Duration.
A definition, in plain English — with the books that teach it.
What it means
Duration measures a bond's sensitivity to changes in interest rates, expressed in years. More precisely, it estimates the percentage change in a bond's price for a 1% change in yield — a bond with duration of 7 years will fall roughly 7% in price if interest rates rise 1%. Longer-maturity and lower-coupon bonds carry higher duration. Portfolio managers use duration to match assets and liabilities and to express a view on the direction of interest rates.
Example
An investor holds a 10-year Treasury bond with a duration of 8.5 years. When the Federal Reserve raises the fed funds rate by 0.75%, yields across the curve move up roughly 0.75%, causing the bond's price to fall approximately 6.4% (8.5 × 0.75%). A shorter 2-year note with duration of 1.9 years loses only about 1.4%.
