Senior tranches

The static, no-loss return of the various tranches in this case might have the profile shown in Exhibit 22.6. Here the equity tranche constitutes the first 50 million of risk, and is compensated for its position in the capital structure with a very high notional spread of 20.5%, or 10.25 million per year on 50 million notional. This spread represents the annual return to the equity holder in the scenario where no losses are incurred. Conversely, the most senior tranche of risk receives only 1.05 million per year on a notional position of 700 million. The low spread return of only 15 bps ( 1.05 million/ 700 million) underscores the perceived safety of the super-senior tranche. 

Of the total spread of the assets available to fund the tranches of liabilities in this example, fully 68.33% goes to the first loss piece even though this piece only represents 5% of the total potential loss. Meanwhile, a mere 7% of the available 15 million asset spread accrues to the most senior 70% of the capital structure. As with all CDOs, in this synthetic deal the senior tranches are providing leverage to the junior tranches in exchange for safety. 

In an ABS or CDO structure the issuer will usually issue different tranches of notes with different levels of seniority. As losses occur in the portfolio, the most junior investors will start losing their investment. The mezzanine investors will only face a loss on their investment after the junior tranche has been lost, that is, the losses on the portfolio are greater than the junior tranche. The senior tranche investors will only face a loss on their investments when the losses on the portfolio are greater than the sum of the junior tranche and the mezzanine tranche together. 

The deal is structured as a senior-subordinated overcollateralization, with the first three notes all rated as AAA. These are ranked further into a super-senior and junior-senior tranche. The note tranching is the principal form of credit enhancement, in addition to the overcollateralization of 0.85 percent. There is also a reserve account to trap excess spread, which is a further credit enhancement. 

Because the SPV now owns the assets, it has an asset-and-liability profile that must be managed during the term of the CDO. The typical liability structure includes a senior tranche rated Aaa/Aa, a junior tranche rated Ba, and an unrated equity tranche. The equity tranche is the riskiest, since it is the first to absorb any losses in the underlying portfolio. For this reason, it is often referred to as t c first-loss tranche. 

The senior tranches of a synthetic CDO, however, may be delinked from the bank s rating by using AAA-rated collateral and default swaps, as described above. The final rating is influenced by the credit rating of the default-swap provider and the extent to which the cash flows to investors are exposed to the risk of default by the asset pool. 

Subordination. Each tranches rights to and priority in receiving interest and principal payments are set out in an issues offering circular, which provides a detailed description of the notes and their legal structure. In allocating cash flows, typically, fees and expenses are subtracted from the cash flows, then the most senior tranches are serviced, followed by the junior tranches, and finally the equity tranche. This method of cash flow is sometimes referred to as a cash flow waterfall. 

As illustrated in Figure 15.1, in a securitization the issued notes are structured to reflect specified risk areas of the asset pool, and thus are rated differently. The senior tranche is usually rated AAA. The lower-rated notes usually have an element of overcollateralization and are thus capable of absorbing losses. The most junior note is the lowest rated or nonrated. It is often referred to as th.t first-loss piece, because it is impacted by losses in the underlying asset pool first. The first-loss piece is sometimes called the equity piece or equity note (even though it is a bond) and is usually held by the originator. 

A typical auto or consumer loan ABS transaction features one to four tranches, generally rated between triple-A and triple-B. Exhibit 14.11 shows the credit enhancement levels for the FIAT 1, the Globaldrive B, and the PPAF 1 transactions. The three transactions are all structured differently and as such, the senior notes in each issue benefit from different levels as well as types of credit enhancement. 

On the liability side, the structure will have tranches whose allocations of income and loss are predefined. From most junior to most senior, the tranches include equity, mezzanine, senior, and super-senior. Equity, or first loss, is analogous to the equity in a company s balance sheet, and represents the residual interest remaining after other liabilities are paid off. The mezzanine, or middle tier of risk, typically represents low-rated tranches all the way up to AA risk. Senior usually refers to AA and AAA risk. Super-senior represents a level of risk that is deeply subordinated (usually by at least 10%) to AAA, and as its name implies is regarded as extremely safe. In a structure that is not uncommon, we will assume all of the liability tranches are unfunded except for the equity. ... 

In fact, the position of the 5% funded equity holder is exactly equivalent to an investor that has purchased 1 billion of assets with 20 times the nonrecourse leverage. The implied borrowing rate of such leverage is equivalent to the blended spread of the tranches that are senior to the equity. In our case the premiums due to the three tranches above the equity total 4.75 million, and the total tranches of risk that they represent equal 950 million. The annual spread due is 0.50% of the notional on these liability tranches and, thus, in this case the equity holder has borrowed 950 million at a blended borrowing cost of 50 bps. 

A collateralized mortgage obligation, or CMO, differs from a passthrough in that the underlying mortgage pool is separated into different maturity classes, or tranches, and the cash flow distributions to investors are prioritized based on the class of the tranche they hold. It is possible to have two tranches of the same rating, but one more senior than the other. Typically, each tranche also pays a different interest rate and appeals to a different class of investors. 

The multitranche structure, with its prioritization of cash flow payments to investors, provides the CDO with a credit enhancement. To enhance the credit of the senior notes, the originating bank may also use other mechanisms, such as credit insurance on the underlying portfolio, known as a credit wrap, and reserve accounts that absorb a loss before the equity tranche. 

If the underlying portfolio performs well and its loss profile is more attractive than projected, because of better-than-expected default and recovery rates, the return to the equity holder after payments to the senior and junior tranche will be higher than expected. If, however, the underlying portfolio performs poorly and default and recovery rates are worse than projected, perhaps because of adverse economic conditions, the tranche returns will be lower than expected. Poor investment management will also have an adverse impact on the return to investors. 

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