问题如下：
10. If the market price of Pro Star’s common stock falls from its level on 19 October 20X0, the price of the convertible bond will most likely:
选项：
A. fall at the same rate as Pro Star’s stock price.
B. fall but at a slightly lower rate than Pro Star’s stock price.
C. be unaffected until Pro Star’s stock price reaches the conversion price.
解释：
B is correct.
The market price on 19 October 20X0 ($37.50) is above the conversion price of $1,000/31 = $32.26 per share. Thus, the convertible bond exhibits mostly stock risk-return characteristics, and a fall in the stock price will result in a fall in the convertible bond price. However, the change in the convertible bond price is less than the change in the stock price because the convertible bond has a floor—that floor is the value of the straight bond.
为什么股票下降幅度小于可转债下降幅度？因为可转债内由两部分组成：1.straight bond；2.call option on stock.只有第二部分和股价联动所以下降幅度小？有没有数学依据？