Flash Boys summary

The moment Brad Katsuyama hit “Enter,” he knew there was a problem. It was 2007, and Katsuyama was working in New York for the Royal Bank of Canada (known as RBC). The problem was, whenever he hit Enter to place an order – like buying 10,000 shares of Intel – the price would suddenly go haywire. Thinking he’d be able to turn around and sell for $22 a share, the moment he pressed that button, the share price would plummet, leaving him with massive losses. Suddenly, Katsuyama could no longer trust the market.

The problem was compounded by the fact that the stock market had become so complex that even veteran Wall Street brokers were largely clueless about the finer details. But by gathering a team of experts in various fields and merging their minds, Katsuyama was able to figure out exactly what was going on.

The problem was that Katsuyama’s orders were being “front-run.” The instant a big order – like 10,000 shares of Intel – appeared on the market, the algorithms being used by high-frequency trading firms (known as HFT firms) were able to get ahead of that order before it was broken up and distributed to the various stock exchanges. We’re talking about milliseconds here: the time it takes for an electronic order to make its way from Manhattan to New Jersey. But that was enough time to bombard the markets with competing orders, which would cause the price to change before the transaction was complete. This is what’s known as “front-running.”

Now, thanks to expert knowledge of the fiber optic networks in the tri-state area, Katsuyama and his team were able to develop a tool known as “Thor.” This program could stagger the release of an order so that it reached the various stock exchanges at exactly the same time, effectively ruining any opportunity for front-running.

But as it turned out, Thor was a tiny band-aid on a widespread problem that was being enabled by some of Wall Street’s biggest banks. A complex system of incentives was in place that allowed HFT firms to earn as much as $160 million a day by essentially screwing over investors. A loophole in electronic trading had been discovered and was being ruthlessly exploited, with little consideration for the long-term damage it was causing to both investor confidence and market stability.

It was going to take more than Thor to fix this problem.