EX-99 2 mo793729-ex99.txt COMPUTATIONAL MATERIALS EXHIBIT 99 ==================================================== MASTR Adjustable Rate Mortgages Trust SERIES 2004-11 ==================================================== -------------------------------------------------------------------------------- THE INFORMATION CONTAINED HEREIN WILL BE SUPERSEDED BY THE DESCRIPTION OF THE MORTGAGE LOANS CONTAINED IN THE PROSPECTUS SUPPLEMENT -------------------------------------------------------------------------------- [UBS INVESTMENT BANK LOGO] PRELIMINARY BACKGROUND INFORMATION MASTR Adjustable Rate Mortgages Trust Series 2004-11 DISCLAIMER -------------------------------------------------------------------------------- The information herein has been provided solely by UBS Securities LLC. Neither the issuer of certificates nor any of its affiliates makes any representation as to the accuracy or completeness of the information herein. The information herein is preliminary, and will be superseded by the applicable prospectus supplement and by any other information subsequently filed with the Securities and Exchange Commission. The information contained herein will be superseded by the description of the mortgage loans contained and/or incorporated by reference in the Prospectus Supplement relating to the Certificates and supersedes all information contained in any collateral term sheets relating to the mortgage pool previously provided by UBS Securities LLC. -------------------------------------------------------------------------------- 1 ==================================================== MASTR Adjustable Rate Mortgages Trust SERIES 2004-11 ==================================================== -------------------------------------------------------------------------------- THE INFORMATION CONTAINED HEREIN WILL BE SUPERSEDED BY THE DESCRIPTION OF THE MORTGAGE LOANS CONTAINED IN THE PROSPECTUS SUPPLEMENT -------------------------------------------------------------------------------- MASTR Adjustable Rate Mortgages Trust, Series 2004-11

(1) Approximate, subject to adjustment as described in the Prospectus Supplement. (2) The pass-through rate for the Cl ass 1-A-1 certificates for each distribution date will equal LIBOR plus []% (subject to increases to LIBOR plus []% after the first distribution date on which the optional termination may be exercised), in each case, subject to a maximum per annum rate equal to the weighted average of the net mortgage rates on the group 1 loans, as further described under "Net WAC Cap". (3) The pass-through rate for the Class 1-A-2 certificates for each distribution date will equal LIBOR plus []% (subject to increases to LIBOR plus []% after the first distribution date on which the optional termination may be exercised), in each case, subject to a maximum per annum rate equal to the weighted average of the net mortgage rates on the group 1 loans, as further described under "Net WAC Cap". (4) The pass-through rate for the Class 1-A-3 certificates for each distribution date will equal LIBOR plus []% (subject to increases to LIBOR plus []% after the first distribution date on which the optional termination may be exercised), in each case, subject to a maximum per annum rate equal to the weighted average of the net mortgage rates on the group 1 loans, as further described under "Net WAC Cap". (5) The pass-through rate for the Class 1-A-4 certificates for each distribution date will equal LIBOR plus []% (subject to increases to LIBOR plus []% after the first distribution date on which the optional termination may be exercised), in each case, subject to a maximum per annum rate equal to the weighted average of the net mortgage rates on the group 1 loans, as further described under "Net WAC Cap". (6) The pass-through rate for the Class 2-A-1 certificates for each distribution date will equal LIBOR plus []% (subject to increases to LIBOR plus []% after the first distribution date on which the optional termination may be exercised), in each case, subject to a maximum per annum rate equal to the weighted average of the net mortgage rates on the group 2 loans, as further described under "Net WAC Cap". (7) The pass-through rate for the Class 2-A-2 certificates for each distribution date will equal LIBOR plus []% (subject to increases to LIBOR plus []% after the first distribution date on which the optional termination may be exercised), in each case, subject to a maximum per annum rate equal to the weighted average of the net mortgage rates on the group 2 loans, as further described under "Net WAC Cap". (8) The pass-through rate for the Class M-1 certificates for each distribution date will equal LIBOR plus []% (subject to increases to LIBOR plus []% after the first distribution date on which the optional termination may be exercised), in each case, subject to a maximum per annum rate equal to the weighted average of the net mortgage rates on the aggregate loans, as further described under "Net WAC Cap". (9) The pass-through rate for the Class M-2 Certificates for each distribution date will equal LIBOR plus []% (subject to increases to LIBOR plus []% after the first distribution date on which the optional termination may be exercised), in each case, subject to a ma ximum per annum rate equal to the weighted average of the net mortgage rates on the aggregate loans, as further described under "Net WAC Cap". -------------------------------------------------------------------------------- The information herein has been provided solely by UBS Securities LLC. Neither the issuer of certificates nor any of its affiliates makes any representation as to the accuracy or completeness of the information herein. The information herein is preliminary, and will be superseded by the applicable prospectus supplement and by any other information subsequently filed with the Securities and Exchange Commission. The information contained herein will be superseded by the description of the mortgage loans contained and/or incorporated by reference in the Prospectus Supplement relating to the Certificates and supersedes all information contained in any collateral term sheets relating to the mortgage pool previously provided by UBS Securities LLC. -------------------------------------------------------------------------------- 2 ==================================================== MASTR Adjustable Rate Mortgages Trust SERIES 2004-11 ==================================================== -------------------------------------------------------------------------------- THE INFORMATION CONTAINED HEREIN WILL BE SUPERSEDED BY THE DESCRIPTION OF THE MORTGAGE LOANS CONTAINED IN THE PROSPECTUS SUPPLEMENT -------------------------------------------------------------------------------- (10) The pass-through rate for the Class B-1 certificates for each distribution date will equal LIBOR plus []% (subject to increases to LIBOR plus []% after the first