# Options Open Interest Analysis > Open interest counts option contracts still open. Learn how to read open interest with volume, the put call ratio, max pain and unusual activity, and their limits. Source: https://learn.tradelabsai.com/options/options-open-interest-analysis/ Track: Options · Level: Advanced · Updated: 2026-10-03 Publisher: TradeLabs AI (https://tradelabsai.com). Education, not financial advice. Cite as: TradeLabs Learn, "Options Open Interest Analysis", https://learn.tradelabsai.com/options/options-open-interest-analysis/ Open interest is the number of option contracts that are open at the end of a trading day, contracts that have been opened and not yet closed, exercised or expired. Together with daily volume, it shows where traders are positioned, which strikes are liquid and how activity is changing. Traders use open interest to find liquid options, gauge sentiment, spot unusual activity and estimate where hedging flows might matter. The general concept across futures and options is in [Open Interest](https://learn.tradelabsai.com/markets/open-interest/). ## Open interest vs volume | | Volume | Open interest | |---|---|---| | What it counts | Contracts traded today | Contracts still open at the end of the day | | Resets | Every day | Carries over | | Updated | Live | Once a day, usually overnight | | Tells you | Today's activity | Accumulated positioning | A trade can raise, lower or leave open interest unchanged: | Buyer | Seller | Effect on open interest | |---|---|---| | Opening | Opening | Rises by the trade size | | Closing | Closing | Falls by the trade size | | Opening | Closing | Unchanged (position passes to a new holder) | ## Using open interest for liquidity Options with high open interest and volume usually have tighter bid ask spreads, making it cheaper to enter and exit. Before trading, check both. A strike with open interest of 15 and no volume today may be very costly to trade. See [Liquidity](https://learn.tradelabsai.com/markets/liquidity/) and [Bid-Ask Spread](https://learn.tradelabsai.com/markets/bid-ask-spread/). ## Reading changes in open interest **Example: Volume much larger than open interest** A $60 call expiring in three weeks had open interest of 1,200 yesterday. Today 9,500 contracts trade, mostly at the ask, as the stock is flat. Tomorrow open interest shows 8,900. Most of today's trading opened new positions, and buying at the ask suggests buyers were aggressive. This is the kind of pattern labelled "unusual options activity". It could be informed buying, a hedge, part of a spread or a large fund's routine trade. ## The put call ratio ``` put call ratio = put volume (or open interest) / call volume (or open interest) ``` - **High ratio:** more put activity, often read as fear or hedging demand. - **Low ratio:** more call activity, often read as optimism or speculation. Many traders treat extreme readings as contrarian signals, because crowd positioning tends to be most one sided near turning points. The equity only ratio, which excludes index options used for hedging, is often watched separately. See [Sentiment Data](https://learn.tradelabsai.com/alternative-data/sentiment-data/). ## Max pain Max pain is the strike price at which the total value of all outstanding options would be lowest at expiration, meaning option holders as a group would lose the most. Some traders believe prices drift towards max pain into expiry. Evidence for this is mixed; any pinning effect is more plausibly linked to dealer hedging around large open interest strikes. See [Dealer Gamma Exposure](https://learn.tradelabsai.com/options/dealer-gamma-exposure/). ## Open interest by strike Plotting open interest across strikes shows where positions are concentrated. Large open interest at certain strikes: - **May act as magnets or barriers** near expiration because of hedging flows. - **Shows where traders have bought protection** (put strikes) or placed upside bets (call strikes). - **Helps estimate dealer gamma.** ## Limitations - **Open interest does not show direction:** each contract has a buyer and a seller. - **Spreads and hedges** make individual strikes hard to interpret. - **Data is delayed** until the next morning. - **Unusual activity is often not informed.** Many large trades are hedges or rolls. ## Practical uses 1. **Choose liquid strikes** for trading. 2. **Watch expiration weeks** for strikes with very large open interest. See [Option Expiration Dates](https://learn.tradelabsai.com/options/option-expiration-dates/). 3. **Track sentiment** with put call ratios over time rather than single days. 4. **Investigate unusual activity** by checking whether it was bought or sold, and whether it was part of a spread. ## Frequently asked questions ### What is open interest in options? The total number of option contracts that are open and have not been closed, exercised or expired. ### What does a high put call ratio mean? More put activity relative to calls, often interpreted as bearish sentiment or hedging demand, and sometimes used as a contrarian signal. ### Is max pain real? The calculation is real, but evidence that prices reliably move toward max pain is weak. Any pinning near expiry is more likely linked to hedging around large open interest strikes. Next, start multi leg strategies with [Vertical Spreads](https://learn.tradelabsai.com/options/vertical-spreads/). ## Continue learning - Next lesson: [Vertical Spreads](https://learn.tradelabsai.com/options/vertical-spreads/) - Previous lesson: [Dealer Gamma Exposure](https://learn.tradelabsai.com/options/dealer-gamma-exposure/) - Related: [Dealer Gamma Exposure](https://learn.tradelabsai.com/options/dealer-gamma-exposure/): Dealer gamma exposure estimates how option dealers' hedging may dampen or amplify moves. Learn how GEX is calculated, what it suggests and its big limitations. - Related: [Open Interest](https://learn.tradelabsai.com/markets/open-interest/): Open interest is the number of futures or options contracts still open. Learn how it differs from volume, how it changes and how traders read it with price. - Related: [Sentiment Data](https://learn.tradelabsai.com/alternative-data/sentiment-data/): Sentiment data measures how optimistic or fearful investors are. Learn survey, positioning, options and crypto sentiment indicators and how to use them. - Related: [Liquidity](https://learn.tradelabsai.com/markets/liquidity/): Liquidity is how easily you can trade without moving the price. Learn the signs of a liquid market, how illiquidity costs you and when liquidity disappears. - Related: [Option Expiration Dates](https://learn.tradelabsai.com/options/option-expiration-dates/): Every option has an expiration date when it must be used or expire. Learn monthly, weekly and 0DTE cycles, what happens at expiry and how to choose an expiration.