Shares of Chinese brokerage Citic fall on police probe

Mainland Chinese shares have lost nearly 40% of their value since mid-June

Shares of China's largest brokerage, state-owned Citic Securities, fell as much as 4% after it said three executives, including its president, were under police investigation.

The executives are being investigated for suspected insider trading and "leaking inside" information.

The probe comes as Beijing intensifies the scrutiny on irregular stock trading that has rocked Chinese shares.

Mainland Chinese shares have lost about 40% of their value since mid-June.

Those being investigated are Cheng Boming, the general manager and president of Citic since 2012, Wang Jinling, the vice manager of information technology, and Yu Xinli, the head of operational management, the company said in a statement on the Shanghai stock exchange website.

Last month, four other senior executives admitted to insider trading, according to state media.

Citic's Shanghai and Hong Kong listed shares were down over 2% on the news on Wednesday. Its Shanghai listed shares have lost over 60% of their value so far this year.

Chinese regulators have been cracking down on alleged market manipulation intensely among other restrictive measures since mainland shares started their steep slide downwards in June.