China's largest e-commerce company Alibaba Group Holding has agreed to buy a controlling stake in ChinaVision Media Group Ltd for $804 million, giving it access to TV and movie content as competition in the world's biggest Internet market becomes increasingly cutthroat. The pact, which sent ChinaVision's stock surging, comes amid a flurry of deals as Alibaba, social media giant Tencent Holdings Ltd and search engine Baidu Inc seek to expand into each other's turf. This week Tencent said it was taking a stake in China's No. 2 online retailer JD.com, with the new partnership gunning for Alibaba's Achilles heel – its weakness in mobile. ChinaVision and Alibaba said they will establish a strategic committee to explore future opportunities in online entertainment and media-related areas.