Zhong Ju Investment Group (HKG:1959) flagged a high concentration of shareholding in the firm's shares following a request from the Hong Kong Stock Exchange, according to a filing with the city's bourse Tuesday.

Shares of the automotive seller fell nearly 31% in morning trade Wednesday.

According to the notice, 21 shareholders collectively controlled 90.31% of the company's issued share capital, leaving only 9.69% of the issued shares in the hands of other shareholders.

This meant that the shares may not have a genuine market and prices could fluctuate "substantially" even with a small number of shares traded, Zhong Ju Investment said.