An order (buy or sell order) that is placed by a customer determining that it will consist of two transactions provided that a specific price differential is attainable between the transactions. Otherwise, the order is not executed. In other words, it is n order to buy one security and then sell another at a differential, or to sell one security and then to buy another at a differential. The transaction will be called a proceeds sale if the proceeds from the sell order exceed the expenses of the buy order.

For example, the customer may construct the order in a way that 100 shares are purchased and 100 different shares are sold only if the price differential between the sell order and buy order is 7 monetary units.

Contingent orders (contingent trade orders) are also known as swap orders or switch orders.