What is Open Interest?
Open interest represents the total number of outstanding derivative contracts, such as futures or options, that remain open and have not been settled or closed. It measures the total amount of money invested in a derivatives market and is a key indicator of market activity, liquidity, and trader commitment.
How Open Interest Works
When a new buyer and seller create a fresh derivatives position, open interest increases by one contract. When an existing position holder closes their position with an existing opposite position, open interest decreases. If an existing holder trades with a new participant taking over their position, open interest remains unchanged.
Unlike trading volume, which counts every trade regardless of whether positions are new or closing, open interest only tracks net new positions. High volume with stable open interest suggests position rotation. High volume with rising open interest indicates new money entering the market.
Open Interest in Perpetual Futures
For perpetual futures, open interest represents the total notional value of all long positions, which equals all short positions since every long has a corresponding short. Rising open interest in perps indicates increasing market participation and often correlates with trending price action.
Different platforms express open interest differently. Some show the number of contracts, others show USD notional value, and some show the amount of the underlying asset represented.
Interpreting Open Interest Changes
Rising price with rising open interest suggests strong bullish conviction with new money supporting the move. Rising price with falling open interest might indicate short covering rather than genuine buying. Falling price with rising open interest suggests new short interest and bearish pressure. Falling price with falling open interest implies long liquidation or profit-taking.
Open Interest as a Market Indicator
High open interest indicates deep liquidity and easier trade execution. Rapidly increasing open interest during a price trend often signals trend continuation. Extremely high open interest can indicate overleveraged markets vulnerable to cascading liquidations during sharp price moves.
Comparing open interest levels to historical norms helps contextualize current market positioning. Unusually high or low open interest relative to history can signal potential inflection points.