讲原理时说 immunization的条件是 macaulay duration = investment horizon.
那为啥到构建portfolio时 条件变成了 macaulay duration of asset = macaulay duration of liability?
有没有可能 Mac D asset = Mac D liability but they are not equal to investment horizon呢？
为什么可以把investment horizon这个条件丢掉了呢？
