Bristol-Myers Squibb Co. and Celgene Corp. have entered into a definitive merger agreement under which BMS will acquire Celgene in a cash and stock transaction valued at approximately $74 billion. Celgene shareholders will also be eligible to receive a payment for the achievement of future regulatory milestones. When completed, BMS shareholders are expected to own approximately 69 percent of the company, and Celgene shareholders are expected to own approximately 31 percent.   The transaction w...