be necessary or desirable under all applicable laws or regulations or
      otherwise in connection with the execution, delivery and performance of
      this Guaranty Agreement and will promptly furnish copies thereof to
      Lender.

            (d) Guarantor will at all times own directly or indirectly and free
      and clear of all liens and encumbrances whatsoever at least the same
      percentage of voting shares of Borrower, if any, as it owns directly or
      indirectly on the date hereof.

      8. LENDER'S RIGHTS WITH RESPECT TO GUARANTOR'S PROPERTY IN LENDER'S
POSSESSION. Lender shall have the right to set off and apply against this
Guaranty Agreement or the Guaranteed Indebtedness or both, at any time and
without notice to Guarantor, any and all deposits (general or special, time or
demand, provisional or final) or other sums at any time credited by or owing
from Lender to Guarantor whether or not the Guaranteed Indebtedness is then due
and irrespective of whether or not Lender shall have made any demand under this
Guaranty Agreement. As security for this Guaranty Agreement and the Guaranteed
Indebtedness, Guarantor hereby grants Lender a security interest in all money,
instruments, certificates of deposit, and other property of Guarantor now or
hereafter held by Lender, including, without limitation, property held in
safekeeping. In addition to Lender's right of setoff and as further security for
this Guaranty Agreement and the Guaranteed Indebtedness, Guarantor hereby grants
Lender a security interest in all deposits (general or special, time or demand,
provisional or final) and all other accounts of Guarantor now or hereafter on
deposit with or held by Lender and all other sums at any time credited by or
owing from Lender to Guarantor. The rights and remedies of Lender hereunder are
in addition to other rights and remedies (including, without limitation, other
rights of setoff) which Lender may have.

      9. SUBORDINATION. (a) Guarantor hereby agrees that the Subordinated
Indebtedness (as hereinafter defined) shall be subordinate and junior in right
of payment to the prior payment in full of all Guaranteed Indebtedness, and
Guarantor hereby assigns the Subordinated Indebtedness to Lender as security for
the Guaranteed Indebtedness. If any sums shall be paid to Guarantor by Borrower
or any other person or entity on account of the Subordinated Indebtedness, such
sums shall be held in trust by Guarantor for the benefit of Lender and shall
forthwith be paid to Lender without affecting the liability of Guarantor under
this Guaranty Agreement and may be applied by Lender against the Guaranteed
Indebtedness in such order and manner as Lender may determine in its sole
discretion. Upon the request of

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 4

<PAGE>

Lender, Guarantor shall execute, deliver, and endorse to Lender such documents
and instruments as Lender may request to perfect, preserve, and enforce its
rights hereunder. For purposes of this Guaranty Agreement, the term Subordinated
Indebtedness" means all indebtedness, liabilities, and obligations of Borrower
to Guarantor, whether such indebtedness, liabilities, and obligations now exist
or are hereafter incurred or arise, or whether the obligations of Borrower
thereon are direct, indirect, contingent, primary, secondary, several, joint and
several, or otherwise, and irrespective of whether such indebtedness,
liabilities, or obligations are evidenced by a note, contract, open account, or
otherwise, and irrespective of the person or persons in whose favor such
indebtedness, obligations, or liabilities may, at their inception, have been, or
may hereafter be created, or the manner in which they have been or may hereafter
be acquired by Guarantor.

            (b) Guarantor agrees that any and all liens, security interests,
      judgment liens, charges, or other encumbrances upon Borrower's assets
      securing payment of any Subordinated Indebtedness shall be and remain
      inferior and subordinate to any and all liens, security interests,
      judgment liens, charges, or other encumbrances upon Borrower's assets
      securing payment of the Guaranteed Indebtedness or any part thereof,
      regardless of whether such encumbrances in favor of Guarantor or Lender
      presently exist or are hereafter created or attached. Without the prior
      written consent of Lender, Guarantor shall not (i) file suit against
      Borrower or exercise or enforce any other creditor's right it may have
      against Borrower, or (ii) foreclose, repossess, sequester, or otherwise
      take steps or institute any action or proceedings (judicial or otherwise,
      including without limitation the commencement of, or joinder in, any
      liquidation, bankruptcy, rearrangement, debtor's relief or insolvency
      proceeding) to enforce any liens, security interests, collateral rights,
      judgments or other encumbrances held by Guarantor on assets of Borrower.

            (c) In the event of any receivership, bankruptcy, reorganization,
      rearrangement, debtor's relief, or other insolvency proceeding involving
      Borrower as debtor, Lender shall have the right to prove and vote any
      claim under the Subordinated Indebtedness and to receive directly from the
      receiver, trustee or other court custodian all dividends, distributions,
      and payments made in respect of the Subordinated Indebtedness. Lender may
      apply any such dividends, distributions, and payments against the
      Guaranteed Indebtedness in such order and manner as Lender may determine
      in its sole discretion.

