Sanofi board ousts boss Chris Viehbacher after intense speculation

Chairman Serge Weinberg set to take on the role of CEO until a replacement for Viehbacher is found

Sanofi's board has ousted chief executive Chris Viehbacher amid speculation that his relationship with the French drug maker's chairman had soured.

Rumours began swirling on Monday after it emerged Viehbacher reportedly wrote a letter to the board asking directors to dismiss speculation and clarify his role.

Yesterday, he was unable to confirm whether he still had the backing of the board during a conference call after the drug maker warned its diabetes business had slowed and would probably not grow next year.

Shares in Sanofi fell more than 10 per cent, wiping off 13 billion euros of the drugmaker's market value in two days. The stock extended losses in early trading today, down 4 per cent.

Chairman Serge Weinberg is set to take on the role of CEO until a replacement for the ousted Viehbacher is announced.

He took the job in late 2008, becoming Sanofi's first non-French chief executive, and had taken on an ambitious international expansion strategy.

But tensions with Weinberg had intensified in recent years and his relationship with the board had come under scrutiny. In a recent interview with the Financial Times, Weinberg argued the board had concerns about his "management style" and said there was a general dissatisfaction among directors.