Market Roundup

Shares of Walgreen Co

rose about 1.7% after the company reported a 4.6% drop in its February same-store sales. Total sales at the pharmacy chain climbed 1.5% to $5.9 billion. Shares of Alkermes plc

declined about 1.1% after the company named Mark Stejbach as its Chief Commercial Officer. Shares of Archipelago Learning Inc

surged about 22.3% after the company agreed to be bought by Plato Learning, a unit of Thomas Bravo LLC for $11.10 per share in cash. The offer price represents a 23% premium over Shares of EXCO Resources Inc

fell about 4.8% after the company appointed Wilbur L. Ross, Jr. to its Board of Directors, effective March 2, 2012 Shares of Singapore Telecommunications Ltd

dropped about 1.2% after the company announced its plans to buy US-based Amobee Inc. SingTel will buy Amobee for US$321 million in cash.