How Wall Street computers cheat

Well, the investment firms running those computers wouldn't put it that way. But how else do you describe a process in which data is fed into supercomputers that calculate stock prices a fraction of a second before most other investors ever see the numbers? The difference in prices is not much, but with so many trades executed it could add up to some serious money. One critic of the practice, called latency arbitrage, says "it's a rigged game." From the WSJ:

The SEC, in a broad review of market structure earlier this year, said information from trading-center data feeds "can reach end-users faster than the consolidated data feeds." The latency arbitrage trade aims to game the so-called national best bid and offer price on a stock, which sets the price most investors use to trade. The ability to estimate price moves ahead of the national best bid and offer price, which is consolidated electronically from exchanges, can give traders an advantage of about 100 to 200 milliseconds over investors who use standard market tools, according to a November 2009 report on such trading activities by Jefferies & Co. An advanced look at exchange data and order flow can provide firms "the ability to forecast future prices" and "make adjustments to their orders in the market or send new orders which are based on this information," the report found.