Finally, a senior banking regulator has acknowledged the so-called repeal of Glass-Steagall had nothing to do with the 2008 financial crisis. In a recent speech, Fed governor Daniel Tarullo noted that most firms at the center of the financial crisis in 2008 were either stand-alone commercial banks or investment banks, and therefore would not have been affected by the repeal. Tarullo also expressed concern that a reinstatement of Glass-Steagall would be costly for banks and their clients and would result in less product diversification.

Of all the myths underpinning the response to the 2008 financial crisis, one of the most persistent is that the repeal of Glass-Steagall was a major contributing factor. So Tarullo’s comments are heartening. But still, he misses out one key piece of the puzzle, namely, that multifunctional, diversified financial firms are not just more efficient and cost-effective than their more specialized counterparts; they are frequently more stable.

The banks that got into trouble in 2008 did so because they concentrated their risk in one kind of asset. The firms that did comparatively well throughout the crisis avoided this particular mistake and were able to come to the rescue, admittedly with some government assistance, of their ailing counterparts—think Wells Fargo or JPMorgan. Firms fail when they make bad investment decisions, regardless of their structure.