To protect our clients as well as IB from losses associated with significant and rapidly changing prices, IB generally simulates market orders by submitting a series of marketable limit orders. Alternatively, where available, IB may simulate market orders by using Market With Protection orders.
Although these limit prices are set at a level intended to balance the objectives of execution certainty and minimized price risk, there exists a remote possibility that an execution will be delayed or may not take place. In addition, please note that certain exchanges may impose their own price caps or bands upon market orders at levels that can be more or less restrictive than those imposed by IB, and which may similarly affect the speed and certainty of order execution.