TRUST AGREEMENT


                  TRUST AGREEMENT, between MS Structured Asset Corp. (the
"Depositor") and LaSalle Bank National Association (the "Trustee"), made as of
the date set forth in Schedule I attached hereto, which Schedule together with
Schedules II and III attached hereto, are made a part hereof. The terms of the
Standard Terms for Trust Agreements, dated March 5, 2003 (the "Standard Terms")
are, except to the extent otherwise expressly stated, hereby incorporated by
reference herein in their entirety with the same force and effect as though set
forth herein. Capitalized terms used herein and not defined shall have the
meanings defined in the Standard Terms. References to "herein", "hereunder",
"this Trust Agreement" and the like shall include the Schedule I attached hereto
and the Standard Terms so incorporated by reference.

                  WHEREAS, the Depositor and the Trustee desire to establish the
Trust identified in Schedule I attached hereto (the "Trust") for the primary
purposes of (i) holding the Underlying Securities, (ii) entering into any Swap
Agreement with the Swap Counterparty and (iii) issuing the Units;

                  WHEREAS, the Depositor desires that the respective beneficial
interests in the Trust be divided into transferable fractional shares, such
shares to be represented by the Units;

                  WHEREAS, the Depositor desires to appoint the Trustee as
trustee of the Trust and the Trustee desires to accept such appointment;

                  WHEREAS, the Depositor shall transfer, convey and assign to
the Trust without recourse, and the Trust shall acquire, all of the Depositor's
right, title and interest in and under the Underlying Securities and other
property identified in Schedule II to the Trust Agreement (the "Trust
Property"); and

                  WHEREAS, the Trust agrees to acquire the Trust Property
specified herein in consideration for Units having an initial Unit Principal
Balance identified in Schedule I attached hereto, subject to the terms and
conditions specified in the Trust Agreement;

                  NOW THEREFORE, the Depositor hereby appoints the Trustee as
trustee hereunder and hereby requests the Trustee to receive the Underlying
Securities from the Depositor and to issue in accordance with the instructions
of the Depositor Units having the terms specified in Schedule I attached hereto,
and the Trustee accepts such appointment and, for itself and its successors and
assigns, hereby declares that it shall hold all the estate, right, title and
interest in any property contributed to the trust account established hereunder
(except property to be applied to the payment or reimbursement of or by the
Trustee for any fees or expenses which under the terms hereof is to be so
applied) in trust for the benefit of all present and future Holders of the
fractional shares of beneficial interest issued hereunder, namely, the
Unitholders, and subject to the terms and provisions hereof.



<PAGE>


                  IN WITNESS WHEREOF, each of the undersigned has executed this
instrument as of the date set forth in the Schedule I attached hereto.

                              LASALLE BANK NATIONAL ASSOCIATION
                                as Trustee on behalf of the Trust identified
                                in Schedule I hereto, and not in its individual
                                capacity



                              By:  /s/ Ann M. Kelly
                                   ----------------------------
                                   Name:   Ann M. Kelly
                                   Title:  Assistant Vice President


                              MS STRUCTURED ASSET CORP.



                              By: /s/ John Kehoe
                                  ----------------------------
                                   Name:  John Kehoe
                                   Title: Vice President



Attachments: Schedules I, II and III



<PAGE>



                                   Schedule I
                           (Terms of Trust and Units)

Trust:                                      SATURNS Trust No. 2003-4

Date of Trust Agreement:                    March 20, 2003

Trustee:                                    LaSalle Bank National Association

 Units:                                     The Trust will issue two classes of
                                            Units: the Class A Units and the
                                            Class B Units.  Only the Class A
                                            Units will be publicly offered.

Initial Unit Principal Balance
of the Class A Units:                       $25,975,000

Initial Notional Amount
of the Class B Units:                       $25,975,000

Issue Price of Units:                       Class A Units: 100%

                                            Class B Units: $2,216,000

Number of Units:                            Class A Units:

                                            1,039,000 (Unit Principal Balance
                                            of $25 each)

                                            Class B Units:

                                            As specified by the Depositor

Minimum Denomination:                       Class A Units:

                                            $25 and $25 increments in excess
                                            thereof. Each $25 of Unit Principal
                                            Balance is a Unit.

                                            Class B Units:

                                            $100,000 and $1,000 increments in
                                            excess thereof.

Cut-off Date:                               March 20, 2003

Closing Date:                               March 20, 2003

Specified Currency:                         United States dollars

Business Day:                               New York, New York and Chicago,
                                            Illinois

Interest Rate:                              Class A Units:

                                            6.375% per annum on the basis of a
                                            360 day year consisting of twelve
                                            30 day months.

                                            Class B Units:

                                            0.9499% per annum on the basis of a
                                            360 day year consisting of twelve
                                            30 day months.

