Sanofi’s Genzyme Bid May Need to Reach $80 to Win

Sanofi-Aventis SA may have to pay at least $80 a share, or $21.3 billion, to acquire genetic-disease drugmaker Genzyme Corp. as activist directors drive up the price, investors in the U.S. biotechnology company say.

Sanofi Chief Executive Officer Chris Viehbacher has support from his board to offer as much as $70 a share, or about $18.7 billion, and is preparing a formal offer letter for Genzyme, according to three people familiar with the situation who declined to be named because the deliberations are private.