SHANGHAI, Jan 29 (Reuters) - China's stocks fell at open on Thursday after sources told Reuters that regulators are launching a fresh investigation into margin trading at brokerages.
The CSI300 index opened down 1.4 percent, to 3,474.91 points, and the Shanghai Composite Index also opened down 1.4 percent, to 3,259.00 points.
The CSI300 stock index futures for February fell 1.8 percent to 3471.8 in early trade.
The official Xinhua news agency said late on Wednesday the stock regulator would inspect margin trading of 46 companies as part of regular supervision.
The last time China regulators cracked down on margin lending, punishing three brokerages for inappropriate handling of leveraged trade earlier this month, stock indexes collapsed dramatically for a day, prompting regulators to move to reassure the market that they were not trying to cap a long-running rally. (Reporting by Sue-Lin Wong; Editing by Kazunori Takada)