An immediate-or-cancel (IOC) order is an order to buy or sell a stock with an instruction to execute it immediately. Any portion of an IOC order that cannot be filled immediately will be cancelled.

The condition of immediate execution to buy or sell a security (e.g., a stock) is valid until the order is wholly or partially filled, and any portion that remains unfilled will be cancelled. Execution may involve all or a portion of the order’s quantity at a specific or better price (higher for a sell order and lower for a buy order).

This type of order aims is to execute as much of the order as possible immediately, and up to the full amount specified in the order.

It is also known as an accept order.