Credit Suisse First Boston and Lazard are set to add a €50bn ($59bn) bid to their league table rankings as client Novartis starts takeover talks with Franco-German rival Aventis. The arrival of Novartis brings to 19 the number of investment banks with an advisory or financing role in Europe's biggest hostile M&A battle since 2000.

CSFB and Lazard are understood to be advising Novartis on a potential white knight bid for Aventis, the franco-German pharmaceuticals company, which is the subject of a €48bn hostile bid by Sanofi, its French rival. Novartis declined to comment.