In musical chairs, players whose seats are filched sometimes sit on the floor with a bump. This was the undignified position of Credit Suisse announcing a stiff SFr4.4bn ($4.7bn) impairment. The implosion of US family office client Archegos has obliterated 18 months of average net profits and cost two senior executives their jobs. Agile Wall Street banks, such as Goldman Sachs and Morgan Stanley, appear to have escaped unscathed. But the stability of systemically important banks should not rely on a talent for party games.

Regulators led by the US Securities and Exchange Commission should investigate the prime broking industry. This is the low-profile business of helping funds such as Archegos to structure and finance bets.

The risk to capital buffers is clear when six or more institutions are lending separately to a little-known investor in volatile stocks while apparently knowing little about the others. Without strong retained profits, Credit Suisse’s core equity tier one capital would have dropped uncomfortably below 12 per cent of risk-weighted assets.