The Communist Party's corruption watchdog said Li Liang, head of the investor protection bureau of the China Securities Regulatory Commission (CSRC), was under investigation for "violation of laws and discipline".
The Central Commission for Discipline and Inspection gave no further details in its statement, issued late yesterday, but the phrase is normally code for graft.
The investigation comes as China's securities regulator is pushing to make the IPO approval process more transparent, and during a government clampdown on corruption.
ChiNext now lists 400 companies with a market capitalisation of USD 390 billion, according to the exchange.
Caixin said some "controversial" approvals for listings might be behind his downfall.
The magazine also linked Li to another corruption case involving businessman Ling Wancheng, the brother of former politician Ling Jihua who was sacked after his son was killed in a scandalous Ferrari crash in 2012.
Ling Wancheng invested in seven companies before they launched their IPOs, six of which listed on ChiNext, Caixin said.
The CSRC could not be reached for comment.