distribution date on which the optional termination may be exercised), in each case, subject to a maximum per annum rate equal to the weighted average of the net mortgage rates on the aggregate loans, as fu rther described under "Net WAC Cap". (11) The pass-through rate for the Class B-2 certificates for each distribution date will equal LIBOR plus []% (subject to increases to LIBOR plus []% after the first distribution date on which the optional termination may be exercised), in each case, subject to a maximum per annum rate equal to the weighted average of the net mortgage rates on the aggregate loans, as further described under "Net WAC Cap". (12) See "Pricing Prepayment Speed" below. -------------------------------------------------------------------------------- The information herein has been provided solely by UBS Securities LLC. Neither the issuer of certificates nor any of its affiliates makes any representation as to the accuracy or completeness of the information herein. The information herein is preliminary, and will be superseded by the applicable prospectus supplement and by any other information subsequently filed with the Securities and Exchange Commission. The information contained herein will be superseded by the description of the mortgage loans contained and/or incorporated by reference in the Prospectus Supplement relating to the Certificates and supersedes all information contained in any collateral term sheets relating to the mortgage pool previously provided by UBS Securities LLC. -------------------------------------------------------------------------------- 3 ==================================================== MASTR Adjustable Rate Mortgages Trust SERIES 2004-11 ==================================================== -------------------------------------------------------------------------------- THE INFORMATION CONTAINED HEREIN WILL BE SUPERSEDED BY THE DESCRIPTION OF THE MORTGAGE LOANS CONTAINED IN THE PROSPECTUS SUPPLEMENT -------------------------------------------------------------------------------- DESCRIPTION OF SECURITIES Pricing Prepayment Speed: The Certificates will be priced at 30% CPR. Payment Date: The 25th day of each month (or the next succeeding business day) commencing in November 2004. Estimated Closing Date: October 28, 2004 Investor Settlement Date: October 29, 2004 Accrued Interest: The price to be paid by investors for the Certificates will include one day of the accrued interest. Interest Accrual Period: The "Interest Accrual Period" for each Distribution Date with respect to the Floating Rate Certificates will be the period beginning with the 25th day of the prior month (or, in the case of the first Distribution Date, the Settlement Date) and ending on the 24th day of the current month (on an actual/360 day basis). Pass-Through Rate: With respect to any Distribution Date, the Class 1-A-1, 1-A-2, 1-A-3, 1-A-4, 2-A-1, 2-A-2, M- 1, M-2, B-1 and B-2 Pass-Through Rates will be equal to the lesser of (A) One Month LIBOR plus the related certificate margin and (B) the Net WAC Cap. Current Interest: For any class of the Certificates and any distribution date, the amount of interest accruing at the applicable Pass-Through Rate on the related Class Principal Balance during the related Interest Accrual Period. Basis Risk Shortfall: The excess, if any, of the interest that any of the Class 1-A-1, Class 1-A-2, Class 1-A-3, Class 1-A-4, Class 2-A-1, Class 2-A-2, Class M-1, Class M-2, Class B-1 and Class B-2 Certificates would have been entitled to receive on that distribution date had the Pass-Through Rate of such Class not been subject to the Net WAC Cap. Payment Delay: 0 days Issuer: MASTR Adjustable Rate Mortgages Trust Series 2004-11 Depositor: Mortgage Asset Securitization Transactions, Inc. Master Servicer: Wells Fargo Bank Minnesota, N.A. Trustee TBD -------------------------------------------------------------------------------- The information herein has been provided solely by UBS Securities LLC. Neither the issuer of certificates nor any of its affiliates makes any representation as to the accuracy or completeness of the information herein. The information herein is preliminary, and will be superseded by the applicable prospectus supplement and by any other information subsequently filed with the Securities and Exchange Commission. The information contained herein will be superseded by the description of the mortgage loans contained and/or incorporated by reference in the Prospectus Supplement relating to the Certificates and supersedes all information contained in any collateral term sheets relating to the mortgage pool previously provided by UBS Securities LLC. -------------------------------------------------------------------------------- 4 ==================================================== MASTR Adjustable Rate Mortgages Trust SERIES 2004-11 ==================================================== -------------------------------------------------------------------------------- THE INFORMATION CONTAINED HEREIN WILL BE SUPERSEDED BY THE DESCRIPTION OF THE MORTGAGE LOANS CONTAINED IN THE PROSPECTUS SUPPLEMENT -------------------------------------------------------------------------------- Transferor: UBS Warburg Real Estate Securities, Inc. Servicer Advancing: The Servicers are required to make cash advances to cover delinquent payments of principal and interest to the extent deemed recoverable. Optional Redemption: The terms of the transaction allow for a clean-up call (the "Clean-up Call"), which may be exercised once the current aggregate principal balance of the Mortgage Loans is less than or equal to 5% of the initial aggregate principal balance of the Mortgage Loans. Mortgage Loans: As of the Closing Date, it is anticipated that the aggregate principal balance of the Mortgage Loans will be approximately $ []. Net WAC Cap: The Class 1-A-1, Class 1-A-2, Class 1-A-3 and Class 1-A-4 Certificates will be subject to a Net WAC Cap equal to the weighted average of the net mortgage rates on the Group 1 Mortgage Loans. The Class 2-A-1 and Class 2-A-2 Certificates will be subject to a Net WAC Cap equal to the weighted average of the net mortgage rates on the Group 2 Mortgage Loans. The Class M-1, Class M-2, Class B-1 and Class B-2 Certificates will be subject to a Net WAC Cap equal to the minimum of the weighted average of the net mortgage rates on the aggregate Mortgage Loans. Credit Enhancement: Credit enhancement for the Certificates will consist of (i) Excess Interest, (ii) Overcollateralization and (iii) Subordination provided to the more senior classes of Certificates by the more subordinate classes of Certificates. Excess Interest: The interest collections from the Mortgage Loans less the sum of (i) the interest paid on the Certificates; and (ii) the aggregate of all fees and payments due by the Trust in respect of the Mortgage Loans. Overcollateralization: Commencing in March 