What is the Put/Call Ratio?
The put/call ratio is the volume (or open interest) of puts divided by that of calls. A textbook contrarian sentiment indicator — used carefully, it works; used naively, it lies.
Definition
The put/call ratio (PCR) is the simplest possible aggregation of options activity: total put volume (or open interest) divided by total call volume (or open interest). High PCR = lots of puts being traded relative to calls = supposed bearish sentiment = contrarian bullish signal. Low PCR = call-buying frenzy = bullish complacency = contrarian bearish signal. The folklore version works some of the time, but the modern reality is far more nuanced: a lot of put volume is institutional hedging (mechanically neutral), and a lot of call volume is retail speculation (often genuinely bullish in regime, not contrarian). Reading PCR properly means looking at it by venue, by underlying, and by strike — not as a single market number.
Why it matters & how it's calculated
Several PCRs coexist on a serious desk. The "total" PCR (every put and every call on every name) is the most quoted and least useful — it averages signal-free noise. The "index" PCR (SPX, NDX only) is cleaner — most index puts ARE hedges, so a spike in index PCR reflects an increase in hedging demand, which IS often a regime signal. The "equity" PCR (single names) reflects speculation more than hedging. The "OEX PCR" (or any institutional venue) has historically been treated as "smart money" and run as a contrarian signal. Combining PCR with positioning data — does a high PCR coincide with dealer-long-gamma regime or short-gamma? — multiplies its information content. The biggest mistake retail makes with PCR is treating it as a level rather than a Z-score: a PCR of 1.0 means different things depending on whether the 90-day average is 0.7 or 1.2. Always normalise.
Worked example
Total index PCR jumps from 1.0 to 1.8 in a single session as SPX falls 2%. Naive reading: extreme bearishness, contrarian buy. Better reading: check dealer-positioning data. If GEX is now deeply negative AND PCR spike came from put-BUYING (not selling), this is genuine hedging-flow stress, and the contrarian setup needs at least a stabilisation in PCR before triggering. PCR alone gave a fake long signal in March 2020; PCR plus positioning got it right.
Related concepts
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