Fill or Kill (FOK) is a specific “Time in Force” order type that involves either the full and instant execution of a trade or its cancellation. It is typically used when traders try to fill large orders on the spot, at a specific price and are not interested in partial fills (= everything or nothing, right away).
Pros: Useful for large volume orders fulfillment (Institutions and Funds). Can trigger hidden orders from opposite side.
Cons: Risks of no execution for high volumes in low liquidity markets. Difficulty to control buy/sell price efficiently.
Fill or Kill can be used in combination with limit and stop orders. In such case, they trigger only when a threshold is met and have to execute fully and nearly instantly or be cancelled.
FOK orders pay taker fees.
