Treasury Yields Hit 5.15%. Why Is Your Bond Fund Losing Money?

You bought a bond fund for income. Watching its balance fall while yields rise can feel like being charged for the improvement.

The U.S. 10-year Treasury yield reached about 5.15% during Thursday, September 24 trading, its highest since 2007, according to Reuters, whose report is also carried by CNA. Longer-dated yields subsequently retreated from their earlier highs but remained elevated as inflation concerns unsettled markets. These figures describe the September 24 Reuters report’s intraday snapshot, not closing figures or live quotes.

For someone shopping for income, higher yields can look inviting. For someone already holding a bond fund, the account balance may tell a less cheerful story. Understanding why takes one number that tends to get much less attention than the advertised yield.

Your old bond has new competition

Imagine you own a fixed-rate bond paying $40 a year on $1,000 of face value. Comparable new bonds now offer more income. A buyer looking at yours will generally want a lower purchase price to make its smaller payments competitive.

The payments didn’t suddenly shrink. The price someone will pay for them changed. When a fund owns those bonds, their changing market values feed into the fund’s value.

The SEC’s bond-fund guidance makes an easily missed point: even a fund holding U.S. government bonds can lose money as interest rates rise. Confidence that the borrower will repay and stability of the price you can sell at are separate questions.

Look for “duration” on the fact sheet

Duration estimates how sensitive a bond or bond fund’s price is to changes in yields. It’s expressed in years, which is an excellent way to make a useful concept sound like paperwork.

As FINRA explains, a higher duration generally means a larger price reaction. For a rough estimate, use effective or modified duration and multiply it by the change in yield, with the price moving in the opposite direction.

Here’s a hypothetical $20,000 holding. Assume relevant yields rise by half a percentage point, such as from 5% to 5.5%, across the portfolio. That’s a 0.5-percentage-point change, not a 0.5% relative increase.

These are approximate immediate price effects before interest income, fees and taxes. Actual results depend on the portfolio, changes in credit conditions and the shape of the yield curve. Duration is an estimate, and its accuracy weakens for larger moves. This table doesn’t describe today’s returns or any particular fund.

Still, $200 versus $1,500 is a meaningful difference when both holdings appear under “fixed income” on a brokerage screen.

A bigger income number needs some context

I wouldn’t dismiss higher yields. They can improve the income available on new investments. But I’d be wary of choosing a fund by sorting the yield column from highest to lowest and declaring the research complete.

Check what the figure measures and its date. A trailing distribution yield based on past payments and a standardized SEC yield aren’t interchangeable, and neither guarantees your total return. Price changes count too.

Vanguard’s guide highlights maturity and credit quality as considerations when choosing bond funds. Reaching for extra income may mean accepting more sensitivity to rates, more risk that borrowers struggle to pay, or both. A lower-duration fund still needs a credit-risk check.

Put a dollar figure next to the discomfort

Open your fund provider’s current fact sheet and find effective or modified duration. Note the date. Use the half-point example above to estimate a price change on your actual holding, then compare that amount with when you’ll need the money.

Someone funding a bill in six months has a different problem from someone building retirement income over fifteen years. “I own bonds for safety” is too vague to settle either decision. Safety from what, and until when?

There’s no need to guess the next Fed decision to do this exercise. Write down the fund’s duration, the rough dollar sensitivity and the date you expect to spend the money. If those three things surprise you when placed together, you’ve found something worth investigating before the next yield headline arrives.

General information, not personalized investment advice.

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