What Is Interest Rate Risk in Bonds?
Bond prices and interest rates tend to move like two ends of a seesaw — when one rises, the other typically falls — and understanding why is central to understanding what it actually means to hold a bond.
The short answer
Interest rate risk is the possibility that a bond’s market value falls because prevailing interest rates rise after the bond was purchased. Existing bonds with lower fixed coupons become less attractive once new bonds are issued at higher rates, so their prices adjust downward to compensate a buyer for the difference. This risk affects the bond’s price if sold before maturity; it generally doesn’t affect the scheduled interest and principal payments themselves, which continue under the bond’s original terms.
Why prices and rates move in opposite directions
A bond pays a fixed coupon set when it was issued. If new bonds come to market offering a higher rate, an existing bond with a lower fixed coupon becomes comparatively less appealing, and its price has to drop so that its effective yield lines up with what’s currently available elsewhere. The reverse happens when rates fall: an older bond with a relatively higher fixed coupon becomes more valuable, and its price tends to rise. This relationship is the mechanical core of interest rate risk, and it applies to essentially any bond with a fixed payment stream.
How maturity length changes the exposure
A bond with a longer time to maturity locks in its fixed coupon for longer, which means more future payments are exposed to the gap between the old rate and whatever new rate the market later settles on. That’s why longer-term bonds tend to see larger price swings for a given change in interest rates than shorter-term bonds do. This sensitivity is often measured using bond duration, a figure that translates maturity, coupon, and other terms into a single estimate of how much a bond’s price might move for a given shift in rates.
How coupon size plays a role
Coupon size matters too, somewhat independently of maturity. A bond with a smaller coupon returns a larger share of its total value at maturity rather than through interim interest payments, which tends to make it more sensitive to rate changes than a higher-coupon bond of the same maturity. Zero-coupon bonds, which pay no interim interest at all, sit at the far end of this spectrum and are typically the most rate-sensitive structure for a given maturity.
Who tends to be most exposed
- Long-maturity bondholders. Extended time horizons mean more future cash flows are locked in at a rate that could become outdated.
- Holders of low- or zero-coupon bonds. A smaller stream of interim payments concentrates more value at the far end of the timeline, amplifying price sensitivity.
- Anyone who might need to sell before maturity. A bond held to maturity generally returns its face value regardless of rate swings in between, but a bond sold early is exposed to whatever price the market is offering that day.
What to weigh
Interest rate risk isn’t unique to any one type of bond — it’s a structural feature of fixed-rate debt generally, whether a corporate bond or a treasury security. What varies is the degree of exposure, which depends heavily on maturity length, coupon size, and how likely the holder is to need to sell before the bond matures. Comparing bonds along those dimensions, rather than assuming all bonds carry the same rate sensitivity, is a more useful way to think about this risk.