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Chapter 6. The Risk of Changing Interest Rates. Short Horizon Investors. Maturity. 0. 1. n. Time. P 0. P 1. y 0. y 1. P 1 , the price at Time 1, is important. Long Horizon Investors. Maturity. 0. 1. 2. n. Time. P 0. C. C. C + PAR. Reinvest.
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Chapter 6 The Risk of Changing Interest Rates
Short Horizon Investors Maturity 0 1 n Time P0 P1 y0 y1 P1, the price at Time 1, is important.
Long Horizon Investors Maturity 0 1 2 n Time P0 C C C + PAR Reinvest Value at some distant date n is important.
Bond Price Interest Rates
Bond Price P0 Actual Price Change P1 y0 y1 Interest Rates
= derivative of bond price as yield to maturity changes = slope of tangent of price curve
Duration as an Approximation of Price Change Price Price Slope of tangent equals numerator of duration Actual price change equals P0 P1 Tangent Duration approximation of price changeequals P0 P´1 P0 P1 P´1 Interest rate y0 y1
Move along tangent to approximate price change. From calculus Divide both sides by price = a measure of sensitivity of bond prices to changes in yields = a measure of risk
Percent Price [Duration][Yield Change].Change is called “modified” duration.
-[dP/dy](1+y) Price Macaulay’s Duration (DUR) Often used by short horizon investors as a measure of price sensitivity. DUR = % change in price as yield changes DUR = .
1c/(1+y)1 +2c/(1+y)2 +…+n(c+PAR)/(1+y)n Price DUR = . This expression may be interpreted as the weighted average maturity of a bond.
Macaulay’s Duration for Special Types of Bonds Bond Price Volatilities for Special Types of Bonds Type of bond Duration Zero-coupon n Par Perpetual (1 + y)/y
Duration for Various Coupons and Maturities YTM of 8% Coupon Maturity 0 0.04 0.06 0.08 0.10 0.12 1 1 1 1 1 1 1 5 5 4.59 4.44 4.31 4.20 4.11 10 10 8.12 7.62 7.25 6.97 6.74 15 15 10.62 9.79 9.24 8.86 8.57 20 20 12.26 11.23 10.60 10.18 9.88 25 25 13.25 12.15 11.53 11.12 10.84 30 30 13.77 12.73 12.16 11.80 11.55 Note: Perpetual bond has duration of 1.08/0.08 = 13.50.
Bond Price High RiskBond PH,2 PL,2 P0 LowRisk Bond PL,1 PH,1 y2 y0 y1 Interest Rates
Duration Zero-coupon Discount 1 + y y 1 + y y Par Premium . 1 Maturity 1 Duration versus Maturity
Duration Zero-coupon Discount 1 + y y 1 + y y Par Premium . 1 Maturity 1 Duration versus Maturity Feasible (Risk) High Risk Low Risk 30
Points in Time 0 n Buy zero coupon bond -$P Receive par value +$X The zero coupon strategy Immunization at a Horizon Date
Points in Time . . . 0 1 2 n Buy coupon-bearingbond Receive coupons Receive par + 1 coupon . . . -$P +c +c c + Par Reinvest coupons Maturity strategy
Points in Time . . . 0 1 2 n m Buy coupon-bearingbond Receive coupons + reinvest Sell original bond + reinvested coupons Maturity of bond . . . -$P +c +c c c + Par Reinvest coupons Duration strategy