In July 2010, President Obama signed the Dodd-Frank financial-reform bill. Thanks to the law, “no firm is … protected because it is ‘too big to fail,'” the chief executive said. Three years later, nobody — including the regulators who are supposed to implement it — knows quite what Dodd-Frank does.

Now, Obama faces pressure from left and right to fix his financial fix. And in 2016 —eight years after Lehman Brothers failed — reining in Wall Street could lurk again as an election issue.