Immediate-⁠or-⁠Cancel Order

What is an immediate-or-cancel order?

An immediate-or-cancel order, or IOC, is an order that takes eligible liquidity at evaluation and cancels the unfilled balance. It permits complete, partial or zero execution, and the remaining quantity does not rest for a later fill. IOC controls duration. A limit controls accepted prices, and the route controls the destinations used. Specify these together for the intended execution.

IOC vs fill-or-kill and minimum-quantity orders

IOC accepts the immediate partial execution. Fill-or-kill requires full completion for any execution. On a venue supporting the combination, a minimum-quantity instruction sets an additional threshold for the IOC.

For a multi-leg strategy, use a supported native package instruction to control the complete structure. Separate orders each have their own execution and remaining quantity.

How to reconcile partial IOC fills

Add all child-order fills to calculate the parent’s completed quantity and weighted average price. Use the final order report for the canceled balance. The public trade record contains executions; the account’s order record contains the complete fill-and-cancel result.

Compare the remaining target quantity with the next available prices before resubmitting. Calculate total execution cost from actual fills and explicit fees across all attempts. On an options order, enter the remaining quantity at the next price in the options profit calculator, and read how that fill moves the position’s breakeven and payoff before the order goes back in.

Limitations of immediate-or-cancel orders

• Plan for the partial fill. The order buys 1,200 of 2,000 shares, so the position stays smaller than planned until a new order completes it.
• Reprice the balance before the next attempt. The canceled balance does not wait for liquidity, so when prices move, the remaining 800 shares take a fresh price decision.
• Loosen the limit when completion matters more than price. The 900 shares offered at $18.06 sit above the $18.04 limit, so the order cannot reach them.
• Send a multi-leg structure as one native package instruction. Separate single-leg IOC orders execute independently.
• Reconcile from the account’s order record. The public trade record shows executions only, so the canceled 800 shares show in the order record and never print on the tape.

Bottom line

An immediate-or-cancel order takes whatever eligible liquidity is available at once and cancels the rest, so it can fill fully, partly or not at all. Use it to take current liquidity without leaving a resting order, then reconcile the filled quantity and average price before deciding how to complete the remainder.