When I was actively trading, I used a product that was the equivalent of today's E-Signal. All trades have time/date stamps, and most pass thru an ECN. Very transparent, except for the "back room" specialist deals during the good ole boy days at the NYSE.
While I can understand large swings based on the international overnight stuff happening in Spain and Greece, a mid day "trading error" that drops the Dow by 1,000, and then recoups two-thirds of that in just 30 minutes really pizzes me off.
Then these financial writers have the balls to justify this with those ridiculous on-line articles.
The game is "still" rigged.