Traders who seek to manipulate the U.S. stock market are meant to encounter resistance from the market itself. During the flash crash, Navinder Sarao apparently used Jon Corzine’s now defunct MF Global to place orders and clear trades. Why didn’t MF Global see what he was up to, or at least call him to ask him about it? There’s now a big business on Wall Street of firms renting out their HFT infrastructure to prop shops. Does that business depend on the brokers paying no attention to what their customers are doing? Do the big Wall Street firms that rent out their technology bear any responsibility for what their customers do with the weapons they've been given? For that matter, why don’t U.S. securities exchanges assume any responsibility for what happens on them?
Sarao’s manipulative orders were placed on the Chicago Mercantile Exchange. Why didn’t the CME notice what was going on? Or did they notice, and simply not care, as the behavior was standard practice for their high-frequency trading clients?
Then there is the biggest question of all: How can a guy working from his parents’ house in suburban England whose only actionable orders were to BUY stock market futures cause such a sensational collapse in U.S. stocks? On the day of the flash crash, Sarao never actually sold stocks. He was trying to trick the market into falling so that he could buy in more cheaply. But whom did he fool with his trick? Whose algorithms were so easily gamed that they responded to phony sell orders by creating a crash? Stupidity isn’t a crime. Still, it would be interesting to know who, at this particular poker table, on this particular day, was the fool.
It would also be interesting to know how it occurred to Sarao that his trick might work. There’s a fabulous yet-to-be-told story here, about a smart kid in the U.K. who somehow figures out that the machines that execute the stock market trades of others might be gamed -- and so he games them. One day while he is busy trying to trick the U.S. stock market into falling, the market collapses, more sensationally than it has ever collapsed. And instead of digging some hole in Hounslow in which he might hide for a decade or so, or fleeing to Anguilla, where he has squirreled away his profits, he stays in his parents’ home and
keeps right on spoofing the U.S. stock market -- and then is shocked when people turn up to accuse him of wrongdoing. He’s not some kind of exception to the standard operating procedure in finance. He’s a parody of it.