Glossary term
All-or-None Order
An all-or-none order is a trading instruction requiring the entire order to be executed or none of it to be executed, preventing partial fills.
Updated
Read time
What Is an All-or-None Order?
An all-or-none order, or AON order, is a trading instruction requiring the entire order to be executed or none of it to be executed. It is used when an investor does not want a partial fill.
The instruction can be useful when order size matters, but it can also make execution harder. A broker or venue must find enough available shares or contracts to satisfy the whole order under the order's other conditions.
Key Takeaways
- An all-or-none order prevents partial fills.
- The full order must execute or no part of the order executes.
- AON is different from fill-or-kill because AON does not necessarily require immediate execution.
- The instruction can reduce unwanted partial positions but may lower the chance of a fill.
- Availability and handling can vary by broker, security, venue, and order type.
How AON Orders Work
Suppose an investor wants to buy 5,000 shares but does not want to end up with only 1,300 shares. An AON instruction tells the broker that the order should fill only if the full quantity can be completed. If the market cannot supply the full quantity under the order's price and timing conditions, the order may remain open or go unfilled, depending on the order setup.
AON is often paired with a limit price. The investor controls the maximum purchase price or minimum sale price, while the AON condition controls quantity completeness.
AON Versus Related Instructions
Instruction | Main idea |
|---|---|
All-or-none | Fill the entire order or none of it. |
Fill-or-kill | Fill the entire order immediately or cancel it. |
Immediate-or-cancel | Fill what can be filled immediately and cancel the rest. |
What to Watch
AON can be helpful when partial fills would create an awkward position, increase transaction costs, or leave a strategy incomplete. It can also be frustrating because the order may sit even when smaller quantities are available at the desired price.
In less liquid securities, an AON condition can materially reduce execution probability. The investor is trading flexibility for completeness. That tradeoff should be intentional rather than accidental.
Example
Imagine an investor wants to sell exactly 2,000 shares to fund another purchase. If only 700 shares sell, the investor may still hold an unwanted position and may not have enough cash for the next trade. An AON instruction avoids that partial outcome, but the trade may not execute if the market cannot absorb the full 2,000 shares under the order terms.
AON instructions can be less attractive when speed matters more than completeness. In an active market, accepting partial fills may be the more practical way to build or exit a position without waiting for a full-size match.
The Bottom Line
An all-or-none order is a quantity condition: complete the whole order or do not complete it at all. It can protect against partial fills, but it can also make the order harder to execute.