The mainland's former top securities regulator – appointed to clean up markets following a 2015 market meltdown – is under investigation for unspecified wrongdoing, authorities say.
Liu Shiyu was suspected of "violating the law", said a brief notice on the website of the Communist Party agency responsible for policing corruption.
He had turned himself in, the notice said, but gave no further information.
A former banker and deputy governor with the central bank, Liu was installed as head of the China Securities Regulatory Commission (CSRC) in early 2016, with a mission to restore confidence in financial markets.
The previous year, the mainland's traditionally volatile markets slumped precipitously in a disastrous meltdown worsened by an erratic response from regulators.
Liu declared war on financial "crocodiles" and "barbarians" who manipulate the market.
He launched a crackdown that saw dramatically enhanced enforcement of securities regulations and sharply increased the amount of fines levied.
He was replaced in January by Yi Huiman, former chairman of the giant Industrial and Commercial Bank of China.
Liu is not the first financial regulator felled in a crackdown on corruption by President Xi Jinping's government.
Yao Gang, the former vice chairman of the CSRC, was last year sentenced to 18 years in jail for taking bribes and insider trading.
Xiang Junbo, China's former insurance regulator, also pleaded guilty to taking bribes last year. (AFP)