                                            The right of the Class A Units to
                                            accrued interest is pari passu with
                                            the right of the Class B Units to
                                            accrued interest from accrued
                                            interest on the securities.

Interest Reset Period:                      Not Applicable

Rating:                                     Class A Units:

                                            A3 by Moody's

                                            A- by S&P

Rating Agencies:                            Moody's and S&P

Scheduled Final Distribution Date:          November 1, 2029. The Units will
                                            have the same final maturity as the
                                            Underlying Securities.

Prepayment/Redemption:                      The Trust Property is subject to
                                            call in accordance with Schedule
                                            III. Any such call will cause a
                                            redemption of a corresponding
                                            portion of the Class A Units and a
                                            proportional reduction in the
                                            Notional Amount of the Class B
                                            Units.

                                            If the call rights under the Swap
                                            Agreement are partially exercised,
                                            (i) the Trustee will randomly select
                                            Class A Units to be redeemed in full
                                            from the proceeds of such partial
                                            exercise of the Swap Agreement and
                                            (ii) the Trustee will first redeem,
                                            up to a Notional Amount equal to the
                                            principal amount of Underlying
                                            Securities subject to such exercised
                                            call, Class B Units held by any Swap
                                            Counterparty who has exercised its
                                            call rights under the Swap Agreement
                                            and then by random selection. If
                                            sufficient funds are not available
                                            to redeem each such redeemed Unit in
                                            full, one Unit may be fractionally
                                            redeemed as a result of each such
                                            partial exercise.

Additional Distribution:                    Class A Units:

                                            If the Underlying Security Issuer
                                            gives notice of a self-tender as to
                                            Underlying Securities held by the
                                            Trust and a Swap Counterparty
                                            exercises its call rights under a
                                            Swap Agreement in connection with
                                            such self-tender prior to March 20,
                                            2008, each redeemed Class A
                                            Unitholder shall receive an
                                            additional distribution of $1.50 per
                                            Class A Unit from the proceeds of
                                            such exercise in respect of
                                            principal, price or premium with
                                            respect to the Underlying Securities
                                            in excess of the corresponding Unit
                                            Principal Balance of the Class A
                                            Units to be redeemed.

                                            Class B Units:

                                            If a Swap Counterparty exercises its
                                            call rights under the Swap
                                            Agreement, then the Class B Units
                                            designated for a reduction in
                                            Notional Amount in connection with
                                            such exercise shall receive an
                                            amount equal to the Class B Present
                                            Value Amount as of the date of such
                                            reduction in Notional Amount as an
                                            additional distribution from any
                                            Class B Unit Payment Obligation as
                                            payable under the Swap Agreement in
                                            connection with such exercise, as
                                            applicable. In no event will amounts
                                            payable on the Class B Units under
                                            this provision exceed the Class B
                                            Present Value Amount.

                                            "Class B Present Value Amount"
                                            means, with respect to a date, an
                                            amount equal to the present value of
                                            the Future Class B Unit Interest for
                                            such date in respect of the
                                            corresponding portion of the
                                            Notional Amount of the Class B Units
                                            being reduced discounted at a rate
                                            of 7.375% per annum on the basis of
                                            a 360 day year consisting of twelve
                                            30 day months.

                                            "Future Class B Unit Interest" means
                                            with respect to any date of
                                            reduction in the Notional Amount of
                                            the Class B Units resulting from an
                                            exercise of call rights under the
                                            Swap Agreement, the interest on the
                                            corresponding portion of the
                                            Notional Amount of the Class B
                                            Units, other than interest paid or
                                            accrued through such date, that
                                            would accrue at the rate and in the
                                            manner specified hereunder and would
                                            be payable at the times specified
                                            hereunder on such corresponding
                                            portion of the Notional Amount of
                                            the Class B Units to the Scheduled
                                            Final Distribution Date had such
                                            reduction of the Notional Amount of
                                            the Class B Units not occurred.

Swap Agreement:                             The ISDA Master Agreement referred
                                            to in Schedule III and any
                                            assignment thereof.

Swap Counterparty:                          Party A to the Swap Agreement
                                            referred to in Schedule III or any
                                            assignee thereof.

                                            In the event of a self-tender for
                                            the Underlying Securities the
                                            Trustee shall tender to the
                                            Underlying Security Issuer an amount
                                            of the Underlying Securities equal
                                            to the total number of options
                                            exercised, and shall apply the
                                            proceeds of such tender in cash
                                            settlement of such options as
                                            provided in the Swap Agreement;
                                            provided, however, that to the
                                            extent any amount of Underlying
                                            Securities tendered is not accepted
                                            by the Underlying Security Issuer
                                            and paid for in accordance with the
                                            terms of the tender offer, such
                                            options relating to the Underlying
                                            Securities so tendered and not
                                            accepted shall be deemed rescinded
                                            and no settlement thereof shall be
                                            deemed to have occurred, with the
                                            number of such rescinded options to
                                            be allocated among the Swap
                                            Counterparties in proportion to the
                                            number of options initially
                                            exercised (and each Swap
                                            Counterparty shall be entitled to
                                            exercise such rescinded options in
                                            the future).

