Swap Spread

In an interest rate swap, two counterparties exchange cash flows: one party pays a fixed interest rate while the other pays a floating rate (historically tied to LIBOR, now more commonly to SOFR). The fixed rate agreed upon in the swap is called the swap rate. The swap spread is the difference between this swap rate and the yield on a U.S. Treasury bond of the same maturity. For example, if the 10-year swap rate is 4.50% and the 10-year Treasury yield is 4.20%, the 10-year swap spread is 30 basis points.

Historically, swap spreads were positive — meaning swaps traded at higher yields than Treasuries of the same maturity. This positive relationship reflected the credit risk embedded in swaps: unlike Treasuries, which carry the full faith and credit of the U.S. government, swaps are bilateral contracts with counterparty credit risk (though this risk is substantially mitigated by central clearing, which became standard after the Dodd-Frank Act). In addition, Treasuries commanded a liquidity premium as the global safe-haven asset, further justifying their lower yield relative to swaps.

The level of swap spreads historically served as a gauge of financial conditions. Widening swap spreads — meaning swaps yielding significantly more than Treasuries — historically coincided with periods of credit stress and elevated counterparty risk concerns, as observed during the 2008 financial crisis. Narrowing swap spreads indicated calmer credit conditions.

An unusual phenomenon that began around 2015 and became more prominent in subsequent years was the emergence of negative swap spreads at longer maturities — particularly the 30-year swap spread. In this condition, the 30-year swap rate fell below the 30-year Treasury yield, seemingly inverting the credit risk logic. Analysts attributed this anomaly to several factors: heavy Treasury supply pressures, regulatory changes that increased the cost of holding Treasuries on bank balance sheets, strong demand from pension funds and insurance companies for fixed-rate swap receivers, and the mechanics of the post-Dodd-Frank central clearing regime.

Swap spreads are closely monitored by fixed income portfolio managers, corporate treasurers, bank risk managers, and central bank analysts. Because corporations frequently use interest rate swaps to manage the duration risk of their debt — converting fixed-rate bonds to floating-rate obligations or vice versa — swap spread levels directly affect corporate financing costs and hedging economics.

The swap spread market also reflects the plumbing of the financial system in ways that are not always visible on the surface. Persistent anomalies in swap spreads — like the extended negative 30-year spread observed in the mid-2010s onward — can signal structural changes in who owns Treasuries, how financial institutions are funded, and how regulatory capital rules shape relative asset valuations across the fixed income market.