An investment firm, Jana Partners LLC, announced its intention to stop the acquisition of WuXi PharmaTech by Charles River Laboratories. Jana Partners has purchased 4.7 million shares of Charles River in recent weeks, making it the company’s largest shareholder. When the transaction was announced, Charles River’s stock price dropped 15%. Jana Partners most likely hopes it can recover part of that loss by halting the purchase or forcing WuXi to accept a lower price. More details...

Stock Symbols: (NYSE: WX) (NYSE: CRL)