The cases, involving price manipulation through various channels, have exacerbated the ups and downs in the recent market rout, Deng Ge, spokesman of China Securities Regulatory Commission, told reporters.
One case involved an overseas firm using the Qualified Foreign Institutional Investor (QFII) programme to manipulate prices, state-run Xinhua news agency cited Deng as saying.
He did not give other details.
China's stockmarket experienced a dramatic summer that saw the key stock index plunge over 40 per cent from its June peak of 5,166 points.
The wild swings have continued despite government efforts to restore confidence.
The benchmark Shanghai Composite Index rose 1.3 per cent to end at 3,412.43 points today, while the Shenzhen Component Index rose 2.64 per cent to close at 11,603.46 points.
