Final - Interest Rate Sensitivity and Duration in Fixed Income
KELLEY SCHOOL OF BUSINESS
F303 - Intermediate Investments
Professor Mathias S. Kruttli
Spring 2026
11 - Fixed Income III: Interest Rate Sensitivity
Agenda
Interest rate sensitivity
Concept of duration
Calculating durations
Approximating bond price changes with duration
Bond Price Interest Rate Sensitivity
The percentage change in bond price is inversely related to changes in yield to maturity.
Quantitative Representation: -
Maturity Sensitivity
Long-term vs. Short-term Bonds: - Long-term bonds tend to exhibit greater sensitivity to interest rate changes compared to short-term bonds.
Coupon Sensitivity
High-Coupon vs. Low-Coupon Bonds: - Prices of high-coupon bonds are less sensitive to interest rate changes than those of low-coupon bonds.
Coupon Rate and Interest Rate Sensitivity
Example 1: Prices of an 8% coupon bond (with semi-annual payments) affected by YTM. - | YTM | T = 1 | T = 10 | T = 20 | |-------|-------|--------|--------| | 8% | $1,000| $1,000 | $1,000 | | 9% | $990.64| $934.96| $907.99| | Price Change (%) | 0.94% | 6.50% | 9.20% |
Example 2: Prices of zero-coupon bonds (with semi-annual compounding). - | YTM | T = 1 | T = 10 | T = 20 | |-------|--------|---------|---------| | 8% | $924.56| $456.39 | $208.29 | | 9% | $915.73| $414.64 | $171.93 | | Price Change (%) | 0.96% | 9.15% | 17.46% | - Conclusion: The zero-coupon bond demonstrates longer duration and more pronounced price changes when yield shifts from 8% to 9%.
Yield to Maturity Sensitivity
High-YTM vs. Low-YTM Bonds: - Prices of low-YTM bonds show greater sensitivity to interest rate changes than those of high-YTM bonds.
Duration Concept
Definition of Duration: - Duration measures the average time to receive the bond's promised cash flows. It provides a metric for how sensitive a bond is to interest rate changes—greater duration equates to higher sensitivity.
Macaulay Duration Equation: - For a bond with cash flows, where is the yield to maturity: - - Macaulay's Duration is computed as: - , where: - for cash flows at time .
Duration: Calculation Examples
Example 1: Determining duration for a 10-year zero-coupon bond priced at $500 with a YTM of 3.526% (semi-annual).
Example 2: Duration for an 18-month bond with an 8% coupon rate, semi-annual payments, BEY of 10%, face value of $1,000.
Example 3: Macaulay’s duration for a 2-year bond with a 4% semiannual coupon and face amount of $2,000, BEY of 2.5%.
Estimating Bond Price Changes with Duration
Approximation Formula:
- The bond's percentage price change can be estimated using: - - Modified Duration Definition:
-
Duration Approximation Accuracy
Graphical Representation:
- Comparison of Duration Approximation vs. Actual Change: - Actual price changes are not perfectly predicted by duration approximation. - Accuracy diminishes with larger changes in interest rates.
Duration: Example Calculations
Example 4 Calculation:
- If the YTM changes from 5% to 6% for the 18-month bond (BEY of 10%, coupon rate of 8%, face value of $1,000, initial price of $972.77): - Approximate percentage change in price calculated as: -
Summary of Duration Metrics
The duration of a zero-coupon bond is equivalent to its maturity.
For constant maturity and YTM, a bond's duration increases with a lower coupon rate.
For a constant coupon rate, duration and interest rate sensitivity generally increase with longer maturities.
For consistent factors, a bond's duration is higher with a lower YTM.
Quick Quiz: Duration Consideration
If all else being equal, does a higher coupon payment lead to lower duration?
- A. Yes
- B. No
- C. Not enough information
Quiz Example Calculation
Find the Macaulay’s duration of a 2-year bond with a semiannual coupon rate of 6%, face amount of $1,000, and BEY of 10%: - Possible options: - A. 3.82
- B. 1.21
- C. 2.74
Modified Duration Portfolio Example
A bond portfolio has a modified duration of 5 years. If the annual yield for all bonds decreases by 2%, the approximate percentage change in portfolio value can be estimated as: - A. 2%
- B. 10%
- C. 15%
Next Lecture
Preview of Options topics.