a. The MBSs dealt with so far are the agency mortgage-backed securities. There are other MBSs that can be for any kind of real estate property.
b. For the non-agency-backed securities, the first lien is on the mortgaged property.
c. The non-agency securities can take the form of pass-throughs or CMOs. In this market, the CMOs are created either from a pool of pass-throughs or the CMOs.
d. The main difference between an agency MBS and a non-agency MBS is that the latter does not carry a precise government guarantee of the payment of interest and principal as is with the agency security.
e. The credit ratings for these types of securities generally require credit enhancement, either internal or external credit enhancement.
f. Credit enhancement of security implies the existence of support for one or more of the bondholders in the structure.
1.1. External Credit Enhancement
a. It is in the form of third-party guarantees which protect against losses up to a particular fixed level.
b. This is available in form of a corporate guarantee, a letter of credit from a bank, or bond insurance.
c. Though a third-party guarantee is referred to as a ‘first-loss protection’, it is generally not used as primary protection.
d. For example, if in a $ 100 million ABS deal, 10% is guaranteed, then for any losses that are in excess of 10%, the sponsor will not be liable. However, the ABSs backed by external credit support is prone to the credit risk of the third-party guarantor. If the third-party guarantor undergoes a downward change in credit ratings, the ratings of the issue will also be lowered, even if the performance of the entire structure is intact.
1.2. Internal Credit Enhancement
a. The internal credit enhancement can be in the form of reserve funds, over-collateralization, or a senior-subordinate structure.
b. The senior-subordinate tranche structure is the most common form of internal credit enhancement. Here there are two different types of asset tranches, some being superior to the other ones. The subordinate tranches provide credit support to the senior tranches; in case of any default, the senior tranches have priority in terms of the claim over the receipts from the assets.
c. The reserve funds can be kept in form of cash reserve funds or the excess spread accounts. The cash reserve funds are a part of underwriting profits deposited in funds, which are normally in money market instruments and generally form a separate fund. The excess spread account, on the other hand, is the profits made on the spread from the cash flow expected from the receivables and cash flow payables.
d. Overcollateralization is a process of holding extra assets as collateral than the liabilities, i.e. the bonds issued against them.