It can be defined as a buy or a sell order that needs to be executed completely or not at all.
Partial execution of an order is not possible. Either the broker should fill out the order completely or not at all. It is sometimes called a duration order. Usually, an investor tells a broker how to fill the order, thus impacting its period of operation.
Points to remember:
An all or none order is executable only when there are enough shares available to make a transaction. In case this condition is not fulfilled, the order is cancelled.
They are similar to fill or kill orders.
The main disadvantage of an all or none order is that a change in the price of the stock during the transaction process will impact the total cost incurred by the investor for the order.