Swap Termination Payment:                   With respect to each $1,000 face
                                            amount of Underlying Securities and
                                            each corresponding option under the
                                            Swap Agreement, an amount equal to
                                            the excess (if any) of the sale
                                            proceeds of the Underlying
                                            Securities, reduced by (x) accrued
                                            interest on the Underlying
                                            Securities, (y) the $1,000 of Unit
                                            Principal Balance of the Class A
                                            Units and the Class B Present Value
                                            Amount with respect to $1,000 of the
                                            Notional Amount of Class B Units to
                                            be redeemed in relation to such sale
                                            and (z) any additional distribution
                                            on the Class A Units to be redeemed
                                            in relation to such sale or
                                            distribution.

Swap Notional Amount:                       The notional amount specified in
                                            Schedule III.

Swap Payment Date:                          Not Applicable

Swap Rate:                                  Not Applicable

Distribution Date:                          Each May 1 and November 1, or
                                            the next succeeding Business Day if
                                            such day is not a Business Day,
                                            commencing May 1, 2003, and any
                                            other date upon which funds are
                                            available for distribution in
                                            accordance with the terms hereof.

                                            If any payment with respect to the
                                            Underlying Securities held by the
                                            Trust is not received by the Trustee
                                            by 12 noon (New York City time) on a
                                            Distribution Date, the corresponding
                                            distribution on the Units will not
                                            occur until the next Business Day
                                            that the Trust is in receipt of
                                            proceeds of such payment prior to 12
                                            noon, with no adjustment to the
                                            amount distributed or the Record
                                            Date.

Record                                      Date: The record date for each
                                            Distribution Date shall be the third
                                            Business Day prior to such
                                            Distribution Date, without
                                            adjustment for any change in the
                                            Distribution Date due to the receipt
                                            of funds for distribution after 12
                                            noon.

Form:                                       Global Security

Depositary:                                 DTC

Trustee Fees and Expenses:                  As compensation for and in payment
                                            of trust expenses related to its
                                            services hereunder other than
                                            Extraordinary Trust Expenses, the
                                            Trustee will receive Trustee Fees on
                                            each Distribution Date in the amount
                                            equal to $2,000. The Trustee Fee
                                            shall cease to accrue after
                                            termination of the Trust. The
                                            "Trigger Amount" with respect to
                                            Extraordinary Trust Expenses for the
                                            Trust is $25,000 and the Maximum
                                            Reimbursable Amount is $100,000. The
                                            Trustee Fee will be paid by the
                                            Expense Administrator. Expenses will
                                            be reimbursed by the Expense
                                            Administrator in accordance with the
                                            Expense Administration Agreement.

Expense Administrator:                      The Trustee will act as Expense
                                            Administrator on behalf of the Trust
                                            pursuant to an Expense
                                            Administration Agreement, dated as
                                            of the date of the Trust Agreement
                                            (the "Expense Administration
                                            Agreement"), between the Trustee as
                                            Expense Administrator (the "Expense
                                            Administrator") and the Trust.

                                            The Expense Administrator will
                                            receive a fee equal to $6,507
                                            payable on each Distribution Date.
                                            Amounts in respect of an additional
                                            payment obligation of the Swap
                                            Counterparty in respect of the
                                            Expense Administrator's fee shall
                                            also be considered part of the
                                            Expense Administrator's fee
                                            hereunder and under the Expense
                                            Administration Agreement. The
                                            Expense Administrator's fee is
                                            payable only from available interest
                                            receipts received with respect to
                                            the Underlying Securities after
                                            application of such receipts to
                                            payment of accrued interest on the
                                            Units. The Amounts specified in the
                                            paragraph are also referred to as
                                            the "Expense Administrator's Fee".

                                            The Expense Administrator will be
                                            responsible for paying the Trustee
                                            Fee and reimbursing certain other
                                            expenses of the Trust in accordance
                                            with the Expense Administration
                                            Agreement.

Listing:                                    The Depositor has applied to list
                                            the Class A Units on the New York
                                            Stock Exchange.

ERISA Restrictions:                         With respect to the Class A Units,
                                            no ERISA Restrictions apply. With
                                            respect to the Class B Units, the No
                                            Plan Restriction applies.

QIB Restriction:                            Not applicable to the Class A Units.
                                            Applicable to the Class B Units.

