Sanofi-Aventis Reportedly Planning Major U.S. Acquisition

Sanofi-Aventis (SNY) is preparing a major acquisition in the U.S. worth $20 billion or more, according to Bloomberg, which cited five people with knowledge of the situation.

Like many pharmaceutical firms, Sanofi is facing a looming patent cliff -- when major drugs lose their patent protection and cheaper generics flood the market. And, like many pharmaceuticals, Sanofi doesn't have a large enough pipeline of new drugs to make up for the lost sales.

According to Bloomberg's sources, CEO Chris Viehbacher briefed the board on the transaction at a special meeting this week, but added that the process is in very early stages.

As for the target, Reuters reports that analysts cite Allergan (AGN) and Biogen Idec (BIIB) as possibles. Those companies have market values of $17 billion and $12.7 billion respectively.

After a Sanofi spokesperson declined to comment on "market rumors or speculation," the company's share price fell in Europe by 2.4%.