Bond ETFs: Duration, Credit Risk, Yield, and Portfolio Role

BND seeks to track the Bloomberg U.S. Aggregate Float Adjusted Index, while AGG seeks to track the Bloomberg US Aggregate Bond Index. Both provide broad investment-grade U.S. bond exposure, but their benchmark construction and implementation are not identical.

A broad aggregate fund can hold U.S. government, agency, mortgage-backed, and investment-grade corporate debt. It does not represent every bond or eliminate credit, prepayment, or interest-rate risk.

Duration is a measure used to assess a bond or bond fund’s sensitivity to changes in interest rates. It is an estimate, not a guarantee, and large rate changes or embedded options can make realized behavior differ.

A short-term bond ETF and a long-term Treasury ETF can respond very differently even when both are labeled fixed income. Compare effective duration and maturity distribution before comparing yields.

The 30-day SEC yield is a standardized measure; trailing distributions and yield to maturity are different measures. Each is dated and can change as holdings, prices, and interest rates change.

A higher yield may reflect longer duration, lower credit quality, optionality, or another source of risk. Yield alone does not reveal the stability or total-return behavior of the fund.

An individual bond has a stated maturity, subject to default and call provisions. A bond ETF continually holds and replaces securities under its mandate, so the shareholder does not receive a single promised principal payment on a personal maturity date.

Bond ETF shares trade at market prices and can lose value. For near-term obligations, compare the fund’s duration and volatility with Treasury bills, insured deposits, money market funds, or a defined bond ladder as applicable.