Internet search provider Baidu Inc (BIDU) - Get Report and e-commerce company (JD) - Get Report will join other Chinese tech firms to invest $12 billion in the Shanghai-listed unit of state-owned China Unicom (CHU) - Get Report , Reuters reported.

The joint investment is part of an initiative to rejuvenate state-owned firms with private capital. Unicom is the weakest of China's state-owned telecom companies, lagging China Mobile (CHL) - Get Report and China Telecom (CHA) - Get Report . But Unicom is one of the world's largest mobile carriers by user numbers.

Alibaba Group Holdings (BABA) - Get Report and Tencent Holdings (TCTZF) said last month that they will be part of a joint $10 billion investment into Unicom's Shanghai-listed unit, China United Network Communications Ltd.

The Unicom investments will be the largest capital raising initiative in the Asia-Pacific region since insurer AIA Group's (AAIGF) 2010 IPO, Reuters said.

China Unicom stock traded up premarket.

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