Pan, who has almost 14 million followers on China’s micro-blogging service Sina Weibo, speaks out regularly on a variety of topics. Besides discussing social issues and his personal life, the Soho China chairman often writes about real estate.

But investors believe some of his posts with confidential information have led to unusual fluctuations in share prices.

In a post published on December 6, 2012, Pan congratulated Zhejiang Hangxiao Steel Structure, a mainland listed company, on winning a contract for a Soho project.

The company’s price rose 6 per cent after the post.

In a similar post revealing Beijing’s Jiangho Curtain Wall winning a Soho contract last October its stock price rose 1.86 per cent within six minutes of Pan’s Weibo message.

However, Shenyang Yuanda Aluminium Industry Engineering, a Hong Kong-listed company, was not so lucky. Its price dropped 8 per cent after Pan’s Weibo post.

Huang Jianzhong, a finance professor at Shanghai Normal University, said Pan’s comments were almost manipulating the stock market.

“He didn’t specify the amount of the contract and the timeline of the project,” said Huang, “This leaves investors confused and [with] room to imagine.”

Huang said listed companies were obligated to inform investors whether the contract’s amount exceeds 10 per cent of the company’s annual income. If Pan revealed this information before the listed company did, he would be violating regulations, Huang explained.

“Pan should be held accountable for what he says as a public figure,” he added. “At least he shouldn’t mislead investors.”

Soho China has still not responded to SCMP’s request for an interview on Wednesday afternoon.