What Is a Credit Spread?
A credit spread is the difference between a bond's yield and the yield on a risk-free security with similar maturity, most often a U.S. Treasury. If a 10-year corporate bond yields 6.5% while the 10-year Treasury yields 4.5%, the credit spread is 200 basis points. That gap is the compensation investors demand for bearing the risk that the issuer defaults, plus a premium for thinner liquidity.
Spreads scale with credit quality. Investment-grade bonds might trade 80 to 150 basis points over Treasuries, while high-yield bonds often trade several hundred basis points over, and names beyond 1,000 basis points are conventionally labeled distressed. The same phrase also describes an options strategy, but in fixed income conversations it almost always refers to bond yields.
How Spreads Are Measured and Traded
Practitioners use several conventions. The G-spread compares a bond's yield to an interpolated government curve, while the Z-spread is the constant spread added to the entire zero-coupon Treasury curve that reprices the bond exactly. For callable bonds, the option-adjusted spread strips out the value of the embedded option, and credit default swap premiums offer a market-based read on the same underlying risk.
Spreads widen when perceived risk rises and tighten when confidence returns, independent of what underlying Treasury rates do. A bond's spread duration measures how much its price falls per basis point of widening. Credit investors effectively trade this variable, buying when spreads look wide relative to expected defaults and cutting exposure when spreads leave little room for error.
Why It Matters
Aggregate spread indices are macro barometers. High-yield spreads blew out past 1,900 basis points in the 2008 crisis and jumped above 1,000 in March 2020, and sudden widening often precedes recessions as lenders retreat. Policymakers watch spreads because they translate directly into borrowing costs for companies and, through mortgage rates, for households as well.
In careers, spreads are the working currency of credit. Debt capital markets bankers price new issues as a spread over Treasuries, and credit analysts argue a bond is cheap or rich by comparing its spread with rating peers. Interviewers commonly ask why spreads widen in downturns or how a rating downgrade would move a bond's price.
