It seems like you're describing flash trading, in which some customers pay to receive market data a split second before everyone else. In particular, this is no

It seems like you're describing flash trading, in which some customers pay to receive market data a split second before everyone else. In particular, this is not the same as co-locating to reduce latency: it's programatically implemented on the exchange side. Flash trading no longer exists on any major exchange. AFIAK only the relatively minor exchange Direct Edge has them. http://en.wikipedia.org/wiki/Flash_order http://en.wikipedia.org/wiki/Flash_order