NO.PZ2017121002000006
问题如下：
Which type of sovereign bond has the lowest interest rate risk for an investor?
选项：
A.Floaters
B.Coupon bonds
C.Discount bonds
解释：
A is correct.
Floaters are bonds with a floating rate of interest that resets periodically based on changes in the level of a reference rate. Because changes in the reference rate reflect changes in market interest rates, price changes of floaters are far less pronounced than those of fixed-rate bonds, such as coupon bonds and discount bonds. Thus, investors holding floaters are less exposed to interest rate risk than investors holding fixed-rate discount or coupon bonds.
考点：利率风险
解析：本题建议直接从久期的角度来考虑，因为duration代表的是债券价格对于利率变化的敏感程度。题目让我们选出利率风险最低的风险，换句话就是选出duration最小的债券。浮动利率的久期为重置期的一半，接近零。因此浮动利率债券的利率风险最小，故选项A正确。
老师您好，我已经学过久期这个章节。但是对“浮动利率的久期为重置期的一半，接近零”还是无法理解。
问题一：（1）可以请老师详细的展开解释一下这句话吗？
问题二：（2）浮动债券的久期如何计算？未来现金流不确定的情况下，浮动债券的是否无法用修正久期计算？那么应该如何计算呢
