Exhibit A Underlying Certificates Trust Asset Group Issuer Series Class Issue Date CUSIP Number Interest Rate Interest Type(1) Final Distribution Date Principal Type(1) Original Principal or Notional Balance of Class Underlying Certificate Factor(2) Principal or Notional Balance in the Trust Percentage of Class in Trust Approximate Weighted Average Coupon of Mortgage Loans Approximate Weighted Average Remaining Term to Maturity of Mortgage Loans (in months) Approximate Weighted Average Loan Age of Mortgage Loans (in months) Ginnie Mae I or II 2 Ginnie Mae   2007-040   FA(4)  July 30, 2007 38375KZR6 (3) FLT July 2037 PT $464,285,713   0.98369375   $  89,235,074 19.5384612233% 6.880% 354 5 II 2 Ginnie Mae   2007-040 FT July 30, 2007 38375KYR7 (3) FLT July 2037 PT 448,275,861 0.98369375 95,172,370 21.5826923592% 6.880 354 5 II 2 Ginnie Mae   2007-040 MT July 30, 2007 38375KYT3 (3) FLT/INV/SP July 2037 PT 16,009,852 0.98369375 3,399,013 21.5826917076% 6.880 354 5 II 2 Ginnie Mae   2007-040 SB July 30, 2007 38375KA77 (3) INV/IO July 2037 NTL (PT) 100,000,000 0.98369375 40,450,622 41.1211540000% 6.880 354 5 II 2 Ginnie Mae   2007-040 SC July 30, 2007 38375KA85 (3) INV/IO July 2037 NTL (PT) 121,428,571 0.98369375 49,118,611 41.1211534393% 6.880 354 5 II 2 Ginnie Mae   2007-040 SD July 30, 2007 38375KA93 (3) INV/IO July 2037 NTL (PT) 121,428,571 0.98369375 49,118,611 41.1211534393% 6.880 354 5 II 2 Ginnie Mae   2007-040 SE July 30, 2007 38375KB27 (3) INV/IO July 2037 NTL (PT) 121,428,571 0.98369375 49,118,611 41.1211534393% 6.880 354 5 II 6 Ginnie Mae   2007-040   FG(5)  July 30, 2007 38375KZS4 (3) FLT July 2037 PT 232,142,857 0.96584518 108,312,637 48.3076922759% 6.885 346 12 II 7 Ginnie Mae   2004-047 FP June 30, 2004    38374HBY5 (3) FLT August 2033 PAC 104,839,000 0.40343648 42,295,877 100.0000000000% 6.500 309 44 I (1)  As defined under "Class Types" in Appendix I to the Base Offering Circular. (2)  Underlying Certificate Factors are as of October 2007. (3)  These Underlying Certificates bear interest during their respective interest accrual periods, subject to the applicable maximum and minimum interest rates, as further described in the related Underlying Certificate Disclosure Documents, excerpts of which are attached as Exhibit B to this Supplement. (4)  MX Class. For the avoidance of doubt, it is intended that the Class Principal Balance of the FA Class as of any date of determination is the maximum outstanding Class Principal Balance for which the FA Class can be issued as of such date of determination for purposes of determining the notional balance of each of Class SB, SC, SD and SE. (5)  MX Class. A-1