UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington D. C. 20549 Form 8-K Current Report Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): April 26, 2004 BEAR STEARNS ASSET BACKED SECURITIES TRUST Asset-Backed Certificates, Series 2003-SD1 Trust (Exact name of registrant as specified in its charter) New York (governing law of 333-91334-09 54-2126335 Pooling and Servicing Agreement) (Commission 54-2126334 (State or other File Number) IRS EIN jurisdiction of Incorporation) c/o Wells Fargo Bank, N.A., 9062 Old Annapolis Road Columbia, MD 21045 (Address of principal executive offices) (Zip Code) Registrant's telephone number, including area code: (410) 884-2000 (Former name or former address, if changed since last report) ITEM 5. Other Events On April 26, 2004 a distribution was made to holders of BEAR STEARNS ASSET BACKED SECURITIES TRUST, Asset-Backed Certificates, Series 2003-SD1 Trust. ITEM 7. Financial Statements and Exhibits (c) Exhibits furnished in accordance with Item 601(a) of Regulation S-K Exhibit Number Description EX-99.1 Monthly report distributed to holders of Asset-Backed Certificates, Series 2003-SD1 Trust, relating to the April 26, 2004 distribution. Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. BEAR STEARNS ASSET BACKED SECURITIES TRUST Asset-Backed Certificates, Series 2003-SD1 Trust By: Wells Fargo Bank, N.A. as Securities Administrator By: /s/ Beth Belfield as Assistant Vice President By: Beth Belfield as Assistant Vice President Date: 5/4/04 INDEX TO EXHIBITS Exhibit Number Description EX-99.1 Monthly report distributed to holders of Asset- Backed Certificates, Series 2003-SD1 Trust, relating to the April 26, 2004 distribution. EX-99.1 Bear Stearns Asset Backed Securities Asset-Backed Certificates Record Date: 3/31/04 Distribution Date: 4/26/04 BSA Series: 2003-SD1 Contact: Customer Service - CTSLink Wells Fargo Bank, N.A. Securities Administration Services 7485 New Horizon Way Frederick, MD 21703 Telephone: (301) 815-6600 Fax: (301) 815-6660 Certificateholder Distribution Summary Certificate Certificate Beginning Class Pass-Through Certificate Interest Principal Class CUSIP Description Rate Balance Distribution Distribution <s> <c> <c> <c> <c> <c> <c> A 07384YKL9 SEN 1.54000% 138,674,983.56 189,830.64 5,854,430.92 R-1 BSA03S1R1 RES 0.00000% 0.00 0.00 0.00 R-2 BSA03S1R2 RES 0.00000% 0.00 0.00 0.00 M-1 07384YKM7 MEZ 1.94000% 8,295,000.00 14,304.27 0.00 M-2 07384YKN5 MEZ 3.14000% 7,258,000.00 20,257.88 0.00 B 07384YKP0 SUB 4.59000% 5,185,000.00 21,154.80 0.00 B-IO BSA03SBIO IO 0.00000% 0.00 621,471.69 0.00 OC BSA03S1OC OC 0.00000% 4,146,749.09 0.00 0.00 Totals 163,559,732.65 867,019.28 5,854,430.92 Certificateholder Distribution Summary (continued) Current Ending Cumulative Realized Certificate Total Realized Class Loss Balance Distribution Losses <s> <c> <c> <c> <c> A 0.00 132,820,552.64 6,044,261.56 0.00 R-1 0.00 0.00 0.00 0.00 R-2 0.00 0.00 0.00 0.00 M-1 0.00 8,295,000.00 14,304.27 0.00 M-2 0.00 7,258,000.00 20,257.88 0.00 B 0.00 5,185,000.00 21,154.80 0.00 B-IO 0.00 0.00 621,471.69 0.00 OC 0.00 4,146,749.09 0.00 0.00 Totals 0.00 157,705,301.73 6,721,450.20 0.00 <FN> All distributions required by the Pooling and Servicing Agreement have been calculated by the Certificate Administrator on behalf of the Trustee. </FN> Principal Distribution Statement Original Beginning Scheduled Unscheduled Face Certificate Principal Principal Realized Class Amount Balance Distribution Distribution