One of China’s richest men, GuoGuangchang, is reported to be missing.
Financial magazine Caixin said that staff at MrGuo’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 MrGuo, 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 MrGuo 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. MrGuo was linked to a corruption court case in August.
MrGuo’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.