Used in context of general equities. Order giving a broker a choice between two courses of action, either to buy or sell, never both. Execution of one course automatically eliminates the other. An example is a combination buy limit/ buy stop order, where the buy limit is below the current market and the buy stop is above. If the order is for one unit of trading, when one part of the order is executed on the occurrence of one alternative, the order on the other alternative is to be treated as cancelled. If the order is for an amount of more than one unit of trading, the number of units executed determines the amount of the alternative order to be treated as cancelled. Sometimes known as One Cancels the Other. Also see: Either-or order.
An order to conduct two transactions such that, if one transaction is done, then the other is cancelled. For example, an investor may wish to buy both stocks and bonds at a certain price. If the price becomes available for bonds first, that part of the order is filled while the order to buy stocks is cancelled. OCO orders may apply to different types of securities or even to different types or orders; for example, one may contain both stop-loss orders and limit orders. OCO orders are useful to investors who have limited funds and perhaps are unsure about the market's direction at a given time. It is also called an either-or order.
A customer order that instructs a broker to complete only one of two possible transactions. For example, an investor holding shares of USX Corp. that were acquired at $45 may have a price target of $75 but may wish to limit any losses to a maximum of $5 per share. The investor would place a limit order to sell at $75 and a stop order to sell at $40. Whichever occurs first will trigger a transaction and cancel the other part of the order. Also called combination order, either-or order, one-cancels-the-other order.