      10. AMENDMENTS; CUMULATIVE REMEDIES. No amendment or waiver of any
provision of this Guaranty Agreement nor consent to any departure by Guarantor
therefrom shall in any event be effective unless the same shall be in writing
and signed by Lender. No failure on the part of Lender to exercise, and no delay
in exercising any right, power, or privilege hereunder shall operate as a waiver
thereof; nor shall any single or partial exercise of any right, power, or
privilege hereunder preclude any other or further exercise thereof or the
exercise of any other right, power, or privilege. The remedies herein provided
are cumulative and not exclusive of any remedies provided by law.

      11. SUCCESSORS AND ASSIGNS. This Guaranty Agreement is for the benefit of
Lender and its successors and assigns, and in the event of an assignment of the
Guaranteed Indebtedness, or any part thereof, the rights and benefits hereunder,
to the extent applicable to the indebtedness so assigned, may be transferred
with such indebtedness. This Guaranty

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 5

<PAGE>

Agreement is binding not only on Guarantor, but on Guarantor's heirs and
personal representatives.

      12. RELIANCE BY LENDER. Guarantor recognizes that Lender is relying upon
this Guaranty Agreement and the undertakings of Guarantor hereunder in making
extensions of credit to Borrower under the Loan Agreement and further recognizes
that the execution and delivery of this Guaranty Agreement is a material
inducement to Lender in making the Term Loan under the Loan Agreement. Guarantor
hereby acknowledges that there are no conditions to the full effectiveness of
this Guaranty Agreement.

      13 GOVERNING LAW. THIS GUARANTY AGREEMENT SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS.

      14. FEES AND EXPENSES. Guarantor shall pay on demand all reasonable
attorneys' fees and all other costs and expenses incurred by Lender in
connection with the enforcement or collection of this Guaranty Agreement.

      15. WAIVERS BY GUARANTOR. Guarantor hereby waives promptness, diligence,
notice of any default under the Guaranteed Indebtedness, demand for payment,
notice of acceptance of this Guaranty Agreement, presentment, notice of protest,
notice of dishonor, notice of the incurring by Borrower of additional
indebtedness, and all other notices and demands with respect to the Guaranteed
Indebtedness and this Guaranty Agreement.

      16. VALIDITY; ENFORCEABILITY. The Loan Agreement, and all of the terms
thereof, are incorporated herein by reference, the same as if stated verbatim
herein, and Guarantor agrees that Lender may exercise any and all rights granted
to it under the Loan Agreement and the other Loan Documents (as defined in the
Loan Agreement) without affecting the validity or enforceability of this
Guaranty Agreement.

      17. NO RELIANCE ON LENDER. Guarantor hereby represents and warrants to
Lender that Guarantor has adequate means to obtain from Borrower and the
Subsidiaries on a continuing basis information concerning the financial
condition and assets of Borrower and the Subsidiaries and that Guarantor is not
relying upon Lender to provide (and Lender shall have no duty to provide) any
such information to Guarantor either now or in the future.

      18. NO ORAL AGREEMENTS. THIS GUARANTY AGREEMENT REPRESENTS THE FINAL
AGREEMENT OF GUARANTOR AND LENDER WITH RESPECT TO GUARANTOR'S GUARANTY OF THE
GUARANTEED INDEBTEDNESS AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR,
CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS. THERE ARE NO UNWRITTEN ORAL
AGREEMENTS AMONG THE PARTIES HERETO.

      [Remainder of Page Intentionally Left Blank. Signature Page Follows]

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 6

<PAGE>

            EXECUTED as of the 31st day of December, 2002.

                                           GUARANTOR:

                                           /s/ William D. Gross
                                           -------------------------------------
                                           William D. Gross

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Signature Page

<PAGE>

                  FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT
                                    (LIMITED)

      WHEREAS, the execution of this Fifth Amended and Restated Guaranty
Agreement (this "Guaranty Agreement"), which amends and restates that certain
Fourth Amended and Restated Guaranty Agreement dated as of July 31, 2002 (the
"Prior Guaranty"), is a condition to SAI HOLDINGS, INC., formerly known as
SERVICE ASSET INVESTMENT, INC., a Texas corporation ("Borrower"), borrowing from
GUARANTY BANK, a federal savings bank, formerly known as Guaranty Federal Bank,
F.S.B. ("Lender"), a term loan pursuant to that certain Amended and Restated
Loan Agreement dated as of April 30, 2001 (such Loan Agreement, as it has been
or may hereafter be amended or modified from time to time, being hereinafter
referred to as the "Loan Agreement") between Borrower and Lender; and

      WHEREAS, Borrower and Lender have agreed to modify the Loan Agreement, and
as a condition thereto, Guarantor has agreed to amend and restate the Prior
Guaranty according to the terms hereof.

