“Buy, buy, sell,” intones a machine-like voice emanating from a keyboard on a desk in a dealing room in Amsterdam. It is almost lost in the din of human shouts as traders call out bids to one another or turn up the volume on squawk-boxes connecting this dealing-room with those of clients. Despite the imperative tone, the computerised voice is not issuing instructions, it is simply reporting its actions as it trades derivatives faster than the beat of a dragon-fly’s wing.