Property tycoon and star blogger Pan Shiyi is under fire from investors, who complain he has been posting price-sensitive information about other companies on his weibo account and are calling on the authorities to open an investigation.
The posts by the Soho China chairman, whose microblog is followed by more than 13 million people, have also raised questions about the manner in which listed companies disseminate information on social media.
"One shouldn't do it, it's common sense. But corporate governance is a bit loose on the mainland," said Alan Jin, an analyst at Mizuho Securities.
According to reports by mainland media, the controversy over Pan's posts on the Twitter-like microblogging site deepened when a group of 20 investors wrote a 3,000-word complaint to the mainland regulator and the Hong Kong stock exchange on December 27 detailing how Pan's blog has been affecting the shares in some of the companies he wrote about.
Sina.com  quoted a reply from the Hong Kong stock exchange on weibo acknowledging "receipt of the complaints" and the promise to "review them to determine what action to take".
But when contacted by the South China Morning Post, an exchange spokeswoman refused to comment on individual companies or cases.
In one instance, on December 6, shares in Zhejiang Hangxiao Steel Structure jumped 6 per cent shortly after Pan disclosed on his weibo account that Soho China had awarded the steel works for a Beijing office project to the Shanghai-listed company.
Again, in late October, shares in Beijing Jangho Curtain Wall went up nearly 2 per cent just eight minutes after Pan blogged that Soho had awarded the Shanghai commercial project's curtain wall project to the mainland-listed company.
But Pan's words failed to influence the stock of a Hong Kong-listed company when he posted on December 25: "The curtain wall contract for Soho's office project in Beijing just closed … Congratulations Yuanda China Holdings for successfully winning the tender."
On December 27, when the market resumed after the Christmas holiday, shares in Hong Kong-listed Yuanda China actually fell 8 per cent rather than going up, as it would normally be expected to. But in this case, it was because Yuanda China also announced a profit warning on Christmas Eve, offsetting the impact of Pan's post.
Christopher Cheung Wah-fung, legislator for financial services, said the regulator should closely monitor how listed firms or their senior management communicate on social media.
"Senior management of listed companies should exercise caution when handling price-sensitive information," he said.
Pan was unavailable for comment yesterday.