The interest rate that the issuer of a bond must pay is influenced by a variety of factors, such as current market interest rates, the length of the term and the credit worthiness of the issuer. Since these factors are likely to change over time, the market value of a bond can vary after it is issued.

The market price of a bond is the present value of all future interest and principal payments of the bond discounted at the bond's yield, or rate of return. The yield represents the current market interest rate for bonds with similar characteristics. The yield and price of a bond are inversely related so that when market interest rates rise, bond prices generally fall and vice versa.

The market price of a bond may include the accrued interest since the last coupon date (some bond markets include accrued interest in the trading price and others add it on explicitly after trading). The price including accrued interest is known as the "flat" or "tel quel price". (See also Accrual bond.)

The interest rate adjusted for the current price of the bond is called the "current yield" or "earnings yield" (this is the nominal yield multiplied by the par value and divided by the price).

Taking into account the expected capital gain or loss (the difference between the current price and the redemption value) gives the "redemption yield": roughly the current yield plus the capital gain (negative for loss) per year until redemption.

The relationship between yield and maturity for otherwise identical bonds is called a yield curve.