      NOW, THEREFORE, for valuable consideration, the receipt and adequacy of
which are hereby acknowledged, ROGER J. ENGEMOEN, JR., an individual residing at
1907 Georgia Landing Cove, Austin, Texas 78746 (the "Guarantor"), hereby
irrevocably and unconditionally guarantees to Lender, subject to the terms of
this Guaranty Agreement, the full and prompt payment and performance of the
Guaranteed Indebtedness (hereinafter defined), this Guaranty Agreement being
upon the following terms:

      1. DEFINITION OF GUARANTEED INDEBTEDNESS. The term "Guaranteed
Indebtedness" as used herein means Borrower's obligations under the Term Loan
(as defined in the Loan Agreement), provided that after additional capital is
raised in an amount of no less than $6,000,000 after December 31, 2002 and
injected into Penson Financial Services, Inc. on terms and conditions
satisfactory to Lender, Guarantor's liability with respect to such obligations
shall be limited to an amount not to exceed an amount equal to $1,408,000.00.
All capitalized terms used and not otherwise defined herein shall have their
respective meanings as set forth in the Loan Agreement.

      2. ABSOLUTE GUARANTY; NO SET-OFF RIGHTS. This instrument shall be an
absolute, continuing, irrevocable, and unconditional guaranty of payment and
performance, and not a guaranty of collection, of the Guaranteed Indebtedness as
provided herein, and Guarantor shall remain liable on its obligations hereunder
until the payment and performance in full of the Guaranteed Indebtedness,
subject to the terms of Section 1 of this Guaranty Agreement. No set-off,
counterclaim, recoupment, reduction, or diminution of any obligation, or any
defense of any kind or nature which Borrower may have against Lender or any
other party, or Guarantor may have against Borrower, Lender, or any other party,
shall be available to, or shall be asserted by, Guarantor against Leader or any
subsequent holder of the Guaranteed Indebtedness or any part thereof or against
payment of die Guaranteed Indebtedness or any part thereof.

      3. NO IMPAIRMENT OF RIGHTS. If Guarantor becomes liable for any
indebtedness owing by Borrower to Lender by endorsement or otherwise, other than
under this

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 1

<PAGE>

Guaranty Agreement, such liability shall not be in any manner impaired or
affected hereby, and the rights of Lender hereunder shall be cumulative of any
and all other rights that Lender may ever have against Guarantor. The exercise
by Lender of any right or remedy hereunder or under any other instrument, or at
law or in equity, shall not preclude the concurrent or subsequent exercise of
any other right or remedy.

      4. OBLIGATIONS OF GUARANTORS; NO DUTY TO EXHAUST REMEDIES; WAIVER OF
SUBROGATION. In the event of default by Borrower in payment or performance of
the Guaranteed Indebtedness, or any part thereof, when such Guaranteed
Indebtedness becomes due, whether by its terms, by acceleration, or otherwise,
Guarantor shall promptly pay the amount due thereon to Lender without notice or
demand in lawful money of the United States of America and it shall not be
necessary for Lender, in order to enforce such payment by either Guarantor,
first to institute suit or exhaust its remedies against Borrower or any other
guarantor or others liable on such Guaranteed Indebtedness, or to enforce any
rights against any collateral which shall ever have been given to secure such
Guaranteed Indebtedness. Notwithstanding anything to the contrary contained in
this Guaranty Agreement, until such time as the Guaranteed Indebtedness had been
paid in full, Guarantor hereby irrevocably waives any and all rights it may now
or hereafter have under any agreement or at law or in equity (including, without
limitation, any law subrogating Guarantor to the rights of Lender) to assert any
claim against or seek contribution, indemnification or any other form of
reimbursement from Borrower or any other guarantors or any other party liable
for payment of any or all of the Guaranteed Indebtedness for any payment made by
Guarantor under or in connection with this Guaranty Agreement or otherwise. If
acceleration of the time for payment of any amount payable by Borrower under the
Guaranteed Indebtedness is stayed upon the insolvency, bankruptcy, or
reorganization of Borrower, all such amounts otherwise subject to acceleration
under the terms of the Guaranteed Indebtedness shall nonetheless be payable by
Guarantor hereunder forthwith on demand by Lender.

      5. NO IMPAIRMENT OF GUARANTOR'S OBLIGATIONS. Guarantor hereby agrees that
its obligations under this Guaranty Agreement shall not be released, discharged,
diminished, impaired, reduced, or affected for any reason or by the occurrence
of any event, including, without limitation, one or more of the following
events, whether or not with notice to or the consent of Guarantor: (a) the
taking or accepting of collateral as security for any or all of the Guaranteed
Indebtedness or the release, surrender, exchange, or subordination of any
collateral now or hereafter securing any or all of the Guaranteed Indebtedness;
(b) any partial release of the liability of Guarantor hereunder, or the full or
partial release of any other guarantor or obligor from liability for any or all
of the Guaranteed Indebtedness; (c) any disability of Borrower, or the
dissolution, insolvency, or bankruptcy of Borrower, Guarantor, or any other
party at any time liable for the payment of any or all of the Guaranteed
Indebtedness; (d) any renewal, extension, modification, waiver, amendment, or
rearrangement of any or all of the Guaranteed Indebtedness or any instrument,
document, or agreement evidencing, securing, or otherwise relating to any or all
of the Guaranteed Indebtedness; (e) any adjustment, indulgence, forbearance,
waiver, or compromise that may be granted or given by Lender to Borrower.
Guarantor, or any other party ever liable for any or all of the Guaranteed
Indebtedness; (f) any neglect, delay, omission, failure, or refusal of Lender to
take or prosecute any action for the collection of any of the Guaranteed
Indebtedness or to foreclose or take or prosecute any action in connection with
any instrument, document, or agreement evidencing, securing, or otherwise

