Orders & ExecutionFOKAll-or-None Immediate
Fill or Kill (FOK)
An order that must be executed immediately in its entire quantity or be cancelled outright.
What Fill or Kill (FOK) means
Fill or kill combines two conditions: the whole quantity must be executed, and it must be executed straight away. If the available liquidity at an acceptable price cannot cover the full size at that instant, nothing is done and the order is cancelled. There is no partial fill and nothing rests on the book. The instruction is used when a partial position would be worse than no position, for example when legging into a hedge or when a strategy depends on a precise notional.
In retail forex, fill or kill often appears as the execution mode behind instant execution requests: the broker either fills the stated volume at the requested price or rejects the order, which the trader experiences as a requote. On ECN and multi-bank venues it is a genuine order attribute, evaluated against the aggregated depth of book at the moment of arrival. Large sizes in less liquid crosses are the most common cause of rejection.
The natural comparison is with immediate or cancel, which shares the immediacy requirement but permits a partial fill. Choosing between them is a judgement about which risk matters more: the unwanted residual exposure and mismatched stop sizing that follow a partial fill, or the execution risk of getting nothing at all and having to resubmit into a market that has already moved. Fill or kill also differs from an all-or-none instruction, which insists on the full quantity but is willing to wait on the book for it rather than demanding immediacy.
Worked example
A trader sends a fill or kill order to buy 10 standard lots of EUR/USD at 1.08515; only 6 lots are available at that price, so the entire order is cancelled and no position is opened.
Related terms
- Immediate or Cancel (IOC)An order that executes whatever quantity is immediately available and cancels the remainder.
- Partial FillExecution of only part of an order's requested quantity, with the balance either resting or cancelled.
- LiquidityThe ease with which an instrument can be traded in size without materially moving its price.
- Depth of Market (DOM)A display of the quantity of bids and offers resting at each price level around the current market.
- RequoteA broker's response offering a new price when the price the trader clicked is no longer available.
Frequently asked questions
What does Fill or Kill (FOK) mean in forex trading?
An order that must be executed immediately in its entire quantity or be cancelled outright.
How does Fill or Kill (FOK) work in practice?
In retail forex, fill or kill often appears as the execution mode behind instant execution requests: the broker either fills the stated volume at the requested price or rejects the order, which the trader experiences as a requote. On ECN and multi-bank venues it is a genuine order attribute, evaluated against the aggregated depth of book at the moment of arrival. Large sizes in less liquid crosses are the most common cause of rejection.
What is an example of Fill or Kill (FOK)?
A trader sends a fill or kill order to buy 10 standard lots of EUR/USD at 1.08515; only 6 lots are available at that price, so the entire order is cancelled and no position is opened.
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