All-or-None: Fill the Full Order or Nothing

Key Takeaways

• An all or none order AON fills the entire quantity or none, never a partial amount.
• It does not require immediate execution, so it can keep working over time.
• That patience is the key difference from a fill-or-kill order.
• Traders use AON for full-size positions where partial fills cause problems.

What an All or None Order AON Is

An all or none order AON is a condition placed on an order requiring that the whole quantity trade together or not at all. The SEC defines it as "an order to buy or sell a stock that must be executed in its entirety, or not executed at all."

The defining contrast is timing. FINRA notes that AON orders "prevent partial filling of orders, but they don't have the immediacy of an FOK order." Instead, the firm keeps trying to fill the entire order until you cancel it or it reaches any expiration the firm sets. The order can wait, but it can never fill in pieces.

The Intuition

Suppose you want a specific number of shares and a partial fill would create headaches. Maybe you are sizing a position to a fixed dollar amount, or you want to avoid paying multiple commissions on scattered small fills. A standard order would happily hand you a fragment of your size whenever liquidity is thin.

The AON condition prevents that. It tells the market you will accept the full quantity or nothing. Unlike an order that insists on instant action, an AON is content to wait in the wings until enough liquidity gathers to fill the whole thing at once.

How It Works

An AON condition sits on top of a limit order. The order stays eligible to trade, but the matching engine will only execute it when the complete quantity can be satisfied at an acceptable price. Until then, it waits.

AON: fill the entire order, but it can keep working over time
FOK: fill the entire order immediately, or cancel all of it
IOC: fill what you can immediately, cancel only the remainder

The cleanest comparison is with fill or kill. Both demand the full size, but FOK adds an immediacy requirement: if the whole order cannot fill at once, FOK cancels it instantly. An AON drops that immediacy. It will sit and keep trying, so it trades patience for the chance to complete later. An immediate-or-cancel order is the opposite of AON on the partial-fill question, since IOC gladly takes a fraction and cancels the rest.

Worked Example

A trader wants 8,000 shares as a single block and does not want partial fills that would trigger several commissions. The stock trades around 25.00.

The trader enters a buy all or none order AON for 8,000 shares with a limit of 25.00. At that moment only 5,000 shares are available at 25.00, so the order does not execute. Rather than canceling, the AON keeps working. Twenty minutes later a seller posts 8,000 shares at 25.00, and the AON fills the entire block in one trade.

Compare a fill-or-kill order for the same size. When only 5,000 shares were available at entry, the FOK would have canceled immediately and the trader would have missed the later block. The AON waited and captured the full size, which is the trade-off it offers: patience in exchange for completeness.

Common Mistakes

1. Assuming AON acts immediately. It does not. An AON can rest for a long time, so it is the wrong tool when you need to act this second.
2. Confusing AON with fill-or-kill. Both want the full size, but FOK cancels at once if it cannot fill, while AON keeps working.
3. Using AON on small or liquid orders. For modest sizes that fill easily, the AON condition adds delay with little benefit.
4. Forgetting it may never fill. If liquidity never gathers at your price, the AON simply waits and expires unfilled.
5. Ignoring venue support. Not every market or broker offers AON, and minimum-size rules sometimes apply, so confirm availability before relying on it.

Frequently Asked Questions

What is an all or none order AON in simple terms? An all or none order AON buys or sells the entire amount or none at all. Unlike fill-or-kill, it can keep working over time instead of canceling right away.

How does an all or none order AON affect investment decisions? It guarantees you get the full position or none, avoiding scattered partial fills and extra costs. In the worked example, the AON waited and filled all 8,000 shares once a matching block appeared.

What is a real-world example of an all or none order AON? A trader wanting 8,000 shares enters an AON; only 5,000 are available at first, so it waits, then fills the entire 8,000 when a larger seller posts.

How can investors use an all or none order AON effectively? Use it when a partial fill would cause problems, set a patient limit price, and accept that the order may rest unfilled if enough liquidity never gathers.

How is an all or none order AON different from a fill-or-kill order? An AON demands the full quantity but can keep working over time. A fill-or-kill order demands the full quantity immediately and cancels everything if it cannot fill at once.

Sources

1. SEC Investor.gov. All-Or-None Order. https://www.investor.gov/introduction-investing/investing-basics/glossary/all-or-none-order
2. FINRA. Trading Terms: Time Parameters and Qualifiers on Stock Orders. https://www.finra.org/investors/insights/time-parameters-qualifiers-stock-orders
3. Nasdaq Glossary. All or None Order (AON). https://www.nasdaq.com/glossary/a/all-or-none-order
4. SEC Investor.gov. Investor Bulletin: Understanding Order Types. https://www.investor.gov/introduction-investing/general-resources/news-alerts/alerts-bulletins/investor-bulletins-14

Disclaimer

This article is educational content only and is not financial advice. Nothing here is a recommendation to buy, sell, or hold any security. Consult a licensed advisor before making investment decisions.