Sanofi-aventis on Sunday made public its proposal to

acquire Genzyme in a cash transaction valued at approximately $18.5 billion. The non-binding offer, initially submitted on July 29, was reiterated in a letter to Genzyme CEO Henri Termeer "after several unsuccessful attempts to engage Genzyme’s management in discussions." Chris Viehbacher, chief executive at sanofi-aventis, stated in the letter that "it is our preference to work together with you and the Genzyme board to reach a mutually agreeable transaction."

He added that "your continued refusal to enter into constructive discussions will serve only to further delay the ability of your shareholders to receive the substantial value represented by our all-cash offer." Viehbacher disclosed that early in the negotiation process the companies had "one phone call in general terms and (Genzyme) immediately called a board meeting and said they weren't for sale, without me even saying the price." The Wall Street Journal last week reported that talks between the companies had stalled over the "threshold" price at which sales negotiations could begin.

Under the terms of the proposal, Genzyme shareholders would receive $69-per-share in cash, representing a 38-percent premium over the biotechnology company's share price on July 1, sanofi-aventis said. Viehbacher indicated that the offer price takes into account Genzyme's "upside potential" as the biotech company tries to rectify manufacturing problems that led to shortages of its Gaucher disease drug Cerezyme (imiglucerase) and Fabry disease treatment Fabrazyme (agalsidase beta). Sanofi-aventis said it intends to make Genzyme its global centre for rare diseases, while using its resources to allow Genzyme to accelerate investment in new treatments and expand further into emerging markets.

Sanofi-aventis noted that "at this stage, there can be no assurance that any agreement could be reached between the two companies," but that the drugmaker "is prepared to consider all alternatives to successfully complete this transaction." Commenting on the news, Mark Schoenebaum of ISI Group remarked that "if [sanofi-aventis] goes hostile, I don’t believe a price under $75 [per share] will get it done...The majority of shareholders probably will hold out until [sanofi-aventis] offers something closer to $80 than $70." The analyst also suggested that the takeover process could be drawn out as it is unlikely another buyer will approach Genzyme