Accretion Directed Classes Classes  CA,  VM,  VN,  YC  and  YD  are  Accretion  Directed  Classes.  The  related  Accrual Amount will be applied to making principal distributions on those Classes as described in this Supplement. Each of the Accretion Directed Classes has the AD designation in the suffix position, rather than the prefix position, in its class principal type because it does not have principal payment stability through the applicable pricing prepayment assumption. Classes VM and VN will have principal  payment  stability  only  through  the  prepayment  rate  shown  in  the  table  below. Classes CA, YC and YD are not listed in the table below because, although they are entitled to receive  payments  from  the  related  Accrual  Amounts,  they  do  not  have  principal  payment stability through any prepayment rate significantly higher than 0% PSA. The Accretion Directed Classes are entitled to principal payments in an amount equal to interest accrued on the related Accrual Classes. With respect to the Classes listed in the table below, the Weighted Average Life of each such Class cannot exceed its Weighted Average Life as shown in the following table under any prepayment scenario, even a scenario where there are no prepayments. •   Moreover, based on the Modeling Assumptions, if the related Mortgage Loans prepay at any constant rate at or below the rate for an Accretion Directed Class shown in the table below, the Class Principal Balances of Classes VM and VN would be reduced to zero on, but not before, their Final Distribution Dates, and the Weighted Average Life of each of these Classes would equal its maximum Weighted Average Life. •   However, the Weighted Average Lives of Classes VM and VN, will be reduced, and may be reduced significantly, at prepayment speeds higher than the constant rates shown in the table below.  See "Yield, Maturity and Prepayment Considerations – Decrement Tables" in this Supplement. Accretion Directed Classes Class Maximum Weighted Average Life (in Years) Final Distribution Date Prepayment Rate at or below VM 6.0 September 2018 142% PSA VN 16.0 February 2028 34% PSA The  Mortgage  Loans  will  have  characteristics  that  differ  from  those  of  the  Modeling Assumptions. Therefore, even if the related Mortgage Loans prepay at a rate at or somewhat below  the  "at  or  below"  rate  shown  for  any  Accretion  Directed  Class,  the  Class  Principal Balance  of  that  Class  could  be  reduced  to  zero  before  its  Final  Distribution  Date,  and  its Weighted Average Life could be shortened. Securities that Receive Principal on the Basis of Schedules As described in this Supplement, each PAC and TAC Class will receive principal payments in accordance with a schedule calculated on the basis of, among other things, a Structuring Range or Rate. See "Terms Sheet – Scheduled Principal Balances." However, whether any such Class will adhere to its schedule and receive "Scheduled Payments" on a Distribution Date will largely depend on the level of prepayments experienced by the related Mortgage Loans. S-16