"Automated Trading System"
An automated trading system (ATS) is a computer trading program that automatically submits trades to an exchange.
An example of an early ATS is Instinet. This allows traders to input trades invisibly to the market, with a crossing price determined by a VWAP measure. Instinet also enables anonymous conversations and negotiations to take place between bidders, and so reduces informational costs to the participants. Automated trading systems are created by converting your trading system's rules into code that your computer can understand. Your computer then runs those rules through your trading software, which looks for trades that adhere to your rules. Finally, the trades are automatically placed with your broker.