Orders & Execution
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Fill or Kill (FOK)
Also called: FOK
An order that must fill entirely and immediately, or be cancelled — no partial fills allowed.
Definition
FOK is an execution instruction used mostly in institutional and ECN trading. The order must fill in full, at the specified price, the instant it hits the venue — otherwise it’s cancelled.
Rarely needed in retail FX (typical retail orders fill in full anyway at the broker’s quoted price), but available on some ECN platforms.
Example
You submit a 50-lot FOK buy limit at 1.0800. The order book shows only 30 lots available at 1.0800. The order is killed — you don't get the 30 lots.