2005, any Excess Cashflow will be applied as principal on the Offered Certificates. This will cause the principal balance of the Mortgage Loans to exceed the Class Principal Balance of the Certificates, resulting in Overcollateralization. Any realized losses on the Mortgage Loans will be applied first to Excess Cashflow and then to Overcollateralization. In the event that the Overcollateralization is so reduced, Excess Cashflow will be directed to pay principal on the Certificates, resulting in the limited acceleration of the Certificates relative to the amortization of the Mortgage Loans, until the Overcollateralization reaches the Overcollateralization Target. Upon this event, the acceleration feature will cease, unless the amount of Overcollateralization is reduced by realized losses. -------------------------------------------------------------------------------- The information herein has been provided solely by UBS Securities LLC. Neither the issuer of certificates nor any of its affiliates makes any representation as to the accuracy or completeness of the information herein. The information herein is preliminary, and will be superseded by the applicable prospectus supplement and by any other information subsequently filed with the Securities and Exchange Commission. The information contained herein will be superseded by the description of the mortgage loans contained and/or incorporated by reference in the Prospectus Supplement relating to the Certificates and supersedes all information contained in any collateral term sheets relating to the mortgage pool previously provided by UBS Securities LLC. -------------------------------------------------------------------------------- 5 ==================================================== MASTR Adjustable Rate Mortgages Trust SERIES 2004-11 ==================================================== -------------------------------------------------------------------------------- THE INFORMATION CONTAINED HEREIN WILL BE SUPERSEDED BY THE DESCRIPTION OF THE MORTGAGE LOANS CONTAINED IN THE PROSPECTUS SUPPLEMENT -------------------------------------------------------------------------------- Overcollateralization Target: Prior to the Distribution Date in March 2005, the Overcollateralization Target will be zero. For any Distribution thereafter, the Overcollateralization Target will be equal to [0.75%]* of the Cut-off Date Balance (the "Overcollateralization Target"). On or after the Stepdown Date, the Overcollateralization Target will be equal to [1.50%]* of the aggregate principal balance of the Mortgage Loans for the related Distribution Date, subject to a floor of [0.75%]* (the " O/C Floor") of the Cut-off Date Balance of the Mortgage Loans; provided, however, that if a Trigger Event (as described herein) is in effect on the related Distribution Date, the Overcollateralization Target will be equal to the Overcollateralization Target on the Distribution Date immediately preceding the Distribution Date on which such Trigger Event is in effect. Excess Cashflow: "Excess Cashflow" for any Distribution Date will be equal to the available funds remaining after interest and principal distributions as described under Clauses 1) and 2) of "Priority of Distributions." Trigger Event: After the Stepdown Date, (i) the quotient (expressed as a percentage) of (x) the principal balance of the rolling three month average of Loans 60 days delinquent or more (including each Loan in foreclosure, each Loan for which the related borrower has filed for bankruptcy after the Closing Date and each Loan related to a REO Property) and (y) the principal balance of the Loans, as of the last day of the related Due Period, equals or exceeds [5.00%]* or (ii) the aggregate amount of Realized Losses with respect to the Loans incurred since the Cut-Off Date through the last day of the related Prepayment Period divided by the initial principal balance of the Loans as of the Cut-Off Date exceeds the applicable percentages described below with respect to such Distribution Date: Distribution Date Occurring In Loss Percentage --------------------------------------------------------- October 2007 through September 2008 [1.00%]* October 2008 through September 2009 [1.50%]* October 2009 through Septemb er 2010 [1.75%]* October 2010 and thereafter [2.00%]* 1-A-4 Trigger Event: Prior to the Stepdown Date, the aggregate amount of Realized Losses with respect to the Loans incurred since the Cut-Off Date through the last day of the related Prepayment Period divided by the initial principal balance of the Loans as of the Cut-Off Date exceeds [1.00%]* to such Distribution Date. After the Stepdown date the "1-A-4 Trigger Event" is in effect if the "Trigger Event", described above, is in effect on such Distribution Date. * Subject to change based on final approval by rating agencies. -------------------------------------------------------------------------------- The information herein has been provided solely by UBS Securities LLC. Neither the issuer of certificates nor any of its affiliates makes any representation as to the accuracy or completeness of the information herein. The information herein is preliminary, and will be superseded by the applicable prospectus supplement and by any other information subsequently filed with the Securities and Exchange Commission. The information contained herein will be superseded by the description of the mortgage loans contained and/or incorporated by reference in the Prospectus Supplement relating to the Certificates and supersedes all information contained in any collateral term sheets relating to the mortgage pool previously provided by UBS Securities LLC. -------------------------------------------------------------------------------- 6 ==================================================== MASTR Adjustable Rate Mortgages Trust SERIES 2004-11 ==================================================== -------------------------------------------------------------------------------- THE INFORMATION CONTAINED HEREIN WILL BE SUPERSEDED BY THE DESCRIPTION OF THE MORTGAGE LOANS CONTAINED IN THE PROSPECTUS SUPPLEMENT -------------------------------------------------------------------------------- Stepdown Date: The earlier to occur of: (i) the Distribution Date on which the aggregate principal balance of the Senior Certificates is reduced to zero; and (ii) the later to occur of: a. the Distribution Date in November 2007. b. the first Distribution Date on which the aggregate principal balance of the Senior Certificates after allocation of principal remittance amount is less than or equal to [84.5%]* of the aggregate principal balance of the Mortgage Loans for such Distribution Date. Allocation of Losses: Any realized losses on the Mortgage Loans not covered by Excess Cashflow or Overcollateralization will be allocated to each class of Certificates in the following order: to the Class B-2, Class B-1, Class