Trust Wind-Up Event:                        If (i) cash settlement applies under
                                            the Swap Agreement (other than in
                                            connection with a self-tender by the
                                            Underlying Security Issuer for the
                                            Underlying Securities), (ii) a Trust
                                            Wind-Up Event has occurred in
                                            connection with the exercise of any
                                            call rights under the Swap Agreement
                                            and (iii) the Selling Agent cannot
                                            obtain a bid for the Underlying
                                            Securities in excess of 100% of the
                                            aggregate Unit Principal Balance of
                                            the Units and accrued interest on
                                            the Underlying Securities, then the
                                            Underlying Securities will not be
                                            sold, the Swap Counterparty's
                                            exercise of the call rights will be
                                            rescinded (and the Swap Counterparty
                                            shall be entitled to exercise such
                                            options in the future) and any
                                            related Trust Wind-Up Event will be
                                            deemed not to have occurred.

Termination:                                If a Trust Wind-Up Event occurs, any
                                            Underlying Securities held by the
                                            Trust will be liquidated (pursuant
                                            to the terms of the Swap Agreement
                                            in the event of an exercise of
                                            options under the Swap Agreement or
                                            otherwise by sale thereof).

                                            If the related Trust Wind-Up Event
                                            occurs due to an exercise of the
                                            call rights under the Swap Agreement
                                            as to all Underlying Securities held
                                            by the Trust, (i) amounts received
                                            as accrued interest on the
                                            Underlying Securities will be
                                            applied to amounts treated as
                                            accrued interest outstanding on the
                                            Class A Units and the Class B Units,
                                            (ii) amounts received as principal
                                            or par on the Underlying Securities
                                            (including any portion of the Strike
                                            Price (as defined in the Swap
                                            Agreement) will be applied to the
                                            Unit Principal Balance of the Class
                                            A Units up to 100% of the Unit
                                            Principal Balance of each Class A
                                            Unit and (iii) any additional
                                            amounts received in respect of
                                            principal, price or premium (or any
                                            portion of the Strike Price in
                                            excess of the amount in (ii)) will
                                            be in each case applied first to the
                                            Class A Units as an additional
                                            distribution and second to the Class
                                            B Units as an additional
                                            distribution in the event of any
                                            payment in connection with any
                                            redemption, but only up to the
                                            amount specified under "Additional
                                            Distributions" in this Trust
                                            Agreement. Notwithstanding the
                                            foregoing, any Class B Unit Payment
                                            Obligation made by the Swap
                                            Counterparty under the Swap
                                            Agreement will be distributed to the
                                            Class B Units as set forth under
                                            "Additional Distributions".
                                            Remaining accrued interest will be
                                            applied to the Expense
                                            Administrator's fee. Amounts in
                                            respect of an additional payment
                                            obligation of each Swap Counterparty
                                            in respect of the Expense
                                            Administrator's Fee will be paid to
                                            the Expense Administrator. Remaining
                                            amounts will be allocated to any
                                            applicable additional distribution
                                            on the Class B Units and then to the
                                            Swap Termination Payment.

                                            If the Trust is terminated for any
                                            other reason, the proceeds of
                                            liquidation will be applied to
                                            redeem the Class A Units, up to
                                            their stated principal balance, and
                                            the Class B Units. The Class A Units
                                            will have a claim on the proceeds of
                                            the liquidation equal to their
                                            aggregate Unit Principal Balance
                                            plus accrued interest. The Class B
                                            Units will have a claim on the
                                            proceeds of liquidation equal to
                                            accrued interest plus the Class B
                                            Present Value Amount, in each case
                                            as of such date of termination. If
                                            the proceeds of the liquidation are
                                            less than the combined claim amounts
                                            of the Class A Units and the Class B
                                            Units, the proceeds will be
                                            distributed in proportion to the
                                            claim amounts of the Class A Units
                                            and the Class B Units in full
                                            satisfaction of the claims of the
                                            Units. If the proceeds of
                                            liquidation exceed the stated
                                            principal balance of the Class A and
                                            the Class B Present Value of the
                                            Class B Units and the accrued
                                            interest on the Underlying
                                            Securities, the excess will be paid
                                            to the Swap Counterparty as a Swap
                                            Termination Payment under the Swap
                                            Agreement, other than amounts
                                            payable to the Expense Administrator
                                            in respect of the Expense
                                            Administrator's Fee.

Self-Tenders by
Underlying Security Issuer:                 The Trust will not participate in
                                            any self-tender by the Underlying
                                            Security Issuer for the Underlying
                                            Securities and the Trustee will not
                                            accept any instructions to the
                                            contrary from the Unitholders,
                                            except in connection with an
                                            exercise by a Swap Counterparty of
                                            its call rights. Any Swap
                                            Counterparty may exercise its call
                                            rights in connection with any
                                            self-tender in accordance with the
                                            Swap Agreement and the Trustee may
                                            participate in the self tender by
                                            the Underlying Security Issuer on
                                            behalf of an exercising Swap
                                            Counterparty.

Depositor Optional Exchange:                Depositor Optional Exchange applies
                                            to this Series of Units.