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 2

<PAGE>

relating to any or all of the Guaranteed Indebtedness; (g) the unenforceability
or invalidity of any or all of the Guaranteed Indebtedness or of any instrument,
document, or agreement evidencing, securing, or otherwise relating to any or all
of the Guaranteed Indebtedness; (h) any payment by Borrower or any other party
to Lender is held to constitute a preference under applicable bankruptcy or
insolvency law or if for any other reason Lender is required to refund any
payment or pay the amount thereof to someone else; (i) the settlement or
compromise of any of the Guaranteed Indebtedness; (j) the non-perfection of any
security interest or lien securing any or all of the Guaranteed Indebtedness;
(k) any impairment of any collateral securing any or all of the Guaranteed
Indebtedness; (l) the failure of Lender to sell any collateral securing any or
all of the Guaranteed Indebtedness in a commercially reasonable manner or as
otherwise required by law; (m) any change in the corporate existence, structure,
or ownership of Borrower; or (n) any other circumstance which might constitute a
defense available to, or discharge of. Borrower or Guarantor.

      6. REPRESENTATIONS AND WARRANTIES. Guarantor represents and warrants to
Lender as follows:

            (a) Guarantor has the power and authority and legal right to
      execute, deliver, and perform its obligations under this Guaranty
      Agreement and this Guaranty Agreement constitutes the legal, valid, and
      binding obligation of Guarantor, enforceable against Guarantor in
      accordance with its terms, except as limited by bankruptcy, insolvency, or
      other laws of general application relating to the enforcement of
      creditors' rights.

            (b) The execution, delivery, and performance by Guarantor of this
      Guaranty Agreement do not and will not violate or conflict with any law,
      rule, or regulation or any order, writ, injunction, or decree of any
      court, governmental authority or agency, or arbitrator and do not and will
      not conflict with, result in a breach of, or constitute a default under,
      or result in the imposition of any lien upon any assets of Guarantor
      pursuant to the provisions of any Indenture, mortgage, deed of trust,
      security agreement, franchise, permit, license, or other instrument or
      agreement to which Guarantor or its properties is bound.

            (c) No authorization, approval, or consent of, and no filing or
      registration with, any court, governmental authority, or third party is
      necessary for the execution, delivery, or performance by Guarantor of this
      Guaranty Agreement or the validity or enforceability thereof.

            (d) The value of the consideration received and to be received by
      Guarantor as a result of Lender making the Term Loan to Borrower under the
      Loan Agreement and Guarantor executing and delivering this Guaranty
      Agreement is reasonably worth at least as much as the liability and
      obligation of Guarantor hereunder, and such liability and obligation and
      the Loan Agreement have benefitted and may reasonably be expected to
      benefit Guarantor directly and indirectly.

            (e) Guarantor has, independently and without reliance upon Lender
      and based upon such documents and information as Guarantor has deemed
      appropriate, made its own analysis and decision to enter into this
      Guaranty Agreement.

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 3

<PAGE>

      7. COVENANTS OF GUARANTOR. Guarantor covenants and agrees that, as long as
the Guaranteed Indebtedness or any part thereof is outstanding or Lender has any
commitment under the Loan Agreement:

            (a) Guarantor will furnish promptly to Lender written notice of the
      occurrence of any default under this Guaranty Agreement or an Event of
      Default under the Loan Agreement of which Guarantor has knowledge.

            (b) Guarantor will furnish promptly to Lender such additional
      information concerning Guarantor as Lender may request.

            (c) Guarantor will obtain at any time and from time to time all
      authorizations, licenses, consents or approvals as shall now or hereafter
      be necessary or desirable under all applicable laws or regulations or
      otherwise in connection with the execution, delivery and performance of
      this Guaranty Agreement and will promptly furnish copies thereof to
      Lender.

            (d) Guarantor will at all times own directly or indirectly and free
      and clear of all liens and encumbrances whatsoever at least the same
      percentage of voting shares of Borrower, if any, as it owns directly or
      indirectly on the date hereof.

      8. LENDER'S RIGHTS WITH RESPECT TO GUARANTOR'S PROPERTY IN LENDER'S
POSSESSION. Lender shall have the right to set off and apply against this
Guaranty Agreement or the Guaranteed Indebtedness or both, at any time and
without notice to Guarantor, any and all deposits (general or special, time or
demand, provisional or final) or other sums at any time credited by or owing
from Lender to Guarantor whether or not the Guaranteed Indebtedness is then due
and irrespective of whether or not Lender shall have made any demand under this
Guaranty Agreement. As security for this Guaranty Agreement and the Guaranteed
Indebtedness, Guarantor hereby grants Lender a security interest in all money,
instruments, certificates of deposit, and other property of Guarantor now or
hereafter held by Lender, including, without limitation, property held in
safekeeping. In addition to Lender's right of setoff and as further security for
this Guaranty Agreement and the Guaranteed Indebtedness, Guarantor hereby grants
Lender a security interest in all deposits (general or special, time or demand,
provisional or final) and all other accounts of Guarantor now or hereafter on
deposit with or held by Lender and all other sums at any time credited by or
owing from Lender to Guarantor. The rights and remedies of Lender hereunder are
in addition to other rights and remedies (including, without limitation, other
rights of setoff) which Lender may have.

