Few noticed after French insurer Axa's announcement of a €7.9bn ($10bn) takeover of Swiss rival Winterthur that it had handed the advisory mandate not to its long-standing adviser, but to a competitor.

Axa agreed a deal for Winterthur, owned by Credit Suisse, on June 14, worth more than 11 times the target's net income from last year. The Swiss banking group used its internal team and Evercore partners to advise on the sale.