all these problems can be alleviated if glass-steaggal was still in place. the problem I see with these HFTs are many use their own clients money to play their HFT bets like big banks. Event though they put on a show briefly that prop trading at banks has been brought down - it hasn't. I know a few traders at top banks who insist it still goes on in more subtle ways and utilizing leverage of technology. The way they see it is they can't win or shake regulators but they can stay 1 step ahead.