Guotai Junan International Holdings has revealed Yim Fung, its chairman, executive director, and chief executive officer, has been missing since Wednesday, South China Morning Post reported, citing a filing to the Hong Kong Stock Exchange. Hong Kong-listed shares in the company – one of the mainland’s largest financial firms – slid 16% in response to the news, which follows the detainment of various other influential figures in Chinese finance amid a sector-wide crackdown: Citic Securities President Cheng Boming and several other top executives are under investigation for trading irregularities, while Yao Gang, vice chairman of the China Securities Regulatory Commission, is under investigation for corruption.