Duration is a risk measure for bonds and bond funds. In plain terms, it estimates how much a bond’s price tends to move when interest rates change. If a fund’s effective duration is about 6 years, a rough rule of thumb is that a 1 percentage-point rise in yields may push the price down on the order of ~6% (and the reverse when yields fall)—before counting coupon income. Duration is why “safe” intermediate bond funds at Vanguard, Fidelity, or Schwab can show negative years when the Federal Reserve hikes.
This is not the same as maturity (the date principal is scheduled to repay). A bond can mature in 10 years and have a duration shorter than 10 because coupons arrive along the way. Fund vs ladder context: Bond funds vs bond ladders. First-dollar investing frame: Investing basics for beginners.
Duration vs maturity vs “interest-rate risk”
| Term | What it answers | Consumer takeaway |
|---|---|---|
| Maturity | When final principal is due | Ladder rungs are labeled by maturity |
| Duration (Macaulay / effective) | Sensitivity of price to yield changes | Higher duration → bumpier fund NAV when rates move |
| Credit risk | Chance issuer pays late or not at all | Separate from rate risk; corporates ≠ Treasuries |
When rates rise, existing bonds with lower coupons look less attractive, so their prices fall. When rates fall, prices of existing bonds often rise. Long-duration funds move more than short-duration funds or T-bills. Cash-like Treasuries: Treasury bills for cash.
Where you see duration on a fund page
On a bond mutual fund or ETF factsheet (Vanguard Total Bond Market, iShares Core U.S. Aggregate, Fidelity U.S. Bond Index, and similar), look for:
- Average effective duration (years)
- Average maturity (often longer than duration)
- SEC yield / distribution yield (not a promised forward return); for individual bonds, rank-order quotes with Yield to maturity basics
A short-term bond fund might show ~2-year duration; an intermediate aggregate fund ~6 years; a long Treasury fund ~15+ years. Those numbers explain why two “bond” tickers behave differently in the same rate move. Expense ratios still matter inside the sleeve: Expense ratios.
Worked example: two funds, one rate jump
Casey holds $20,000 for a goal seven years out and compares:
- Fund S: short-term Treasury ETF, effective duration 1.8 years
- Fund L: long-term Treasury ETF, effective duration 16 years
Illustrative only: yields rise 1 percentage point across the curve. A duration-based sketch suggests Fund S might fall on the order of ~2%, Fund L on the order of ~16%, before coupons. Casey’s seven-year goal does not require Fund L’s volatility; a ladder of Treasuries or a short/intermediate fund may fit better—see Treasury bond laddering. Tax-exempt muni funds carry duration too: Municipal bonds basics. Buying an individual taxable bond above par also has tax-basis rules: Bond premium amortization basics.
How those duration numbers play out when yields are rising—including total return vs NAV: Bond funds in a rising-rate world.
How duration fits allocation
Asset allocation decides how much you hold in bonds at all (Asset allocation basics). Duration decides which bonds. A 40% bond sleeve built from long Treasuries is a different risk profile than 40% in short Treasuries or a bond ladder you hold to maturity.
Practical cues (not advice):
- Money needed in under ~3 years: prefer cash, T-bills, CDs, or very short duration—not a long bond fund.
- Multi-year dry powder you can leave invested: intermediate funds or ladders are common tools.
- Do not buy long duration just because the headline yield looks higher after a selloff without accepting NAV swings.
Long Treasury bonds carry more duration than intermediate notes or short bills: product labels in Treasury notes vs bonds.
Call features can shorten the cash-flow path you expected: Callable bond risks.
Checklist
- Read effective duration on any bond fund before you buy.
- Separate rate risk (duration) from credit risk (issuer quality).
- Match duration to when you need the dollars.
- Remember coupons cushion total return but do not erase price declines.
- Revisit duration when you rebalance or change goals.
- Use ladders when you need specific payoff dates more than fund liquidity.
When rate shocks are large, duration alone understates the curved price path—see Bond convexity basics.
Educational only. Not investment advice. Duration approximations omit convexity, spreads, and fees; fund factsheets and prospectuses control.