Open interest (OI) is the number of futures or options contracts that are open and not yet closed. It is not the day's trading volume but the number of positions that remain in the market at the end of the day. Open interest tells you whether new money is entering a market and at which prices it sits.
Open interest in plain words
Every contract has two sides, a buyer and a seller. When both open a new position, open interest rises by one contract. When both close, it falls by one. If one closes while another opens in their place, open interest does not change: the contract simply changed hands.
So open interest answers a question the price chart cannot: is the move driven by new positions or by old ones being closed?
How open interest differs from volume
- Volume is how many contracts traded during the day. The count restarts from zero every day.
- Open interest is how many contracts remain open. It accumulates day after day and drops to zero only on expiration day.
High volume with flat open interest means positions changed hands or were opened and closed intraday. High volume with rising open interest means new participants have entered.
Price and open interest: four combinations
The classic reading of futures open interest comes down to four cases:
- Price up, open interest up. New positions are being opened; the rise is backed by fresh money.
- Price up, open interest down. The rise is driven by short covering. Such moves are considered less durable.
- Price down, open interest up. New positions are being opened in the direction of the decline.
- Price down, open interest down. The decline is driven by longs being closed: participants are leaving rather than selling anew.
This is a first approximation, not a rule. Open interest does not say who opened a position: a speculator, a hedger or a market maker, and each has different reasons and behaves differently afterwards.
Options open interest: levels instead of one number
A future has one open-interest number per contract. For options it is counted at every strike, separately for calls and puts. Instead of one number you get a map of the prices where most positions sit.
- Strikes with the largest open interest are called option walls. Option sellers are hurt if price moves beyond such a strike, so price often reacts there.
- Inflow is a rise in open interest at a strike over the day. It shows where participants have just stepped in. See OI flows: progress and regress.
- Outflow is a decline: participants are leaving the level.
- The open-interest balance point is the "center of mass" of all positions in a series. In our test on 17 CME markets (June–September 2026) price moved toward it in 44% of cases versus 30% for a mirror level at the same distance on the other side.
- The put/call ratio, PCR: which side holds more positions.
- Max Pain: the price at which payouts on open options are smallest; also derived from open interest by strike.
Where to see open interest
- CME futures and options (currencies, gold, oil, indices, Bitcoin). The exchange publishes a daily report with open interest for every contract and every strike. The data is free, but it comes as tables: to see levels on a chart you have to parse it and overlay it on price.
- Crypto exchanges show open interest for perpetual futures in real time inside their terminals.
- Forex. The spot market has no single exchange, so it has no open interest. For currency pairs, traders use CME currency futures and options: EUR/USD, GBP/USD, AUD/USD, yen, franc, Canadian dollar.
On this site, current call and put open interest and the main levels for every instrument are in Analytics, updated every trading day. For example: gold, EUR/USD, S&P 500.
How to use open interest
- Find the boundaries. The strikes with the largest open interest above and below price define a corridor that large participants have an interest in holding.
- Check whether they are alive. If open interest at a boundary is growing, the level is strengthening. If it is falling, the backing is leaving and the level may not hold.
- See where new positions are going. Inflows over recent days show which prices participants consider important now, not a month ago.
- Compare with the big picture. Whether total futures open interest rises or falls together with price tells you about the nature of the move.
- Mind the clock. A series' open interest disappears on expiration day. The closer expiration is, the more positions affect price and the sooner the picture goes stale.
Example: gold, early October 2026
From September 25 to October 2, gold futures fell from $4,330 to $4,165, or 3.8%. Open interest in the options series expiring October 27 grew on both sides meanwhile: calls from 88,453 to 100,854 contracts (+14%), puts from 57,485 to 64,219 (+12%).
By strike: 3,064 new calls at $4,510 and 1,369 at $4,400, both above price; 2,495 new puts at $3,800, roughly 9% below the market. Puts at $4,400, now deep in the money, were cut by 1,019 contracts.
The price chart shows only a decline. Open interest shows more: during the decline call positions above the market were not unwound but added to, while puts were added far below price. The report does not say who was the buyer and who the seller, so this is a map of where positions sit, not a prediction.
What open interest does not show
- Direction. Every contract bought has one sold. Rising call open interest includes both buyers and sellers.
- Who the participant is. The exchange report does not split positions into hedgers and speculators. For futures, that breakdown comes from a different report, the weekly COT, which has no strikes.
- Intraday changes. CME open interest is published once a day after the trading day ends.
- The future. It is a snapshot. Participants may close tomorrow.
Questions and answers
Is rising open interest good or bad? Neither. It means there are more positions in the market. What that implies for price depends on where price is moving at the same time and at which levels positions are being opened.
What is open-interest delta? The change in open interest over a period, a day or a candle. The same thing as inflow and outflow.
Is there an open-interest indicator for MetaTrader? Forex brokers' MetaTrader has no exchange open interest. OLIMP takes CME data and draws options open interest by strike right on the chart; see the open interest indicator for MetaTrader 5 page. You can download the OLIMP indicator for free.
Can I see open interest historically? The indicator has a "Contract history" mode: levels are drawn for every report day, so you can see how positions changed.
This article describes open positions based on exchange data and is not investment advice.