1. A method of managing trading, comprising: in a market for a particular type of instrument, receiving trading orders from a plurality of traders, each trading order having an associated price; placing each of the received trading orders on a trading exchange such that the trading orders may be executed; determining whether the price of a particular trading order differs from a previous trade price by more than a threshold value; and if it is determined that the price of the particular trading order differs from the previous trade price by more than the threshold value, taking a restrictive action regarding the particular trading order.