Open interest (OI) measures the number or notional value of derivative contracts that remain open and have not yet been closed, settled, or exercised.

The metric is particularly important in futures and other derivatives markets. It represents accumulated open exposure rather than the number of trades executed during a particular period.

Open interest vs. trading volume

Trading volume measures the amount of trading activity completed during a period. Open interest measures the contracts that remain open.

For example, when two traders open a new futures contract, open interest increases. When an existing position is fully closed, open interest decreases. A transfer of an existing position can have a different effect depending on how the transaction is structured.

How OI is used

Traders use open interest to assess the amount of capital and exposure currently committed to derivative markets. Changes in OI are often considered alongside price, volume, and funding rate.

A rise or fall in open interest by itself does not determine the future direction of price. OI describes outstanding contracts rather than providing a guaranteed market forecast.