Tencent (700.HK) Chairman Pony Ma said that his firm will double its investment fund aimed at third-party software developers to US$1.5 billion, the Wall Street Journal reported. The firm is seeking to expand beyond its bread-and-butter services of instant messages and online games. The investment fund was created in January to target online game developers and other companies. Tencent has previously said that it would open its online platform up to third-party software developers to create applications, suggesting the firm may be moving towards an open platform model. Besides its instant messaging service QQ and affiliated social networking and games sites, the firm has been focusing on expanding its microblog website, Tencent Weibo, to compete with the larger Sino (SINA.NASDAQ) Weibo service.