Technology has been disrupting Wall Street for years.  Look at the NYSE / Archipelago reverse merger where a young, tech-savvy upstart ECN essentially took over the iconic New York bourse.<p>"In the old days, short-term liquidity was provided by specialists or floor-traders. In the past 10 years, their role has largely been replaced by sophisticated high-speed computer models. CNBC still reports live from the floor of the NYSE to preserve an outdated illusion for the public - the reality is the vast majority of the trading is now done by computers."<p>From Tradebot Systems' homepage (<a href="http://www.tradebotsystems.com/" rel="nofollow">http://www.tradebotsystems.com/</a>) - a proprietary trading group out of Kansas City that competes with major investment banks.<p>I disagree with the author's characterization of market-making as predatory.  There are risks involved in providing liquidity, so there should be some cost, and as a purely competitive enterprise with many players, the costs will be very low.  All brokerage houses allow you to submit your own limit orders if you don't want to pay the spread.  I fail to see how a bunch of computer market-makers competing with one another to offer spreads tight as 1 cent are worse than the old monopolist NYSE specialist quoting in $1/16ths while seeing all order flow.