One of China`s richest men, Guo Guangchang, is reported to be missing. Financial magazine Caixin said that staff at Guo`s company, Fosun International, had been unable to contact their boss since Thursday afternoon. Fosun, one of China`s biggest private conglomerates, halted trading of its Hong Kong shares following the reports.There is speculation that Guo, described as China`s Warren Buffett, has been detained by the police. Caixin quoted social media messages saying he had last been seen with police in Shanghai. A source close to the Fosun Group told the BBC that Guo had not been contactable via an internal company-wide mobile app. ‘It’s very likely he`s been asked by the Chinese authorities to co-operate in an investigation. He is not being investigated himself,’ the source said.He declined to speculate about the details of the investigation. Fosun said it would release further details later. Guo was linked to a corruption court case in August.BBC Asia-Pacific analyst Michael Bristow says Guo’s empire extends across the world, while the publisher Forbes estimates his fortune at $7bn (£4.6bn).Fosun Group has interests spanning media, insurance, real estate and retail. Recently, it took control of French holiday group Club Med. Fosun International, the parent company of Shanghai-based Fosun Group, was listed in Hong Kong in 2007.In a statement to the Hong Kong stock exchange on Friday, the firm said its shares would be halted from trade ‘with effect from 9:00 on Friday, 11 December 2015 pending the release of an announcement containing inside information’.As part of the statement, Guo’s name was included in the list of Fosun’s executive directors.