[Imprecate]

http://www.nasdaqtrader.com/trader.aspx?ID=topliquidity

GS isn't even top-5 on NASDAQ.

Professional trading was never cheap. The barrier to entry for becoming a high-frequency trading firm is much, much lower than becoming a NYSE specialist was a decade ago. You could co-locate there for a few million dollars, which is small money all things considered.

[joe-mccann]

Top-5 in LIQUIDITY PROVIDERS, not necessarily the same as in programatiC/algo trading. Goldman tops the list and anyone that's traded on a prop desk knows how much influence they have on the domestic equities market:

http://subprint.com/u/28