"It sounds like science fiction -- something from I, Robot or The Terminator, where the machines take over. But totally automated "high-frequency trading" is part of the stock market right now -- a big part.

According to some estimates, high-frequency trading by investment banks, hedge funds and other players accounts for 60% to 70% of all trades in U.S. stocks, explaining the enormous increase in trading volume over the past few years. Profits were estimated at between $8 billion and $21 billion in 2008."