In a great article about the anti-capitalist nature of big banks, James Kwak sums up the different rules medium sized business and giant financial institutions are subjected to:

In general, the mechanism that breaks up inefficient conglomerates is the market for corporate control: takeovers. But the megabanks are virtually immune to takeover (except by each other, which would only make the problem worse). For one thing, the banking regulators wouldn’t let a private equity firm take over a systemically important megabank. For another, the banks are already leveraged to the hilt, so you couldn’t issue any new debt to fund a takeover. So to buy JPMorgan, you’d basically have to come up with $150 billion in cash, which isn’t going to happen.....

In other words, CEOs and directors of midsize retail companies have to worry about being taken over by Bain Capital. But Jamie Dimon, Brian Moynihan, and Vikram Pandit have no one to fear. The basic rules of capitalism don’t apply to them.