When did Merck buy Schering plow and what happened to Schering plow shares?

Merck & Co. announced its acquisition of Schering-Plough in March 2009, completing the deal in November of the same year. Following the announcement, Schering-Plough shares rose significantly, reflecting investor confidence in the merger and the premium offered by Merck. The deal was valued at approximately $41.1 billion, marking one of the largest pharmaceutical mergers at the time.