An illegal act in which a broker or other representative, just before filling a large order on behalf of a client, conducts a transaction in the same security on his/her own account. A large order to buy or sell usually affects the price of a security; the broker conducts the transaction hoping to profit on the movement in price after he/she fills the client's order. This is a form of insider trading, as the broker filling the order knows something about the market's probable movement that other market participants do not know. It is also known as tape racing.
The illegal purchase or sale of a security by a broker for his or her personal account before execution of customer orders in the same security. If a brokerage firm issues a negative report on a company, a broker acting on the report for his or her own account before telling clients about the report would be running ahead. See also front running.