      9. SUBORDINATION. (a) Guarantor hereby agrees that the Subordinated
Indebtedness (as hereinafter defined) shall be subordinate and junior in right
of payment to the prior payment in full of all Guaranteed Indebtedness, and
Guarantor hereby assigns the Subordinated Indebtedness to Lender as security for
the Guaranteed Indebtedness. If any sums shall be paid to Guarantor by Borrower
or any other person or entity on account of the Subordinated Indebtedness, such
sums shall be held ire trust by Guarantor for the benefit of Lender and shall
forthwith be paid to Lender without affecting the liability of Guarantor under
this Guaranty Agreement and may be applied by Lender against the Guaranteed
Indebtedness in such order and manner as Lender may determine in its sole
discretion. Upon the request of

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 4

<PAGE>

Lender, Guarantor shall execute, deliver, and endorse to Lender such documents
and instruments, as Lender may request to perfect, preserve, and enforce its
right hereunder. For purposes of this Guaranty Agreement, the term "Subordinated
Indebtedness" means all indebtedness, liabilities, and obligations of Borrower
to Guarantor, whether such indebtedness, liabilities, and obligations now exist
or are hereafter incurred or arise, or whether the obligations of Borrower
thereon are direct, indirect, contingent, primary, secondary, several joint and
several, or otherwise, and irrespective of whether such indebtedness,
liabilities, or obligations are evidenced by a note, contact, open account, or
otherwise, and irrespective of the person or persons in whose favor such
indebtedness, obligations, or liabilities may, at their inception, have been, or
may hereafter be created, or the manner in which they have been or may hereafter
be acquired by Guarantor.

            (b) Guarantor agrees that any and all liens, security interests,
      judgment liens charges, or other encumbrances upon Borrower's assets
      securing payment of any Subordinated Indebtedness shall be and remain
      inferior and subordinate to any and all liens, security interests,
      judgement liens, charges, or other encumbrances upon Borrower's assets
      securing payment of the Guaranteed indebtedness or any part thereof,
      regardless of whether such encumbrances in favor of Guarantor or Lender
      presently exist or are hereafter created or attached. Without the prior
      written consent of Lender, Guarantor shall not (i) file suit against
      Borrower or exercise or enforce any other creditor's right it may have
      against Borrower, or (ii) foreclose, repossess, sequester, or otherwise
      take steps or institute any action or proceedings (judicial or otherwise,
      including without limitation the commencement of, or joinder in, any
      liquidation, bankruptcy, rearrangement, debtor's relief or insolvency
      proceeding) to enforce any liens, security interests, collateral rights,
      judgments or other encumbrances held by Guarantor on assets of Borrower.

            (c) In the event of any receivership, bankruptcy, reorganization,
      rearrangement, debtor's relief, or other insolvency proceeding involving
      Borrower as debtor, Lender shall have the right to prove and vote any
      claim under the Subordinated Indebtedness and to receive directly from the
      receiver, trustee or other court custodian all dividends, distributions,
      and payments made in respect of the Subordinated Indebtedness. Lender may
      apply any such dividends, distributions, and payments against the
      Guaranteed Indebtedness in such order and manner as Lender may determine
      in its sole discretion.

      10. AMENDMENTS: CUMULATIVE REMEDIES. No amendment or waiver of any
provision of this Guaranty Agreement nor consent to any departure by Guarantor
therefrom shall in any event be effective unless the same shall be in writing
and signed by Lender. No failure the part of Lender to exercise, and no delay in
exercising any right, power, or privilege hereunder shall operate as a waiver
thereof; nor shall any single or partial exercise of any right, power, or
privilege hereunder preclude any other or further exercise thereof or the
exercise of any other right, power, or privilege. The remedies herein provided
are cumulative and not exclusive of any remedies provided by law.

      11. SUCCESSORS AND ASSIGNS. This Guaranty Agreement is for the benefit of
Lender and its successors and assigns, and in the event of an assignment of the
Guaranteed Indebtedness, or any part thereof, the rights and benefits hereunder,
to the extent applicable to the indebtedness so assigned, may be transferred
such indebtedness. This Guaranty

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 5

<PAGE>

Agreement is binding not only on Guarantor, but on Guarantor's heirs and
personal representatives.

      12. RELIANCE BY LENDER. Guarantor recognizes that Lender is relying upon
this Guaranty Agreement and the undertakings of Guarantor hereunder in making
extensions of credit to Borrower under the Loan Agreement and further recognizes
that the execution and delivery of this Guaranty Agreement is a material
inducement to Lender in making the Term Loan under the Loan Agreement. Guarantor
hereby acknowledges that there are no conditions to the full effectiveness of
this Guaranty Agreement.

