Duration

Duration is best understood as a bond's "sensitivity gauge." If a bond has a duration of seven years, a one-percentage-point rise in interest rates would cause its price to fall by roughly seven percent, and a one-percentage-point decline in rates would push its price up by roughly the same amount. The longer the duration, the more volatile the bond's price will be as rates move.

For families managing substantial fixed-income holdings — discussed further in our fixed income overview — duration is a primary tool for understanding how much interest-rate risk lives in a portfolio. A family holding long-duration bonds before a period of rising rates could see meaningful paper losses, even if those bonds eventually pay every dollar promised.

A common confusion: duration is not the same as maturity. A thirty-year bond paying large annual coupons has a shorter duration than a thirty-year zero-coupon bond, because the coupon payments return cash earlier, reducing average waiting time. Duration blends both the timing and size of every cash flow into a single number, making it more informative than maturity alone for measuring rate sensitivity.