A bond fund can be a sensible long-term investment and a poor place for a down payment due in six months. Its yield does not resolve that conflict. Your deadline does.
The iShares Core U.S. Aggregate Bond ETF, or AGG, reported a 5.22% average yield to maturity and 5.74 years of effective duration, both dated September 10, 2026. The first number describes the portfolio's yield; the second estimates its sensitivity to changes in market yields. Neither tells you what you will earn by the day you need to sell. iShares portfolio data
Put $10,000 against that duration. A hypothetical one-percentage-point rise in the relevant yields implies an immediate price decline of about $574, before income. A comparable fall implies an approximate gain of the same size. Those are sensitivity estimates, not forecasts.
The useful question is therefore more specific than whether bonds are attractive: Can this money stay invested through a price decline, or must it fund a payment on a particular date?
The number that does not appear on the factsheet
Imagine two people considering the same fund. One needs the money for a house closing in six months. The other is building the bond allocation of a retirement portfolio with no planned withdrawal for a decade. These are hypothetical investors, not reported case studies.
For the first, an interim loss can become a shortfall at closing. For the second, lower prices may coincide with higher yields available for reinvestment. Time can change the balance between those effects. It does not eliminate risk or ensure a profit. Vanguard on higher yields and investment horizons
A person can be both investors at once: long-term retirement money in one account, next year's tuition in another. An account label such as “savings” or “brokerage” does not establish the time horizon of every dollar inside it.
Start with the payment, then work backward to the investment.
What 5.74 years actually means
Duration is stated in years, but it is not a withdrawal restriction, a maturity date, or a countdown to recovering a loss. In the price-sensitivity sense used here, it translates a change in yield into an approximate change in price:
Price change (%) ≈ −duration × yield change (percentage points).
A duration of 5.74 and a yield increase of one percentage point give an estimated price change of −5.74%. Multiplying by $10,000 gives −$574. A half-point increase gives approximately half that price effect. FINRA's duration explainer
There are three limits to that arithmetic. It estimates an immediate price change, not a total return over a year. It assumes a parallel move in the relevant yields, whereas a Fed decision need not move all yields together. And it holds duration fixed for the estimate; actual duration and cash flows can change.
AGG also holds corporate and mortgage-backed debt. Credit spreads and changes in mortgage repayments can affect its results. Duration isolates one source of risk; it does not turn the entire portfolio into a Treasury bond. AGG prospectus and fund documents
Do not subtract 5.74% from 5.22% and call the result a one-year return forecast. One number describes immediate price sensitivity; the other is a portfolio yield measure. The timing of rate changes, distributions, reinvestment, expenses, and changes in holdings all matter.
Cash protects a different kind of certainty
A savings balance can remain steady while its income falls. A fixed-rate bond can keep paying its coupon while its resale value falls. These are different forms of stability.
This distinction helps separate five products that often appear on the same shortlist:
High-yield savings. A bank deposit has no bond-style daily market price for the depositor. Its interest rate can change. Eligible deposits are FDIC-insured up to $250,000 per depositor, per insured bank, per ownership category; accounts in the same category at one bank are combined. That protection does not freeze the APY. FDIC coverage
Treasury bills. Bills are issued with terms from four to 52 weeks, bought at a discount or at face value, and repay face value at maturity. A bill due before a known expense can avoid the need to sell early. Rolling it into another bill exposes you to the next available yield. TreasuryDirect: bills
Treasury notes. Newly issued notes run from two to ten years and pay fixed interest every six months. They can trade below your purchase price before maturity. A ten-year note and a note with three months remaining are very different exposures: the remaining cash flows matter. TreasuryDirect: notes
Money market funds. Government and retail money funds generally seek a stable $1 share price, while certain institutional funds have floating prices. None is FDIC-insured. Income changes as short holdings mature or reset. Their regulatory maturity measures are not interchangeable with effective duration. SEC: money market funds
Ultrashort bond funds. Their prices fluctuate, and holdings can introduce corporate-credit or securitized-debt risk. A short duration does not make them insured deposits or money market funds. Check the actual portfolio, fees, and effective duration rather than relying on the category name. SEC: ultrashort bond funds
Savings and money funds belong in this comparison, but forcing them onto a conventional bond-duration scale would imply a precision they do not have. “Cash equivalent” also has narrower accounting meanings; this is a household-planning comparison, not an accounting classification.
How much price movement are you accepting?
The illustration below uses the same $10,000 balance and one-percentage-point yield increase across five hypothetical examples. The Treasury notes start at par with 4% coupons and yields; the ultrashort duration is an assumption, not a category average.
Explore the rate risk
What could a yield move do to your money?
Change the amount or move the slider. Bars show the estimated immediate price change, before income.
Losses extend left; gains extend right. Select any bar to see the calculation.
3-month bill: −$25 (-0.25%)
$10,000 × −0.2451 duration × 1.00% yield change. Uses unrounded duration.
Zero-coupon teaching model. This is price sensitivity, not your return over a holding period.
