Among the stock activity stories for Thursday, Oct. 29, from AP Financial News: HARTFORD, Conn. (AP) ¿ Shares of Manitowoc Co. jumped Thursday as an analyst upgraded the heavy equipment maker on improved crane orders. PHILADELPHIA (AP) ¿ Shares of Symantec Corp. soared Thursday after the antivirus software maker reported second-quarter earnings that exceeded investors' expectations amid signs that stabilization in its business has begun to take hold. NEW YORK (AP) ¿ Shares of IMAX Corp. jumped in Thursday trading after Piper Jaffray put its highest rating on the company, saying more theaters are likely to install its big screens as film distribution costs drop. NEW YORK (AP) ¿ Shares of Cytokinetics Inc. plunged Thursday after the biotechnology company said development of a potential heart failure drug could take a year longer than previously anticipated. NEW YORK (AP) ¿ Shares of ambulatory surgery center operator Novamed Inc. fell Thursday after the company reported a slight dip in third-quarter profit and earnings per share missed Wall Street expectations.