The so-called Volcker rule would be slightly less feared. Prop trading is not as profitable over the long run as many realise, but if banks are also forced to stop investing in hedge funds and private equity, normalised earnings could fall by about 2 per cent, according to Goldman Sachs.
There is also this from Tyler Durden
So with a delay of about six months since Zero Hedge started pounding on the topic of prop trading as the last bastion of perfectly legal front-running, which co-opts clients into "efficient" flow execution with the few remaining monopolist entities left on Wall Street in exchange for assorted prop trading desks taking advantage of complete flow visibility (i.e., the hedge fund nature of all modern Wall Street bail out recipients) which is simply a way to run alongside (or in front of) whale orders, thus providing guaranteed and risk free returns, the administration has finally realized what we have claimed for many months: that prop trading is nothing but a quasi-illegal operation, which was made explicitly and perfectly permissible with the adoption of the disastrous Gramm-Leach-Bliley act. As long as prop trading exists, Goldman (which is reporting earnings tomorrow, and we expect will announce another quarter of 90%+ profitable trading days only thanks to it taking full advantage of a thorough visibility of the FICC and equity flow market and a commingled prop and flow order book) will have record earnings, until such time as the Minsky Moment in Goldman's balance sheet arises again and blows up the financial system one more time.