What happens to unexecuted parts of IOC orders?

IOC, or Immediate or Cancel, orders are designed to ensure that any portion of the order that cannot be executed immediately is cancelled right away. This means that any unexecuted parts of IOC orders do not remain on the order book for potential future execution. Instead, they are immediately cancelled to keep the order book clean and efficient. The main intention behind an IOC order is to allow traders to quickly execute part of an order while discarding any leftover portion that cannot be completed right away. This provides traders with flexibility while ensuring that they are not left with pending orders in the system.