      13. GOVERNING LAW. THIS GUARANTY AGREEMENT SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS.

      14. FEES AND EXPENSES. Guarantor shall pay on demand all reasonable
attorneys' fees and all other costs and expenses incurred by Lender in
connection with the enforcement or collection of this Guaranty Agreement.

      15. WAIVERS BY GUARANTOR. Guarantor hereby waives prompiness, diligence,
notice of any default under the Guaranteed Indebtedness, demand for payment,
notice of acceptance of this Guaranty Agreement, presentment, notice of protest,
notice of dishonor, notice of the incurring by Borrower of additional
indebtedness, and all other notices and demands with respect to the Guaranteed
Indebtedness and this Guaranty Agreement.

      16. VALIDITY; ENFORCEABILITY. The Loan Agreement, and all of the terms
thereof, are incorporated herein by reference, the same as if stated verbatim
herein, and Guarantor agrees that Lender may exercise any and all rights granted
to it under the Loan Agreement and the other Loan Documents (as defined in the
Loan Agreement) without affecting the validity or enforceability of this
Guaranty Agreement.

      17. NO RELIANCE ON LENDER. Guarantor hereby represents and warrants to
Lender that Guarantor has adequate means to obtain from Borrower and the
Subsidiaries on a continuing basis information concerning the financial
condition and assets of Borrower and the Subsidiaries and that Guarantor is not
relying upon Lender to provide (and Lender shall have no duty to provide) any
such information to Guarantor either now or in the future.

      18. NO ORAL AGREEMENTS. THIS GUARANTY AGREEMENT REPRESENTS THE FINAL
AGREEMENT OF GUARANTOR AND LENDER WITH RESPECT TO GUARANTOR'S GUARANTY OF THE
GUARANTEED INDEBTEDNESS AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR,
CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS. THERE ARE NO UNWRITTEN ORAL
AGREEMENTS AMONG THE PARTIES HERETO.

       [Remainder of Page Intentionally Left Blank. Signature Page Follows]

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Page 6

<PAGE>

              EXECUTED as of the 31st day of December, 2002.

                                        GUARANTOR:

                                        /s/ Roger J. Engemoen, Jr.
                                        --------------------------------
                                        Roger J. Engemoen, Jr.

FIFTH AMENDED AND RESTATED GUARANTY AGREEMENT - Signature Page

<PAGE>

            ELEVENTH AMENDMENT TO AMENDED AND RESTATED LOAN AGREEMENT

      This Eleventh Amendment to Amended and Restated Loan Agreement (this
"Amendment") is dated as of March 24, 2005 by and between SAI HOLDINGS, INC.,
formerly known as SERVICE ASSET INVESTMENTS, INC., a Texas corporation
("Borrower"), and GUARANTY BANK, a federal savings bank ("Bank").

                                    RECITALS:

      A. Borrower and Bank have entered into that certain Amended and Restated
Loan Agreement dated as of April 30, 2001 (as the same has been or may be
amended, restated, modified or supplemented, the "Agreement"), pursuant to which
Bank agreed to extend credit to Borrower in the form of a term loan under the
terms and provisions stated therein.

      B. Borrower has requested Bank to amend certain provisions of the
Agreement, to consent to advance an additional $10,000,000 under the Term Loan,
which Bank is willing to do pursuant to the terms and conditions hereinafter
provided.

      C. Borrower and Bank now desire to amend the Agreement as herein set
forth.

      NOW, THEREFORE, in consideration of the premises herein contained and
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the parties hereto agree as follows:

                                    ARTICLE I

                                   DEFINITIONS

      Section 1.1 Definitions. Capitalized terms used in this Amendment, to the
extent not otherwise defined herein, shall have the same meaning as in the
Agreement, as amended hereby.

                                   ARTICLE II

                             AMENDMENTS TO AGREEMENT

      Section 2.1 Amendment to Recitals. The reference to the amount
"$24,266,192.00" in the second paragraph in the Recitals section of the
Agreement is hereby modified to the amount "$32,244,099.00."

      Section 2.2 Modification of Definitions. Effective as of the date hereof,
the definition of the following defined term is hereby amended to read as
follows:

            "Term Loan Commitment" means the obligation of Bank to make the Term
      Loan pursuant to Section 2.1 in an aggregate principal amount up to but
      not exceeding $32,244,099.00.

<PAGE>

      Section 2.3 Amendment of Section 2.3. Effective as of the date hereof.
Section 2.3 is hereby amended in its entirety and shall read as follows:

            Section 2.3 Repayment of Term Loan. Borrower shall repay the unpaid
      principal amount of the Term Loan in monthly installments of $537,400.15,
      commencing on April 1, 2005 and continuing on each Monthly Payment Date,
      with a final installment in the amount of all outstanding principal of the
      Term Loan payable on the Maturity Date.

      Section 2.4 Addition of Section 2.8. Effective as of the date hereof,
Section 2.8 is hereby added to the Agreement and shall read as follows:

            Section 2.8 Commitment Fee. A Commitment Fee in the amount of
      $50,000.00 shall be due and payable on March 24, 2005.