Hypothetical examples. Treasury notes assume 4% coupons and yields; the bill uses a zero-coupon teaching model. Ultrashort duration is assumed. First-order parallel yield shift; excludes income, fees, taxes, credit changes and convexity. Larger moves make the approximation less precise.
The difference matters most when you may need to sell. An individual Treasury held to maturity repays face value if paid as promised, even if its market price fluctuates along the way. Face value may differ from your purchase price. A standard bond fund keeps managing a portfolio; its average maturity is not a date on which it promises to return your original investment. FINRA: bond funds
Market liquidity is a separate question. Being able to sell quickly does not mean being able to sell without a loss. Account rules matter too: TreasuryDirect requires a transfer to a bank, broker, or dealer for an early sale, and its initial 45-day holding restriction prevents transferring a four-week bill before maturity. TreasuryDirect sale rules
The strongest argument for taking duration risk
Avoiding price swings has a cost: you may have to accept a new interest rate sooner.
Suppose $10,000 earns a simple 4% annual rate. If that rate falls to 3% halfway through the year, income totals $350 instead of $400. The principal has not fallen. The income available to spend has.
A one-year fixed-rate instrument bought at par at the same simple 4% rate would preserve its scheduled $400 of annual interest, assuming payment as promised. Selling it before maturity could still expose you to a price change. This example is hypothetical and excludes fees, taxes, and compounding.
For money with a flexible, longer horizon, locking in fixed cash flows or maintaining a bond allocation can be a deliberate choice. Rising yields can improve reinvestment opportunities after an initial price decline; falling yields can lift prices while reducing future reinvestment income. Which effect dominates depends on the path of rates and withdrawals.
That is why 5.74 years is not a guaranteed break-even period. A rolling fund does not automatically shorten its exposure as your deadline approaches. Revisit the allocation as the spending date gets closer.
First compare the yield definitions
AGG's 5.22% is an average yield to maturity. It is not a savings APY, a promised annual distribution, or a guaranteed return on the fund. The issuer also publishes a separate 30-day SEC yield. Different labels answer different questions.
| Label | What it measures |
|---|---|
| APY | Annual deposit interest including compounding, under stated assumptions. |
| 7-day yield | A recent week of money-fund income, annualized. |
| 30-day SEC yield | A standardized annualized bond-fund income measure after expenses. |
| Yield to maturity | A bond's price relative to its promised cash flows. |
A variable APY assumes a rate that may not persist. A bond's yield to maturity uses promised payments; achieving the associated compounded outcome also depends on reinvestment. A fund's portfolio yield is not a contractual maturity payout to its shareholders. CFPB: APY, Fidelity yield definitions
More duration does not always offer more yield, either. The Treasury yield curve can slope upward, flatten, or invert. An inverted curve can offer a higher yield at a shorter maturity. These diagrams show possible shapes, not current market rates. Fidelity: yield curves
Taxes can change the comparison. Direct Treasury interest is generally exempt from state and local income taxes; bank interest generally is not. Fund distributions require their own tax review. And even a stable nominal balance can lose purchasing power to inflation. IRS: interest income
Give each dollar a deadline
A hypothetical household has $30,000: $10,000 for unpredictable expenses, $10,000 for a payment in about three months, and $10,000 for another in about six months.
The emergency portion calls for dependable access. The dated payments can be compared with securities maturing before they are due, leaving room for settlement and transfers. The illustration is a planning method, not a recommended allocation.
Before buying, record four things: the amount needed, the spending date, the loss you can tolerate before that date, and when sale or maturity proceeds become spendable. Then compare net yields, insurance, credit exposure, fees, and account restrictions. The Treasury bill ladder calculator and cash comparison calculator can help test the arithmetic.
The 5.22% yield deserves attention. So does the 5.74-year duration. But the deciding number belongs to you: how long until this money has to do its job?
Sources and method
Reviewed September 12, 2026. AGG's yield and effective duration are issuer-reported observations dated September 10, 2026, checked against the iShares portfolio page. They are a dated snapshot, not a live quote or a recommendation to buy the fund. The $574 sensitivity calculation is our first-order estimate using that reported duration; it is not an observed loss.
All other numerical investment scenarios are hypothetical. Note durations use par bonds with 4% annual coupons and 4% nominal yields, semiannual compounding, and exact coupon dates. The bill is a zero-coupon teaching model using that same compounding convention, not an auction discount-rate quote. Modified durations are independently checked against small-change repricing. Effective duration is a different measure used for the issuer's AGG figure.
Price estimates exclude income, taxes, fees, credit-spread changes, and convexity, and assume a parallel yield shift. The income example uses simple interest with interest withdrawn. Curve shapes are schematic. Sources are linked beside the claims they support; calculations are available below.
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Turn the article into a next step.
SwitchWize takeaway
Find your number, not the market's.
Run a Money Map to see how your cash, debt, and rates stack up against the best available options.
Start Money Map →AGG yield and effective duration are issuer observations dated September 10, 2026. Other numerical scenarios are hypothetical, not current offers or forecasts. Calculated Treasury durations assume 4% coupons and yields with semiannual compounding; the bill uses a zero-coupon teaching model. Ultrashort duration is an assumption. Sources and downloadable calculations appear in the article.