                                            Section 5.12(c)(ii) of the Standard
                                            Terms shall be incorporated herein
                                            by replacing 5.12 (c)(ii) with the
                                            following: "(ii) such exchange is to
                                            be effected on any Distribution Date
                                            or any date that is 90 days before
                                            or after a Distribution Date (or the
                                            succeeding Business Day if such date
                                            is not a Business Day) with 45 days
                                            notice".

                                            Pursuant to 5.12(c)(iii) each Swap
                                            Counterparty and the Expense
                                            Administrator must consent to such
                                            an exchange.

Terms of Retained Interest:                 Notwithstanding any other provision
                                            herein or in the Standard Terms, the
                                            Depositor retains the right to
                                            receive any and all interest that
                                            accrues on the Underlying Securities
                                            prior to the Closing Date. The
                                            Depositor will receive such accrued
                                            interest on the first Distribution
                                            Date (or redemption date if earlier)
                                            for the Units and such amount shall
                                            be paid from the interest payment
                                            made with respect to the Underlying
                                            Securities on the first Distribution
                                            Date.

                                            The amount of the Retained Interest
                                            is $724,632.

                                            If an Underlying Security Default
                                            occurs on or prior to the first
                                            Distribution Date and the Depositor
                                            does not receive such Retained
                                            Interest amount in connection with
                                            such Distribution Date, the
                                            Depositor will have a claim for such
                                            Retained Interest, and will share
                                            pro rata with holders of the Units
                                            to the extent of such claim in the
                                            proceeds from the recovery on the
                                            Underlying Securities.

Call Option Terms:                          Not Applicable.

Sale of Underlying Securities:              If the Swap Counterparty is not an
                                            affiliate of the Selling Agent, the
                                            Selling Agent will extend a right of
                                            first refusal to each Swap
                                            Counterparty to purchase the
                                            Underlying Securities at the highest
                                            bid received by the Selling Agent.

                                            If more than one Swap Counterparty
                                            exercises such right of first
                                            refusal, Underlying Securities will
                                            be sold to each exercising Swap
                                            Counterparty in proportion to the
                                            number of options held by such Swap
                                            Counterparty; provided, that if only
                                            one Swap Counterparty exercises such
                                            right of first refusal, such Swap
                                            Counterparty shall be entitled to
                                            purchase all of the Underlying
                                            Securities to be sold by the Selling
                                            Agent.

                                            If cash settlement applies and if
                                            the Swap Counterparty exercises any
                                            of its call rights other than in
                                            connection with a self-tender for
                                            the Underlying Securities by the
                                            Underlying Security Issuer (or
                                            extent thereof in the event of an
                                            exercise of call rights in excess of
                                            the amount to be redeemed), a number
                                            of Underlying Securities
                                            corresponding to the number of call
                                            rights exercised by the Swap
                                            Counterparty will be sold by the
                                            Selling Agent on behalf of the
                                            Trust. If the Selling Agent cannot
                                            obtain a bid for the Underlying
                                            Securities in excess of the amount
                                            specified in the Swap Agreement,
                                            then the Underlying Securities will
                                            not be sold, the Swap Counterparty's
                                            exercise, will be rescinded (and the
                                            Swap Counterparty shall be entitled
                                            to exercise such call rights in the
                                            future) and any related Trust
                                            Wind-Up Event will be deemed not to
                                            have occurred.

Selling Agent:                              Morgan Stanley & Co. Incorporated.

Rating Agency Condition:                    The definition of Rating Agencies
                                            Condition in the Standard Terms
                                            shall not apply.

                                            "Rating Agency Condition": With
                                            respect to any specified action or
                                            determination, means receipt of (i)
                                            written confirmation by Moody's (if
                                            the Units are rated by Moody's, for
                                            so long as the Units are outstanding
                                            and rated by Moody's) and (ii)
                                            written confirmation by S&P (if the
                                            Units are rated by S&P, for so long
                                            as the Units are outstanding and
                                            rated by S&P), that such specified
                                            action or determination will not
                                            result in the reduction or
                                            withdrawal of their then-current
                                            ratings on the Units. Such
                                            satisfaction may relate either to a
                                            specified transaction or may be a
                                            confirmation with respect to any
                                            future transactions which comply
                                            with generally applicable conditions
                                            published by the applicable rating
                                            agency.



<PAGE>


                                   Schedule II
                            (Terms of Trust Property)

Underlying Securities:                      Dow Chemical Company 7.375%
                                            debentures due November 1, 2029

Underlying Security Issuer:                 Dow Chemical Company

Principal Amount:                           $25,975,000

Underlying Security Rate:                   7.375%

Credit Ratings:                             A3 by Moody's

                                            A- by S&P

Listing:                                    None

Underlying Security
Issuance Agreement:                         An indenture dated as of April 1,
                                            1992 between the Underlying Security
                                            Issuer and the Underlying Security
                                            Trustee as supplemented and amended
                                            from time to time.

