Among the stock activity stories for Wednesday, Dec. 16, from AP Financial News: NEW YORK (AP) ¿ Shares of Adobe Systems Inc. climbed in midday trading after the company said demand for its software picked up strongly in November. MILWAUKEE (AP) ¿ Shares of wine maker Constellation Brands Inc. tumbled after a downgrade amid news the company was being sued by its Mexican-based partner in a joint venture. BOSTON (AP) ¿ Shares of Charles Schwab Corp. rose after a Deutsche Bank Securities analyst upgraded the retail brokerage's stock and another analyst initiated coverage with a favorable rating. CHICAGO (AP) ¿ Shares of restaurant owner Darden Restaurants Inc., which operates Olive Garden, Red Lobster and Longhorn Steakhouse, climbed after an analyst upgraded the stock. NEW YORK (AP) ¿ Shares of industrial equipment maker Roper Industries Inc. rose after Standard & Poor's said it will add the company to the S&P 500 index next week. NEW YORK (AP) ¿ Shares of CardioNet Inc. gained ground after a Leerink Swann Research analyst upgraded the stock, citing an "encouraging" outlook for the wireless heart-monitoring device maker.