A former vice-chairman of China's securities regulator, Yao Gang, is being investigated for taking bribes, the official China Daily said, citing the prosecutors' office.
Yao was one of the most senior figures arrested in a crackdown on suspected stock manipulation in late 2015, after the mid-year collapse of the Chinese stock market following a long bull run.
Yao was subject to "coercive measures," which can range from summons and surveillance to detention and arrest, among other actions, the Supreme People's Procuratorate said, without specifying which he faced, the newspaper said on Thursday.
In July, China's graft watchdog said Yao would be prosecuted for offences that included taking bribes and "destroying the order of capital markets".
Yao, 55, was the general manager of Guotai Junan Securities in 1999 before taking a position with the China Securities Regulatory Commission in 2002, the paper said.
At the CSRC, he was known as the "King of IPOs", overseeing initial public offerings on the Chinese mainland for 13 years, it added.