Fill or Kill (FOK) Orders: What They Are, How They Work, and Real-World Examples


Fill or Kill (FOK) orders in securities trading ensure immediate execution of an entire transaction or none at all. This comprehensive guide delves into the intricacies of FOK orders, their benefits, and real-world applications. Learn how they expedite trading for large stock quantities and prevent market disturbances, and explore a detailed example illustrating their functionality.

What are Fill or Kill (FOK) orders?

Fill or Kill (FOK) orders are specialized time-in-force directives in the world of securities trading. They instruct a brokerage to execute a transaction immediately and in its entirety or cancel the order entirely.

Primarily used by active traders dealing with substantial quantities of stock, FOK orders are a combination of an all-or-none (AON) specification and an immediate-or-cancel (IOC) timeframe.

How does fill or kill work?

Fill or Kill orders aim to ensure the prompt and complete execution of a trade at prevailing prices. Without this directive, executing a large order might take an extended period, potentially causing significant changes in stock prices and market disruptions.

On various exchanges, FOK orders are handled differently. Some exchanges execute FOK orders within seconds, similar to an “all or none” order, promptly canceling the order if not entirely filled. Conversely, on other exchanges, the order is filled by the number of shares available at the first bid or offer, with any unfilled shares being canceled.

However, in practice, Fill or Kill trades are relatively rare. Other methods of instructing brokerage firms on trade execution timeframes include Immediate or Cancel (IOC) orders, which fill all or part of the order immediately, canceling any unfilled portion, and Good ‘til Canceled (GTC) orders, which remain open until the specified price is reached.

Weigh the risks and benefits

Here is a list of the benefits and the drawbacks to consider.

  • Immediate execution at the desired price.
  • Minimizes market disruption for large trades.
  • No partial fills allowed, potentially leading to missed opportunities.
  • Changes in conditions may result in the order being canceled without execution.

Fill or kill example

Illustrating a Fill or Kill order through an example can provide a clearer understanding. Imagine an investor seeking to purchase 1 million shares of Stock XYZ at $15 per share. To buy 1 million shares immediately, and at $15 or better, an FOK order would be necessary. If the broker has 700,000 shares available at $15 or all 1 million shares at $15.01, the order would be killed. However, if the broker sells the full 1 million shares at $15 or at a better price like $14.99, the order would be filled instantly.

Frequently asked questions

Why might a Fill or Kill order be preferable over other order types?

A Fill or Kill order can be preferable for traders dealing with large quantities as it ensures immediate execution or no execution at all, preventing disruptions due to partial fills.

Do FOK orders guarantee the best price?

While FOK orders aim for immediate execution at a specified price, they might not always secure the absolute best price due to their all-or-none nature.

How often are Fill or Kill orders used in trading?

FOK orders are relatively rare compared to other order types in trading due to their stringent requirement of immediate and complete execution.

Key takeaways

  • Fill or Kill (FOK) orders execute a trade immediately and completely or not at all.
  • They are commonly used for large stock quantities to prevent market disruption.
  • FOK orders combine an all-or-none (AON) requirement with an immediate-or-cancel (IOC) timeframe.
View article sources
  1. Fill-Or-Kill Order – U.S. Securities and Exchange Commission
  2. Investor Bulletin: Understanding Order Types – U.S. Securities and Exchange Commission
  3. What Is Time In Force? Examples & Strategies – SuperMoney
  4. Applying For a Loan Online vs. In Person: What’s Better? – SuperMoney