Zero-Coupon Swap Valuation

As discussed above, vanilla swap rates are often quoted as a spread that is a function mainly of the credit spread required by the market over the risk-free government rate. This convention is logical, because government bonds are the principal instrument banks use to hedge their swap books. It is unwieldy, however, when applied to nonstandard tailor-made swaps, each of which has particular characteristics that call for particular spread calculations. As a result, banks use zero-coupon pricing, a standard method that can be applied to all swaps. 

As explained in chapter 3, zero-coupon, or spot, rates are true interest rates for their particular terms to maturity. In zero-coupon swap pricing, a bank views every swap, even the most complex, as a series of cash flows. The zero-coupon rate for the term from the present to a cash flows payment date can be used to derive the present value of the cash flow. The sum of these present values is the value of the swap. 

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Banks generally use par or zero-coupon swap pricing, which is discussed in detail in the next section. This section introduces the subject with a description of intuitive swap valuation. 

It is important for a zero-coupon yield curve to be constructed as accurately as possible. This because the curve is used in the valuation of a wide range of instruments, not only conventional cash market coupon bonds, which we can value using the appropriate spot rate for each cash flow, but other interest-rate products such as swaps. 

The fundamental principle of valuation is that the value of any financial asset is equal to the present value of its expected future cash flows. This principle holds for any financial asset from zero-coupon bonds to interest rate swaps. Thus, the valuation of a financial asset involves the following three steps ... 

The zero-coupon curve is used in the asset swap valuation. This curve is derived from the swap curve, so it is the implied zero-coupon curve. The asset swap spread is the spread that equates the difference between the present value of the bond s cash flows, calculated using the swap zero rates, and the market price of the bond. This spread is a function of the bond s market price and yield, its cash flows, and the implied zero-coupon interest rates. ... 

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