但事实上波动率是随着执行价格的变化而变化，尤其是对于那些深度实值期权和虚值期权，这就是我们经常观察到的波动率微笑现象。
But in fact , volatility changes as exercise price , especially for the deep in-the-money and out-the-money options , which is the observed phenomenon of " volatility smile " .
深度实值期权