M-2 and Class M-1 Certificates, in that order, in each case until the respective Class Principal Balance of such class of Certificates has been reduced to zero. Following the reduction of the Class Principal Balance of each Class of Mezzanine and Subordinate Certificates to zero, such realized losses will be allocated to the Senior Certificates as follows: (i) realized losses on Group 1 Mortgage Loans will be allocated concurrently (a) to the Class 1-A-2 and Class 1-A-1 Certificates, in that order, and (b) to the Class 1-A-4 and 1-A-3 Certificates, in that order, in each case until the respective Class Principal Balance of such Class has been reduced to zero; and (ii) realized losses on Group 1 Mortgage Loans will be allocated to the Class 2-A-2 and Class 2-A-1 Certificates, in that order, in each case until the respective Class Principal Balance of such Class has been reduced to zero. * Subject to change based on final approval by rating agencies. -------------------------------------------------------------------------------- The information herein has been provided solely by UBS Securities LLC. Neither the issuer of certificates nor any of its affiliates makes any representation as to the accuracy or completeness of the information herein. The information herein is preliminary, and will be superseded by the applicable prospectus supplement and by any other information subsequently filed with the Securities and Exchange Commission. The information contained herein will be superseded by the description of the mortgage loans contained and/or incorporated by reference in the Prospectus Supplement relating to the Certificates and supersedes all information contained in any collateral term sheets relating to the mortgage pool previously provided by UBS Securities LLC. -------------------------------------------------------------------------------- 7 ==================================================== MASTR Adjustable Rate Mortgages Trust SERIES 2004-11 ==================================================== -------------------------------------------------------------------------------- THE INFORMATION CONTAINED HEREIN WILL BE SUPERSEDED BY THE DESCRIPTION OF THE MORTGAGE LOANS CONTAINED IN THE PROSPECTUS SUPPLEMENT -------------------------------------------------------------------------------- Priority of Distributions: Available funds from the Mortgage Loans (which are net of any servicing, master servicing, trustee fees and private mortgage insurance premium fees) will be distributed in the following order of priority: 1) Interest funds sequentially to (i) concurrently, to the Senior Certificates, pro-rata (including any unpaid interest amounts from prior distribution dates), and (ii) sequentially to the Class M-1, Class M-2, Class B-1 and Class B-2 Certificates; 2) Principal funds, as follows: (i) to the Senior Certificates (in the manner and priority set forth under "Senior Certificates Principal Distributions" below), then (ii) sequentially, to the Class M-1, Class M-2, Class B-1 and Class B-2 Certificates, each as described more fully under "Principal Paydown" below; 3) Beginning on the Distribution Date in March 2005, any remaining Excess Cashflow, to the Senior Certificates, Mezzanine Certificates and/or Subordinate Certificates (as applicable) to build or maintain Overcollateralization as described under "Overcollateralization Target" and "Principal Paydown," respectively; 4) Any remaining Excess Cashflow to pay (i) any unpaid interest sequentially, to the Class M-1, Class M-2, Class B-1 and Class B-2 Certificates, then (ii) any unpaid realized loss amounts sequentially, to the (a) Class 1-A-1, Class 1-A-3 and Class 2-A-1, pro-rata, (b) Class 1-A-2, Class 1-A-4 and Class 2-A-2, pro-rata, (c) Class M-1, (d) Class M-2, (e) Class B-1 and (f) Class B-2 Certificates; 5) Any remaining Excess Cashflow to pay Basis Risk Shortfalls, and 6) To the Class X Certificates, any remaining amount. Proceeds from Excess Cashflow available to cover Basis Risk Shortfalls shall generally be distributed to the Senior Certificates on a pro rata basis, first based on the Class Principal Balances thereof and second based on any remaining unpaid Basis Risk Shortfalls, and then sequentially to the Class M-1, Class M-2, Class B-1 and Class B-2 Certificates in that order. Principal Paydown: Prior to the Stepdown Date or if a Trigger Event is in effect on any Distribution Date, 100% of the available principal funds from the Mortgage Loans minus the Overcollateralization released amount will be paid to the Senior Certificates, provided, however, that if the Senior Certificates have been retired, such amounts will be applied sequentially, to the Class M-1, Class M-2, Class B-1 and the Class B-2 Certificates. On any Distribution Date on or after the Stepdown Date, and if a Trigger Event is not in effect on such Distribution Date, all of the Senior, Mezzanine and Subordinate Certificates will be entitled to receive payments of principal in the following order of priority: (i) first, to the Senior Certificates (as described under "Senior Certificates Principal Distributions" below) such that the Senior Certificates in the aggregate will have [15.50%]* subordination, (ii) second, to the Class M-1 Certificates such that the Class M-1 Certificates will have [9.00%]* subordination, (iii) third, to the Class M-2 Certificates such that the Class M-2 Certificates will have [4.30%]* subordination, (iv) fourth, to the Class B-1 Certificates such that the Class B-1 Certificates will have [3.10%]* subordination and (v) fifth, to the Class B-2 Certificates such that the Class B-2 Certificates will have [1.50%]* subordination; each subject to the required Overcollateralization Target. *Subject to change based on final approval by rating agencies. -------------------------------------------------------------------------------- The information herein has been provided solely by UBS Securities LLC. Neither the issuer of certificates nor any of its affiliates makes any representation as to the accuracy or completeness of the information herein. The information herein is preliminary, and will be superseded by the applicable prospectus supplement and by any other information subsequently filed with the Securities and Exchange Commission. The information contained herein will be superseded by the description of the mortgage loans contained and/or incorporated by reference in the Prospectus Supplement relating to the Certificates and supersedes all information contained in any collateral term sheets relating to the mortgage pool previously provided by UBS Securities LLC. -------------------------------------------------------------------------------- 8 ==================================================== MASTR Adjustable Rate Mortgages Trust SERIES 2004-11 ==================================================== -------------------------------------------------------------------------------- THE