问题如下：
Is Petit’s prediction correct that the EKN bond price will not change in response to the interest rate and credit spread changes, all else being equal?
选项：
A. Yes
B. No, the bond price should
decrease.
C. No, the bond price should
increase.
解释：
B is correct.
An increase in interest rates results in a decrease in the bond price. An increase in the credit spread also results in a decrease in the bond price. For the EKN bond, its modified duration shows the effect of the 20 bp increase in interest rates. The approximate percentage price change resulting from the increase in interest rates is –8.47 × 0.0020 = –1.694%. The spread duration shows the effect of the 20 bp increase in the credit spread. The approximate percentage price change resulting from the increase in the credit spread is –8.47 × 0.0020 = –1.694%. The combined effect is a total change of –3.388%, or a price decrease of roughly 3.4%
题目只说credit spread变化了 并没有说benchmark YTM发生了变化，为什么要从两方面计算呢？
