How does z-spread differ from nominal spread?

Nominal (G-spread) is the bond's YTM minus the interpolated Treasury yield. Z-spread is more theoretically correct: it adds a constant spread to the entire Treasury spot curve, properly accounting for the term structure of risk-free rates. Z-spread equals G-spread only for flat yield curves.

When would a z-spread overstate credit compensation?

For callable or putable bonds, z-spread ignores embedded option value. OAS (option-adjusted spread) removes the option value to isolate the pure credit spread. Using z-spread for callable bonds overstates credit compensation by the value of the call option.

Z-Spread Over Benchmark Treasury

Calculate the z-spread (zero-volatility spread) as the constant spread added to each Treasury spot rate that makes the discounted cash flows equal to the bond's market price, measuring credit and liquidity premium.

Principal ($)

Annual Rate (%)

Years

Compounding / Year

$ Finance Disclaimer: These calculators are for educational and illustrative purposes only. Results do not constitute financial advice. Consult a licensed financial advisor before making investment or borrowing decisions.

How to Use

Enter the values for the scenario you are assessing. Calculate the z-spread (zero-volatility spread) as the constant spread added to each Treasury spot rate that makes the discounted cash flows equal to the bond's market price, measuring credit and liquidity premium. Use the z-spread result to inform your calculation.

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Option-Adjusted Spread

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