Shares of Amylin Pharmaceuticals (AMLN) popped nearly 9% in early trading Monday, reacting to late Friday news that the biotech is being bought by Bristol-Myers Squibb (BMY) for $5 billion. The move brought Amylin's stock to its highest point in nearly four years, after it had already been inflated by a report that surfaced in March that Amylin had rejected a $3.5 billion bid from Bristol-Myers earlier this year. That news brought a lawsuit from