(Yicai Global) Sept. 28 -- A culture of investing based on rumors has plagued China's A-share market. With more social media platforms emerging, untrustworthy "bull news" has provoked the greed of many private investors.

Some insiders holding key information are no longer satisfied with telling their siblings and friends, so they give "bull news" to their business partners, their children's teachers and local governmental officers as a gift, the China Securities Regulatory Commission (CSRC) told Yicai Global.

Among 89 insider traders officially investigated by the CSRC last year, those acting on information themselves accounted for 31 percent, while insiders' relatives, friends, classmates and business partners made up 69 percent.

Some 60 percent of new rat trading cases this year involve information transmission, and those with inside information used many mediums to send multiple recipients info in 40 percent of such cases.

The regulator began looking into 18 cases in its third round of action against insider trading this July. It has almost completed these investigations, which were mainly in the areas of mergers and acquisitions as well as ownership structure changes

"The CSRC has never relaxed supervision on insider trading," an officer in the CSRC's audit department of told Yicai Global. Although authorities have contained rat trading to a certain degree, it is still very likely to happen in view of the development trend of investor structure, stock market culture and communication means, she said. The audit department will impose harsh measures against it.