As every investor knows, rigging the market is a criminal offence – unless it is the authorities pulling the strings. Some watchdogs, however, seem to be wishing they had not meddled. The UK’s Financial Services Authority did its best to bury an announcement late on Monday that September’s ban on shorting UK deposit-takers would not continue. In a recent interview, Christopher Cox, the Securities and Exchange Commission chairman, suggested that he was uncomfortable with the US shorting ban all along.

The interventions, intended to stabilise bank shares at a time of real stress, were demonstrably ineffective. In the UK, the stocks placed on the protected list fell three times more than the broader market in the fourth quarter. In the US, a bounce during a three-week ban on uncovered shorting last summer was brief respite from a relentless downward tumble.