Sanofi-Aventis, France's largest pharmaceutical, is expected to make a formal bid of as much as $18.7 billion for the U.S. biotech giant Genzyme and its portfolio of rare-disease therapeutics, which could help staunch its losses as low-priced generic competition erodes its sales.

Sanofi's board has authorized CEO Chris Viehbacher to bid up to $70 per share for Genzyme, according to reports, although some analysts suggest Genzyme may hold out for as much as $75 per share. Anticipation of the deal, which first surfaced earlier in July when reports suggested Sanofi had lined up a $20 billion takeover fund, has already boosted the value of Genzyme's shares. They traded for near $70 per share Thursday.

One investor likely pleased by Sanofi's approach is Carl Icahn. The billionaire investor, who controls two seats on Genzyme's board, has publicly pushed the company to seek out potential suitors ever since a manufacturing snafu hobbled its ability to produce two lucrative drugs, Cerezyme and Fabrazyme.

Viehbacher, Sanofi's CEO, has yet to speak publicly about the offer, but has spoken in general terms about what such an acquisition might represent for his company. Sanofi is “all around trying to build these platforms of sustainable growth,” he told investors during a conference call about it first quarter 2010 earnings. “We know that over the next two years we’re going to lose a number of products, Eloxatin and Taxotere and Plavix, first in Europe and then in the U.S. And one day Ambien. Can’t do much about that,” he said.

Facing such certain losses, Viehbacher has been clear in other forums that he considers acquisitions to be a viable growth strategy, but has told analysts he doesn't feel pressured to pursue a deal.

Though a small part of the bigger picture, the necessity of Sanofi diversifying its portfolio became all the more clear Wednesday as an FDA panel voted to recommend that the agency approve AstraZeneca's Brilinta, a blood thinner that will create yet more competition for one of Sanofi's long-time bestsellers, Plavix.