Form:                                       Global

Currency of
Denomination:                               United States dollars

Acquisition Price by Trust:                 $27,837,725

Underlying Security
Payment Date:                               Each May 1 and November 1

Original Issue Date:                        The Underlying Securities were
                                            issued on or about November 9, 1999.

Maturity Date:                              November 1, 2029

Sinking Fund Terms:                         Not Applicable

Redemption Terms:                           Not Applicable

CUSIP No.:/ISIN No.                         260543BJ1

Underlying Security Trustee:                The First National Bank of Chicago

Available Information
Regarding the Underlying Security Issuer
(if other than U.S.
Treasury obligations):                      The Underlying Security Issuer is
                                            subject to the informational
                                            requirements of the Securities
                                            Exchange Act of 1934, as amended,
                                            and in accordance therewith files
                                            reports and other information with
                                            the Securities and Exchange
                                            Commission (the "Commission"). Such
                                            reports and other information can be
                                            inspected and copied at the public
                                            reference facilities maintained by
                                            the Commission at 450 Fifth Street,
                                            N.W., Washington, D.C. 20549 and at
                                            the following Regional Offices of
                                            the Commission: Woolworth Building,
                                            233 Broadway, New York, New York
                                            10279, and Northwest Atrium Center,
                                            500 West Madison Street, Chicago,
                                            Illinois 60661. Copies of such
                                            materials can be obtained from the
                                            Public Reference Section of the
                                            Commission at 450 Fifth Street,
                                            N.W., Washington, District of
                                            Columbia 20549 at prescribed rates.


<PAGE>


                                  Schedule III
                              (Call Option Confirm)


<PAGE>


--------------------------------------------------------------------------------
Date:      March 20, 2003

To:        SATURNS Trust No. 2003-4         From:      Morgan Stanley & Co.
                                                       International Limited

Attn:      Asset-Backed Securities Group    Contact:   Chris Boas
           SATURNS Trust No. 2003-4

Fax:       312-904-2084                     Fax:       212-761-0406

Tel:       312-904-9387                     Tel:       212-761-1395
--------------------------------------------------------------------------------

Re: Bond Option Transaction. MS Reference Number SQ28D

         The purpose of this letter agreement is to confirm the terms and
conditions of the Transaction entered into between you and Morgan Stanley & Co.
International Limited ("MSIL"), with Morgan Stanley & Co. Incorporated
("MS&Co."), as agent, on the Trade Date specified below (the "Transaction").
This letter agreement constitutes a "Confirmation" as referred to in the
Agreement below.

         The definitions and provisions contained in the 1997 ISDA Government
Bond Option Definitions as published by the International Swaps and Derivatives
Association, Inc. ("ISDA") are incorporated into this Confirmation and this
transaction shall be deemed a "Government Bond Option Transaction" for purposes
of such definitions. In the event of any inconsistency between those definitions
and this Confirmation, this Confirmation will govern.

         1. This Confirmation supplements, forms a part of, and is subject to,
the ISDA Master Agreement dated as of the date hereof, as amended and
supplemented from time to time (the "Agreement"), between you and us. All
provisions contained in the Agreement govern this Confirmation except as
expressly modified below.

         2. The terms of the particular Transaction to which this Confirmation
relates are as follows:

I. General Terms

Trade Date:                         March 20, 2003

Option Style:                       American

Option Type:                        Call

Buyer:                              MSIL ("Party A")

Seller:                             SATURNS Trust No. 2003-4 ("Party B")

Bonds:                              The obligation identified as follows:

                                    Bond Issuer:           Dow Chemical Company
                                    Issue:                 7.375% debentures
                                                           due 2029
                                    CUSIP:                 260543BJ1
                                    Coupon:                7.375%
                                    Maturity Date:         November 1, 2029
                                    Face Amount Purchased: USD 25,975,000


Premium:                            USD $64,938

Premium Payment Date:               March 20, 2003

Number of Options:                  25,975

Option Entitlement:                 USD 1,000 of face amount of the Bonds per
                                    Option.

Strike Price:                       (i) For any Exercise Date prior to March 20,
                                    2008, 106%, in the case of an exercise
                                    related to a self-tender by the Bond Issuer
                                    for Bonds held by the Trust, of the
                                    corresponding portion of the face amount of
                                    the Bonds, but exclusive of accrued interest
                                    on the Bonds or (ii) for any Exercise Date
                                    on or after March 20, 2008, 100% of the face
                                    amount of the Bonds exclusive of accrued
                                    interest.

