Fill-Or-Kill (FOK)
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What Is a Fill-Or-Kill Order?
A Fill-Or-Kill (FOK) order is a type of time-in-force designation used in securities trading that instructs a brokerage to execute a transaction immediately and completely or not at all.
A Fill-Or-Kill (FOK) order combines two other order types: "All-or-None" (AON) and "Immediate-or-Cancel" (IOC). It tells the market: "Give me all the shares I asked for, right now, at my price. If you can't do that, cancel the whole thing." This order type is typically used for large orders where the trader does not want a partial fill. For example, if a trader wants 10,000 shares but there is only liquidity for 500 shares, a standard order might fill the 500 and leave 9,500 pending. An FOK order would see that 10,000 aren't available and simply cancel the order, leaving the trader with zero shares.
Key Takeaways
- Must be executed immediately and in its entirety.
- If the full order cannot be filled at the specified price (or better), it is cancelled.
- Partial fills are NOT allowed.
- Used to ensure a large order is entered at a single price.
- Commonly used by active traders and institutions to avoid partial positions.
When to Use FOK
FOK orders are useful in fast-moving markets or when executing arbitrage strategies where getting only half the position would ruin the strategy. For example, if you are buying a basket of stocks to hedge an option position, you need the *exact* amount of stock to remain delta neutral. If you only get a partial fill, your hedge is incomplete. Using FOK ensures you are either fully hedged or not involved at all.
Real-World Example: Buying Thinly Traded Stock
A trader wants to buy 100,000 shares of XYZ Corp at $10.00.
FOK vs. IOC vs. AON
Understanding the nuances of execution instructions.
| Order Type | Immediate Execution? | Partial Fills Allowed? | Result if Not Met |
|---|---|---|---|
| Fill-Or-Kill (FOK) | Yes | No | Cancelled completely |
| Immediate-Or-Cancel (IOC) | Yes | Yes | Fills what it can, cancels the rest |
| All-Or-None (AON) | No (can wait) | No | Sits on order book until full size is available |
FAQs
Partial fills can be annoying or costly. If you pay a commission per trade, multiple partial fills increase costs. Also, if you need a specific number of shares for a strategy (like an arbitrage or hedge), a partial fill leaves you exposed to risk without the full benefit of the strategy.
Rarely. Most retail traders trade small enough sizes (100-500 shares) that liquidity is not an issue. FOK is primarily a tool for institutional investors or high-volume day traders moving large blocks of stock.
Yes, if it is a Limit FOK order. It guarantees that if the trade happens, it happens at your limit price or better. If the market moves away, the order is simply cancelled.
The Bottom Line
The Fill-Or-Kill order is a precision tool for traders who deal in bulk. It demands perfection: the right quantity, at the right price, right now. By refusing partial fills, it prevents traders from ending up with fragmented positions that are difficult to manage. While rarely needed by the average investor, it is a vital mechanism for institutions maintaining clean, hedged books.
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At a Glance
Key Takeaways
- Must be executed immediately and in its entirety.
- If the full order cannot be filled at the specified price (or better), it is cancelled.
- Partial fills are NOT allowed.
- Used to ensure a large order is entered at a single price.