Sept 17 (Reuters) - Hong Kong's benchmark Hang Seng Index surrendered early gains of as much as 1 percent and ended Thursday lower, dragged by a last-hour slide in mainland stocks, as investors awaited the U.S. Federal Reserve's policy decision later in the day.
But an index tracking Hong Kong-listed Chinese shares managed to stay in positive territory.
The Hang Seng index fell 0.5 percent, to 21,854.63, while the China Enterprises Index gained 0.6 percent, to 9,964.17 points.
The U.S. central bank is considering raising interest rates for the first time since 2006, although economists are split in their expectations. The Fed's decision is due at 1800 GMT.
Sam Chi Yung, analyst at Delta Asia Financial Group, said Hong Kong stocks would benefit from a U.S. rate rise because the action would remove one of the biggest uncertainties facing investors, and would also help strengthen the Hong Kong dollar, which is pegged to the U.S. currency.
Energy, industrials and financial shares gained while declining sectors included utilities, IT and telecommunications . (Reporting by Samuel Shen and Pete Sweeney; Editing by Jacqueline Wong)