Under the terms of the proposed deal, Celgene shareholders will receive one Bristol-Myers Squibb share and $50 in cash for each Celgene share held, according to a statement from the companies on Thursday. That would value Celgene at $102.43 a share, a 54% premium to the stock's closing price on Jan 2. Celgene shares soared more than 30% to $87.20 in premarket trading in New York, while Bristol shares fell more than 16% to $44. The transaction would combine two companies that both have strong-selling cancer drugs but that have also faced investor skepticism about their growth prospects. Bristol-Myers (BMY) shares declined more than 15% in 2018, while Celgene shares (CELG) sank more than 41%. The deal is Bristol's largest under Chief Executive Officer Giovanni Caforio, and comes after the drugmaker has suffered some high-profile setbacks in immuno-oncology, its biggest line of business. Bristol has been under pressure to diversify its portfolio.