What is "program trading"

alt. (label en business finance computing) high-volume and high-speed buying and selling of investment security, such as stocks and bonds, which is initiated and executed by brokerage firms' computer programs that continually monitor market conditions. n. (label en business finance computing) high-volume and high-speed buying and selling of investment security, such as stocks and bonds, which is initiated and executed by brokerage firms' computer programs that continually monitor market conditions.

n. a trading technique involving large blocks of stock with trades triggered by computer programs

Program trading is a type of trading in securities, usually consisting of baskets of fifteen stocks or more that are executed by a computer program simultaneously based on predetermined conditions. Program trading is often used by hedge funds and other institutional investors pursuing index arbitrage or other arbitrage strategies. There are essentially two reasons to use program trading, either because of the desire to trade a large number of stocks at the same time (for example, when a mutual fund receives an influx of money it will use that money to increase its holdings in the multiple stocks which the fund is based on), or alternatively to arbitrage temporary price discrepancies between related financial instruments, such as between an index and its constituent parts.

According to the New York Stock Exchange, in 2006 program trading accounts for about 30% and as high as 46.4% of the trading volume on that exchange every day. Barrons breaks down its weekly figures for program trading between index arbitrage and other types of program trading. As of July 2012, program trading made up about 25% of the volume on the NYSE; index arbitrage made up less than 1%.