normal bond has positive convexity while callable bond has call price let's say 10 year bond at maturity 2011, while can be called @ 103 on some call dates. then it has negative convexity when yield gets very low. not only callable bond, mortgage bond also has this features, when yield / rates low, people starts to refi.

没弄明白  

顶点人气吧

我觉得也是你画的这个道理呢

你把债券赎回是需要成本的，假设你当时为了筹资100万发行了一个callable bond，那么你想call回来，那要给人家比如103万，但是这个103万你还要再融资，而且未必搞得到，所以不是直接顶到call的价格上，我的理解是这样