The put call ratio refers to the number of put options divided by the number of call options. For example, the total trading volume of SPY call options on a day is 300k, and the total trading volume of SPY put options is 200k, so the put call ratio is 200k/300k=0.67.
This indicator can be seen as a reverse indicator. If most people choose one direction, then reverse thinkers will take the opposite direction. Taking the above example as an example, most traders are bullish, then the reverse thinker will treat it as a bearish signal.
Under normal circumstances, the number of call options purchased is always greater than that of put options.
看跌看涨比率指将看跌期权的数量除以看涨期权的数量，例如当天SPY看涨期权的总成交量为300k手，SPY看跌期权的总成交量为200k手，那么看跌看涨比率为200k/300k=0.67
这个指标可以看作为一个反向指标，如果大多数人选定了一个方向，那么反向思维者就会采取相反方向。以上面的例子为例，大部分交易者看涨，那么反向思维者就会当作是一个看空的信号。
在通常情况下，看涨期权的买入数量总是大于看跌期权。