Bond investors often focus on a bond's yield, maturity date, and credit quality. Another important measure is duration, which helps estimate how sensitive a bond or bond portfolio may be to changes in interest rates.
Duration is especially relevant for investors who hold bond funds or individual bonds that may be sold before maturity.
What duration measures
Duration is a measure of the timing and present value of a bond's expected cash flows. Modified duration is commonly used to estimate how much a bond's price may change when market interest rates move.
As a general rule, a bond with a longer duration is more sensitive to interest-rate changes than a bond with a shorter duration, all else being equal.
A simplified example
Imagine a bond portfolio with a modified duration of five years. A one-percentage-point increase in market yields would generally correspond to an estimated price decline of about 5%, while a one-percentage-point decrease would generally correspond to an estimated price increase of about 5%.
This is only an approximation. Actual results can differ because of convexity, credit spreads, changing cash flows, embedded options, and other market factors.
Why bond funds can lose value
A bond fund does not have a single maturity date in the same way that an individual bond does. Its duration can change as the manager buys and sells securities, receives payments, and adjusts the portfolio.
Even when a bond fund pays income, its share price can decline if market yields rise. Income distributions do not guarantee that the investor's total return will be positive over a particular period.
Match duration to your needs
Investors saving for a near-term expense may be uncomfortable with a bond fund that has substantial interest-rate sensitivity. Someone with a longer investment horizon may be more able to tolerate temporary price changes.
Investors should review a fund's stated duration, maturity profile, credit quality, and expense ratio. Duration is one tool for understanding risk, not a complete measure of safety.
Bottom line: Bond duration helps investors understand how fixed-income investments may react to interest-rate changes. Checking duration alongside credit quality and investment horizon can provide a clearer picture of potential volatility.
This article is for educational purposes and is not individualized investment advice.
