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Financial Definition of FOK
What It Is
Fill or kill (FOK) is a client's instruction to his or her broker to either fill the entire order immediately or to cancel the order.
How It Works
Why It Matters
When traders are aware of a big order, they will drive the price up, thinking that the big buyer will be willing to pay more. Fill or kill orders are useful in these circumstances because the investor can attempt to lock in a certain price.
Seen and Heard
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