A fixed-rate bond does not change its promised coupon just because interest rates rise. However, the market value of that bond can fall because new bonds may now offer investors higher interest payments.
The key is to separate the bond’s contractual payments from the price another investor is willing to pay for it today. This is interest-rate risk: a change in market value that can happen even when the borrower continues to make every promised payment.
When rates rise, newly issued bonds can offer higher yields. An older fixed-rate bond with a lower coupon becomes less attractive at its old price, so its market price may need to fall to give a new buyer a competitive yield. Longer-maturity and higher-duration bonds are generally more sensitive to this repricing. This is different from default risk, and it works differently for a bond fund than for one bond held to maturity.
The coupon stays fixed, but the market price does not
A fixed-rate bond is an IOU with stated terms. The issuer promises scheduled interest payments, called coupons, and repayment of principal at maturity under those terms. If the bond was issued with a lower coupon, a later rate hike does not cause the issuer to increase that coupon for existing holders.
What changes is the comparison available to a new buyer. If newly issued comparable bonds now offer more interest, an older bond paying less is unlikely to attract a buyer at the same price as before. Its price can fall until the return available from buying it becomes more competitive with the new market rate.
A simple yield comparison explains the price move
Coupon and yield are related, but they are not the same thing. The coupon is the fixed payment written into the bond’s terms. Yield is the return a buyer expects based on the price paid today and the bond’s future cash flows.
When an investor buys an older bond below its face value, the unchanged coupon is spread over a lower purchase price. If the bond is then repaid at its stated principal amount at maturity, that difference between the purchase price and repayment can also contribute to the investor’s return. This is why a lower price can help an older, lower-coupon bond compete with newer bonds.
Why maturity and duration matter
Maturity is the date when a bond’s principal is due under its terms. It is an important clue to interest-rate sensitivity because a bond with more time remaining has more future fixed payments being compared with the new rate environment.
Duration is a common way to describe how sensitive a bond’s price may be to changes in yields. It considers the timing of the bond’s payments, not only its final maturity date. As a practical rule, a bond with a longer maturity or higher duration is usually more exposed to price changes when market rates move.
A modified duration of 7 years is a rough estimate: it says a 1-percentage-point rise in market yields corresponds to roughly a 7% fall in price. This shortcut works best for small, single-step rate moves; it does not capture the fact that the relationship curves slightly (a property called convexity), so a very large or repeated rate move would need a more complete calculation. A bond with a shorter duration, say 2 years, would see roughly a 2% move for the same 1-point yield change — a much smaller swing.
| Bond characteristic | Why a rate rise can matter | What the investor should understand |
|---|---|---|
| Shorter remaining maturity | There are fewer future payments priced against the new market rate. | Its price can still move, but the period of exposure is shorter. |
| Longer remaining maturity | More fixed payments lie further in the future while new bonds may offer higher rates. | Its market price is generally more sensitive to rate changes. |
| Higher duration | Its cash-flow pattern is more sensitive to changes in required yield. | Duration is an estimate of price sensitivity, not a promise of a specific outcome. |
A falling bond price is not the same as a default
Interest-rate risk is the risk that a bond’s market price changes when market interest rates change. If you need to sell after rates have risen, you may receive less than the price you paid. That price decline can happen even if the issuer remains able to make its scheduled payments.
Default risk is different. It is the risk that the borrower cannot meet the promised interest or principal payments. A bond can have interest-rate risk without a default, and an investor can face default risk regardless of whether market rates rise or fall.
Holding an individual bond to maturity means you may not need to sell it at today’s market price. It does not remove the risk that the issuer fails to meet its obligations. It also does not apply to a bond fund in the same simple way, because a fund does not usually have one shared maturity date for all investors.
Why a bond fund does not simply mature like one bond
An individual bond has its own coupon, issuer, and maturity date. If you hold that bond until maturity, the stated repayment is governed by its terms and the issuer’s ability to pay. The market price along the way matters most if you sell before maturity.
A bond fund is a wrapper that holds a group of bonds rather than one single bond. Its holdings can have different maturity dates, and maturing bonds can be replaced with new ones. The fund itself can continue rather than reaching one date when every investor receives a fixed face-value repayment.
That means a bond fund’s share price can fall when rates rise, and there is not necessarily a future date when the whole fund simply matures back to a set value. As the fund’s holdings change over time, its exposure to the rate environment can change too.
What to check before buying or selling
Do not judge a bond only by its coupon. Ask what yield the market is offering now, how long the bond has until maturity, and whether the price has already adjusted to the current rate environment. These questions help explain why two bonds with similar issuers can trade at different prices.
Also identify the wrapper before you act. Buying one bond and buying shares in a bond fund may both provide bond exposure, but their maturity experience and price behaviour are not identical. Understanding that difference can prevent a temporary market-price move from being mistaken for a broken contract.
- Check whether the coupon is fixed and compare it with current market yields.
- Look at the remaining maturity and recognise that duration describes rate sensitivity more directly.
- Separate interest-rate risk from the issuer’s ability to make payments.
- Decide whether you own an individual bond or a continuing bond fund.
- Consider whether you may need to sell before an individual bond reaches maturity.
