Quick Answer
A fill-or-kill (FOK) order must be filled immediately and in its entirety, or the whole order is canceled. It permits no partial fills and no resting. FOK bundles two demands at once: immediate execution and the complete quantity, all-or-nothing, right now.
FOK is the strictest contingency order in this unit, and the exam tests it by pairing it with two look-alikes that each relax one of its two demands. Keep FOK in one hand and its two cousins in the other the whole way through.
What a FOK Order Is
A FOK order is a one-shot instruction: fill the whole thing this instant, or cancel all of it.
- Fill-or-kill (FOK) order: an order that must be filled immediately and in its entirety (the complete quantity), or it is canceled ("killed") in full.
- No partial fills and no resting: the exchange tries to fill the whole order one time only. If the full quantity cannot be matched at that instant, the entire order is withdrawn. It never sits on the book waiting.
- Immediate AND complete-or-nothing: this is the heart of FOK. Both conditions must be satisfied at the same moment. Miss either one, and the order dies.
How FOK Differs From Its Look-Alikes
The two orders the exam pairs with FOK each drop exactly one of its two demands, so naming which demand is missing is how you tell them apart.
- Immediate-or-cancel (IOC) order, also called fill-and-kill (FAK): fills whatever quantity is available immediately and cancels the unfilled remainder. IOC (or FAK) keeps the immediacy but drops the all-or-nothing part, so it permits partial fills, unlike FOK.
- All-or-none (AON) order: requires the complete quantity but not immediacy. An AON order may rest and wait until the full size can be filled, so it keeps the all-or-nothing part but drops the "right now," unlike FOK.
Here is the three-way split the exam draws on, lined up by the two demands.
| Order | Fill immediately? | Fill in full? | Partial fills? | Can rest and wait? |
|---|---|---|---|---|
| FOK | Yes | Yes | No | No |
| IOC / FAK | Yes | No | Yes | No |
| AON | No | Yes | No | Yes |
Think of it this way: imagine you need exactly 100 concert tickets and you walk up to the booth. FOK says "all 100 right now, or I walk away with none." Immediate-or-cancel says "give me whatever you have right now, even 60, and forget the rest." All-or-none says "I will only take all 100, but I am happy to wait in line until you can find all 100." Only FOK insists on both the full order and the very next instant, so it is the one most likely to come back empty.
Exam Tip: Gotchas
- FOK bundles two demands: immediate and entire. If a choice describes only one (fills part now and cancels the rest, or fills the whole thing but can wait), it is describing a look-alike, not FOK. Only FOK insists on all-or-nothing, right now.
- Immediate-or-cancel allows partial fills; FOK does not. The single word that separates them is "partial." If the order can take whatever is available and cancel the rest, that is immediate-or-cancel (fill-and-kill), never fill-or-kill.
- All-or-none can wait; FOK cannot. All-or-none also wants the complete quantity, but it does not demand instant execution and may rest on the book. If the order is allowed to sit and wait for full size, it is all-or-none, not fill-or-kill.