 Before becoming an exchange, IEX operated a dark pool which did not adhere entirely to priority by price then time, unlike other U.S. trading venues.Instead, the IEX prioritized orders by price, followed by broker, and lastly time.Katsuyama argues that this arrangement advantages regular investors contrarily to high frequency trading (HFT) firms, by preventing, for instance, HFT firms from jumping to the top of the order queue and front-running normal investors.