Zhang Yujun, the assistant to the chairman of China's securities regulatory commission, is being investigated for violating rules.
No further details have been revealed yet.
This comes amid the central authorities intensifying its probe into irregular market trading.
On Tuesday, several senior executives from CITIC Securities were confirmed as being probed by police.
The three senior staffs, including the brokerage's general manager, are being investigated for insider trading and leaking information.
CITIC Securities is China's largest brokerage.