I have to admit that I was not a big fan of the forced separation between investment banking and commercial banking along the lines of the Glass-Steagall Act in the US. I do not like restrictions to contractual freedom, unless I see a compelling argument that the free market gets it wrong. Nor did I buy the argument that the removal of Glass- Steagall contributed to the 2008 financial crisis. The banks that were at the forefront of the crisis – Bear Stearns, Lehman Brothers, Washington Mutual, Countrywide – were either pure investment banks or pure commercial banks. The ability to merge the two types was crucial in mounting swift rescues to stabilise the system – such as the acquisition of Bear Stearns by JP Morgan and of Merrill Lynch by Bank of America.

Over the last couple of years, however, I have revised my views and I have become convinced of the case for a mandatory separation.

There are certainly better ways to deal with excessive risk-taking behaviour by banks, but we must not allow the perfect to become the enemy of the good. In the absence of these better mechanisms, it makes perfect economic sense to restrict commercial banks’ investments in very risky activities, because their deposits are insured. Short of removing that insurance – and I doubt commercial banks are ready for that – restricting the set of activities they undertake is the simplest way to cope with the burden that banks can impose on taxpayers.