Merck agreed to buy the Bertarelli family’s 64.5% stake in Serono in September 2006. Merck had originally turned its attention to the acquisition of Serono after it lost out in a bidding war with Bayer for Schering AG earlier in the year.
In the proposed takeover, Merck will buy Serono for $13.31 billion. Merck’s Pharma Ethicals division will be combined with Serono to create Merck-Serono Biopharmaceuticals. The transaction received US antitrust approval in October.