Chinese tycoon Guo Guangchang is reported to be missing.

According to financial magazine Caixin, staff at Guo Guangchang’s company, Fosun International, had been unable to contact their boss since Thursday afternoon, December 10.

Fosun, one of China’s biggest private conglomerates, halted trading of its Hong Kong shares following the reports.

There is speculation that Guo Guangchang, described as China’s Warren Buffett, has been detained by the police.

Caixin quoted social media messages saying Guo Guangchang had last been seen with police in Shanghai.

Fosun said it would release further details later. Guo Guangchang was linked to a corruption court case in August.

The tycoon’s empire extends across the world, while the publisher Forbes estimates his fortune at $7 billion.

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 December 11, Fosun said its shares would be halted from trade “with effect from 9:00 on Friday, December 11, 2015 pending the release of an announcement containing inside information”.

As part of the statement, Guo Guanchang’s name was included in the list of Fosun’s executive directors.

Fosun International posted a 24% rise in profit for the year ending in December 2014 from a year earlier to 6.86 billion yuan ($1.1 billion). Its shares fell close to 2% on the news, however, by mid-afternoon they had recovered lost ground to be down 0.45%.