Big banks aren't just black boxes. They are black boxes within black boxes.

That has always been the challenge for investors- exactly what their assets are worth isn't always clear, and just how they make their money is sometimes hard to discern. Going into 2013, that potentially becomes an even bigger issue. Investors still can't say for sure how a plethora of regulatory actions, ranging from expected final interpretations of Basel capital requirements to the Volcker rule prohibition on proprietary trading, will affect revenue and profit.