问题
单项选择题
An analyst does research about price-discount rate relationship. With respect to the price-discount rate relationship, which of the following statements is least accurate（）
A. The shape of the price-discount rate relationship for an option-free bond is referred as negative convex.
B. If the discount rate rises, the price of a putable bond declines by less than the price of an option-free bond.
C. If the discount rate falls, the price of acallable bond increases by less than the price of an option-free bond.
答案
参考答案：A
解析：
根据凸性的定义，对于putable bond，当利率上升时价格比option-free bond下跌得少，对于callable bond，当利率下跌时价格比option-free bond上涨得少，都被put price和call price给限制了。不含权的债券的价格与折现率的关系反映的是一种正凸性。