Chinese shares closed lower on Monday, with the benchmark Shanghai Composite Index down 1.68 percent, or 38.38 points, to end at 2,240.02, its lowest level in nearly four months.
The Shenzhen Component Index shed 1.1 percent, or 100.27 points, to 8,999.02.
Combined turnover shrank to 153.1 billion yuan (24.4 billion U.S. dollars) from 185.53 billion yuan the previous trading day.
Bank of China chairman Xiao Gang, who resigned on Sunday due to "the necessity of the country's financial work," was reported to have replaced Guo Shuqing as head of the China Securities Regulatory Commission.
The chairman change triggered concerns whether the reforms launched under Guo's leadership would continue.
Nearly 80 percent of shares saw losses on Monday, with the market seemingly spooked by the uncertainty.
Shares of high-end liquor brands, which have frequently appeared on government banquets, fell after China's new premier Li Keqiang on Sunday promised to practice frugality in government spending.
Kweichow Moutai declined 4.25 percent to end the day at 169.45 yuan per share, while Wuliangye closed at 22.91 yuan, off 1.09 percent.
Chinese automaker JAC halted trading on Monday after a China Central Television program scheduled to mark International Consumer Rights Day exposed the company's use of substandard steel plates in its cars.
Bucking the trend, media and entertainment shares rose on Monday, with Enlight Media up 6.02 percent to 38.19 yuan per share.