In China, app makers face competition from local apps built by companies like Tencent Holdings Ltd.

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Other new-economy stars, such as Lenovo Group, Tencent Holdings and search-engine Baidu, are already in the second 500 of our list.

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Last year was a watershed year for users of weibo sites such as those run by Sina Corp and Tencent Holdings.

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In China, app makers face competition from local apps built by companies like Tencent Holdings Ltd. and Sina Corp.

WSJ: For App Makers, China Is Untapped and Untamed

Besides Alibaba Group, other Chinese companies, such as Tencent Holdings Ltd.

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Chinese social media companies, including Sina, Renren and Tencent Holdings Ltd.

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Tencent Holdings, which has its own hugely popular social media app (Weixin, or WeChat) and is trying to build up its e-commerce platform.

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In fact, the two companies that started the weibo craze, Sina Corporation and Tencent Holdings now count eight times more users than Twitter worldwide.

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That includes stakes in China's Internet and instant messaging leader Tencent Holdings (run by Chinese billionaire Ma Huateng), Russian Internet giant Mail.ru and Brazilian magazine publisher Abril.

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Sina and Tencent Holdings Ltd.

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