Hong Kong's Securities and Futures Commission (SFC) warned that Deewin Tianxia (HKG:2418) has a "high" concentrated shareholder base, with 10 investors holding 98.9% of its issued H shares as of Nov. 18, according to a Tuesday bourse filing.

Shares of the commercial vehicle supply chain service provider were down nearly 20% in Wednesday morning trade.

Only about 6.05 million H shares, or 1.1% of the total, were held by other shareholders, posing a risk of substantial price volatility even on limited turnover, the regulator said.

Deewin Tianxia's H shares climbed 304% from Sept. 29 to Nov. 18 and closed at HK$9.88 on Dec. 1, representing a 330% gain from the Sept. 29 level, the filing showed.

In a separate filing, the company said at least 25% of its issued shares were held by the public as of Nov. 18 and confirmed it remains in compliance with the Hong Kong Stock Exchange's public float requirements.