INFORMATION CONTAINED HEREIN WILL BE SUPERSEDED BY THE DESCRIPTION OF THE MORTGAGE LOANS CONTAINED IN THE PROSPECTUS SUPPLEMENT -------------------------------------------------------------------------------- Senior Certificates Principal Distributions: Group 1 Principal Distribution: Allocate 55.14% to the Class 1-A-1 and Class 1-A-2, pro-rata, until retired Allocate 44.86% to the Class 1-A-3 and Class 1-A-4, pro-rata, unless 1-A-4 trigger is hit, in which case the bonds will pay sequentially. Group 2 Principal Distribution: To the Class 2-A-1 and Class 2-A-2, pro-rata, until retired. -------------------------------------------------------------------------------- The information herein has been provided solely by UBS Securities LLC. Neither the issuer of certificates nor any of its affiliates makes any representation as to the accuracy or completeness of the information herein. The information herein is preliminary, and will be superseded by the applicable prospectus supplement and by any other information subsequently filed with the Securities and Exchange Commission. The information contained herein will be superseded by the description of the mortgage loans contained and/or incorporated by reference in the Prospectus Supplement relating to the Certificates and supersedes all information contained in any collateral term sheets relating to the mortgage pool previously provided by UBS Securities LLC. -------------------------------------------------------------------------------- 9 ==================================================== MASTR Adjustable Rate Mortgages Trust SERIES 2004-11 ==================================================== -------------------------------------------------------------------------------- THE INFORMATION CONTAINED HEREIN WILL BE SUPERSEDED BY THE DESCRIPTION OF THE MORTGAGE LOANS CONTAINED IN THE PROSPECTUS SUPPLEMENT -------------------------------------------------------------------------------- Average Life Tables Settle 10/29/2004 LIBOR_1MO 1.76 First Payment 11/25/2004 LIBOR_6MO 2.06 LIBOR_1YR 2.355 CMT_1YR 2.08 Class 1-A-1 and Class 1-A-2 to Optional Call Date -------------------------------------------------------------------------------- WAL 7.18 3.82 2.44 1.69 1.19 Principal Window Begin 1 1 1 1 1 Principal Window End 258 150 98 70 52 Class 1-A-3 and Class 1-A-4 to Optional Call Date ** -------------------------------------------------------------------------------- 10% CPR 20% CPR 30% CPR 40% CPR 50% CPR WAL 7.18 3.82 2.44 1.69 1.19 Principal Window Begin 1 1 1 1 1 Principal Window End 258 150 98 70 52 Class 2-A-1 to Optional Call Date -------------------------------------------------------------------------------- 10% CPR 20% CPR 30% CPR 40% CPR 50% CPR WAL 7.23 3.84 2.45 1.70 1.20 Principal Window Begin 1 1 1 1 1 Principal 258 150 98 70 52 Window End Class 2-A-2 to Optional Call Date -------------------------------------------------------------------------------- 10% CPR 20% CPR 30% CPR 40% CPR 50% CPR WAL 7.23 3.84 2.45 1.70 1.20 Principal Window Begin 1 1 1 1 1 Principal Window End 258 150 98 70 52 ** Assuming there is no "1-A-4 Trigger Event" -------------------------------------------------------------------------------- The information herein has been provided solely by UBS Securities LLC. Neither the issuer of certificates nor any of its affiliates makes any representation as to the accuracy or completeness of the information herein. The information herein is preliminary, and will be superseded by the applicable prospectus supplement and by any other information subsequently filed with the Securities and Exchange Commission. The information contained herein will be superseded by the description of the mortgage loans contained and/or incorporated by reference in the Prospectus Supplement relating to the Certificates and supersedes all information contained in any collateral term sheets relating to the mortgage pool previously provided by UBS Securities LLC. -------------------------------------------------------------------------------- 10 [UBS INVESTMENT BANK LOGO] MARM 04-11: PRELIMINARY COLLATERAL Pool 1 2 Total: -------------------------------------------------------------------------------- Total Balance $334,172,281 $334,309,512 $668,481,793 Avg Balance $170,845 $461,753 $249,434 WA Gross Rate 5.969 5.636 5.802 WA Net Rate 5.605 5.273 5.439 WA Roll 24 23 24 WA Gross Margin 3.09 2.86 2.973 WA First Rate Cap 3.58 4.02 3.788 WA Periodic Rate Cap 1.13 1.57 1.344 WA Max Rate 12.29 12.13 12.205 WA FICO 698 701 699 WA Orig LTV 86.0 80.6 83.3 CA % 16.5 49.0 32.7 Prepay % 43.1 33.3 38.2 Full Doc % 12.3 7.5 9.9 IO % 43.6 56.0 49.8 WA Rem Term 358 358 358 *NOTE: This collateral is preliminary and could change prior to deal close. UBS Securities LLC. This material has been prepared by UBS AG or an affiliate thereof (" UBS"). It has no regard to the specific investment objectives, financial situation or particular needs of any specific recipient. It is published solely for informational purposes and is not to be construed as a solicitation or an offer to buy or sell any securities or related financial instruments. No representation or warranty, either express or implied, is provided in relation to the accuracy, completeness or reliability of the information contained herein, except with respect to information concerning UBS AG, its subsidiaries and affiliates. Opinions expressed herein are subject to change without notice and may differ or be contrary to opinions expressed by other business areas or groups of UBS as a result of using different assumptions and criteria. UBS is under no obligation to update or keep the information current. The securities described herein may not be eligible for sale in all jurisdictions or to certain categories of investors. UBS, its directors, officers and employees (excluding the US broker- dealer unless specifically disclosed under required disclosures) or clients may have or have had interests or long or short positions in the securities or other financial instruments referred to herein, and may at any time make purchases and/ or sales in them as principal or agent. UBS (excluding the US broker- dealer unless specifically disclosed under Required Disclosures) may act or have acted as market- maker in the securities or other financial instruments discussed in this material. UBS may provide investment banking and other services to and/ or serve as directors of the companies referred to in this report. Neither UBS nor any of its affiliates, nor any of UBS' or any of its affiliates, directors, employees or agents accepts any liability for any loss or damage arising out of the use of all or any part of this report. [UBS INVESTMENT BANK LOGO] Collateral Stratification Report All records ================================================================================

