Open Interest Explained: Definition, Use, FAQs
By Ken Chigbo, Founder, KenMacro. Published 2026-05-13.
Quick answer
Open interest is the total number of outstanding futures or options contracts that have not yet been closed, exercised, or expired. Unlike volume, which counts trades during a session, open interest tracks the live obligation pool. Rising open interest signals fresh capital entering a market; falling open interest signals positions being unwound.
What is open interest?
Open interest is the count of derivatives contracts, futures or options, that remain open at the end of a trading session. Each contract has a long side and a short side, and open interest counts the pair once. When a new buyer meets a new seller, open interest rises by one. When an existing long sells to an existing short, it falls by one. When positions simply change hands between new and old participants, open interest is unchanged. Exchanges such as the CME publish daily open interest figures after the close, typically the following morning, alongside volume statistics.
How traders use open interest
Retail traders watch open interest at specific strike prices in options markets to identify where dealer hedging flows and gamma exposure concentrate. In futures, the desk treats rising open interest alongside a trending price as confirmation that fresh money is supporting the move, while rising price on falling open interest often indicates short covering rather than genuine demand. The CFTC Commitments of Traders report, published Fridays at 3:30pm ET, breaks open interest down by participant category, letting traders see whether commercials, managed money, or other reportables are accumulating. Institutional desks use open interest term structure across futures expiries to gauge hedging pressure and roll dynamics, and options market makers reference open interest to estimate hedging obligations into expiry.
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Common misconceptions about open interest
Traders often confuse open interest with volume. Volume resets each session and counts every trade; open interest is a running tally of live contracts. A second misconception is that high open interest automatically means a price move is coming. It does not. Open interest measures participation, not direction. Another error is double-counting: open interest already counts the long and short pair as a single contract, so adding both sides inflates the figure. Finally, rising open interest is not inherently bullish. It only confirms whichever trend price is delivering, since both buyers and sellers are committing capital.
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Frequently asked
What is the difference between open interest and volume?
Volume counts the number of contracts traded during a single session, including contracts that open and close intraday. Open interest counts only contracts still live at the close. A scalper who buys and sells one contract within an hour adds two to volume but nothing to open interest. A position trader who buys and holds adds one to both. Volume measures activity; open interest measures committed positioning carried overnight.
Where can I find open interest data?
Exchanges publish daily open interest after the close. The CME Group posts futures and options open interest the morning following each session on its website. The CFTC Commitments of Traders report, released Fridays at 3:30pm ET, aggregates open interest by trader category for US-listed futures. Most retail trading platforms display open interest on the option chain and futures contract specifications alongside volume.
Does open interest matter in spot forex?
Spot forex has no central exchange, so there is no true open interest figure for spot pairs. Traders interested in positioning use CME currency futures open interest as a proxy, since speculators and commercials hedge similar exposures there. The CFTC report on currency futures is widely watched as a sentiment gauge for EUR, JPY, GBP, and other major crosses, even by traders who only operate in the spot market.
How do options traders use open interest?
Options traders track open interest at each strike to map where positions concentrate. Heavy open interest at a strike often acts as a magnet or barrier into expiry due to dealer gamma hedging. The desk also compares put and call open interest to estimate sentiment skew. Changes in open interest from one day to the next, combined with price action, reveal whether traders are opening fresh exposure or closing existing positions.
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