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What is open interest?
Open interest is the total number of futures or options contracts that are still open: entered into and not yet closed by an offsetting trade, delivery or exercise. It measures how many positions exist, not how much trading happened.
What it means for you
Open interest shows how much is committed to a derivatives market, not which way it leans: every open long has an open short on the other side. High open interest built with heavy leverage can mean many positions exposed to forced liquidation in a sharp move. It is reported per contract or market, so compare like with like.
How it works
Every contract has a buyer and a seller, so total long open interest always equals total short open interest. A contract counts from the moment it is entered into until it is offset by an opposite trade, fulfilled by delivery or exercised; so open interest rises when two traders open a new contract and falls when both sides close. Trading volume counts contracts traded during a period; open interest is a snapshot of contracts outstanding. Technical analysts chart it alongside price and volume.
An example
Say a market starts with no contracts. A buys one from B: open interest is 1. C buys one from D: it is 2. Then B buys one back from A, closing both their positions: it falls to 1. Volume for the day was 3 contracts.
Sources: CFTC: Commitments of Traders explanatory notes, CFTC Glossary · checked 4 October 2026
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