Swap Spread
The swap spread is the difference between the fixed rate on an interest rate swap and the yield of an equivalent-maturity government bond, expressed in basis points. It is a widely used measure of credit risk, liquidity conditions, and market stress in the fixed income markets, reflecting the premium investors demand for holding bank credit risk and less liquid instruments relative to sovereign obligations.
Key takeaways
- Swap spreads are typically positive in normal market conditions, reflecting the credit risk of the banking system (as swap counterparties are predominantly banks) relative to the risk-free government yield.
- Swap spreads widened dramatically during financial crises (e.g., 2008 financial crisis, 2020 COVID shock), serving as leading indicators of banking system stress and liquidity demand.
- In late 2015 and again in 2019, US 30-year swap spreads turned negative, an anomaly attributed to the scarcity of Treasuries relative to MBS hedging demand and balance sheet constraints at primary dealers.
- Basis traders exploit deviations in swap spreads from theoretical fair value through cash-futures basis trades or swap-bond arbitrage, though these strategies require significant leverage and careful margin management.
- Swap spreads are closely related to—but distinct from—credit spreads, OIS-LIBOR spreads, and TED spreads, each measuring a related but different aspect of credit and liquidity conditions.
Explanation
The swap spread occupies a central position in fixed income analytics as a summary measure of the credit premium of the banking system relative to sovereign credit. Theoretically, the swap spread should equal the credit risk of the average counterparty in the interbank lending market—approximately the average credit quality of large international banks—relative to the risk-free Treasury yield. In practice, the swap spread is influenced by multiple additional factors: supply and demand for fixed-rate payers in the swap market, the relative liquidity of swap markets versus Treasury markets, balance sheet constraints of primary dealer banks, and the technical demand for swaps from the mortgage-backed securities market.
The most commonly quoted US swap spread is the 10-year swap spread: the difference between the 10-year USD interest rate swap rate (the fixed rate in a standard receive-fixed/pay-floating swap) and the 10-year on-the-run Treasury yield. Historically, this spread has ranged from 10 to 130 basis points, with the widest levels observed during the 2008 financial crisis (100–130 bps) and the lowest levels during periods of low volatility and abundant banking system liquidity. The spread can be interpreted as the market's consensus assessment of the 10-year bank credit spread, adjusted for the relative liquidity of swap versus Treasury markets.
The puzzling phenomenon of negative 30-year swap spreads in the United States—first observed in November 2015 and persistent in subsequent years—challenged the theoretical foundations of swap spread pricing. A negative swap spread implies that the swap market prices bank credit as safer than US sovereign credit over 30 years, which appears paradoxical. The explanation lies in market technicals: enormous demand for fixed-rate paying swaps from mortgage servicers hedging convexity (duration extension) of their MBS portfolios depresses swap rates below the theoretical fair value; simultaneously, balance sheet constraints prevent dealers from arbitraging the spread by receiving fixed on swaps and purchasing Treasuries (the arbitrage requires leverage that consumes regulatory capital); and the scarcity of long-dated Treasury supply relative to swap demand further compresses the spread. This market structure insight has important implications for fixed income relative value funds attempting to exploit theoretical mispricings.
Swap spreads are also used as hedging instruments by financial institutions managing asset-liability mismatches. A commercial bank that has lent at fixed rates for 5 years but funded itself at floating rates may pay fixed on a 5-year swap to create a synthetic fixed-rate funding profile, purchasing protection against rising rates. The swap spread embedded in this hedge represents the bank's cost of accessing synthetic fixed-rate funding versus directly issuing a fixed-rate bond—a comparison banks make continuously in their treasury management decisions.
In credit analysis and portfolio management, swap spreads serve as reference points for pricing corporate credit and as components of the total yield on corporate bonds. A corporate bond might be quoted as 'Treasuries + 150 bps' or as 'SOFR + 200 bps' or as 'Swaps + 75 bps,' with each convention embedding assumptions about the swap spread level. Asset swap spreads—which express the spread of a bond's cash flows relative to the floating rate leg of a swap package—are a more precise measure of the bond's credit spread that removes the Treasury yield component and is particularly useful for comparing bonds of different maturities and coupon structures.
Formula
Swap Spread = Swap Fixed Rate − Treasury Yield (same maturity)
Example
On a given trading day, the 10-year US Treasury yield is 4.25% and the 10-year USD interest rate swap rate is 4.50%. The 10-year swap spread is therefore 25 basis points (4.50% − 4.25%). During the peak of the 2008 financial crisis in October 2008, the 10-year Treasury yield was approximately 4.00% while the 10-year swap rate was approximately 5.00%, yielding a swap spread of 100 basis points—reflecting severe banking system stress and extreme demand for fixed-rate protection. A fixed income relative value fund observing the 100 bp spread might establish a 'swap-spread tightening' trade by receiving fixed on a $1 billion 10-year swap (at 5.00%) and simultaneously shorting 10-year Treasuries at 4.00%, profiting as the spread normalized to historical levels over subsequent months.
Related terms
Arbitrage Balance Sheet Basis Bond Callable Bond Commercial Bank Convexity Corporate Bond Credit Analysis Credit Risk Credit Spread Duration