Definition
A tranche (French for “sliceâ€) is a distinct layer within a structured finance transaction, such as a CMBS deal. Each tranche has a defined priority of payment, credit risk exposure, and expected return.
How Tranches Work
In a securitization, multiple loans are pooled together. The pool’s cash flow is distributed according to a predefined waterfall structure. Tranches are paid sequentially based on seniority.
Basic Structure
- Senior Tranches (AAA/AA): First to receive payments, lowest risk, lowest yield.
- Mezzanine Tranches (A/BBB): Moderate risk and return.
- Subordinate / B-Piece: Absorb first losses, highest risk, highest yield.
Loss Allocation
Losses from loan defaults are applied from the bottom up. Subordinate tranches absorb losses first, protecting senior bondholders until their credit support is exhausted.
Why Tranching Exists
- Risk segmentation: Different investors prefer different risk-return profiles.
- Capital efficiency: Senior bonds can achieve high credit ratings.
- Market depth: Broadens investor participation in commercial real estate debt.
Investor Implications
- Risk concentration: Lower tranches experience higher volatility.
- Return variability: Yield correlates directly with loss exposure.
- Cycle sensitivity: Subordinate bonds are more exposed in downturns.
- Control dynamics: In CMBS, controlling class investors often come from subordinate tranches.
Example
A $400M CMBS transaction may be divided into:
- $300M Senior AAA bonds
- $60M Mezzanine bonds
- $40M Subordinate B-piece
If $30M in losses occur, they are absorbed entirely by the $40M subordinate tranche. Senior bondholders remain unaffected.
Common Pitfalls
- Ignoring structure: Two bonds in the same deal can have drastically different risk.
- Overreliance on ratings: Credit ratings do not eliminate structural risk.
- Misjudging cycle exposure: Subordinate tranches are highly cyclical.
- Liquidity assumptions: Lower tranches may trade thinly in stressed markets.