Bond ETFs Explained: Duration, Yield and How They Differ From Bonds
A bond ETF holds hundreds of bonds in one fund that trades like a stock, but it behaves differently from owning a single bond: it never matures, its payout changes monthly and its price can drift from the value of its holdings. Here is how to read one, and where the trade-offs sit.
A bond ETF bundles many bonds into a single fund whose shares trade on an exchange all day like a stock. It offers diversification and easy trading, but it is not the same as owning a bond. An individual bond has a maturity date and a fixed promise of repayment; a bond ETF does not. Understanding that difference, plus a few numbers on the fund's fact sheet, explains most of what you need to compare these funds.
How a bond ETF works
The fund holds a portfolio of bonds, such as U.S. Treasuries, corporate bonds or municipal bonds, and tracks an index or follows a stated strategy. It collects the interest the bonds pay and passes it to shareholders, usually as a monthly distribution. Shares can be bought and sold during market hours through a brokerage account.
Two prices matter:
- Net asset value (NAV): the per-share value of everything the fund holds, calculated at the end of each trading day.
- Market price: what shares trade for on the exchange right now.
Usually the two stay close, thanks to a process in which large financial institutions create and redeem shares. For more on that mechanism, see How to Evaluate an ETF: Costs, Tracking, Liquidity and What It Holds.
The big difference: no maturity date
When you hold a Treasury note to maturity, you know when the principal comes back and how much it will be, barring default. Interest-rate swings in the meantime affect the market value of your bond but not what you receive at the end.
A standard bond ETF behaves differently. It keeps a roughly constant profile by selling bonds as they get shorter and buying new ones. There is no date on which the fund returns your principal. Your result depends on the price at which you sell, plus the distributions you collected.
| Feature | Individual bond | Typical bond ETF |
|---|---|---|
| Maturity date | Fixed | None; fund rolls its holdings |
| Principal returned at maturity | Yes, if issuer pays | No; you sell shares at market price |
| Income | Fixed coupon | Varies month to month |
| Diversification | One issuer unless you buy many | Often hundreds of bonds |
| Minimum investment | Often $1,000 or more per bond | Price of one share |
| Costs | Dealer markups | Expense ratio plus trading spread |
| Trading | Over the counter, can be less transparent | On an exchange, visible prices |
Neither is better in every case. Individual bonds suit someone who wants a known payment on a known date, as in a bond ladder; see Bond Ladders Explained: How to Build One With Treasuries and CDs. A fund suits someone who values simplicity, diversification and ease of buying and selling.
Duration: the rate-sensitivity number
Duration estimates how much a bond or fund's price is likely to move when interest rates change. It is expressed in years, and the rule of thumb is that a fund with a duration of, say, five years would be expected to move roughly five percent in price for each one-percentage-point change in rates, in the opposite direction. This is an approximation, not a guarantee, and it works best for small moves.
Why this matters:
- Short-duration funds fall less when rates rise, and usually pay less income.
- Long-duration funds can fall sharply when rates rise and can rise strongly when rates fall.
Duration is a better guide than the fund's name. Two funds both called "bond funds" can have very different risk. The fund's fact sheet lists its average duration, and issuers publish it on their websites. For the underlying relationship between rates and prices, see Why Bond Prices Fall When Rates Rise: Yield, Duration and Credit Risk.
Credit quality: who is borrowing
The second risk is credit risk: the chance that a borrower will not pay as promised. Funds differ widely here:
- Treasury funds hold debt backed by the U.S. government, so credit risk is minimal, though they still carry interest-rate risk.
- Investment-grade corporate funds hold bonds from companies rated as relatively safe by the rating agencies.
- High-yield funds, sometimes called junk bond funds, hold lower-rated debt that pays more because the risk of default is higher.
- Municipal funds hold bonds from state and local governments, with interest that may be exempt from federal income tax.
Higher yield usually signals higher risk. When prices in stocks fall, lower-rated bonds often fall with them, while Treasuries have historically tended to behave differently, though that relationship is not fixed.
Reading yield numbers
Funds quote several yields, and mixing them up causes confusion.
- Distribution yield: recent payouts divided by price. It looks backward and can overstate future income if rates are falling.
- SEC yield: a standardized 30-day figure net of fund expenses, designed to let you compare funds on the same basis.
- Yield to maturity: the average yield of the bonds in the portfolio if all were held to maturity, before fund costs.
None of these is a forecast of what you will earn. Because the fund's price moves, your total return, meaning income plus price change, is what ultimately counts.
Costs and trading quirks
Bond ETFs charge an annual expense ratio, which comes out of the fund's returns. Even small differences compound over time, so compare funds with similar holdings. See Fund Fees Explained: Expense Ratios, Loads, 12b-1 and Advisory Fees.
There is also the bid-ask spread, the gap between the price at which you can buy and the price at which you can sell. Large, heavily traded funds usually have narrow spreads. Funds that hold less liquid bonds can see wider spreads and larger gaps between market price and NAV during market stress, because the underlying bonds trade over the counter and may be harder to price on volatile days. Placing a limit order, rather than a market order, helps control the price you pay.
Taxes in brief
Distributions from most bond funds are generally taxed as ordinary income, while qualified municipal bond income may be exempt from federal tax, and Treasury interest is typically exempt from state and local income tax. Selling shares for a gain triggers capital gains tax. Details depend on your situation, so check the IRS and a tax professional.
A checklist for comparing funds
Before choosing between two bond ETFs, look at:
- Duration: how sensitive is the price to rates?
- Credit quality: what share is government, investment grade or high yield?
- SEC yield and expense ratio: are you comparing like with like?
- Holdings and index: how many bonds, and how concentrated?
- Fund size and trading volume: are spreads narrow?
- Premium or discount to NAV: has it stayed close in volatile weeks?
- Structure: open-ended and perpetual, or defined-maturity?
The fund's prospectus and fact sheet answer most of these questions. The SEC's investor education site and FINRA offer neutral explanations of how bond funds work and what to ask before buying.
The takeaway
A bond ETF is a convenient container, not a fixed-income guarantee. Its income varies, its price moves with interest rates and credit conditions, and it has no maturity date. If you want a known payout on a known date, individual bonds fit that need better. If you want broad exposure with easy trading, a fund does the job, provided you understand its duration, credit quality and costs.
Frequently asked questions
Does a bond ETF have a maturity date?
No. The fund keeps buying new bonds as old ones mature or are sold, so it does not return a fixed amount on a set date. Some funds, often called defined-maturity or target-maturity funds, hold bonds that mature around a particular year and then wind down, which is closer to owning a bond.
Can a bond ETF lose money?
Yes. Its share price moves with interest rates, credit conditions and market demand, so it can fall even when the bonds inside are paying interest. Funds holding longer-term or lower-quality bonds generally swing more than funds holding short-term Treasuries.
What is the difference between distribution yield and SEC yield?
Distribution yield looks backward at what the fund paid recently, while SEC yield is a standardized calculation based on the fund's holdings over the past 30 days, net of expenses. SEC yield makes funds easier to compare, but neither figure is a promise of future income.
