Interpositioning is the placing of another broker dealer in between the customer and the best market. Interpositioning is prohibited, unless it can be demonstrated that the customer received a better price because of it.
Applying "Interpositioning" to Securities Exams:
When a customer gives an order to a broker dealer to buy or sell securities that broker dealer is obligated to try to exectute that order at the best possible price. A broker dealer may not accept a customer’s order and then transmist that order to a second broker dealer to execute and have both broker dealers earn a fee for handling the order.