Yield to maturity

The Yield to maturity (YTM), book yield or redemption yield of a bond or other fixed-interest security, such as gilts, is the internal rate of return (IRR, overall interest rate) earned by an investor who buys the bond today at the market price, assuming that the bond will be held until maturity, and that all coupon and principal payments will be made on schedule.[1] Yield to maturity is the discount rate at which the sum of all future cash flows from the bond (coupons and principal) is equal to the price of the bond. The YTM is often given in terms of Annual Percentage Rate (A.P.R.), but more usually market convention is followed. In a number of major markets (such as gilts) the convention is to quote annualised yields with semi-annual compounding (see compound interest); thus, for example, an annual effective yield of 10.25% would be quoted as 10.00%, because 1.05 × 1.05 = 1.1025.[2]

Main assumptions

The main underlying assumptions used concerning the traditional yield measures are:

Coupon rate vs. YTM

Variants of yield to maturity

As some bonds have different characteristics, there are some variants of YTM:

Formula for yield to maturity for zero-coupon bonds


\text{Yield to maturity(YTM)} = \sqrt[\text{Time period}]{\dfrac{\text{Face value}}{\text{Present value}}} - 1

Example 1

Consider a 30-year zero-coupon bond with a face value of $100. If the bond is priced at an annual YTM of 10%, it will cost $5.73 today (the present value of this cash flow, 100/(1.1)30 = 5.73). Over the coming 30 years, the price will advance to $100, and the annualized return will be 10%.

What happens in the meantime? Suppose that over the first 10 years of the holding period, interest rates decline, and the yield-to-maturity on the bond falls to 7%. With 20 years remaining to maturity, the price of the bond will be 100/1.0720, or $25.84. Even though the yield-to-maturity for the remaining life of the bond is just 7%, and the yield-to-maturity bargained for when the bond was purchased was only 10%, the return earned over the first 10 years is 16.25%. This can be found by evaluating (1+i) from the equation (1+i)10 = (25.842/5.731), giving 1.1625.

Over the remaining 20 years of the bond, the annual rate earned is not 16.25%, but rather 7%. This can be found by evaluating (1+i) from the equation (1+i)20 = 100/25.84, giving 1.07. Over the entire 30 year holding period, the original $5.73 invested increased to $100, so 10% per annum was earned, irrespective of any interest rate changes in between.

Example 2

You buy ABC Company bond which matures in 1 year and has a 5% interest rate (coupon) and has a par value of $100. You pay $90 for the bond.

The current yield is 5.56% (5/90).

If you hold the bond until maturity, ABC Company will pay you $5 as interest and $100 par value for the matured bond. Now for your $90 investment, you get $105, so your yield to maturity is 16.67% [= (105/90)-1] or [=(105-90)/90].

Assume now that you had to pay $101 for the same bond with a 5% interest rate. When the coupon is paid, you get $5. But you had to pay an extra $1 when buying the bond compared to the par value, your real gain is $4 for an initial investment of $101. Your yield to maturity is 4/101 = 3.96%

If you had paid $105 for the same bond, you would get $5 when the coupon is paid. However you had to compensate for the extra $5 of your initial investment. Your gain is 0 and so is your yield to maturity.

Coupon-bearing Bonds

For bonds with multiple coupons, it is not generally possible to solve for yield in terms of price algebraically. A numerical root-finding technique such as Newton's method must be employed to approximate the yield which renders the present value of future cash flows equal to the bond price.

See also

References

  1. Definition of 'Yield To Maturity (YTM)'
  2. Formulae for Calculating Gilt Prices from Yields
  3. Fabozzi, Frank. The Handbook of Fixed Income Securities. McGraw-Hill, 2005, p. 87.

External links

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