本来觉得期权就是简单的行权被行权，看准了方向然后买卖或者是做个对冲。这两天看了雪球上精大的文章，发现not even close. 还是要先把各个概念弄得清清楚楚来。今天先说一下波动率和delta吧。
波动率 X（又叫波幅）是说某个期权底下的标的资产在未来有68%的概率落在今天价格的正负X的范围内。（from 精大）
从tastytrade.com上看到了另一个解释，解释了为啥是68%。
In simple terms, IV is determined by the current price of option contracts on a particular stock or future. It is represented as a percentage that indicates the annualized expected one standard deviation range for the stock based on the option prices. For example, an IV of 25% on a $200 stock would represent a one standard deviation range of $50 over the next year.
IV代表了期权价格下的一个标准差单位下，标的的波动百分比。打个比方，一个股票价格为200美金，IV为25%。那么下一年中在一个标准差单位下会波动50美金。
标准差单位是这样解释的：
Before diving into how it applies to options trading, it’s important to understand the probabilities associated with certain multiples of standard deviations:
- 1 standard deviation encompasses approximately 68.2% of outcomes in a distribution of occurrences
- 2 standard deviations encompasses approximately 95.4% of outcomes in a distribution of occurrences
- 3 standard deviations encompasses approximately 99.7% of outcomes in a distribution of occurrences
简单点说就是，1标准差单位是68.2的百分比，2标准差单位是95.4的百分比，3标准差单位是99.7的百分比。
Delta有两个含义，第一个含义是期权价格对于正股价格变化的敏感度，即正股每变化1块钱，期权价格的变化。比如说一个call的delta为0.3，就是说正股每升1块钱，期权会升0.3元。（from 精大）
Delta的第二个含义是，该期权到期时被行权的概率。打个比方，某个股票为X时，X+Y的call的delta为0.3，这意味着，市场认为，该期权有30%的概率会被行权。也就是说，该股有30%的机会达到X+Y或者超过X+Y。（from 精大）
未完待续...
