回复：金融工程家坛 long gamma=long vol, short gamma=short vol,vomma is 2n

The purchased short-term put option will make money when the S&P 500 moves more than the expected 16% implied volatility that you purchased it at. The written 1 year put option out of the money will make money as that long term implied volatility falls, but if you hold it to expiration it will make money as realized volatility comes in less than the 25% implied that you sold it at.

 

so don't by call option when sina already jumped big or dropped little, u're over paying for the volatility implied based on historical or realized volatility