Accretion Loss (1) <s> <c> <c> <c> <c> <c> <c> A 186,599,000.00 138,674,983.56 0.00 5,854,430.92 0.00 0.00 R-1 50.00 0.00 0.00 0.00 0.00 0.00 R-2 50.00 0.00 0.00 0.00 0.00 0.00 M-1 8,295,000.00 8,295,000.00 0.00 0.00 0.00 0.00 M-2 7,258,000.00 7,258,000.00 0.00 0.00 0.00 0.00 B 5,185,000.00 5,185,000.00 0.00 0.00 0.00 0.00 B-IO 0.00 0.00 0.00 0.00 0.00 0.00 OC 454.31 4,146,749.09 0.00 0.00 0.00 0.00 Totals 207,337,554.31 163,559,732.65 0.00 5,854,430.92 0.00 0.00 <FN> (1) Amount Does Not Include Excess Special Hazard, Bankruptcy, or Fraud Losses Unless Otherwise Disclosed. Please Refer to the Prospectus Supplement for a Full Description. </FN> Principal Distribution Statement (continued) Total Ending Ending Total Principal Certificate Certificate Principal Class Reduction Balance Percentage Distribution <s> <c> <c> <c> <c> A 5,854,430.92 132,820,552.64 0.71179670 5,854,430.92 R-1 0.00 0.00 0.00000000 0.00 R-2 0.00 0.00 0.00000000 0.00 M-1 0.00 8,295,000.00 1.00000000 0.00 M-2 0.00 7,258,000.00 1.00000000 0.00 B 0.00 5,185,000.00 1.00000000 0.00 B-IO 0.00 0.00 0.00000000 0.00 OC 0.00 4,146,749.09 9,127.57608241 0.00 Totals 5,854,430.92 157,705,301.73 0.76062102 5,854,430.92 Principal Distribution Factors Statement Original Beginning Scheduled Unscheduled Face Certificate Principal Principal Class (2) Amount Balance Distribution Distribution Accretion <s> <c> <c> <c> <c> <c> A 186,599,000.00 743.17109717 0.00000000 31.37439600 0.00000000 R-1 50.00 0.00000000 0.00000000 0.00000000 0.00000000 R-2 50.00 0.00000000 0.00000000 0.00000000 0.00000000 M-1 8,295,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 M-2 7,258,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 B 5,185,000.00 1000.00000000 0.00000000 0.00000000 0.00000000 B-IO 0.00 0.00000000 0.00000000 0.00000000 0.00000000 OC 454.31 9127576.08241069 0.00000000 0.00000000 0.00000000 <FN> All classes are per $1,000 denomination. </FN> Principal Distribution Factors Statement (continued) Total Ending Ending Total Realized Principal Certificate Certificate Principal Class Loss (3) Reduction Balance Percentage Distribution <s> <c> <c> <c> <c> <c> A 0.00000000 31.37439600 711.79670116 0.71179670 31.37439600 R-1 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 R-2 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 M-1 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 M-2 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 B 0.00000000 0.00000000 1,000.00000000 1.00000000 0.00000000 B-IO 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 OC 0.00000000 0.00000000 9,127,576.08241069 9127.57608241 0.00000000 <FN> (3) Amount Does Not Include Excess Special Hazard, Bankruptcy, or Fraud Losses Unless Otherwise Disclosed. Please Refer to the Prospectus Supplement for a Full Description. </FN> Interest Distribution Statement Beginning Payment of Original Current Certificate/ Current Unpaid Current Face Certificate Notional Accrued Interest Interest Class Amount Rate Balance Interest Shortfall Shortfall <s> <c> <c> <c> <c> <c> <c> A 186,599,000.00 1.54000% 138,674,983.56 189,830.64 0.00 0.00 R-1 50.00 0.00000% 0.00 0.00 0.00 0.00 R-2 50.00 0.00000% 0.00 0.00 0.00 0.00 M-1 8,295,000.00 1.94000% 8,295,000.00 14,304.27 0.00 0.00 M-2 7,258,000.00 3.14000% 7,258,000.00 20,257.88 0.00 0.00 B 5,185,000.00 4.59000% 5,185,000.00 21,154.80 0.00 0.00 B-IO 0.00 0.00000% 163,559,732.65 0.00 0.00 0.00 OC 454.31 0.00000% 4,146,749.09 0.00 0.00 0.00 Totals 207,337,554.31 