What Is a Tranche?
Tranche comes from the French word for slice. In finance it refers to one portion of a pooled security or debt package that has been split into pieces with distinct terms. A mortgage-backed security might be divided into senior, mezzanine, and equity tranches, each sold to investors with different appetites for risk and return.
The same idea appears in lending. A leveraged buyout is typically financed with several tranches of debt, such as a first-lien term loan alongside second-lien or subordinated notes, each with its own interest rate, maturity, and place in line if the borrower defaults.
How Tranching Works
Cash flows from the underlying assets run through a payment waterfall. The senior tranche receives interest and principal first, and only after it is paid in full does money flow down to mezzanine and then equity holders. Losses work in reverse order, so the equity tranche is wiped out before mezzanine investors lose a dollar, and mezzanine is exhausted before senior holders take any loss.
This subordination acts as credit enhancement for the senior notes. If the equity and mezzanine tranches together represent 20% of the structure, the senior tranche is protected until cumulative losses on the pool exceed 20%. Rating agencies size these cushions, known as attachment points, when assigning ratings to each slice.
Why Tranches Matter
Tranching lets a single pool of assets serve investors with very different mandates. An insurance company can buy the AAA-rated senior slice for safety while a hedge fund buys the equity tranche for double-digit yields, all funded by the same collateral. That flexibility is what made securitization one of the largest funding channels in modern markets.
The 2008 crisis showed the downside: when losses on subprime mortgages blew through the junior tranches faster than models predicted, supposedly safe senior tranches were impaired too. Analysts in structured finance, leveraged finance, and restructuring spend much of their time working out exactly where each tranche sits in the capital structure and what it recovers in a downside case.
