It takes barely a second. No human trader could act on that sort of blip, but for a very brief period of time, Roscombe’s stock was at less than half price. Someone could have made a fortune, and someone probably did. There’s a layer of buying and selling now that happens in eyeblinks, as our algorithms and their algorithms fight it out over tiny fluctuations, and may the best software win. The banks have bought up huge warehouses and derelict buildings near the exchanges so as to cut milliseconds off the transmission times of their orders, filled them with the highest specification of computers in rows and rows and rows. There are no offices, just endless clean corridors occasionally patrolled by security men, and humming boxes looking for opportunities. Somewhere in those buildings is a trader—an automated system—that just made out like a pirate. Probably more than one.