Fill or Kill (FOK)
An order that must be filled in its entirety immediately or canceled outright — no partial fills, no waiting.
Fill or Kill (FOK) demands that the entire order quantity be executed at once, right now. If the full size cannot be matched immediately, the order is canceled entirely.
FOK prevents partial fills when you need a specific block size — for example, when entering an options strategy that requires all legs at a target price simultaneously.
FOK orders are less common in retail equity trading and more prevalent in institutional fixed-income and OTC markets where block availability is critical.
Related Terms
All or None (AON)
An order that must fill completely or not at all, but unlike FOK it can wait for a full match.
IntermediateDay Order
An order that expires at the end of the current trading session if not filled.
BeginnerImmediate or Cancel (IOC)
An order that executes as much as possible immediately, then cancels any unfilled portion.
IntermediatePartial Fill
When only part of an order is executed — common with large orders or low-liquidity conditions.
BeginnerTime in Force
The instruction attached to an order specifying how long it remains active before it is canceled if unfilled.
Beginner