Open Interest

Open Interest is the total number of active contracts (like options or futures) that haven't been closed or settled yet. Think of it as a headcount of all the open bets in the market at any given moment. You'll see this number quoted alongside options prices, and it matters because high open interest usually means the contract is liquid—easier to buy or sell without moving the price dramatically. Low open interest can mean you'll struggle to find a buyer or seller when you need one. For example, if a call option on TechCorp has 50,000 open interest, that means 50,000 contracts are still active and waiting to be exercised or closed out.