NEW YORK ( TheStreet) -- 2011 saw renewed corporate merger and acquisition activity across various industry sectors. Investors might want to take a look at the companies resulting from these deals, because the merged companies may wind up with more efficiency or industry heft.The following stocks either completed or announced acquisitions during the past year. They are listed in descending order of total deal value. 1. Express Scripts ( ESRX) is one of the largest pharmacy benefit management companies in North America. It provides network-pharmacy claims processing, home delivery services, specialty benefit management, benefit-design consultation and other services. In July, the company announced it would acquire all of Medco Health Solutions' ( MHS) shares in a cash and stock deal. Under the agreement, Medco's shareholders will receive $28.80 in cash and 0.81 shares of Express Scripts for each Medco share they own. Based on recent stock prices, the purchase price is valued at $25.2 billion, a premium to Medco's recent market capitalization of $21.6 billion. The deal is expected to generate synergies of $1 billion once fully integrated, representing 1% of the combined costs. The transaction is expected to be slightly accretive to EPS in the first year after closing and moderately accretive when fully integrated. The deal is likely to close during the first half of 2012, subject to regulatory approval. Of the 26 analysts covering Express Scripts, 88% rate the stock a buy. Analysts polled by Bloomberg on average expect the stock to gain 26.5% to $56.79 in the coming 12 months.