Zynga Inc. shares jumped 7.6 percent to $3.57 in morning trading Wednesday, shortly after hedge fund manager Barry Rosenstein said his Jana Partners had taken a new stake in the online games developer earlier this year.
The stock price had been under pressure for some time as investors reacted to its slow transformation into a gaming company that's focused on mobile devices such as smartphones and tablets.
Jana Partners, which often pressures the companies it invests in to adjust their business strategies, released its so-called 13-F filing Wednesday, which describes which U.S. stocks it owned at the end of the first quarter of 2013.
Jana owned 24.6 million class A shares of Zynga, according to the filing, which did not say when the hedge fund bought the stock or what it paid for it.
During the first quarter, the Jana Partners fund was up 6.1 percent.