The call put ratio can often reflect the bullish or bearish views of options traders, with more calls trading indicating bullish sentiment. 

The ratio should be used as a relative measurement to its normal level for symbols. For example, the SPX call volume lagged put volume over much of the time since 2007 averaging only 55% as shown below.

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Whereas, the call/put ratio average for the S&P components, as represented by the symbol SPX_C in the ORATS Wheel Chart below, has averaged 150% since 2007.

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Recently, with the pouring in of retail traders into the market, many through the trading app Robinhood, calls are outstripping puts by 200% for the average component.

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Contrast this with the index SPX. Recently, the SPX call put ratio has been below its long term average until yesterday.

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Generally, the SPX represents institutional smart money and the components represent retail traders.

Near the bottom of the Covid crash, the SPX call/put was above its normal 55% hitting 100% a few days after the bottom. The crash saw the S&P components call/put below its average, only rising to its long term average near the top of the shaped recovery.

Matt Amberson was quoted in the Reuters pointing out this ratio. https://www.reuters.com/article/us-health-coronavirus-stock-options-anal/virus-worries-and-fomo-drive-options-bets-on-surging-tech-giants-idUSKCN24F2LN

More reading: https://blog.orats.com/put-call-skew-dips-in-coincidence-with-market-rallies