Sometimes partial fills create problems for your trading strategy. If you need to buy or sell a specific quantity all at once, an all or none order ensures you get everything or nothing. In this guide, we will explain how AON orders work and when they are most useful.
What is an All or None Order?
An all or none (AON) order is an instruction that must be filled completely or not at all. Unlike fill or kill orders that demand immediate execution, AON orders can wait throughout the trading day or longer for enough shares to become available at your price.
The simple version: An AON order says "I want all 500 shares or none. I am willing to wait, but do not give me just 200 shares." It prevents partial fills while allowing time for the full order to execute.
How All or None Orders Work
Here is what happens when you place an AON order:
- Your order is sent with the all or none condition
- The system checks if enough shares are available at your price to fill the entire order
- If yes, the entire order executes
- If no, the order remains pending and keeps checking throughout the day
- The order either fills completely at some point or expires unfilled
All or None Order Examples
Example: AON Order That Fills
You want to buy exactly 1,000 shares of a stock at $25 using an AON order.
- 10:00 AM: You place AON buy order for 1,000 shares at $25
- 10:00 AM: Only 600 shares available at $25, order does not fill
- 11:30 AM: 400 more shares become available at $25
- 11:30 AM: Now 1,000 shares available, your entire order fills
Result: You bought all 1,000 shares at $25 per share, no partial fills.
Example: AON Order That Does Not Fill
You want to buy 2,000 shares of a less liquid stock at $15.
- 9:30 AM: You place AON day order for 2,000 shares at $15
- All day: Maximum available at one time at $15 is 1,500 shares
- 4:00 PM: Market closes, your order never had enough shares available
- 4:00 PM: Order expires unfilled, you bought nothing
Result: Because 2,000 shares were never available at your price simultaneously, you did not buy any shares.
When to Use All or None Orders
AON orders are most useful in these situations:
- Low-priced stocks: When partial fills would result in meaningless position sizes
- Specific position sizing: When you need an exact number of shares for risk management
- Commission considerations: When multiple partial fills would incur excessive commissions
- Matching lot sizes: When you need to match a specific existing position
- Options exercising: When you need shares in exact multiples of 100 for option exercises
- Portfolio rebalancing: When precise share quantities are needed for allocation targets
Advantages of All or None Orders
- No partial fills: Get exactly what you ordered or nothing at all
- Time to fill: Unlike FOK orders, AON orders can wait for shares to become available
- Precise position sizing: Maintain exact share quantities for your strategy
- Simpler management: No need to manage multiple partial positions
- Commission savings: Avoid multiple transaction fees from partial fills
Disadvantages and Risks
AON orders have significant limitations:
- Lower fill priority: AON orders often have lower priority than regular orders at the same price
- Harder to fill: Requiring a complete fill makes execution less likely
- May miss opportunities: You might miss a good entry because you could not get the full amount
- Not available everywhere: Some exchanges and brokers do not support AON orders
- Liquidity dependent: Less liquid stocks make AON orders even harder to fill
Important: AON orders typically have lower priority in the order queue. Even if shares are available at your price, regular orders might get filled first, leaving your AON order waiting.
AON vs FOK: What is the Difference?
Both order types require complete fills, but timing differs significantly:
- All or None (AON): Must fill entirely but can wait throughout the day (or longer with GTC)
- Fill or Kill (FOK): Must fill entirely AND immediately or cancel
Comparison Example
You want to buy 1,000 shares but only 700 are currently available at your price.
- AON result: Order waits. If 1,000 shares become available later today, it fills. Otherwise, it expires at close.
- FOK result: Order immediately canceled because 1,000 shares are not available right now.
AON vs IOC: What is the Difference?
These orders handle partial fills completely differently:
- All or None (AON): Refuses partial fills, waits for complete fill
- Immediate or Cancel (IOC): Accepts partial fills, cancels remainder immediately
Use AON when you must have the exact quantity. Use IOC when you want immediate execution and can work with whatever is available.
AON Order Duration Options
AON can be combined with different time in force options:
- AON Day Order: Must fill completely today or expire at market close
- AON GTC Order: Remains active for multiple days until it fills completely or you cancel it
Using AON with GTC gives your order more time to find enough shares for a complete fill.
Practical Considerations
Before using AON orders, consider these factors:
- Stock liquidity: AON works better on stocks that trade millions of shares daily
- Order size: Smaller AON orders are more likely to fill than very large ones
- Price level: Orders at or near the current market price fill more easily
- Broker support: Verify your broker supports AON orders before relying on them
- Market conditions: Volatile markets may have liquidity that comes and goes quickly
Tips for Using All or None Orders
- Check average volume: Only use AON on stocks with high daily trading volume
- Be patient: AON orders may take longer to fill than regular orders
- Size appropriately: Do not place AON orders larger than typical trade sizes for that stock
- Consider alternatives: If you keep missing fills, standard orders with manual position building might work better
- Monitor your orders: Check if your AON order is still pending or has expired
When AON Orders Make Sense vs Not
Good use of AON:
- Buying 500 shares of a penny stock to avoid tiny partial fills
- Purchasing exactly 200 shares to close out an existing 200 share position
- Getting precisely 1,000 shares to sell covered calls (10 contracts)
Poor use of AON:
- Buying 10,000 shares of a stock that only trades 5,000 shares daily
- Using AON on highly liquid stocks like Apple where partial fills are rare anyway
- Time-sensitive trades where waiting for a complete fill could mean missing the opportunity
Track Your Order Execution
Pro Trader Dashboard helps you track all your trades and analyze your execution quality. See fill rates, average prices, and optimize your order strategy.
Summary
All or none orders ensure you get your exact requested quantity or nothing at all. Unlike fill or kill orders that demand immediate execution, AON orders can wait throughout the day for enough shares to become available. They are most useful for low-priced stocks, precise position sizing, and avoiding multiple partial fills. However, they come with lower fill priority and may not execute at all if liquidity is insufficient.
Want to learn about related order types? Check out our guide on fill or kill orders or learn about immediate or cancel orders.