In finance, the yield spread or credit spread is the difference between the quoted rates of return on two different investments, usually of different credit qualities but similar maturities. It is often an indication of the risk premium for one investment product over another. The phrase is a compound of yield and spread.

The "yield spread of X over Y" is generally the annualized percentage yield to maturity (YTM) of financial instrument X minus the YTM of financial instrument Y.

There are several measures of yield spread relative to a benchmark yield curve, including interpolated spread (I-spread), zero-volatility spread (Z-spread), and option-adjusted spread (OAS).

It is also possible to define a yield spread between two different maturities of otherwise comparable bonds. For example, if a certain bond with a 10-year maturity yields 8% and a comparable bond from the same issuer with a 5-year maturity yields 5%, then the term premium between them may be quoted as 8% – 5% = 3%.