How can a bond’s yield fall while its credit spread widens?

Define a simple spread convention

The San Francisco Fed describes a common credit-spread measure as the difference between a corporate bond yield and a government benchmark of comparable maturity. Its analysis also discusses influences beyond default risk. A spread is not automatically a direct estimate of default probability.

Use an original fictional worksheet with yields quoted as annual percentages on matching conventions at two dates. Stipulate a comparable-maturity benchmark and no changes in which securities are being compared. This simple subtraction is not a calculation of an option-adjusted or other model-based spread.

Calculate the first date

At Date A, assume the benchmark yield is 4.00% and the fictional corporate bond yield is 6.00%. The difference is 2.00 percentage points, or 200 basis points. One percentage point equals 100 basis points in this notation.

Keep the yield labels and units beside the numbers. A 2-percentage-point difference is not the same statement as saying one yield is 2% higher in relative terms. The worksheet uses differences in annual yield, not a percentage return earned by holding the bond.

Reconcile the second date

At Date B, stipulate that the benchmark falls to 3.00% while the bond yield falls to 5.50%. The spread is now 2.50 percentage points, or 250 basis points. The bond’s yield declined 50 basis points, while its spread widened 50 basis points.

The bridge is −100 basis points of benchmark movement plus +50 basis points of spread movement, yielding −50 basis points of bond-yield movement. The wider relative gap is compatible with a lower absolute yield. No market event or credit-rating change is asserted.

Compare an unchanged bond yield

For a separate fictional Date C measured against Date A, let the benchmark rise from 4.00% to 5.00% while the bond remains at 6.00%. The spread narrows from 200 to 100 basis points, even though the bond’s quoted yield is unchanged.

These examples illustrate relative measurement, not price performance. To explain a real spread change, check the benchmark, maturity, currency, cash-flow and option features, observation times, and yield definitions. Differences in those inputs can change what the subtraction means. A larger spread should not be described as free extra return.

Method, sources, and limits

All dates and yields are fictional, and the differences were checked with decimal arithmetic. The San Francisco Fed’s 2004 explanation was opened on 26 October 2026 for definitions and limitations; none of its historical measurements is reused. No current credit conditions, default probability, fair price, or future outcome was assessed. A real investor’s realized result also depends on actual payments and transaction terms, which this quote-comparison worksheet does not model.