Minimum: $20,880.00 Maximum: $1,500,000.00 Average: $249,433.50 % of # of Aggregate Aggregate Current Gross Rate Loans Balance Balance Group 1 Group 2 ------------------------------------------------------------------------------- <= 2.000% 1 $1,115,000 0.17 0.00 0.33 2.751% - 3.000% 6 1,632,800 0.24 0.27 0.22 3.001% - 3.250% 7 2,590,999 0.39 0.30 0.47 3.251% - 3.500% 25 7,057,628 1.06 0.95 1.16 3.501% - 3.750% 46 14,657,525 2.19 1.60 2.79 3.751% - 4.000% 93 24,947,178 3.73 3.42 4.05 4.001% - 4.250% 92 26,909,130 4.03 3.17 4.88 4.251% - 4.500% 166 40,523,548 6.06 6.10 6.02 4.501% - 4.750% 84 24,889,040 3.72 2.61 4.83 4.751% - 5.000% 74 22,933,738 3.43 2.69 4.17 5.001% - 5.250% 47 16,704,797 2.50 1.38 3.61 5.251% - 5.500% 67 21,282,503 3.18 2.11 4.26 5.501% - 5.750% 170 46,628,546 6.98 5.61 8.34 5.751% - 6.000% 361 97,702,383 14.62 12.46 16.77 6.001% - 6.250% 377 93,102,617 13.93 15.54 12.31 6.251% - 6.500% 359 83,466,855 12.49 14.19 10.79 6.501% - 6.750% 266 57,039,360 8.53 10.85 6.22 6.751% - 7.000% 191 38,569,079 5.77 7.72 3.82 7.001% - 7.250% 82 15,730,428 2.35 2.73 1.98 7.251% - 7.500% 64 11,039,031 1.65 2.43 0.87 7.501% - 7.750% 48 9,777,719 1.46 1.71 1.21 7.751% - 8.000% 34 6,809,900 1.02 1.47 0.57 8.001% - 8.250% 11 1,773,381 0.27 0.43 0.11 8.251% - 8.500% 8 1,514,808 0.23 0.24 0.21 8.501% - 8.750% 1 83,799 0.01 0.03 0.00 ------------------------------------------------------------------------------- Total: 2,680 $668,481,793 100.00 100.0 100.00 ------------------------------------------------------------------------------- Minimum: 2.000% Maximum: 8.625% Weighted Average: 5.802% -------------------------------------------------------------------------------- The information herein has been provided solely by UBS Investment Bank. Neither the issuer of certificates nor any of its affiliates makes any representation as to the accuracy or completeness of the information herein. The information herein is preliminary, and will be superseded by the applicable prospectus supplement and by any other information subsequently filed with the Securities and Exchange Commission. The information contained herein will be superseded by the description of the mortgage loans contained and/or incorporated by reference in the Prospectus Supplement relating to the Certificates and supersedes all information contained in any collateral term sheets relating to the mortgage pool previously provided by UBS Investment Bank. -------------------------------------------------------------------------------- Sep 13, 2004 20:20 Page 1 of 6 [UBS INVESTMENT BANK LOGO] Collateral Stratification Report All records ================================================================================ % of # of Aggregate Aggregate Net Rate Loans Balance Balance Group 1 Group 2 ----------------------------------------------------------------------------- <= 2.000% 1 $1,115,000 0.17 0.00 0.33 2.251% - 2.500% 1 720,000 0.11 0.00 0.22 2.501% - 2.750% 9 2,760,599 0.41 0.35 0.47 2.751% - 3.000% 15 3,893,105 0.58 0.65 0.52 3.001% - 3.250% 29 9,457,749 1.41 1.06 1.77 3.251% - 3.500% 69 19,786,577 2.96 2.54 3.38 3.501% - 3.750% 102 28,794,531 4.31 3.44 5.18 3.751% - 4.000% 115 29,522,075 4.42 4.14 4.69 4.001% - 4.250% 138 36,490,708 5.46 4.90 6.02 4.251% - 4.500% 100 31,517,550 4.71 3.32 6.11 4.501% - 4.750% 44 12,939,894 1.94 1.43 2.44 4.751% - 5.000% 60 20,633,475 3.09 1.98 4.20 5.001% - 5.250% 78 22,560,086 3.37 2.75 4.00 5.251% - 5.500% 251 68,210,017 10.20 8.88 11.52 5.501% - 5.750% 370 95,079,327 14.22 13.69 14.76 5.751% - 6.000% 359 87,225,116 13.05 14.01 12.08 6.001% - 6.250% 338 77,093,651 11.53 13.52 9.55 6.251% - 6.500% 254 54,117,154 8.10 10.13 6.06 6.501% - 6.750% 139 26,791,389 4.01 5.76 2.26 6.751% - 7.000% 64 11,973,620 1.79 1.92 1.66 7.001% - 7.250% 73 13,344,501 2.00 2.70 1.29 7.251% - 7.500% 36 8,077,224 1.21 1.34 1.08 7.501% - 7.750% 23 3,960,316 0.59 1.08 0.11 7.751% - 8.000% 10 2,136,129 0.32 0.32 0.32 8.001% - 8.250% 2 282,000 0.04 0.08 0.00 ----------------------------------------------------------------------------- Total: 2,680 $668,481,793 100.00 100.00 100.00 ----------------------------------------------------------------------------- Minimum: 1.625% Maximum: 8.250% Weighted Average: 5.439% % of # of Aggregate Aggregate Index Loans Balance Balance Group 1 Group 2 ----------------------------------------------------------------------------- 1 MONTH LIBOR 150 $43,684,950 6.53 5.29 7.78 1 Year CMT 1 314,000 0.05 0.00 0.09 1 Year Libor 22 5,647,552 0.84 0.69 1.00 6 Month Libor 2,507 618,835,291 92.57 94.01 91.13 ----------------------------------------------------------------------------- Total: 2,680 $668,481,793 100.00 100.00 100.00 ----------------------------------------------------------------------------- % of # of Aggregate Aggregate Months to Roll Loans Balance Balance Group 1 Group 2 ----------------------------------------------------------------------------- 1 172 $47,581,430 7.12 6.31 7.92 2 18 4,085,724 0.61 0.82 0.40 3 16 7,685,700 1.15 0.19 2.11 4 345 95,803,929 14.33 11.79 16.87 5 60 22,088,745 3.30 2.13 4.48 6 1 226,250 0.03 0.07 0.00 16 1 208,336 0.03 0.06 0.00 17 2 332,561 0.05 0.10 0.00 18 24 4,658,559 0.70 1.18 0.21 19 30 6,753,197 1.01 1.30 0.72 20 23 5,584,828 0.84 0.82 0.85 21 160 38,397,250 5.74 6.46 5.03 22 613 146,968,491 21.99 25.81 18.16 23 187 47,467,990 7.10 6.47 7.73 28 1 300,000 0.04 0.09 0.00 29 1 94,586 0.01 0.03 0.00 30 1 713,550 0.11 0.00 0.21 31 2 372,143 0.06 0.11 0.00 32 4 909,590 0.14 0.13 0.14 33 59 12,481,462 1.87 2.22 1.51 34 266 53,590,898 8.02 9.87 6.16 35 482 122,416,063 18.31 16.84 19.79 52 1 475,000 0.07 0.00 0.14 53 1 103,190 0.02 0.03 0.00 56 5 2,643,607 0.40 0.02 0.77 57 8 3,054,993 0.46 0.26 0.66 58 61 12,323,642 1.84 2.35 1.34 59 117 25,435,204 3.80 3.89 3.72 78 1 165,599 0.02 0.05 0.00 81 1 263,200 0.04 0.08 0.00 82 1 100,000 0.01 0.03 0.00 83 2 746,000 0.11 0.09 0.13 116 1 70,975 0.01 0.02 0.00 117 2 404,000 0.06 0.03 0.09 118 8 3,039,799 0.45 0.19 0.72 119 3 935,300 0.14 0.16 0.12 ----------------------------------------------------------------------------- Total: 2,680 $668,481,793 100.00 100.00 100.00 ----------------------------------------------------------------------------- Minimum: 1 Maximum: 119 Weighted Average: 24 -------------------------------------------------------------------------------- The information herein has been provided solely by UBS Investment Bank. Neither the issuer of certificates nor any of its affiliates makes any representation as to the accuracy or completeness of the information herein. The information herein is preliminary, and will be superseded by the applicable prospectus supplement and by any other information subsequently filed with the Securities and Exchange Commission. The information contained herein will be superseded by the description of the mortgage loans contained and/or incorporated by reference in the Prospectus Supplement relating to the Certificates and supersedes all information contained in any collateral