Swap Spread

What Is Swap Spread?

The swap spread is the difference in basis points between the fixed rate on a plain-vanilla interest rate swap and the yield on a U.S. Treasury (or equivalent sovereign bond) of the same maturity. For example, if the 10-year Treasury yields 4.20% and the 10-year fixed rate on a standard LIBOR/SOFR interest rate swap is 4.05%, the swap spread is -15 basis points.

Historically, swap spreads were positive — meaning swaps traded at a premium to Treasuries — because swaps carry counterparty credit risk (the risk that a bank defaults on its obligation) while Treasuries are considered risk-free. A positive swap spread therefore reflected appropriate compensation for bank credit risk. The fact that swap spreads turned and remain persistently negative in the 10- and 30-year tenors since 2015 is one of the most structurally important and underappreciated anomalies in modern fixed income.

Why It Matters for Traders

Swap spreads are a critical signal for several market dynamics:

1. Bank and dealer balance sheet capacity: Negative swap spreads reflect the inability or unwillingness of bank dealers to arbitrage the anomaly. Carrying a swap against a Treasury position consumes leverage ratio and regulatory capital under Basel III rules, making the trade economically unviable for most dealers.
2. Systemic stress indicator: Rapidly widening (more positive) swap spreads signal credit stress in the banking sector — markets demanding more compensation for counterparty risk. This is analogous to what LIBOR-OIS spread measured during the Global Financial Crisis.
3. Pension and insurance hedging flows: Large institutional buyers hedge long-duration liabilities by receiving fixed in swaps rather than buying Treasuries (for balance sheet reasons), pushing swap rates down relative to Treasury yields and driving spreads negative.
4. Relative value for fixed income traders: The basis trade between Treasuries and swaps is a core fixed income relative value strategy.

How to Read and Interpret It

• Positive swap spread (e.g., +20 to +50 bps): Normal regime, markets functioning well, mild bank credit risk priced
• Sharply widening positive spreads (e.g., >+100 bps): Acute stress signal — seen during the 2008 crisis when 2-year swap spreads exceeded +160 bps
• Negative swap spreads (e.g., -20 to -50 bps): Structural regime driven by balance sheet constraints and pension demand; now the norm in 10s and 30s
• Rapidly moving toward zero from negative: Often signals stress buying of Treasuries (flight to quality), reducing Treasury yields faster than swap rates fall

Traders also watch the 2s30s swap spread curve — steepening of this curve (2-year spreads more positive than 30-year) often signals credit stress specifically in short-term bank funding.

Historical Context

The most dramatic swap spread widening in modern history occurred in September–October 2008, when the collapse of Lehman Brothers caused 2-year USD swap spreads to surge from approximately +60 bps to over +160 bps in a matter of weeks. This reflected a complete breakdown in confidence in bank counterparties and a desperate flight into Treasury securities.

Conversely, 30-year swap spreads first turned negative in late 2008 and have remained negative for most of the period since 2015, reaching approximately -50 to -60 bps in late 2023. This structural negativity reflects the post-GFC regulatory regime — specifically leverage ratio requirements — which prevent dealers from running the arbitrage that would otherwise push spreads back to fair value.

Limitations and Caveats

Swap spreads are less reliable as pure credit indicators in the post-2015 regulatory environment because structural forces (pension hedging, balance sheet constraints) dominate over pure credit risk pricing. The transition from LIBOR to SOFR also altered swap spread dynamics, as SOFR-based swaps have a different risk profile. Additionally, swap spreads in non-USD markets (EUR, GBP) behave differently due to differing regulatory regimes and sovereign credit dynamics.

What to Watch

• 2-year and 5-year swap spreads as near-term bank credit stress indicators
• 30-year swap spreads for pension de-risking and LDI flow signals
• Fed balance sheet size — QT reduces Treasury supply absorbed by the Fed, affecting relative pricing
• Leverage ratio and supplementary leverage ratio (SLR) regulatory changes that affect dealer capacity
• Corporate bond issuance hedging flows, which receive fixed in swaps and compress swap rates