Put/call ratio (or put–call ratio, PCR) is a technical indicator demonstrating investors' sentiment. The ratio represents a proportion between all the put options and all the call options purchased on any given day. The put/call ratio can be calculated for any individual stock, as well as for any index, or can be aggregated. The ratio may be calculated using the numbers of puts and calls or on a dollar-weighted basis.
Generally, a lower reading (~0.6) of the ratio reflects a bullish sentiment among investors as they buy more calls, anticipating an uptrend. Conversely, a higher reading (~1.02) of the ratio indicates a bearish sentiment in the market. However, the ratio is considered to be a contrarian indicator, so that an extreme reading above 1.0 is actually a bullish signal, and vice versa.
Moving averages are used to smooth and normalize the series of ratios.