term sheets relating to the mortgage pool previously provided by UBS Investment Bank. -------------------------------------------------------------------------------- Sep 13, 2004 20:20 Page 2 of 6 [UBS INVESTMENT BANK LOGO] Collateral Stratification Report All records ================================================================================ % of # of Aggregate Aggregate Gross Margin Loans Balance Balance Group 1 Group 2 ------------------------------------------------------------------------------- <= 2.000% 117 $29,610,058 4.43 4.82 4.04 2.001% - 2.250% 279 83,852,606 12.54 7.59 17.49 2.251% - 2.500% 139 40,269,115 6.02 4.55 7.50 2.501% - 2.750% 626 153,317,442 22.94 22.06 23.81 2.751% - 3.000% 306 86,189,725 12.89 10.71 15.08 3.001% - 3.250% 341 89,198,472 13.34 13.84 12.85 3.251% - 3.500% 390 87,256,221 13.05 15.45 10.66 3.501% - 3.750% 258 50,419,956 7.54 11.63 3.46 3.751% - 4.000% 128 27,022,728 4.04 5.43 2.65 4.001% - 4.250% 47 9,477,064 1.42 2.23 0.61 4.251% - 4.500% 23 4,803,055 0.72 0.65 0.79 4.501% - 4.750% 7 3,173,999 0.47 0.11 0.84 5.001% - 5.250% 1 325,000 0.05 0.10 0.00 5.251% - 5.500% 2 395,000 0.06 0.12 0.00 5.501% - 5.750% 3 414,900 0.06 0.12 0.00 6.001% - 6.250% 2 981,357 0.15 0.06 0.23 6.251% - 6.500% 4 857,906 0.13 0.26 0.00 6.501% - 6.750% 3 329,926 0.05 0.10 0.00 6.751% - 7.000% 1 270,000 0.04 0.08 0.00 7.001% - 7.250% 1 90,965 0.01 0.03 0.00 7.251% - 7.500% 1 142,500 0.02 0.04 0.00 7.501% - 7.750% 1 83,799 0.01 0.03 0.00 ------------------------------------------------------------------------------- Total: 2,680 $668,481,793 100.00 100.00 100.00 ------------------------------------------------------------------------------- Minimum: 0.750% Maximum: 7.625% Weighted Average: 2.973% % of # of Aggregate Aggregate First Rate Cap Loans Balance Balance Group 1 Group 2 ------------------------------------------------------------------------------- 0.000% 477 $132,054,000 19.75 16.37 23.14 1.000% 63 15,132,900 2.26 2.82 1.71 2.000% 14 2,293,550 0.34 0.46 0.22 3.000% 1,373 317,273,747 47.46 55.32 39.61 3.250% 1 205,000 0.03 0.06 0.00 4.625% 1 105,200 0.02 0.03 0.00 5.000% 616 150,818,302 22.56 21.26 23.87 5.500% 1 515,850 0.08 0.00 0.15 5.875% 1 672,000 0.10 0.00 0.20 6.000% 130 48,863,744 7.31 3.52 11.09 7.375% 1 153,600 0.02 0.05 0.00 7.625% 1 130,400 0.02 0.04 0.00 12.000% 1 263,500 0.04 0.08 0.00 ------------------------------------------------------------------------------- Total: 2,680 $668,481,793 100.00 100.00 100.00 ------------------------------------------------------------------------------- Minimum: 0.000% Maximum: 12.000% Weighted Average: 3.788% % of # of Aggregate Aggregate Periodic Rate Cap Loans Balance Balance Group 1 Group 2 ------------------------------------------------------------------------------- 0.000% 471 $127,594,000 19.09 16.38 21.79 1.000% 2,082 491,529,602 73.53 80.19 66.87 2.000% 52 15,221,313 2.28 1.50 3.06 6.000% 75 34,136,879 5.11 1.93 8.28 ------------------------------------------------------------------------------- Total: 2,680 $668,481,793 100.00 100.00 100.00 ------------------------------------------------------------------------------- Minimum: 0.000% Maximum: 6.000% Weighted Average: 1.344% -------------------------------------------------------------------------------- The information herein has been provided solely by UBS Investment Bank. Neither the issuer of certificates nor any of its affiliates makes any representation as to the accuracy or completeness of the information herein. The information herein is preliminary, and will be superseded by the applicable prospectus supplement and by any other information subsequently filed with the Securities and Exchange Commission. The information contained herein will be superseded by the description of the mortgage loans contained and/or incorporated by reference in the Prospectus Supplement relating to the Certificates and supersedes all information contained in any collateral term sheets relating to the mortgage pool previously provided by UBS Investment Bank. -------------------------------------------------------------------------------- Sep 13, 2004 20:20 Page 3 of 6 [UBS INVESTMENT BANK LOGO] Collateral Stratification Report All records ================================================================================ % of # of Aggregate Aggregate Maximum Rate Loans Balance Balance Group 1 Group 2 -------------------------------------------------------------------------------- 8.751% - 9.000% 4 $692,800 0.10 0.21 0.00 9.251% - 9.500% 5 2,649,123 0.40 0.17 0.62 9.501% - 9.750% 9 2,352,125 0.35 0.21 0.50 9.751% - 10.000% 3 626,020 0.09 0.19 0.00 10.001% - 10.250% 5 936,117 0.14 0.18 0.10 10.251% - 10.500% 5 1,126,056 0.17 0.13 0.20 10.501% - 10.750% 9 3,204,744 0.48 0.25 0.71 10.751% - 11.000% 66 17,155,028 2.57 2.48 2.65 11.001% - 11.250% 68 19,279,953 2.88 2.30 3.47 11.251% - 11.500% 102 27,933,007 4.18 3.56 4.79 11.501% - 11.750% 210 53,329,564 7.98 7.16 8.80 11.751% - 12.000% 884 247,378,520 37.01 30.07 43.93 12.001% - 12.250% 346 84,600,538 12.66 14.67 10.64 12.251% - 12.500% 317 71,950,338 10.76 12.66 8.87 12.501% - 12.750% 227 50,503,489 7.55 9.27 5.84 12.751% - 13.000% 167 33,214,283 4.97 7.17 2.77 13.001% - 13.250% 66 11,860,280 1.77 1.98 1.57 13.251% - 13.500% 57 10,114,691 1.51 2.28 0.74 13.501% - 13.750% 45 8,972,244 1.34 1.63 1.05 13.751% - 14.000% 31 6,328,047 0.95 1.32 0.57 14.001% - 14.250% 11 1,773,381 0.27 0.43 0.11 14.251% - 14.500% 8 1,514,808 0.23 0.24 0.21 14.501% - 14.750% 1 83,799 0.01 0.03 0.00 15.001% - 15.250% 3 1,497,999 0.22 0.08 0.37 15.251% - 15.500% 2 426,250 0.06 0.13 0.00 15.501% - 15.750% 1 250,000 0.04 0.07 0.00 15.751% - 16.000% 3 875,608 0.13 0.16 0.10 16.001% - 16.250% 1 210,000 0.03 0.06 0.00 16.751% - 17.000% 5 1,599,202 0.24 0.36 0.12 17.001% - 17.250% 5 1,390,081 0.21 0.19 0.23 17.251% - 17.500% 2 613,500 0.09 0.03 0.15 17.501% - 17.750% 2 349,829 0.05 0.10 0.00 17.751% - 18.000% 3 859,843 0.13 0.11 0.14 18.001% - 18.250% 7 2,830,525 0.42 0.11 0.74 -------------------------------------------------------------------------------- Total: 2,680 $668,481,793 100.00 100.00 100.00 -------------------------------------------------------------------------------- Minimum: 9.000% Maximum: 18.250% Weighted Average: 12.205% % of # of Aggregate Aggregate FICO Scores Loans Balance Balance Group 1 Group 2 -------------------------------------------------------------------------------- Not Available 0 2 $535,522 0.08 0.07 0.09 561 - 580 1 199,151 0.03 0.06 0.00 581 - 600 4 1,096,334 0.16 0.09 0.24 601 - 620 9 1,863,241 0.28 0.27 0.28 621 - 640 240 63,627,397 9.52 9.82 9.21 641 - 660 338 80,625,306 12.06 12.91 11.21 661 - 680 411 102,327,954 15.31 15.56 15.05 681 - 700 428 107,842,169 16.13 15.61 16.65 701 - 720 407 101,545,058 15.19 14.89 15.49 721 - 740 317 73,680,425 11.02 11.44 10.60 741 - 760 240 58,987,775 8.82 9.22 8.42 761 - 780 168 46,109,045 6.90 5.28 8.52 781 - 800 100 26,498,093 3.96 4.08 3.84 801 - 820 15 3,544,322 0.53 0.68 0.38 -------------------------------------------------------------------------------- Total: 2,680 $668,481,793 100.00 100.00 100.00 -------------------------------------------------------------------------------- Minimum (not less than 400): 580 Maximum: 816 Weighted Average: 699

