Activist investor Starboard Value, which very recently bought a 1 million share in Bristol-Myers Squibb (BMS) and nominated five directors to the board, has now made public its intent to block the proposed $74 million takeover of Celgene.

The hedge fund said it will vote against the merger at the special shareholder meeting scheduled for Apr. 12.

In a letter to BMS shareholders, Starboard said it was extremely surprised by BMS’ intention to acquire Celgene and the merger is “poorly conceived and ill-advised”. It added that the announcement follows years of poor financial and stock price performance at BMS and there is a better path forward, either as a more profitable, standalone entity or through a sale of the whole company.

Starboard’s move came just a day after another major shareholder, Wellington Management, told BMS directors that it would not support the acquisition as it was too risky and expensive.

In an internal letter to employees, BMS said it still believes the Celgene transaction is the best path forward. “While we are very disappointed by the position of Wellington Management, we will continue our discussions with shareholders about this unique opportunity to create sustainable value,” said BMS CEO Giovanni Caforio.

At press time, BMS had not responded to Starboard’s announcement.

There has been much speculation since the acquisition was announced in January that investors could try and derail the deal, or even that another bidder for BMS could emerge.

However, speaking to Reuters news agency, Andy Hsieh, an analyst with William Blair, said: “Even with the combined voting power for both Wellington and Starboard Value, we believe there continues to be a high hurdle for opposition to reach majority.”

According to Reuters, BMS’ fifth largest shareholder, Dodge & Cox, is also unhappy with the deal