PARIS ( TheStreet) -- Sanofi-Aventis ( SNY), the biggest drugmaker in France, is preparing a major U.S. acquisition, Bloomberg reports. Sanofi CEO Chris Viehbacher briefed the board on the transaction at a special meeting this week, said people with knowledge of the situation. The process is in the early stages and an agreement with the unidentified target may not be reached, the people said, Bloomberg reports. Sanofi's U.S. acquisition could be worth $20 billion or more, according to the news agency. A Sanofi spokesman told Bloomberg the company doesn't comment on "rumors or market speculation." Bloomberg notes that Sanofi is counting on acquisitions to help replace revenue it's losing as its medicines face competition from lower-priced generics. Sanofi has spent about $17 billion on 25 acquisitions since Viehbacher joined the company in 2008, according to Bloomberg data. In March, Sanofi and Merck ( MRK) reached a deal to combine their animal health businesses. -- Written by Joseph Woelfel in New York. Get more stock ideas and investing advice on our sister site, Stockpickr.com.