Human specialists and locals usually either had a monopoly on their product or were buddies with everyone in the pit so of course they would collude. Even on th

Human specialists and locals usually either had a monopoly on their product or were buddies with everyone in the pit so of course they would collude. Even on the NASDAQ screen they would collude and intimidate anyone showing tighter prices for showing "Chinese quotes": http://www.acsu.buffalo.edu/~keechung/TEM/Journal%20Articles/Collusion%20A%201994.pdf http://www.acsu.buffalo.edu/~keechung/TEM/Journal%20Articles... Anonymous limit order books are far better. Nobody's price is better than anyone else's and machines have no problem competing spreads down to near-zero.