The put/call ratio divides the number of put contracts by the number of call contracts, either traded in a session (volume) or currently open (open interest). A reading above 1 means more puts than calls, and the ratio is widely used as a gauge of options-market sentiment, often read in a contrarian way at extremes.
How it works
| Version | Formula | What it reflects |
|---|---|---|
| Volume ratio | Put volume ÷ call volume | Today's trading; reacts quickly and is noisy |
| Open interest ratio | Put open interest ÷ call open interest | Positions built up over time; changes slowly |
The ratio can be calculated for one stock, for an ETF such as SPY, or for a whole market. Cboe publishes daily total, equity-only and index put/call ratios. These series behave differently: index options are used heavily by institutions to hedge portfolios, so index ratios tend to run higher than equity-only ratios, which have typically sat well below 1 because individual investors buy more calls than puts on single stocks.
The ratio counts contracts. It does not separate buyers from sellers, weigh contracts by premium or delta, or say whether a trade opens a speculation or hedges a stock position.
How to read it
- Against its own history. A ratio means little in isolation. Compare it with the same series over recent months; a level normal for SPY can be extreme for a single stock.
- Extremes as contrarian signals. A spike in put buying often appears near the late stage of a sell-off, when protection is in heavy demand; a very low ratio can reflect complacency after a rally. These are tendencies, not timing signals.
- Smoothing. Daily volume ratios jump around. Many analysts use a 5-day or 10-day average to see the trend.
- Volume and open interest together. A high volume ratio with a stable open interest ratio suggests short-term trading or positions being closed; both rising suggests new put positions.
- Context. An upcoming earnings report, a known event or index rebalancing can drive put activity that has nothing to do with outright bearishness. Pair the ratio with volatility skew, which shows whether puts are also getting more expensive.
Worked example (illustrative numbers)
Illustrative numbers only, not a recommendation. Ahead of its earnings report, a stock shows the following:
| Measure | Puts | Calls | Ratio |
|---|---|---|---|
| Today's volume | 60,000 | 40,000 | 1.50 |
| Open interest | 300,000 | 500,000 | 0.60 |
Over the past three months the volume ratio has averaged about 0.70, so today's 1.50 is roughly twice its usual level. The open interest ratio of 0.60 shows that, overall, positioning still leans toward calls. One reading is that traders are buying short-dated protection into the report. Another is that some of those puts were sold, not bought, or bought against long stock as a hedge. The ratio alone cannot distinguish these cases; trade-level detail, such as large prints in the unusual options activity table, and the next day's change in open interest help.
Limitations and common mistakes
- High is not automatically bearish. Much put volume is hedging by investors who own the stock and intend to keep it.
- Buyer or seller is unknown. A put sold for income counts the same as a put bought for protection.
- Contracts are not dollars. A thousand cheap far out-of-the-money puts count the same as a thousand at-the-money puts worth many times more.
- Mixing series. Comparing a single stock's ratio with the index ratio, or an equity-only reading with a total reading, gives misleading conclusions.
- Thin options markets. In stocks with little options activity, one large trade can swing the ratio.
- Open interest lags. It is updated once a day, so today's positioning shows up tomorrow. See open interest.
Some composite sentiment indexes include a put/call ratio; see the fear and greed index.
In Clear Tape
On the Options page, the free SPY, QQQ and IWM cards show the put/call open interest ratio across all listed expirations, next to the gamma flip, walls, max pain and skew. Pro members can analyze any stock with listed options: the Unusual flow section shows both the put/call volume ratio and the put/call open interest ratio, together with contracts trading at least 500 lots and more than twice their open interest, and the watchlist scan lists each stock's put/call volume ratio. Clear Tape's own Fear & Greed index does not use a put/call ratio; it is built from price-based indicators. Members see each session's closing data once the next session has opened. See pricing.
For educational purposes only. Not investment advice.