but he was the first to find brad katsuyama, who is the first to figure out how it was being done. >> unlikely character, a trader at the royal bank of canada, a young canadian man named brad katsuyama realized that the market that he thought he knew had changed. the market seemed to be willing to sell a stock. but the minute he went to buy it, someone else bought it, the stock went up. it was as if someone knew what he was doing before he did it. >> kroft: back in 2008, katsuyama was 30 years old and running the royal bank of canada's stock desk in new york with 25 traders working for him. every time one of them tried to buy a large block of stock for a client, their order would only be partially filled and the price of the stock would go up. it kept happening over and over again. >> brad katsuyama: the best analogy i think is that your family wants to go to a concert. you go onto stubhub, there's four tickets all next to each other for 20 bucks each. you put in an order to buy four tickets, 20 bucks each, and it says, "you've bought two tickets at 20 bucks each." and you go back and