Chapter 24 – Managing Risk off the Balance Sheet with Loan Sales and Securitization 6th Edition
prepaid (paid off in full prior to maturity). GNMA and other pass-throughs have little or
no default risk, but they have substantial prepayment risk (see Chapter 7). Prepayments
increase in falling interest rate environments and leave the pass-through holder with a
shorter maturity instrument than expected. The duration is reduced by prepayments so
the price gains anticipated from falling rates are not as large as predicted, but the lost
reinvestment income from having to reinvest at lower rates does occur. This can
substantially reduce the investor’s realized rate of return over time. The dollars of
interest earned each month can decline fairly rapidly as interest rates drop and
prepayments increase. The reduction in total expected cash flows over the life of the
pass-through dampens the increase in price associated with the interest rate drop, but the
future value of the reinvestment income declines due to the lower reinvestment rate and
the lower amount of interest that will be received.
b. Collateralized Mortgage Obligation (CMO)
The CMO was created in 1983 by FHLMC and what was then the investment bank First
Boston as a means of repackaging prepayment risk. CMOs are created by repackaging
mortgage payment streams, or more typically, by repackaging payments on
pass-throughs. The innovation of the CMO is to offer different classes or ‘tranches’ that
offer different degrees of prepayment protection.9 The simplest form of CMO is a
sequential pay CMO (see below). This is a profitable activity for CMO backers because
the CMO investor has a better idea of the prepayment risk they face; consequently, they
are willing to pay more for a CMO than a pass-through, ceteris paribus.
CMOs are a hybrid between a pass-through and a bond. With a sequential pay CMO,
separate classes are created with different levels of prepayment protection. Suppose a
sequential pay CMO with a total pool value of $150 million has three classes, A, B and C
with principal amounts of $50 million per class. The Class A CMO holder would receive
all the initial principal payments (on the entire pool), including all prepayments on the
entire pool. These payments would reduce the Class A holders principal. Initially, Class
B and C holders would receive no principal payments until all of the principal of Class A
holders have been paid. Likewise, Class C is not affected by any prepayments until Class
B holders have been paid. The multiple classes allow investors to better choose the level
of prepayment risk desired.
Example of payments on a Sequential Pay CMO:
Suppose the mortgages in the pool have a 9% interest rate and further suppose the CMO
makes monthly payments. It could make quarterly or semiannual payments as well. The
mortgage holders make their scheduled monthly payments; if there are defaults the pool
organizer will make the scheduled payment:
Month 1 Amount paid into pool in Month 1: $2 million
Class
Beginning
Balance
Interest Due
& Paid Actual Principal reduction End Balance
A $50,000,000 $375,000 $2 mill – $1,125,000 =$875,000 $49,125,000
B $50,000,000 $375,000 $50,000,000
C $50,000,000 $375,000 $50,000,000
9 CMO tranches can also be set up for credit enhancement.
24–4