Bristol-Myers Squibb (BMY - Get Report) traded blows with activist investor Starboard Value LP Tuesday as the pair issued competing presentations linked to the pharmaceutical group's planned $74 billion takeover of cancer drug specialist Celgene Corp. (CELG - Get Report) .

Bristol Myers said the deal, which if first unveiled in early January, would mean give combined companies number one positions in oncology and cardiovascular drug sales, with a top five standing in immunology and inflammation and nine currency products with over $1 billion in sales. It also sees earnings and revenues growing every year through 2025 and an 8% improvement in margins from its 2018 base.

Starboard, for its part, opposes the deal, arguing Celgene is a company facing a "massive patent cliff" that will force it to replace some 60% of its revenues over the next seven years. It also thinks Celgene's drug pipeline is "extremely risky" and says the takeover proposal was too hastily put together. 

"We believe there is a better path forward for Bristol-Myers, either as a more profitable standalone company with a more focused, lower-risk strategy, or in a potential sale of the whole Company," Starboard said.

Bristol Myers shareholders are set to vote on the takeover on April 12.

Bristol Myers shares were 0.18% higher by mid-day in New York following the release of its deal presentation and traded at $49.95 each, a move that would extend the stock's decline since the Celgene deal was first announced on January 3 to around 4.8%. 

Wellington Management, which holds an 8% stake in Bristol-Myers, added its concern for the proposed deal late last month, noting that while it "agrees that Bristol-Myers should be active in business development that secures differentiated science and broadens the future revenue base", it doesn't think the Celgene transaction "is an attractive path towards accomplishing this goal."

"Since announcing the Celgene transaction on January 3, our Board and management team have had numerous conversations and meetings with our stockholders across our ownership base, including Wellington," Bristol Myers said in an emailed statement to TheStreet on February 28. "We believe that we are acquiring Celgene at an attractive price, and that this transaction presents an important and unique opportunity to create sustainable value."

Bristol-Myers offered Celgene investors one Bristol-Myers share and $50 in cash for each Celgene holding, as well as a special rights issue that will pay off if the merged group meets certain business targets, when it unveiled the deal on January 3.

The deal valued Celgene at $102.43 each at the time, a 53.7% premium to the previous session's closing price. The combined group -- which will be 69% owned by Bristol-Myers -- would have a portfolio with nine drugs that generate more than $1 billion in sales, the companies said.

Jefferies analyst Michael Yee said in a client note Tuesday that he saw "nothing new" in the Starboard presentation, adding shareholders should support a deal that is likely to clear the April 12 vote.

"Ultimately we still think the various BMY arguments for the deal will likely lead to the
acquisition of CELG and the spread will likely narrow after (1) ISS should recommend
the deal, and (2) shareholder vote is notable but deal passes April 12 vote," he said. "Indeed, a key development recently is public commentary BMY acknowledged normal conversations
with industry execs but there were never any substantive talks."