Front Running

Front running, also called tailgating, is the practice of trading a stock, option, futures contract or other security on advance, non-public knowledge of a large pending order that will move the price. A broker or trader who knows a big block trade is coming buys or sells ahead of it for a personal or proprietary account and profits when the order moves the market. Many markets treat it as a form of market manipulation, and the typical case involves brokers or brokerage firms trading through undisclosed, unmonitored accounts of relatives or associates.