A CDS is a contract that provides protection against the risk of a credit event by a particular company or country. The company is known as the reference entity and a default by the company is known as a credit event. The buyer of the insurance obtains the right to sell a particular bond issued by the company for its par value when a credit event occurs. The bond is known as the reference obligation and the total par value of the bond that can be sold is known as the swap's notional principal. The buyer of protection makes periodic payments to the protection seller until the occurrence of a credit
event or the maturity date of the contract, whichever is first. If a credit event occurs the buyer is compensated for the loss (possibly hypothetically) incurred as a result of the credit event.
A credit event usually requires a nal accrual payment by the buyer. The swap is then settled by either physical delivery or in cash. If the terms of the swap require physical delivery, the swap buyer delivers the bonds to the seller in exchange for their par value.
When there is cash settlement, the calculation agent polls dealers to determine the midmarket price, Q, of the reference obligation some specified number of days after the credit event. The cash settlement is then $(100 − Q)% of the notional principal.
The valuation of a credit default swap requires estimates of the risk-neutral probability that the reference entity will default at di erent future times. The prices of bonds issued by the reference entity provide the main source of data for the estimation. If we assume that the only reason a corporate bond sells for less than a similar Treasury bond is the possibility of default, it follows that:
Value of Treasury Bond - Value of Corporate Bond = Present Value of Cost of Defaults
By using this relationship to calculate the present value of the cost of defaults on a range of different bonds issued by the reference entity, and making an assumption about recovery rates, we can estimate the probability of the corporation defaulting at di erent future times. If the reference entity has issued relatively few actively traded bonds, we can use bonds issued by another corporation that is considered to have the same risk of default as the reference entity. This is likely to be a corporation whose bonds have the same credit rating as those of the reference entity and ideally a corporation in the same industry as the reference entity.
We start with a simple example. Suppose that a ve-year zero-coupon Treasury bond with a face value of 100 yields 5% and a similar ve-year zero-coupon bond issued by a corporation yields 5.5%. Both rates are expressed with continuous compounding. The value of the Treasury bond is
100 x e^(−0.05×5) = 77.8801
and the value of the corporate bond is 100 x e^(−0.055×5) = 75.9572. The present value of the cost of defaults is, therefore
77.8801 − 75.9572 = 1.9229
Define the risk-neutral probability of default during the five-year life of the bond as p. If we make the simplifying assumption that there are no recoveries in the event of a default, the impact of a default is to create a loss of 100 at the end of the five years. The expected loss from defaults in a risk-neutral world is, therefore, 100p and the present value of the expected loss is
100 x p x e^(−0.05×5)
It follows that: 100 x p x e^(−0.05×5) = 1.9229
so that p = 0.0247 or 2.47%.
There are two reasons why the calculations for extracting default probabilities from bond prices are, in practice, usually more complicated than this. First, the recovery rate is usually non-zero. Second, most corporate bonds are not zero-coupon bonds. When the recovery rate is non-zero, it is necessary to make an assumption about the claim made by bondholders in the event of default.
event or the maturity date of the contract, whichever is first. If a credit event occurs the buyer is compensated for the loss (possibly hypothetically) incurred as a result of the credit event.
A credit event usually requires a nal accrual payment by the buyer. The swap is then settled by either physical delivery or in cash. If the terms of the swap require physical delivery, the swap buyer delivers the bonds to the seller in exchange for their par value.
When there is cash settlement, the calculation agent polls dealers to determine the midmarket price, Q, of the reference obligation some specified number of days after the credit event. The cash settlement is then $(100 − Q)% of the notional principal.
The valuation of a credit default swap requires estimates of the risk-neutral probability that the reference entity will default at di erent future times. The prices of bonds issued by the reference entity provide the main source of data for the estimation. If we assume that the only reason a corporate bond sells for less than a similar Treasury bond is the possibility of default, it follows that:
Value of Treasury Bond - Value of Corporate Bond = Present Value of Cost of Defaults
By using this relationship to calculate the present value of the cost of defaults on a range of different bonds issued by the reference entity, and making an assumption about recovery rates, we can estimate the probability of the corporation defaulting at di erent future times. If the reference entity has issued relatively few actively traded bonds, we can use bonds issued by another corporation that is considered to have the same risk of default as the reference entity. This is likely to be a corporation whose bonds have the same credit rating as those of the reference entity and ideally a corporation in the same industry as the reference entity.
We start with a simple example. Suppose that a ve-year zero-coupon Treasury bond with a face value of 100 yields 5% and a similar ve-year zero-coupon bond issued by a corporation yields 5.5%. Both rates are expressed with continuous compounding. The value of the Treasury bond is
100 x e^(−0.05×5) = 77.8801
and the value of the corporate bond is 100 x e^(−0.055×5) = 75.9572. The present value of the cost of defaults is, therefore
77.8801 − 75.9572 = 1.9229
Define the risk-neutral probability of default during the five-year life of the bond as p. If we make the simplifying assumption that there are no recoveries in the event of a default, the impact of a default is to create a loss of 100 at the end of the five years. The expected loss from defaults in a risk-neutral world is, therefore, 100p and the present value of the expected loss is
100 x p x e^(−0.05×5)
It follows that: 100 x p x e^(−0.05×5) = 1.9229
so that p = 0.0247 or 2.47%.
There are two reasons why the calculations for extracting default probabilities from bond prices are, in practice, usually more complicated than this. First, the recovery rate is usually non-zero. Second, most corporate bonds are not zero-coupon bonds. When the recovery rate is non-zero, it is necessary to make an assumption about the claim made by bondholders in the event of default.