Calculation Agent:                  Party A

II. Exercise Terms

Automatic Exercise:                 Inapplicable

Exercise Period:                    Any Business Day from, and including, 9:00
                                    a.m. (New York time) on March 20, 2008, to,
                                    and including, the Expiration Time on the
                                    Expiration Date; provided, however, the
                                    Exercise Period shall also include any
                                    Business Day prior to March 20, 2008, if
                                    notice of redemption or self-tender has been
                                    delivered by the Bond Issuer as to Bonds
                                    held by the Trust.

Exercise Date:                      For each Option exercised, the day during
                                    the Exercise Period on which that Option is
                                    exercised.

Rescission of Exercise:             Party A may rescind its notice of exercise
                                    at any time prior to the Settlement Date by
                                    providing notice of rescission to Party B.

                                    If Cash Settlement applies and if Party B
                                    cannot obtain a bid for the Bonds held by it
                                    in excess of the Strike Price together with
                                    accrued interest on the Bonds, then Party
                                    A's notice of exercise shall be rescinded.
                                    If Cash Settlement applies and Party A
                                    exercises its Options in connection with a
                                    self-tender for settlement prior to March
                                    20, 2008, Party A's notice of exercise shall
                                    be automatically rescinded if the price
                                    offered by the Bond Issuer does not exceed
                                    the Strike Price together with accrued
                                    interest on the Bonds.

                                    Upon any rescission of exercise (whether
                                    pursuant to the foregoing sentence or
                                    otherwise) the Options for which notice of
                                    exercise was given and for which exercise
                                    was rescinded shall continue in full force
                                    and effect without regard to such provision
                                    of notice.

                                    Any Options exercised under this Transaction
                                    may be deemed rescinded to the extent so
                                    provided under Schedule I to the Trust
                                    Agreement.

Multiple Exercise:                  Applicable

Minimum Number of Options:          1

Written Confirmation of Exercise:   Applicable. Buyer shall give exercise notice
                                    which may be given orally (including by
                                    telephone) during the Exercise Period but no
                                    later than the Notification Date. Buyer will
                                    execute and deliver a written exercise
                                    notice confirming the substance of such oral
                                    notice, however, failure to provide such
                                    written notice will not affect the validity
                                    of the oral notice.

Limitation on Rights of MSIL:       Buyer may, by written notice thereof to
                                    Seller, delegate its rights to provide a
                                    notice of exercise hereunder to a third
                                    party (the "Third Party"). Any such
                                    delegation will be irrevocable by Buyer
                                    without the written consent of the Third
                                    Party. Any such Third Party will have the
                                    same rights and obligations regarding
                                    providing notice of exercise hereunder as
                                    the Buyer had prior to such delegation.
                                    While any such delegation is effective,
                                    Seller will only recognize a notice of
                                    exercise that is provided by the Third
                                    Party.

Notification Date:                  The Swap Counterparty may give notice of its
                                    intention to exercise the call rights under
                                    the Swap Agreement on not less than 15 or
                                    more than 60-calendar days' notice. The Swap
                                    Counterparty may give notice of its
                                    intention to exercise its call rights under
                                    the Swap Agreement with respect to Bonds
                                    held by the Trust as to which the Bond
                                    Issuer has given notice of a self-tender
                                    with two business days notice prior to the
                                    settlement of exercise but no later than
                                    4:00 p.m. New York time on the second
                                    Business Day immediately preceding the
                                    scheduled settlement of the self-tender.

Limited Right to Confirm Exercise:  Inapplicable

Expiration Date:                    November 1, 2026

Expiration Time:                    4:00 p.m. New York time

Business Days:                      New York and Chicago

III. Settlements:

Settlement:                         Cash Settlement if MSIL is Party A or if the
                                    Options are exercised in connection with a
                                    self-tender; otherwise Physical Settlement.
                                    Party A will notify Party B separately
                                    regarding the clearance system details for
                                    Physical Settlement.

Spot Price (Cash Settlement Only):  The cash proceeds received by Party B in
                                    connection with sale of the Bonds by Party
                                    B, excluding any amounts in respect of
                                    accrued interest. In the event of a
                                    self-tender by the Bond Issuer, the self
                                    tender price, as applicable, paid by the
                                    Bond Issuer, excluding accrued interest.

Cash Settlement Amount (Cash        The Cash  Settlement  Amount shall be
Settlement Only):                   adjusted to reflect the Additional Payment
                                    Obligation of Party A.

Bond  Payment (Physical Settlement  The Bond Payment shall also include the
Only):                              Additional Payment Obligation of Party A.

Deposit of Bond  Payment (Physical  Party A must  deposit the Bond Payment with
Settlement Only):                   the Trustee on the Business Day prior to the
                                    Exercise  Date.  The Bonds are to be
                                    delivered "free" to Party A.

