After a bloodbath in the share market in mid-June, Beijing began cracking down on alleged illegal activity, such as insider trading and 'malicious' short-selling, which were blamed partly for volatility.

Investigators in Shanghai have started probing Guotai Junan Securities (>> Guotai Junan Securities Co Ltd) and Haitong Securities (>> HAITONG Securities Company Limited), two of the largest state-owned brokerages, the official Xinhua news agency reported, citing a government paper.

Guotai Junan International (>> GUOTAI JUNAN INTERNATIONAL HOLD. LIMITED), the Hong Kong subsidiary of Guotai Junan, said on Monday its chairman had been missing since Wednesday.

This is the third probe in Shanghai this year, Xinhua said, and will involve sweeping investigations that involve 12 other state-owned companies and six universities.

President Xi Jinping opened a campaign three years ago to root out corruption in all walks of life in China.

Executives at CITIC Securities (>> CITIC Securities Company Limited) have fallen foul of China's corruption authorities and have allegedly admitted to insider trading and leaking information.

Meanwhile, four executives at state-owned People's Insurance Company of China Co (PICC), one of the country's largest insurers, were punished for a wide range of misdemeanours from hiding a spouse's U.S. green card status, to using trade union money to fund shopping sprees, according to a statement posted on the country's main anti-graft body's official website.

The Central Commission for Discipline Inspection (CCDI) said some employees were fired, while others were demoted or given warnings.

On Monday, the CCDI demoted four bank regulators for violating Communist Party rules and procedures.

(Reporting by Engen Tham; Editing by Simon Cameron-Moore)