Final answer:
The yield spread between AA+ T-bonds and AA-corporate bonds is calculated by subtracting the yield on the T-bonds from the yield on the corporate bonds, resulting in a spread of 1.972 percentage points.
Step-by-step explanation:
The yield spread between two bonds is the difference in their respective yield rates. In this case, the average yield on AA+ 30-year Treasury bonds is 7.643% and the average yield on 30-year AA-corporate bonds is 9.615%. To calculate the yield spread, you subtract the yield on the Treasury bonds from the yield on the corporate bonds. Therefore, the yield spread is:
9.615% - 7.643% = 1.972%
The yield spread between AA+ T-bonds and AA-corporate bonds is 1.972 percentage points. This yield spread represents the additional return that investors demand for taking on the higher risk associated with corporate bonds compared to Treasury bonds. T-bonds are considered safer because they are backed by the full faith and credit of the U.S. government.