Understand how Open Interest measures outstanding futures and options contracts, how it differs from trading volume, and how traders interpret OI changes alongside price action.
If you are asking "what is Open Interest", this is the short answer. OI in the stock market counts how many derivatives positions are still alive.
Both sides hold the same 100 contracts, so each contract is counted once.
These hypothetical examples start from 100 outstanding contracts. They describe changes in outstanding contracts, not whether the market is bullish or bearish.
| Situation | Change in OI |
|---|---|
| 1. Both parties open new positions | OI increases by 1 contract 100 → 101 |
| 2. Both parties close existing positions | OI decreases by 1 contract 100 → 99 |
| 3. One party opens while the other closes | OI generally remains unchanged 100 → 100 |
This is a simplified accounting relationship for outstanding contracts.
Hypothetical example: Previous OI 10,000 · Opened 1,500 · Closed 700 · New OI 10,800
Volume and OI measure different things, so they should not be read as the same number.
| Open Interest | Trading Volume |
|---|---|
| Measures outstanding contracts | Measures contracts traded during a period |
| Reflects positions that remain open | Counts trading activity |
| Changes when contracts are opened or closed | Can increase even when OI remains unchanged |
| May carry forward from one trading session to another | Usually resets for the next trading session's volume measurement |
Example: If 500 contracts are traded during a session, volume may be 500 contracts while OI could remain unchanged if opening and closing activity offsets.
Traders often combine price movement with changes in OI to form a market interpretation. These are common labels, not definitive facts. Every futures or options contract has both a buyer and a seller, so OI alone cannot identify every participant's intention.
New positions are being added while price rises. This is often read as bullish participation, but OI alone does not show what each participant intends.
New positions are being added while price falls. This is often read as bearish participation, but the interpretation needs context.
Falling OI during a price rise may indicate that outstanding positions are being closed, including possible short covering.
Falling OI alongside falling price may indicate that outstanding positions are being closed, including possible long unwinding.
Price, volume, contract type, expiry and broader market conditions all matter. None of these patterns guarantees a future direction.
Open Interest in futures and options is counted differently. Options OI is often used to study participation around strike prices, but it does not independently establish market direction.
Enter values as a number of contracts. New OI = Previous OI + New Contracts Opened − Existing Contracts Closed.
This calculator demonstrates a simplified accounting relationship. Actual exchange OI data reflects outstanding contracts according to exchange reporting and settlement rules.
Fact: Rising OI means more contracts are outstanding. Directional interpretation requires price action and additional context.
Fact: Volume measures trading activity during a period; OI measures outstanding contracts.
Fact: Call OI concentrations may be watched by traders, but they do not guarantee that price will reverse.
Fact: Falling OI means outstanding contracts are declining. The market interpretation depends on price movement and context.
OI stands for Open Interest. It is the total number of outstanding futures or options contracts that have not yet been closed, exercised or settled.
Volume counts contracts traded during a period, while OI counts contracts that remain outstanding. Volume can be high while OI stays unchanged.
Rising OI indicates that more contracts are outstanding because new positions are being opened faster than existing ones are closed. It does not show direction by itself, so traders read it with price, volume and context.
Traders examine Call OI and Put OI separately across strike prices and expiries to study where participation is concentrated. These levels may be watched, but they do not guarantee support, resistance or direction.
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