Definition
Credit risk is the possibility that a borrower pays late, restructures, or defaults. A credit spread is the extra yield a risky bond offers over a similar-maturity Treasury. It compensates investors for expected losses, uncertainty, and reduced liquidity.
Ratings summarize an agency's view of creditworthiness. Investment-grade bonds are rated BBB-/Baa3 or above; lower ratings are generally called high yield. Ratings can change and are not guarantees.
A spread is quoted in basis points (100 basis points = 1 percentage point). A corporate bond at 5.6% next to a 4.0% Treasury of similar maturity has a 160-basis-point spread. That extra yield is the market's price for credit, liquidity, and uncertainty — not free income.
This is a risk lesson, not an ETF-wrapper type. The same spread math applies to a single bond, a corporate ETF such as LQD, a high-yield fund such as HYG, or the credit sleeve inside a broad fund such as BND.
Why It Matters
A bond fund's yield is not free income. A wider spread may signal attractive compensation, rising fear, or deteriorating borrowers. During recessions, spreads can widen sharply and bond prices can fall even when Treasury yields decline. Income investors therefore need both yield and credit risk.
Duration explains how a fund moves when *Treasury* yields change. Spread duration explains how it moves when the *gap* over Treasuries changes. A "safe" investment-grade fund can still lose several percent if spreads gap wider, even if the Fed has not hiked.
High-yield and loan funds pay more because default and downgrade risk is the product. In a risk-off month they often trade more like equities than like Treasuries. Ranking them next to SGOV on SEC yield alone hides that difference.
Example
The yields below are illustrative, not live quotes.
A five-year Treasury yields 4.0%, while a similar-duration corporate bond yields 5.6%. Its spread is 1.6 percentage points, or 160 basis points. If the spread later widens to 260 basis points while Treasury rates stay unchanged, the corporate bond's price will generally fall.
A rough price sketch: if the bond's spread duration is 5 years, a 100-basis-point widening implies about a 5% price decline before coupons. The extra yield still arrives, but the mark-to-market hit can erase more than a year of that extra coupon.
The same pattern shows up in ETFs. A high-yield fund whose spread goes from 300 to 500 basis points can drop even as its 30-day SEC yield looks more "attractive." The higher printed yield is often the scar, not the prize.
What to Review on a Bond ETF
- Average rating and the tail. A BBB-heavy "investment-grade" fund can have a junk sleeve that drives losses.
- Spread versus its own history. A rich spread can mean cheap bonds or a worse cohort.
- Sector and issuer concentration. Energy, banks, or a few large names can dominate a "diversified" credit fund.
- Seniority. Loans, high-yield bonds, and CLOs do not share the same recovery profile. See CLO and senior-loan ETFs.
- Total return, not coupon. Income plus price change is the result that pays bills.
Common Mistakes
- Treating a high SEC yield as a guaranteed return.
- Looking only at a fund's average rating and missing lower-rated holdings.
- Assuming diversification removes economy-wide default and downgrade risk.
- Confusing a Treasury-rate move with a credit-spread move.
- Buying the widest-spread fund in a category without asking why the spread is wide.
FAQ
What is spread duration?
Spread duration estimates how much a bond portfolio may move when credit spreads change by one percentage point, similar to how interest-rate duration handles Treasury yields.
Are investment-grade funds risk-free?
No. They have lower expected default risk than high-yield funds, but still face rate, downgrade, spread, and liquidity risk.
Why can a credit ETF fall when Treasuries rally?
Treasuries rally when rates fall or when investors flee risk. Credit spreads can widen in that same flight, offsetting some or all of the rate rally for corporates and junk.
