how is duration used 
investors need to be aware of two main risks that can affect a bond s investment value credit risk default and interest rate risk interest rate fluctuations duration is used to quantify the potential impact that these factors will have on a bond s price because both factors will affect a bond s expected ytm for example if a company begins to struggle and its credit quality declines investors will require a greater reward or ytm to own the bonds to raise the ytm of an existing bond its price must fall the same factors apply if interest rates are rising and competitive bonds are issued with a higher ytm the duration of a zero coupon bond equals its time to maturity since it pays no coupon 