The Economist reports on the practical difficulties of breaking up big banks into ones that are small enough to fail:
banks might have to be ground into gravel rather than just broken in two. The smallest firm subject to the Fed's stress tests in May had risk-adjusted assets of about $100 billion. If this were the minimum size of a systemically important firm, then America's four big banks would need to be split into 48 separate companies to be small enough to fail. American policymakers will be acutely aware that there is almost no appetite anywhere else, except Britain, for breaking up banks.