As of 2014, more than 75 percent of the stock shares traded on United States exchanges (including the New York Stock Exchange and NASDAQ) originate from automated trading system orders.[3][4] ATSs can be designed to trade stocks, options, futures and foreign exchange products based on a predefined set of rules which determine when to enter an order, when to exit a position and how much money to invest in each trading product. Trading strategies differ; some are designed to pick market tops and bottoms, others to follow a trend, and others involve complex strategies including randomizing orders to make them less visible in the marketplace.
