“Banging the close” is a practice in which traders place a large volume of orders just before the close of an exchange. The practice, often with the aid of high-speed computers and sophisticated algorithms, attempts to influence the settlement price of the day with the accumulated large positions. In a 50-page complaint filed in federal court in New York in 2008, the CFTC alleged that Optiver, a Dutch high frequency trading firm, engaged in “banging the close” on 19 different