Additional Payment Obligation of    To the Expense Administrator(the "Expense
Party A:                            Administrator Payment Obligation"):

                                    If any exercise of Options hereunder is an
                                    exercise of less than all Options remaining
                                    unexercised hereunder, Party A shall pay to
                                    the Expense Administrator an amount equal to
                                    the present value of a stream of payments
                                    equal to $6,507 payable on each payment date
                                    for the Bonds until the maturity of the
                                    Bonds discounted at a rate of 5% per annum
                                    on the basis of a 360 day year consisting of
                                    twelve 30 day months from the date of such
                                    exercise until the Scheduled Final
                                    Distribution Date (as defined in the Trust
                                    Agreement), assuming for this purpose that
                                    the Trust (as defined in the Trust
                                    Agreement) is not terminated prior to the
                                    Scheduled Final Distribution Date,
                                    multiplied by the Option Entitlement
                                    multiplied by the number of Options
                                    exercised and divided by $25,975,000.

                                    To Party B for Payment on the Class B Units
                                    (the "Class B Unit Payment Obligation"):

                                    Upon any exercise hereunder, Party A shall
                                    pay to Party B, for distribution with
                                    respect to the Class B Units outstanding
                                    under the Trust Agreement, the Class B
                                    Present Value Amount (as defined in the
                                    Trust Agreement).

Settlement Date:                    For Cash Settlement, as applicable, the
                                    Business Day of settlement of the sale of
                                    the Bonds by Party B or the Business Day of
                                    settlement of a self tender. For Physical
                                    Settlement, the Exercise Date.

         3. Additional Definitions.

         "Expense Administration Agreement" means the expense administration
agreement dated as of the date hereof between Party B and the Expense
Administrator.

         "Expense Administrator" means LaSalle Bank National Association acting
pursuant to the "Expense Administration Agreement".

         "Trust Agreement" means the trust agreement dated as of the date hereof
between the MS Structured Asset Corp. and LaSalle Bank National Association.

         4. Representations. Morgan Stanley & Co. Incorporated is acting as
agent for both parties but does not guarantee the performance of Party A.

         5. Additional Termination Event. As set forth in the Agreement, a Trust
Wind-Up Event will result in an Additional Termination Event under the Agreement
with respect to which Party B shall be the Affected Party and this Transaction
shall be an Affected Transaction. A redemption by the Bond Issuer of a portion
of the Bonds held by Party B will result in a partial Additional Termination
Event to the extent of the Bonds being so redeemed (or, to the extent there are
multiple Swap Counterparties, to such portion of the Bonds being redeemed
allocable to the options held by Party A) if Party A does not exercise Options
hereunder corresponding to such Bonds.

         6. Swap Termination Payments. In the event an Early Termination Date is
designated with respect to which this Transaction is an Affected Transaction,
there shall be payable to Party A as a termination payment for each option so
terminated in lieu of the termination payment determined in accordance with
Section 6(e) of the Agreement, the amount specified as the Swap Termination
Payment in the Trust Agreement.

         7. Assignment. The rights under this Confirmation and the Agreement may
be assigned at any time and from time to time in whole or in part; provided that
the Rating Agency Condition (as defined in the Trust Agreement) is satisfied
with respect to such assignment and any transfer. The transferee in any such
assignment or transfer must be a qualified institutional buyer as defined in
Rule 144A under the Securities Act of 1933, as amended.

         8. Account Details.

Payments to Party A:                   Citibank, N.A., New York
                                       SWIFT BIC Code: CITIUS33
                                       ABA No.  021 000 089
                                       FAO: Morgan Stanley & Co. International
                                            Limited
                                       Account No. 3042-1519

Operations Contact:                    Barbara Kent
                                       Tel  212-537-1449
                                       Fax  212-537-1868

Payments to Party B:                   LaSalle Bank, Chicago, Illinois
                                       ABA No. 071 000 505
                                       Reference:  SATURNS 2003-4
                                       Unit Account / AC-2090067/
                                       Account No.: 67-9180-505

Operations Contact:                    Andy Streepey
                                       Tel:  312-904-9387
                                       Fax: 312-904-2084


<PAGE>


         Please confirm that the foregoing correctly sets forth the terms of our
agreement MS Reference Number SQ28D by executing this Confirmation and returning
it to us.

Best Regards,

MORGAN STANLEY & CO. INTERNATIONAL LIMITED


BY: /s/ John Kehoe
   -------------------------
     Name:  John Kehoe
     Title: Attorney in fact

Acknowledged and agreed as of the date first written above:

SATURNS TRUST NO. 2003-4
BY:  LaSalle Bank National Association,
      solely as Trustee and not in its individual capacity.


BY: /s/ Ann M. Kelly
    ------------------------
     Name:   Ann M. Kelly
     Title:  Assistant Vice President


MORGAN STANLEY & CO. INCORPORATED hereby agrees to and
acknowledges its role as agent for both parties in accordance with
the Schedule to the Agreement.


BY: /s/ John Kehoe
   -------------------------
     Name:  John Kehoe
     Title: Attorney in fact