Lesson · [ 20 ]

OPEN INTEREST & VOLUME

Intermediate5 min

Plain English

Volume = how many contracts traded today. Open Interest = how many contracts exist right now. High numbers in both mean good liquidity — tighter bid-ask spreads and easier fills. Low numbers mean you might get stuck.

Going deeper

Volume counts the number of contracts that changed hands during the current session. Open Interest is the total number of outstanding contracts that have not been closed or exercised. Volume resets daily; Open Interest updates overnight. High Volume and Open Interest indicate liquid markets with tight bid-ask spreads, making it easier to enter and exit positions at fair prices. Low liquidity contracts have wide spreads that immediately cost you money. Always check liquidity before trading an option.

Examples

Liquid Contract

SPY $450 Call: Volume = 50,000, Open Interest = 200,000, Bid = $5.45, Ask = $5.47. The $0.02 spread means excellent liquidity. You can enter and exit with minimal slippage.

Illiquid Contract

A small-cap stock's $30 Call: Volume = 5, Open Interest = 100, Bid = $1.00, Ask = $2.00. The $1.00 spread means you lose 50% immediately just from the bid-ask gap. Avoid these.