Most of us have never heard of high-frequency trading. Yet, many experts predict that the next financial crisis will be caused by this new practice, invented by Wall Street. Thousands of computers are interconnected, buying and selling thousands of market shares every micro-second, with no human control or regulation. We delve into a mad financing world dominated by machines, or rather, by elaborate algorithms carefully developed by mathematicians. The ultimate goal? To reach maximum profit within a few seconds. But sometimes, software breaks down and creates, what experts call a “flash crack,” an instantaneous market collapse. We investigate the job of speed traders and expose the often shocking methods they use to reach their goals.