      Section 2.5 Amendment of Section 10.4. Effective as of the date hereof,
Section 10.4 is hereby amended in its entirety and shall read as follows:

            Section 10.4 Loans and Investments. Borrower will not permit any of
      the following:

                  (a) Penson Worldwide's advance, loan, extension of credit or
            capital contribution to or investment (i) in Worldwide in excess of
            $10,000,000 and (ii) in Worldwide and Canada in the aggregate in
            excess of $15,000,000 (including clause (i) hereof); provided,
            however, that (x) no such advances to Canada may result from the
            proceeds of the Term Loan, (y) no more than $5,000,000 of any
            advances to Worldwide may result from the proceeds of the Capital
            Investment, and (z) no more than $4,000,000 advanced to Worldwide
            may result from the proceeds of the Term Loan.

                                   ARTICLE III

                       ADDITIONAL ADVANCE UNDER TERM LOAN

      Section 3.1 Additional Advance. Upon the effectiveness of this Agreement,
the amount of $10,000,000 shall be advanced to the Borrower under the Term Loan
pursuant to the modification to the Term Loan Commitment set forth in this
Amendment.

                                   ARTICLE IV

          ACKNOWLEDGEMENT AND CLARIFICATION OF SUBSIDIARY MODIFICATIONS

      Section 4.1 Subsidiary Modifications. The parties hereto acknowledge the
following modifications that have occurred since November 1, 2004: (a) Nexa
Technologies, Inc. was merged into Integrated Trading Solutions, Inc., and
Integrated Trading Solutions, Inc. has changed its name to Nexa Technologies,
Inc., a Delaware corporation and (b) Penson Financial Services Venture, Inc.
(sometimes referred to as Penson Ventures, Inc.) was formerly named 3812359
CANADA, Inc.

                                        2

<PAGE>

                                    ARTICLE V

                              CONDITIONS PRECEDENT

      Section 5.1 Conditions. The effectiveness of this Amendment is subject to
the satisfaction of the following conditions precedent:

            (a) Bank shall have received all of the following, each dated
      (unless otherwise indicated) the date of this Amendment, in form and
      substance satisfactory to Bank:

                  (1) Amendment. This Amendment, duly executed by Borrower;

                  (2) Commitment Fee. The fee required by Section 2.8 of the
            Agreement;

                  (3) Attorneys' Fees and Expenses. Payment of all outstanding
            attorneys' fees and expenses incurred by Bank in connection with the
            Agreement, as amended; and

                  (4) Additional Information. Such additional documents,
            instruments and information as Bank or its legal counsel, Winstead
            Sechrest & Minick P.C., may reasonably request.

            (b) The representations and warranties contained herein and in all
      other Loan Documents, as amended hereby, shall be true and correct as of
      the date hereof as if made on the date hereof, except to the extent
      disclosed on Schedules delivered as of the date of this Amendment.

            (c) No Event of Default shall have occurred and be continuing and no
      event or condition shall have occurred that with the giving of notice or
      lapse of time or both would be an Event of Default.

            (d) All corporate proceedings taken in connection with the
      transactions contemplated by this Amendment and all documents,
      instruments, and other legal matters incident thereto shall be
      satisfactory to Bank and its legal counsel, Winstead Sechrest & Minick
      P.C.

                                   ARTICLE VI

                                  MISCELLANEOUS

      Section 6.1 Representations and Warranties. Borrower hereby represents and
warrants to Bank that (a) the execution, delivery and performance of this
Amendment and any and all other Loan Documents executed and/or delivered in
connection herewith have been authorized by all requisite corporate action on
the part of Borrower and will not violate the articles of incorporation or
bylaws of Borrower, (b) the representations and warranties contained in the

                                        3

<PAGE>

Agreement, as amended hereby, and any other Loan Document are true and correct
on and as of the date hereof as though made on and as of the date hereof, (c) no
Event of Default has occurred and is continuing and no event or condition has
occurred that with the giving of notice or lapse of time or both would be an
Event of Default, and (d) Borrower is in full compliance with all covenants and
agreements contained in the Agreement as amended hereby.

      Section 6.2 Ratifications. Except as expressly modified and superseded by
this Amendment, the terms and provisions of the Agreement and the other Loan
Documents are ratified and confirmed and shall continue in full force and
effect. The representations and warranties contained herein and in all other
Loan Documents, as amended hereby, shall be true and correct as of, and as if
made on, the date hereof. Borrower and Bank agree that the Agreement as amended
hereby shall continue to be legal, valid, binding and enforceable in accordance
with its respective terms.

      Section 6.3 Reference to the Agreement. Each of the Loan Documents,
including the Agreement and any and all other agreements, documents or
instruments now or hereafter executed and delivered pursuant to the terms hereof
or pursuant to the terms of the Agreement as amended hereby, are hereby amended
so that any reference in such Loan Documents to the Agreement shall mean a
reference to the Agreement as amended hereby.

