The most basic link in finance is that between risk and reward. Just like alchemists who once sought a path to gold from lead, a great deal of modern finance was built around finding a shortcut between them, but now, what is missing is reward, especially under conditions where there are no longer illusions about risk. We are way, way past Humpty Dumpty time. You can bring back prop trading, but you still have to have asymmetry for banks to trade in it. That ship sailed for good in late July 2011.