A condition that is used on a buy or sell order whereby a broker is instructed to execute the order in its entirety or nothing of it. For example, if an investor wants to purchase 1,000 shares of a particular company at $50 per share “all or nothing,” the broker would have to find all 1,000 shares at $50 in order to carry out the transaction. If the broker could secure 900 shares at $50 and 100 at $52, then the order would be cancelled at the end of the trading day. All-or-nothing (AON) orders or trades help investors avoid buying or selling partially filled orders. In this sense, these orders are particularly proper for thinly traded securities.

All-or-nothing is also known as  “all or none” order.