A condition used on a buy or sell order to instruct the broker to fill the order completely or not at all. If there is insufficient supply to meet the quantity requested by the order then it is canceled at the close of the market.




Taobiz explains All Or None - AON
For example, if you send an AON order to your broker requesting 200 shares at $15, the broker will not fill the order unless he or she can obtain the 200 shares at $15. This prevents investors from having orders half filled before they expire. This is contrary to a common limit order, which is commonly partially filled. For example, if 150 shares trade at $15 and then rise to $17, the 150 shares will be purchased by the investor with the limit order and the remainder will be bought when the shares fall back to $15. If the trader had an AON order then he or she will not receive any shares and will have to resubmit the order the next day to buy the 200 shares at $15.