Despite the Dodd-Frank reforms to Wall Street that followed the financial crisis, the top U.S. banks are bigger than they were before 2008 and still dominate the market.
So what? When banks know they're so important that the government is on the hook to save them, there's a danger they'll stick their necks out to take risks, says MIT economist Simon Johnson.
Size also increases the likelihood of mismanagement, because dodgy practices can be buried in a large organization.
In 1970, the five largest banks held 17% of all U.S. banking assets. By 2010, the five largest banks controlled 52%.