As head of the financial stability unit at the Banque de France, Imène Rahmouni-Rousseau trav- elled to America this month to look at the current turmoil in the US subprime mortgage world.

Although initially that had seemed an all-American saga, Ms Rahmouni suspected that French and other European investors also held assets linked to subprime securities. So on behalf of her central bank she wanted to assess the risks.