New Jersey-based Merck announced its plan to acquire Acceleron for $11.5 billion ($180 per share) in an all-cash deal that amounts to a whopping 38.5% premium of Acceleron's stock value in September.

The announcement was not unexpected as news trickled through the grapevine last week that a major pharma company is in talks with Acceleron for a potential buyout. On Monday, the Wall Street Journal reported that Merck was the highest bidder, edging out fellow competitors like Bristol Myers Squibb.

The acquisition will let Merck lay its hands on Acceleron's lead cardiovascular candidate, sotatercept, an investigational reverse-remodeling agent proposed to rebalance TGF-beta superfamily signaling in patients with pulmonary arterial hypertension (PAH), a rare, progressive, and life-threatening blood vessel disorder. However, Merck might have to divest its own PAH asset, Adempas, an oral sGC stimulator it gained through a 2014 deal with Bayer, over concerns of market monopoly.