      Section 6.4 Expenses of Bank. As provided for in the Agreement, Borrower
agrees to pay on demand all reasonable costs and expenses incurred by Bank in
connection with the preparation, negotiation, execution of this Amendment, and
the other Loan Documents executed pursuant hereto and any and all amendments,
modifications and supplements thereto including, without limitation, the
reasonable costs and fees of Bank's legal counsel, and all reasonable costs and
expenses incurred by Bank in connection with the enforcement or preservation of
any rights under the Agreement, as amended hereby, or any other Loan Documents.

      Section 6.5 Severability. Any provisions of this Amendment held by court
of competent jurisdiction to be invalid or unenforceable shall not impair or
invalidate the remainder of this Amendment and the effect thereof shall be
confined to the provisions so held to be invalid or unenforceable.

      Section 6.6 Applicable Law. This Amendment and all other Loan Documents
executed pursuant hereto shall be governed by and construed in accordance with
the laws of the State of Texas.

      Section 6.7 Successors and Assigns. This Amendment is binding upon and
shall inure to the benefit of Bank and Borrower and their respective successors
and assigns.

      Section 6.8 Counterparts. This Amendment may be executed in one or more
counterparts, each of which when so executed shall be deemed to be an original
but all of which when taken together shall constitute one and the same
instrument.

      Section 6.9 Headings. The headings, captions, and arrangements used in
this Amendment are for convenience only and shall not affect the interpretation
of this Amendment.

                                        4

<PAGE>

      Section 6.10 NO ORAL AGREEMENTS. THIS AMENDMENT AND ALL OTHER INSTRUMENTS,
DOCUMENTS AND AGREEMENTS EXECUTED AND DELIVERED IN CONNECTION HEREWITH REPRESENT
THE FINAL AGREEMENT BETWEEN THE PARTIES, AND MAY NOT BE CONTRADICTED BY EVIDENCE
OF PRIOR, CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS BETWEEN THE PARTIES.
THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

      [Remainder of Page Intentionally Left Blank; Signature Page Follows]

                                        5

<PAGE>

                EXECUTED as of the day and year first above written.

                                        BORROWER:

                                        SAI HOLDINGS, INC., formerly known as
                                        SERVICE ASSET INVESTMENTS, INC.

                                        By: /s/ Roger J. Engemoen, Jr.
                                            ------------------------------------
                                        Name: Roger J. Engemoen, Jr.
                                        Title: Chairman

                                        BANK;

                                        GUARANTY BANK

                                        By: /s/ Coswell O. Robinson, Jr.
                                            ------------------------------------
                                        Name: Coswell O. Robinson, Jr.
                                        Title: Senior Vice President

                                 Signature Page
                   Eleventh Amendment to Amended and Restated
                                 Loan Agreement

<PAGE>

                      REAFFIRMATION OF AMENDED AND RESTATED
                                   GUARANTIES

      Each of the undersigned hereby (i) consents to the execution and delivery
of the Amendment to which this Reaffirmation of Amended and Restated Guaranties
is attached (the "Amendment") by the parties thereto, (ii) agrees that the
Amendment shall not limit or diminish the obligations of each of the undersigned
under certain Fifth Amended and Restated Guaranties (Limited) dated as of
December 31, 2002 (each, a "Guaranty"), executed or joined in by each of the
undersigned and delivered to the Bank, (iii) reaffirms its obligations under its
respective Guaranty, and (iv) agrees that its Guaranty remains in full force and
effect, as limited by the terms of such Guaranty, and is hereby ratified and
confirmed.

Dated as of March ____, 2005.

                                     GUARANTORS:

                                     /s/ William D. Gross
                                     -------------------------------------------
                                     William D. Gross

                                     /s/ Daniel P. Son
                                     -------------------------------------------
                                     Daniel P. Son

                                     /s/ Philip A. Pendergraft
                                     -------------------------------------------
                                     Philip A. Pendergraft

                                     ___________________________________________
                                     Roger J. Engemoen, Jr.

<PAGE>

                      REAFFIRMATION OF AMENDED AND RESTATED
                                   GUARANTIES

      Each of the undersigned hereby (i) consents to the execution and delivery
of the Amendment to which this Reaffirmation of Amended and Restated Guaranties
is attached (the "Amendment") by the parties thereto, (ii) agrees that the
Amendment shall not limit or diminish the obligations of each of the undersigned
under certain Fifth Amended and Restated Guaranties (Limited) dated as of
December 31, 2002 (each, a "Guaranty"), executed or joined in by each of the
undersigned and delivered to the Bank, (iii) reaffirms its obligations under its
respective Guaranty, and (iv) agrees that its Guaranty remains in full force and
effect, as limited by the terms of such Guaranty, and is hereby ratified and
confirmed.

Dated as of March 24, 2005.

                                          GUARANTORS:

                                          ______________________________________
                                          William D. Gross

                                          ______________________________________
                                          Daniel P. Son

                                          ______________________________________
                                          Philip A. Pendergraft

                                          /s/ Roger J. Engemoen, Jr.
                                          --------------------------------------
                                          Roger J. Engemoen, Jr.

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