In the spring of 2007, Brad Katsuyama, a rising New York banker at the Royal Bank of Canada, realised something was funny with the markets. He was trying to buy 10,000 shares of Intel offered at $22. But the moment he pushed the buy button, the offers vanished. It was as if the market were reading his mind and adjusting the prices just before he made his trade. He wasn't far off.

Wall Street has always attracted more than its share of scammers and bandits. Today's prime exemplars, argues Michael Lewis in "Flash Boys," are high-frequency traders-or HFTs-who nickel-and-dime investors by exploiting a technological arsenal of servers, fibre-optic cable and microwave transmission towers to trade milliseconds ahead of everyone else in the markets. They have turned the exchanges into a computerised monster churning up unprecedented market volatility. All this has happened since the 2008 financial crisis, a period in which the markets were supposed to have been under closer scrutiny than ever.