245,547.59 0.00 0.00 Interest Distribution Statement (continued) Remaining Ending Non-Supported Total Unpaid Certificate/ Interest Realized Interest Interest Notional Class Shortfall Losses (4) Distribution Shortfall Balance <s> <c> <c> <c> <c> <c> A 0.00 0.00 189,830.64 0.00 132,820,552.64 R-1 0.00 0.00 0.00 0.00 0.00 R-2 0.00 0.00 0.00 0.00 0.00 M-1 0.00 0.00 14,304.27 0.00 8,295,000.00 M-2 0.00 0.00 20,257.88 0.00 7,258,000.00 B 0.00 0.00 21,154.80 0.00 5,185,000.00 B-IO 0.00 0.00 621,471.69 0.00 157,705,301.73 OC 0.00 0.00 0.00 0.00 4,146,749.09 Totals 0.00 0.00 867,019.28 0.00 <FN> (4) Amount Does Not Include Excess Special Hazard, Bankruptcy, or Fraud Losses Unless Otherwise Disclosed. Please Refer to the Prospectus Supplement for a Full Description. </FN> Interest Distribution Factors Statement Beginning Payment of Original Current Certificate/ Current Unpaid Current Face Certificate Notional Accrued Interest Interest Class (5) Amount Rate Balance Interest Shortfall Shortfall <s> <c> <c> <c> <c> <c> <c> A 186,599,000.00 1.54000% 743.17109717 1.01731864 0.00000000 0.00000000 R-1 50.00 0.00000% 0.00000000 0.00000000 0.00000000 0.00000000 R-2 50.00 0.00000% 0.00000000 0.00000000 0.00000000 0.00000000 M-1 8,295,000.00 1.94000% 1000.00000000 1.72444485 0.00000000 0.00000000 M-2 7,258,000.00 3.14000% 1000.00000000 2.79111050 0.00000000 0.00000000 B 5,185,000.00 4.59000% 1000.00000000 4.08000000 0.00000000 0.00000000 B-IO 0.00 0.00000% 788.85762919 0.00000000 0.00000000 0.00000000 OC 454.31 0.00000% 9127576.08241069 0.00000000 0.00000000 0.00000000 <FN> All classes are per $1,000 denomination. </FN> Interest Distribution Factors Statement (continued) Remaining Ending Non-Supported Total Unpaid Certificate/ Interest Realized Interest Interest Notional Class Shortfall Losses (6) Distribution Shortfall Balance <s> <c> <c> <c> <c> <c> A 0.00000000 0.00000000 1.01731864 0.00000000 711.79670116 R-1 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 R-2 0.00000000 0.00000000 0.00000000 0.00000000 0.00000000 M-1 0.00000000 0.00000000 1.72444485 0.00000000 1000.00000000 M-2 0.00000000 0.00000000 2.79111050 0.00000000 1000.00000000 B 0.00000000 0.00000000 4.08000000 0.00000000 1000.00000000 B-IO 0.00000000 0.00000000 2.99739230 0.00000000 760.62138534 OC 0.00000000 0.00000000 0.00000000 0.00000000 9127576.08241069 <FN> (6) Amount Does Not Include Excess Special Hazard, Bankruptcy,or Fraud Losses Unless Otherwise Disclosed. Please Refer to the Prospectus Supplement for a Full Description. </FN> CERTIFICATEHOLDER ACCOUNT STATEMENT CERTIFICATE ACCOUNT <s> <c> Beginning Balance 0.00 Deposits Payments of Interest and Principal 6,780,460.47 Liquidations, Insurance Proceeds, Reserve Funds 0.00 Proceeds from Repurchased Loans 0.00 Other Amounts (Servicer Advances) 113,103.25 Realized Loss (Gains, Subsequent Expenses & Recoveries) 0.00 Prepayment Penalties 0.00 Total Deposits 6,893,563.72 Withdrawals Reimbursement for Servicer Advances 119,936.77 Payment of Service Fee 52,176.74 Payment of Interest and Principal 6,721,450.21 Total Withdrawals (Pool Distribution Amount) 6,893,563.72 Ending Balance 0.00 PREPAYMENT/CURTAILMENT INTEREST SHORTFALL <s> <c> Total Prepayment/Curtailment Interest Shortfall 0.00 Servicing Fee Support 0.00 Non-Supported Prepayment/Curtailment Interest Shortfall 0.00 SERVICING FEES <s> <c> Gross Servicing Fee 50,813.76 Master Servicing Fee 1,362.98 Supported Prepayment/Curtailment Interest Shortfall 0.00 Net