MBS structure that allocates losses to subordinate classes before senior investor classes.
A senior-subordinate structure is an MBS structure that allocates losses to subordinate classes before senior investor classes.
Senior-subordinate structure matters because it explains how some mortgage-backed securities create different risk levels from the same underlying mortgage collateral.
The structure is especially important in non-agency MBS, where investor protection may depend on transaction design rather than an agency guarantee.
Borrowers usually do not see senior-subordinate structure in ordinary mortgage documents. It appears in the capital-market structure after loans are pooled and securitized.
The term becomes practical when a borrower or learner wants to understand why non-agency mortgage funding can be more complex than mainstream agency execution.
| Class | Plain-language role |
|---|---|
| Senior class | Receives more protection from initial losses |
| Subordinate class | Absorbs certain losses first |
| Tranche | Investor class or slice of cash flow |
| Credit Enhancement | Broader support concept that this structure can provide |
A non-agency MBS has senior and subordinate investor classes. If mortgage losses occur, the subordinate class may absorb losses before the senior class is affected.
Senior-subordinate structure differs from Tranche because tranches are the classes, while senior-subordinate describes how loss priority is arranged among them.
It differs from Credit Enhancement because credit enhancement is the broader support purpose, while senior-subordinate structure is one way to provide it.
It also differs from Agency MBS because agency MBS support usually relies on agency structures rather than this non-agency loss-allocation design.