Fill or Kill (FOK) Order

What is a Fill or Kill (FOK) Order?

A fill or kill (FOK) order is a time-related order type. The placed order must be executed in its entirety as soon as it is placed – either filling the entire order completely at the specified price or better or canceling the entire order without executing anything. FOK orders are considered an “all-or-none” order instruction, meaning no partial fills are allowed.

Executing FOK Orders

To place an FOK order, traders must specify “fill or kill” as the time-in-force when entering the order details like price, quantity, etc. Upon submission to the exchange, the order book is checked to see if the full order quantity can be executed right away. If so, the entire FOK order will be filled out immediately. If not, the full order is canceled without any partial execution.

Advantages and Use Cases of FOK Orders

FOK orders are useful for controlling trading costs and avoiding excessive slippage or partial fills, especially on larger orders. They provide certainty of full execution at the desired price if filled. Common use cases include forex trading, buying/selling large blocks of stocks, and future/option trades where slippage is undesirable.

Risks and Limitations of FOK Orders

The biggest risk of FOK orders is non-execution – the entire order can be canceled without any fills due to insufficient liquidity. They are less flexible than other order types in this sense. Many brokers also have restrictions on size or only allow FOK for certain products.

FOK vs. Other Order Type

 Unlike market orders that execute at the best available price, FOK requires the exact price or better. FOK also differs from limit orders which can remain working if not immediately fillable. Compared to IOC (immediate-or-cancel) orders, FOK does not allow any partial fills.

Using FOK Across Markets/Assets

FOK orders are available for trading many asset types like stocks, options, futures, forex, and more. However, the rules, order entry process, and limitations may vary by broker and market. For example, some restrict the maximum size for FOK stock orders.

Alexander Voigt, CEO
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Alexander Voigt is the founder of DayTradingZ, was a regular contributor to Benzinga and has been featured and quoted on leading financial websites such as,, Business Insider and Forbes.