锦sè♀ 发表于 2014-12-2 13:28 
比较了很多天的,依旧是标普500股指期权的波动率微笑更加明显。听老师说,似乎一直以来美国数据的波动率微 ...
maybe this is because the US stock is at the historical high level now. Anyway, there is no definite explanation on the smile. In financial engineering, smile is a given condition, you just need to calibrate the model according to the smile and do the rest stuff. In a word, just take smile as given.