Guo Guangchang, one of the richest people in China, is reportedly missing.
Guo's company, Fosun International, has suspended the trading of its shares in Hong Kong after being unable to contact Guo since yesterday (Thursday) afternoon.
Some believe that he is being detained by police. An inside source acknowledged the rumors, telling the BBC: "It's very likely he's been asked by the Chinese authorities to co-operate in an investigation. He is not being investigated himself."