Bond Duration Risk

The bond duration risk — also called interest-rate risk — is the risk that a bond’s value will decline if interest rates rise. A bond’s exposure to this risk is measured by its duration, which approximates the percentage price change for each 1% move in yields. A bond with a 7-year duration loses approximately 7% in value when interest rates rise 1%; it gains approximately 7% when rates fall 1%.

Why interest rates affect bond prices

The fundamental principle: when interest rates rise, existing bonds (with fixed coupons) become less attractive to investors. To compensate, their prices must fall so that the yield (coupon ÷ price) becomes competitive with new bonds at higher rates.

Example: A bond paying 4% coupon worth $1,000 when rates are 4%. If rates rise to 5%, the bond’s 4% coupon is now inadequate. Its price must fall to approximately $960 so that $40 ÷ $960 = 4.17%, making it competitive with 5% yields.

Conversely, when rates fall, existing bonds become more attractive, and their prices rise.

This inverse relationship (price down, yield up; price up, yield down) is the cornerstone of bond markets.

Duration as the risk measure

Duration quantifies this risk. A bond with a duration of 7 years will:

• Lose 7% if rates rise 1% (e.g., from 4% to 5%)
• Gain 7% if rates fall 1% (e.g., from 4% to 3%)
• Lose 14% if rates rise 2%
• Gain 14% if rates fall 2%

This linear approximation (duration × rate change) is accurate for small rate moves. For large moves, convexity (the curvature) becomes material.

Sources of duration risk

Maturity is the primary source. A 30-year bond has longer duration than a 5-year bond, making it more sensitive to rates.

Coupon is secondary. A zero-coupon bond has duration equal to maturity. A high-coupon bond has duration much shorter than maturity (coupons returned early).

Yield level affects duration. A high-yield bond has lower duration than a low-yield bond of the same maturity.

Examples of duration risk

Treasury bonds: A 30-year Treasury with duration of 17 loses 17% if rates rise 1%. If you bought at par ($100,000) and rates subsequently rose 1%, your holding is worth $83,000 (17% loss).

Corporate bonds: A 10-year BBB corporate with duration of 8.5 loses 8.5% per 1% rate rise. In a rising-rate environment, many corporate bond holders suffer capital losses.

High-yield bonds: A high-yield bond with 5-year duration loses 5% per 1% rate rise. Though less duration-sensitive than longer bonds, high-yield bonds can suffer 15%+ losses in sharp rising-rate environments.

When duration risk matters

For buy-and-hold investors: Duration risk is irrelevant. If you hold the bond to maturity, you receive full principal regardless of price fluctuations. The coupon is fixed, and duration risk is immaterial.

For investors who sell before maturity: Duration risk is material. If you buy a bond and sell it in an environment where rates have risen, you suffer capital loss proportional to the bond’s duration.

For portfolio rebalancing: If you hold bonds but need to rebalance periodically, duration risk requires selling some bonds. A rising-rate environment forces selling at depressed prices.

For liability matching: If your liabilities are due in 10 years and you hold 30-year bonds, duration mismatch creates risk. If rates rise, bond prices fall, but your liability remains fixed. This creates shortfall risk.

Mitigating duration risk

Reduce duration: Buy shorter-maturity bonds or lower-duration bonds. A 5-year bond is less sensitive than a 30-year bond.

Increase coupon: Buy high-coupon bonds, which have lower duration. But this trades one risk (duration) for another (credit risk if issuer weakens).

Immunization: Match portfolio duration to liability duration. A 10-year liability is matched with 10-year duration bonds.

Hedging: Use interest-rate derivatives (Treasury futures, interest-rate swaps) to offset duration risk. But this adds cost and complexity.

Accept volatility: For risk-on investors with long horizons, accept the volatility and be compensated with higher returns. Over decades, bonds have outperformed inflation.

Duration and Fed policy

The Federal Reserve’s interest-rate policy is the primary driver of duration risk. When the Fed hikes rates aggressively (as in 2022–2023), all bonds with duration exposure suffer losses.

Conversely, when the Fed cuts rates (as in 2019–2020), bonds rally sharply. Long-duration bonds provide outsized gains.

See also