This morning I proposed a simple speculative model of how banking has been transformed. In this model, the business hasn't changed much, but higher capital requirements have made it less profitable for shareholders: You might make the same amount of money doing the same stuff, but you have to share it among more shareholders. This obviously wasn't the whole story -- banks are also making less money and doing different stuff -- but I suggested that it had some explanatory power.
So I figured I should check it against the facts. And ... nah, not that much explanatory power.