It would be regulated by the SEC and be dependent on its own performance and not a bunch of financial activities with leverage that few can understand, much less put a dollar value on.

FORBES: The Profitable Way To Break Up The Giant Banks

Raj Singh, a former investment banker who recently became chief risk officer of Swiss Re, points out that the banks' risk models, which try to put a value on how much they should realistically expect to lose in the 99% of the time that passes for normality, draw on reams of historical data.

ECONOMIST: Risk management

But that is a lame excuse: it should be much easier to count bodies than to put a value on diverse sorts of economic output.

ECONOMIST: Economics focus