Aside from firms that have payment for order flow relationships, the US stock markets are basically the pure capitalism you read about in an economics textbook: Low barriers to entry, undifferentiated product (my quote is as good as anyone else's = best price wins), fierce competition.
Maybe it is today, but as soon as it starts to collapse (subprimes and friends), the textbook model has to be saved by external interventions. And so on and so forth. Long term, I doubt pure liberal free markets take us anywhere.
