Understanding bond yields is essential to comparing fixed-income investments meaningfully. A bond's coupon alone doesn't tell the whole story — its yield, which reflects the relationship between price and return, is what actually matters to investors. This guide breaks down how bond yields work and why they shift.

Coupon Rate vs Yield

The coupon rate is the fixed interest rate set when a bond is issued, calculated as a percentage of its face value. It never changes over the bond's life. Yield, however, reflects the bond's return based on its current market price, which fluctuates with supply, demand, and interest rate expectations.

If a bond with a 5% coupon trades below its face value, its yield will be higher than 5%, because the fixed coupon now represents a larger percentage return relative to the lower price paid. The reverse is true if the bond trades above face value.

Current Yield

Current yield is a simple snapshot: annual coupon payment divided by the bond's current market price. It's useful for a quick comparison but ignores what happens at maturity — whether you'll gain or lose relative to what you paid.

Yield to Maturity (YTM)

Yield to maturity is a more complete measure. It estimates the total annualized return an investor earns if they hold the bond until maturity, factoring in:

  • All remaining coupon payments
  • The price paid for the bond
  • The face value received at maturity

YTM is the standard way professionals compare bonds with different coupons, prices, and maturities on equal footing.

Why Prices and Yields Move Inversely

This is the single most important relationship in bond investing. Because a bond's coupon is fixed, its attractiveness relative to new bonds issued at current rates determines its market price.

If interest rates rise after you buy a bond, newly issued bonds will offer higher coupons. Your existing bond becomes less attractive at its original price, so its market price falls until its yield is competitive with new issues.

This dynamic is explored further in our guide to how interest rates affect bond prices.

The Yield Curve

Plotting yields across different maturities for bonds of similar credit quality produces a yield curve. Under normal conditions, longer maturities yield more than shorter ones, compensating investors for tying up money longer. When short-term yields exceed long-term yields — an "inverted" curve — it is often watched closely as a signal of shifting economic expectations.

Credit Risk and Yield

Not all yield differences come from interest rates alone. Bonds from issuers with weaker credit quality must offer higher yields to attract buyers, a gap known as the credit spread. See our guide on government bonds vs corporate bonds for how this plays out in practice.

Common Mistakes

  • Comparing coupon rates instead of yields when evaluating bonds.
  • Assuming higher yield always means a better deal, without checking why it's higher.
  • Ignoring how yield changes affect bond fund net asset values, not just individual bonds.

Conclusion

Bond yields translate price, coupon, and time into a single comparable number, making them the true measure of a bond's return. Understanding the difference between coupon rate, current yield, and yield to maturity — and why yields and prices move in opposite directions — equips you to evaluate fixed-income opportunities with confidence.