Servicing Fee 52,176.74 OTHER ACCOUNTS Beginning Current Current Ending Account Type Balance Withdrawals Deposits Balance <s> <c> <c> <c> <c> Financial Guaranty 0.00 0.00 0.00 0.00 Reserve Fund 0.00 0.00 0.00 0.00 LOAN STATUS STRATIFICATION/CREDIT ENHANCEMENT STATEMENT DELINQUENCY STATUS DELINQUENT BANKRUPTCY FORECLOSURE REO Total <s> <c> <c> <c> <c> <c> No of Loans No of Loans No of Loans No of Loans No of Loans Principal Balance Principal Balance Principal Balance Principal Balance Principal Balance 0-29 Days 21 0 0 21 2,260,566.33 0.00 0.00 2,260,566.33 30 Days 42 2 1 0 45 6,014,241.54 261,584.15 54,698.98 0.00 6,330,524.67 60 Days 24 5 2 0 31 2,166,592.52 505,390.26 199,482.56 0.00 2,871,465.34 90 Days 6 1 4 0 11 564,769.32 158,030.32 361,188.08 0.00 1,083,987.72 120 Days 4 0 7 0 11 446,761.32 0.00 594,118.13 0.00 1,040,879.45 150 Days 6 1 4 0 11 804,133.43 104,370.57 685,496.68 0.00 1,594,000.68 180+ Days 11 7 3 4 25 1,337,732.22 592,760.60 314,762.11 328,669.10 2,573,924.03 Totals 93 37 21 4 155 11,334,230.35 3,882,702.23 2,209,746.54 328,669.10 17,755,348.22 No of Loans No of Loans No of Loans No of Loans No of Loans Principal Balance Principal Balance Principal Balance Principal Balance Principal Balance 0-29 Days 1.948052% 0.000000% 0.000000% 1.948052% 1.430766% 0.000000% 0.000000% 1.430766% 30 Days 3.896104% 0.185529% 0.092764% 0.000000% 4.174397% 3.806557% 0.165563% 0.034620% 0.000000% 4.006740% 60 Days 2.226345% 0.463822% 0.185529% 0.000000% 2.875696% 1.371288% 0.319874% 0.126257% 0.000000% 1.817419% 90 Days 0.556586% 0.092764% 0.371058% 0.000000% 1.020408% 0.357456% 0.100021% 0.228605% 0.000000% 0.686082% 120 Days 0.371058% 0.000000% 0.649351% 0.000000% 1.020408% 0.282766% 0.000000% 0.376032% 0.000000% 0.658797% 150 Days 0.556586% 0.092764% 0.371058% 0.000000% 1.020408% 0.508955% 0.066059% 0.433867% 0.000000% 1.008881% 180+ Days 1.020408% 0.649351% 0.278293% 0.371058% 2.319109% 0.846683% 0.375172% 0.199220% 0.208023% 1.629098% Totals 8.627087% 3.432282% 1.948052% 0.371058% 14.378479% 7.173705% 2.457455% 1.398601% 0.208023% 11.237784% OTHER INFORMATION <s> <c> Current Period Class A Insufficient Funds 0.00 Principal Balance of Contaminated Properties 0.00 Periodic Advance 113,103.25 COLLATERAL STATEMENT Collateral Description Mixed Fixed Weighted Average Gross Coupon 6.753842% Weighted Average Net Coupon 6.381033% Weighted Average Pass-Through Rate 6.371033% Weighted Average Maturity(Stepdown Calculation ) 355 Beginning Scheduled Collateral Loan Count 1,117 Number Of Loans Paid In Full 39 Ending Scheduled Collateral Loan Count 1,078 Beginning Scheduled Collateral Balance 163,559,732.65 Ending Scheduled Collateral Balance 157,705,301.73 Ending Actual Collateral Balance at 31-Mar-2004 157,996,879.67 Monthly P &I Constant 1,193,923.58 Special Servicing Fee 0.00 Prepayment Penalties 0.00 Realized Loss Amount 0.00 Cumulative Realized Loss 0.00 Ending Scheduled Balance for Premium Loans 157,705,301.73 Scheduled Principal 273,376.40 Unscheduled Principal 5,581,054.52 Required Overcollateralization Amount 0.00 Overcollateralized Increase Amount 0.00 Overcollateralized reduction Amount 0.00 Specified O/C Amount 4,146,749.09 Overcollateralized Amount 4,146,749.09 Overcollateralized Deficiency Amount 0.00 Base Overcollateralized Amount 0.00 Extra principal distribution Amount 0.00 Excess Cash Amount 621,471.69 Miscellaneous Reporting Three month rolling average 0.059275% Trigger Event NO Yield maintenance amount 0