Following the 2008 global financial disaster triggered mostly by U.S. banks taking excessive risks, authorities imposed new safeguards to try to prevent another catastrophe.

That included permanently raising the limit on federally insured bank customer deposits to $250,000.

This was partly to stop future bank runs – when customers panic and pull their deposits.

But four U.S. banks have collapsed recently after dramatic runs on deposits.

Now regulars are thinking about how to reform deposit insurance. But they have to wrangle with the problem of moral hazard.