Open interest (OI) is the total number of outstanding derivative contracts, typically crypto futures or options, that remain open and unsettled. In other words, it measures how many contracts are still active because they have not been closed, offset by an opposing trade, expired, or exercised.
How open interest works in crypto derivatives
In futures and options markets, every contract has a buyer and a seller. Open interest increases when market participants create new positions, for example when a new long and a new short open a contract with each other. Open interest decreases when those positions are closed out, such as when a trader sells to exit a long, buys to exit a short, or when an options contract is exercised or expires.
It is important to distinguish open interest from trading volume. Volume counts how many contracts changed hands during a period, even if the same contract is traded multiple times. Open interest focuses on what remains after trading activity, acting more like a snapshot of how many positions are still on the books.
What open interest can signal
Traders watch open interest because it helps describe participation, liquidity, and positioning in the derivatives market. Rising open interest can indicate fresh capital entering, which often coincides with stronger liquidity and tighter spreads. Falling open interest can suggest positions are being unwound, sometimes reflecting reduced risk appetite or a move toward spot markets.
For example, if open interest climbs alongside an upward move, it may imply that new leveraged positions are contributing to the trend. If price moves sharply while open interest drops, it can indicate that the move is driven by position closures rather than new conviction.
Open interest matters in crypto because derivatives markets influence liquidity, leverage, and volatility, making OI a useful tool for understanding market structure and potential risk.