What Is Open Interest? (In Simple Terms)
Open interest (OI) is the total number of derivative contracts (futures or options) that are currently open — created but not yet closed or settled. It sounds technical, but the idea is just a headcount of live bets.
Open interest vs volume
People confuse OI with volume. Volume counts how many contracts traded during the day (it resets daily). Open interest counts how many are still open right now (it carries over day to day). If two new traders open a fresh contract, OI goes up by one; when they both close it, OI goes back down.
What it signals
Rising open interest means new money is flowing into a contract — more participants are taking positions, which traders read as conviction behind a move. Falling OI means positions are being closed out. Combined with price, OI helps gauge whether a trend has real backing.
A note
Open interest applies to derivatives, not the cash (plain stock) market. Our data focuses on the underlying equities, prices, and fundamentals rather than derivative positions.