Two mainland banks made a lackluster debut on the Hong Kong Stock Exchange on Wednesday amid concerns over declining margins and increasing bad loans.

Share prices were unchanged for both China Zheshang Bank Co and Bank of Tianjin Co on a day the benchmark Hang Seng Index rallied 2.15 percent, or 437.09 points, to close at 20,803.39.

Investors have been cool to mainland lenders lately.