The collapse of three regional U.S. banks last month sent tremors through the financial system, but they were contained after federal government authorities stepped in.

The banks’ bigger competitors reported healthy results for the first three months of this year calming markets further.

But there remain concerns about the surge in bad loans these banks are writing off, because customers can’t repay them.

And that’s happening just as an ominous phrase has been making its return, as Owen Fairclough reports.