Shares in social gaming pioneer Zynga jumped more than 14 percent on Wednesday with a quarterly earnings report that revealed a loss and a plan to buy back stock. Zynga reported that it lost $52.725 million on revenue of $316.637 in the quarter ended September 30 and that it planned to repurchase $200 million worth of its shares. The San Francisco-based firm\'s shares rose to $2.43 on the news in after-market trading.