Merck to buy Acceleron Pharma in deal valued at $11.5 billion

Merck & Co. agreed to buy Acceleron Pharma Inc. in a deal valuing the drugmaker at $11.5 billion, building out its portfolio of therapies to treat cancer and rare diseases. 

Acceleron shareholders will get $180 a share in cash, the companies said in a statement. 

The deal represents a 34% premium over the price at the end of last month, when the shares traded at $133.88. They began soaring in mid-September, and Bloomberg reported Sept. 24 that the company was in advanced sale talks. 

Merck is among several companies that have been on the hunt for future blockbuster drugs through acquisitions, including Sanofi,