French pharmaceutical group Sanofi-Aventis unveiled Sunday a 18.5 billion dollar (14.5 billion euro) cash bid for US biotechnology firm Genzyme, or 69 dollars per share.
The non-binding offer, exclusively in cash, represents a 38 percent premium over the 49.86 dollars Genzyme's shares closed at on July 1 before take-over rumours began to swirl, according to Sanofi.
Sanofi said it was disclosing to Genzyme's shareholders the contents of its offer, which it initially made in July, after the company's management rejected it on August 11 and declined to enter into constructive talks.
"A combination with Genzyme represents a compelling opportunity for both companies and our respective shareholders and is consistent with our sustainable growth strategy," Sanofi chief executive Christopher Viehbacher was quoted as saying in a company statement.