“There is nothing quite as wonderful as money,” trilled Monty Python in their musical ode to cash. Panicked investors who rushed to empty their money market account funds last September after one fund “broke the buck”, presumably agreed.

The US government guarantee that stopped the stampede, and helped push industry assets to a peak of $3,850bn in January, expired on Friday. Rising investor withdrawals this month owe more to a corporate tax deadline than renewed anxiety. Money market funds, though, face other problems.