Rumours that a bank had sustained heavy trading losses hit French banks earlier in the week. Those rumours had centred on Société Générale, France’s second biggest bank, still recovering from January’s €4.9bn ($6.5bn) rogue trading loss, which strongly denied them and complained to the financial regulator.

On Friday, Groupe Caisse d’Epargne, a supposedly boring savings bank that has already devolved its investment bank into Natixis, the quoted company, said it had made a €600m loss last week in equity derivatives after a team of traders had exceeded limits.