What Are Tranches? Meaning and Examples

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A tranche is one slice of a pooled financial product, such as a mortgage-backed security or a collateralized debt obligation, that carries its own risk, maturity, interest rate and claim on the pool’s cash flows. The word is French for “slice.” All the tranches of a deal usually draw on the same underlying assets. What separates them is the order in which they get paid and the order in which they absorb losses. That ordering lets one deal offer a low-risk, low-yield piece to one investor and a high-risk, high-yield piece to another.

How Tranches Work

Tranches come out of securitization. A bank or other originator transfers income-producing assets with steady cash flows, such as mortgages, auto loans, corporate loans or credit card receivables, into a separate entity, which issues several classes of notes backed by the pool. The deal documents define each class’s size, coupon, expected maturity, rating and position in the payment order.

The payment order is called the waterfall. Cash collected from borrowers flows in sequence:

1. Fees and expenses of the structure (servicer, trustee) are paid.
2. Interest is paid to the senior tranche, then to the mezzanine tranche, then to the junior tranche.
3. Principal is distributed according to the deal’s rules, often senior first.
4. Whatever is left goes to the most junior holders, usually called the equity or residual tranche.

Losses run the opposite way. When borrowers default, the shortfall hits the bottom tranche first. Only after that tranche is wiped out do losses reach the next class up. The junior layer acts as a cushion, called credit enhancement or subordination, for everything above it.

Interpreting tranches

Two terms describe where a tranche sits in the loss order:

• Attachment point: the percentage of pool losses at which the tranche starts losing principal.
• Detachment point: the percentage of pool losses at which the tranche is completely written off.

A tranche that attaches at 10% and detaches at 30% is untouched by the first 10% of losses and fully lost once pool losses reach 30%. The thickness of the tranche (here 20% of the pool) and the cushion beneath it determine how sensitive it is to defaults.

Types of Tranches

Pooled securities are generally described as having three layers:

• Senior tranches have first claim on cash flows and the most subordination beneath them. They carry the least risk and the lowest yield, and often receive the highest ratings, including AAA.
• Mezzanine tranches sit in the middle. They take losses only after the junior layer is exhausted and pay a correspondingly higher coupon.
• Junior tranches take the first losses. The lowest of them is often called the equity tranche or first-loss piece; “subordinate” is the broader term for any tranche ranked below another. The equity tranche may have no rating and no fixed coupon, receiving only residual cash.

Mortgage deals add time tranching. In a sequential-pay collateralized mortgage obligation (CMO), principal goes to the first tranche until it is retired, then to the next, and so on. One CMO might offer tranches with expected maturities of 1, 2, 5 and 20 years, each with a different yield: short tranches suit investors who want their money back quickly, long tranches those who want a longer stream of payments.

A Z tranche is the lowest-ranked class in many CMOs. Its holders receive no current coupon payments. Interest accrues and is added to the balance, and no cash is paid until the more senior tranches have been retired.

Example of Tranches

Hypothetical example. A $100 million pool of mortgages backs three tranches:

Assume all losses are measured on principal after recoveries, and ignore fees and interest timing.

• Pool losses of $8 million: the junior tranche absorbs all of it and is left with $2 million. Mezzanine and senior holders lose nothing.
• Pool losses of $15 million: the junior tranche is wiped out ($10 million), and the mezzanine tranche loses the remaining $5 million, or 25% of its principal. Senior holders are still whole.
• Pool losses of $35 million: junior and mezzanine are both gone ($30 million), and the senior tranche loses $5 million, about 7% of its principal.

The junior tranche demands a much higher return because it is effectively leveraged to the pool’s default rate.

A common simplification says the safe mortgages go into the senior tranche and the risky ones into the junior tranche. In a standard credit-tranched deal, every tranche is backed by the whole pool; a senior tranche’s safety comes from its position in the waterfall, not from cherry-picked loans.

Why Tranches Matter

For issuers, tranching widens the buyer base: a pension fund restricted to highly rated debt can buy the senior notes, while a hedge fund seeking higher yield can buy the equity piece. Selling the parts to different buyers can raise more money than selling the pool as a single security.

For investors, tranches fit a debt position to a specific risk tolerance, income need and time horizon. An MBS investor receives monthly cash flow from the interest and principal paid by homeowners in the pool, allocated according to the tranche held, and can hold it for income or sell it in the secondary market.

Because expected return depends on both the coupon and the timing of cash flows, yield measures based on internal rate of return are more informative than the stated coupon alone, particularly for mortgage tranches where prepayments change when principal arrives.

Other Meanings of “Tranche”

The word also appears outside securitization, usually meaning “portion”:

• Loan tranches. A large syndicated loan to a corporation, project or sovereign government can be split into tranches, such as a revolving credit facility and one or more term loans with different maturities and pricing. Pro-rata tranches are typically held by the arranging banks and carry their own credit ratings.
• Multi-tranche bond issues. A company may sell several bond series at once, such as 5-year, 10-year and 30-year notes, each with its own coupon. All rank equally as obligations of the same issuer; they differ by maturity and rate, not by seniority.
• Staged funding. Venture investors, lenders and governments may release money in tranches as milestones are met. Each installment is a tranche, and the final tranche is the last scheduled release.

Limitations of Tranches

Complexity. Waterfalls, triggers and prepayment rules can run to hundreds of pages. An investor who does not understand where a tranche sits, or how prepayments affect it, can end up holding a position that behaves very differently from its label.

Rating risk. Investors often rely on tranche ratings. Before 2007, many tranches backed by subprime mortgages or junk-rated debt were rated AAA. Whether through flawed models or alleged conflicts of interest, those ratings understated the risk, and investors who bought “safe” paper took heavy losses.

Correlation. Senior tranches are protected only as long as defaults stay below their attachment point. When defaults across the pool rise together, as they did in the housing downturn, losses can cut through the junior cushion faster than models assumed.

Conflicts between tranches. Holders of different classes in the same deal can have opposing interests, and after the crisis litigation between them became common enough that the press called it “tranche warfare.” An April 2008 Financial Times report described senior holders of failed CDOs using their priority to seize assets and cut off payments to lower classes; trustees including Deutsche Bank and Wells Fargo went to court to keep funds flowing to all tranches. In 2009, Carrington Investment Partners, holding junior MBS tranches, sued American Home Mortgage Servicing, alleging that foreclosed properties were sold at low prices that damaged the junior tranches’ returns.

Tranches vs. Related Terms

• CMO vs. CDO: a CDO is a pooled security backed by fixed-income assets, most often loans. A CMO is a CDO whose underlying assets are mortgages.
• Tranche vs. securitization: securitization is the process of pooling and repackaging assets; tranches are the classes of notes that process creates.
• Tranche vs. mezzanine debt: a mezzanine tranche is a middle class within a securitization. Mezzanine debt is a separate corporate financing instrument ranking between senior loans and equity on a company’s balance sheet.

The Bottom Line

Tranches matter to anyone buying or holding securitized debt, from pension funds limited to highly rated notes to hedge funds chasing yield. A tranche's safety comes from its position in the waterfall and the cushion beneath it, and ratings can understate that risk. Investors should know a tranche's attachment point and how prepayments and correlated defaults affect it before relying on its label.