Drugmaker Bristol-Myers Squibb announced Thursday a $74 billion deal to buy Celgene, in one of the biggest mergers in pharmaceutical industry history. The deal, which still needs the approval of shareholders and regulators, will be paid with a combination of stock and cash. Bristol-Myers is the result of a 1989 merger of two companies that traced their roots back to the 19th century, and is the eighth largest US drugmaker, with annual revenue of $20.8 billion in 2017. Celgene is the ninth largest with revenue of $13 billion. The combined company could become the fourth largest pharmaceutical firm in the United States. Together they have nine different drugs - six from Bristol-Myers and three from Celgene - with global sales of more than $1 billion each, led by $8.2 billion in sales for Revlimid, the Celgene drug used to treat multiple myeloma, a cancer that affects bone marrow and white blood cells. The companies also said they have six other drugs under development which could debut over the next 12 to 24 months, representing more than $15 billion in potential annual revenue. If three of its drugs receive FDA approval, Celgene shareholders will get an additional $9 for every current share of Celgene stock they held at the time of the merger, an unusual aspect to how the deal was structured. But there are also concerns for both companies. Among them is the Trump administration promise to take action to reign in drug prices. The companies also face looming patent expirations for Revlimid. That could bring generic competitors within four years. And Celgene’s purchase of Juno Therapeutics for $9 billion last year didn’t work out as planned. Shares of Celgene lost 39% during the course of 2018, making it ripe for a possible takeover. Bristol-Myers has had its own problem as well, including the Food and Drug Administration pushing back a decision on its application for approval of two of its drugs , Opdivo and Yervoy. That delay sent shares tumbling 6% in October. Shares of Bristol-Myers (BMY) tumbled more than 13% in Thursday’s trading session, while shares of Celgene (CELG) jumped 20%.