I’m halfway through the new Michael Lewis book – the one that has been turned into not only a breathless 60 Minutes segment but also a long excerpt in the New York Times Magazine. Like all Michael Lewis books, it’s written with great clarity and fluency: you’re not going to have any trouble turning the pages. And, like all Michael Lewis books, it’s at heart a narrative about a person — in this case, Brad Katsuyama, the founder of a small new stock exchange called IEX.