OptionsAcademy

A fill-or-kill order (FOK) is an order that must fill immediately in its entirety, or it cancels automatically. No partial fills allowed.

How It Works

You want to sell 5 call contracts at $2.50. You place a fill-or-kill order.

The broker tries to sell all 5 at your price immediately. If only 3 are available, the order cancels completely rather than selling just 3.

Pros

• All or Nothing: You get exactly what you want or nothing
• No Partial Fills: Avoids awkward partial fills that require additional trades

Cons

• Might Not Fill: If there isn't enough volume, the order cancels
• Rare for Retail: Most retail brokers don't support FOK
• Limited Usefulness: Most options traders don't need FOK

When to Use

• Large block orders (5+ contracts)
• When partial fills would disrupt your strategy
• Professional traders with specific execution needs

Alternatives

Most retail traders just use market or limit orders. FOK is more of an institutional tool.

Availability

Check if your broker supports FOK. Many discount brokers don't. Interactive Brokers does.

Related: Order Types, Limit Order, Market Order