Shares of the online social gaming company Zynga opened the trading day Tuesday up by 10.7 per cent after the struggling company's founder, Mark Pincus, stepped aside as CEO.

Pincus will be replaced by Microsoft executive Don Mattrick, effective July 8, and will stay on as the company's chairman and chief product officer.

"Don is unique in the game business," Pincus said in a statement, "and deeply understands the value of a network and the importance of creating lifelong consumer relationships".

San Francisco-based Zynga is best known for online games like FarmVille and CityVille, which are often connected directly to Facebook.

The change in leadership comes at a key time for Zynga. Since going public in December 2011, the company's stock has fallen 65 per cent, and it laid off 520 employees last month, almost 20 per cent of its workforce.

Zynga's key business has been dropping for nearly a year. Its revenue is at the lowest level it has been since 2011, and its monthly average users in the first quarter of this year are down 13 per cent from the same time last year.

Mattrick made entertainment division profitable

The Canadian-born Mattrick has been with Microsoft since 2007, first as senior vice-president of the Xbox division, then as head of Microsoft's entire interactive entertainment division.

Mattrick has been credited with turning the entertainment division into a profitable business by increasing the number of consoles in active use, referred to as the "install base," to over 80 million and growing the number of Xbox Live subscribers sevenfold to 48 million in six years.

The change in leadership comes at a key time for Zynga. Since going public in December 2011, the company's stock has fallen 65 per cent, and it laid off 520 employees last month, almost 20 per cent of its workforce.

Zynga's key business has been dropping for nearly a year. Its revenue is at the lowest level it has been since 2011, and its monthly average users in the first quarter of this year are down 13 per cent from the same time last year.

Sudden departure

Mattrick's sudden departure from Microsoft comes at a key time for the company's entertainment division, which is launching a new console, the Xbox One, this November.

Mattrick was front and centre during the product's unveiling in late May and during the company's showing at the E3 industry showcase in early June.

Microsoft was forced to change course on a number of key features following strong backlash from consumers. The console was initially designed to require a connection to the internet for authentication and would have imposed restrictions on the re-selling and lending of games.

Reports indicate that Microsoft CEO Steve Ballmer will oversee the interactive entertainment division until Mattrick's replacement can be found.

Zynga's stock ended the trading day up 6.5 per cent to $3.27 US on the Nasdaq while Microsoft's stock was down 1.2 per cent to $33.96 on the Nasdaq.