(Reuters) -Investment management firm Holocene Advisors said it will not back Merck & Co’s offer to buy Acceleron Pharma (NASDAQ:) Inc for $180 per share, saying it significantly undervalues the drugmaker.

Avoro Capital which holds 7% of Acceleron stock also shares that opinion on Merck’s $11.5 billion offer for the company.

Holocene stated in a Wednesday statement that he did not believe the transaction at the current price was compelling. He also noted that Acceleron has strong pipelines and long-term prospects.

Merck will have the opportunity to access Acceleron’s rare drug candidate for sotatercept. This deal is expected to bring in billions in revenues.

Merck has not responded to any requests for comment.

Acceleron said Wednesday that it supported the offer fully and no other negotiations had taken place after its acceptance.

On a conference call with Reuters Todd James, Acceleron’s senior vice president for corporate affairs, and investor relations said that more than half the outstanding shares must be offered to complete deals.

Merck launched its tender offering to purchase Acceleron shares Tuesday.

Holocene had 1.42% ownership of Acceleron’s trade shares at June 30, according to Refinitiv. It is also among the 20 most prominent investors in Acceleron, data shows.