Sina CEO Charles Chao has announced a company restructuring that will see him spend more time focusing on its Weibo microblogging division and “mobile first” strategy, in a year-end letter to employees obtained by Chinese startup blog 36Kr.

Sina’s efforts to monetize on mobile have been public for some time now, but Chao’s letter marks a stronger commitment to mobile platforms. He notes that, in order to improve efficiency at the company, the new division between the Web portal and Weibo was necessary. Weibo had actually been set up as its own business from the start, but it appears that going forward the microblogging service will be even more siloed than before.

Each division will reportedly have its own mobile and PC arm, and their own products, technology and operations. Sina COO Du Hong will lead the portal side of the company and report directly to Chao, who is preparing to dedicate more time to building up the Weibo division.

On the portal side, Executive Vice President Ji Xu will lead product development and technical support for the division, which will now include the wireless business, Sina mobile site and news portal. The video and blog product teams will also fall under the portal team’s jurisdiction.

Wang Gaofei will serve as the general manager for the Weibo department. Sina’s music business will be folded into the microblogging division. Chu Dachen will be in charge of Weibo’s open platform and business development initiatives and report directly to Chao.

Chao also noted that monetization on the service is off to a good start. Weibo has been an impressive success at attracting users, with over 400 million registered accounts, but profits have remained somewhat elusive. It brought in $152.4 million in revenue last quarter, but just $9.9 million in net profit. The company recently enacted an ecommerce experiment with Chinese smartphone maker Xiaomi, where it sold smartphones directly on Weibo.

Weibo is also facing fierce competition from Tencent’s WeChat messaging service. Sina admitted during last quarter’s earnings call that time spent on Weibo is down because users are migrating to WeChat.

Rumors have surfaced that ecommerce giant Alibaba was interested in making a major investment in Weibo, but Sina denied the reports earlier this week.

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