Minimum: 19.94 Maximum: 100.00 Weighted Average: 83.27 -------------------------------------------------------------------------------- The information herein has been provided solely by UBS Investment Bank. Neither the issuer of certificates nor any of its affiliates makes any representation as to the accuracy or completeness of the information herein. The information herein is preliminary, and will be superseded by the applicable prospectus supplement and by any other information subsequently filed with the Securities and Exchange Commission. The information contained herein will be superseded by the description of the mortgage loans contained and/or incorporated by reference in the Prospectus Supplement relating to the Certificates and supersedes all information contained in any collateral term sheets relating to the mortgage pool previously provided by UBS Investment Bank. -------------------------------------------------------------------------------- Sep 13, 2004 20:20 Page 4 of 6 [UBS INVESTMENT BANK LOGO] Collateral Stratification Report All records ================================================================================

Minimum: 19.94 Maximum: 100.03 Weighted Average: 89.00 % of # of Aggregate Aggregate Amortization Loans Balance Balance Group 1 Group 2 -------------------------------------------------------------------------------- Interest In Arrears 1,431 $335,602,501 50.20 56.42 43.99 Interest Only 1,249 332,879,292 49.80 43.58 56.01 -------------------------------------------------------------------------------- Total: 2,680 $668,481,793 100.00 100.00 100.00 -------------------------------------------------------------------------------- % of # of Aggregate Aggregate Top 5 States Loans Balance Balance Group 1 Group 2 -------------------------------------------------------------------------------- California 593 $218,892,712 32.74 16.47 49.01 Florida 169 35,496,413 5.31 6.56 4.06 New York 102 35,320,806 5.28 3.76 6.80 Massachusetts 92 29,855,731 4.47 4.27 4.66 Arizona 162 29,732,784 4.45 6.24 2.66 Other 1,562 319,183,346 47.75 62.70 32.80 -------------------------------------------------------------------------------- Total: 2,680 $668,481,793 100.00 100.00 100.00 -------------------------------------------------------------------------------- % of # of Aggregate Aggregate Prepay Original Term Loans Balance Balance Group 1 Group 2 -------------------------------------------------------------------------------- 0 1,573 $413,159,074 61.81 56.92 66.69 6 26 12,872,902 1.93 0.42 3.43 12 144 39,107,694 5.85 5.50 6.20 24 664 149,872,882 22.42 26.97 17.87 30 2 224,918 0.03 0.07 0.00 36 246 48,240,151 7.22 9.18 5.26 42 1 156,000 0.02 0.05 0.00 60 24 4,848,171 0.73 0.90 0.55 -------------------------------------------------------------------------------- Total: 2,680 $668,481,793 100.00 100.00 100.00 -------------------------------------------------------------------------------- % of # of Aggregate Aggregate Document Type Loans Balance Balance Group 1 Group 2 -------------------------------------------------------------------------------- Alternate 58 $12,285,548 1.84 2.36 1.32 Full 310 66,236,373 9.91 12.33 7.49 No Doc 568 140,794,217 21.06 21.53 20.59 No Ratio 359 77,897,269 11.65 15.05 8.26 Reduced 729 210,108,192 31.43 23.78 39.08 Stated Doc 654 160,786,593 24.05 24.84 23.26 Streamline 2 373,600 0.06 0.11 0.00 -------------------------------------------------------------------------------- Total: 2,680 $668,481,793 100.00 100.00 100.00 -------------------------------------------------------------------------------- % of # of Aggregate Aggregate Loan Purpose Loans Balance Balance Group 1 Group 2 -------------------------------------------------------------------------------- Cash Out Refinance 575 $158,818,386 23.76 22.79 24.72 Purchase 1,890 459,510,961 68.74 69.27 68.21 Rate/Term Refinance 215 50,152,447 7.50 7.93 7.07 -------------------------------------------------------------------------------- Total: 2,680 $668,481,793 100.00 100.00 100.00 -------------------------------------------------------------------------------- % of # of Aggregate Aggregate Owner Occupancy Status Loans Balance Balance Group 1 Group 2 -------------------------------------------------------------------------------- Investor 967 $182,086,220 27.24 38.77 15.71 Primary 1,673 473,418,122 70.82 60.12 81.51 Secondary 40 12,977,451 1.94 1.11 2.77 -------------------------------------------------------------------------------- Total: 2,680 $668,481,793 100.00 100.00 100.00 -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- The information herein has been provided solely by UBS Investment Bank. Neither the issuer of certificates nor any of its affiliates makes any representation as to the accuracy or completeness of the information herein. The information herein is preliminary, and will be superseded by the applicable prospectus supplement and by any other information subsequently filed with the Securities and Exchange Commission. The information contained herein will be superseded by the description of the mortgage loans contained and/or incorporated by reference in the Prospectus Supplement relating to the Certificates and supersedes all information contained in any collateral term sheets relating to the mortgage pool previously provided by UBS Investment Bank. -------------------------------------------------------------------------------- Sep 13, 2004 20:20 Page 5 of 6 [UBS INVESTMENT BANK LOGO] Collateral Stratification Report All records ================================================================================

Minimum: 351 Maximum: 359 Weighted Average: 358

-------------------------------------------------------------------------------- The information herein has been provided solely by UBS Investment Bank. Neither the issuer of certificates nor any of its affiliates makes any representation as to the accuracy or completeness of the information herein. The information herein is preliminary, and will be superseded by the applicable prospectus supplement and by any other information subsequently filed with the Securities and Exchange Commission. The information contained herein will be superseded by the description of the mortgage loans contained and/or incorporated by reference in the Prospectus Supplement relating to the Certificates and supersedes all information contained in any collateral term sheets relating to the mortgage pool previously provided by UBS Investment Bank. -------------------------------------------------------------------------------- Sep 13, 2004 20:20 Page 6 of 6