Fill or kill order
Family II · Orders
Not to be confused with partial fill.
Fill or kill order (FOK) is an order type that demands immediate and complete execution. If the entire order cannot be filled at the specified price or better as soon as it reaches the market, it is cancelled in full. No partial fill is permitted.
How a fill or kill order works
A fill or kill order is submitted with a price limit and a quantity. The receiving venue attempts to match the full quantity immediately. If the full quantity is available at the limit price or better, the trade executes. If not, the order is killed and no trade occurs. The order does not rest in the order book.
FOK orders are common in futures and equities markets, but availability and exact handling vary by broker and exchange. Some venues treat FOK as a time-in-force instruction, while others treat it as a separate order type.
Worked example
Fill or kill vs partial fill
A fill or kill order prohibits partial execution; if the full size is not immediately available, the order is cancelled. A partial fill occurs when an order is executed in part, leaving the remainder open or cancelled depending on its time-in-force. The visible sign that tells them apart is whether any shares change hands: a fill or kill order results in either a complete fill or no trade at all, while a partial fill results in some but not all shares being traded.
Often confused with
- partial fill
- A fill or kill order forbids partial execution and is cancelled if the full quantity is not immediately available, whereas a partial fill is an execution of only part of an order; the visible sign is that a fill or kill order leaves no open quantity, while a partial fill leaves a remainder.