HONG KONG - Hong Kong's stock market will stay open during typhoons and heavy rain effective Sept. 23, a change that will help maintain the global financial hub's competitiveness, city leader John Lee said on Tuesday.

Lee, who made the announcement during a weekly press conference, said the move was in line with other cities and widely supported by traders and banks.

Dickie Wong, executive director of research at Kingston Securities, said there was already market consensus on the rollout of the new measure to allow trading under extreme weather.

"I don't think this measure will greatly help the market sentiment or trading volume," Wong said, adding he is neutral on the measure.

"The market is now more concerned about whether the (Hong Kong-mainland) Stock Connect program can be expanded to include more companies, such as Alibaba. These measures are more important for Hong Kong stock market," Wong added.

Shares of the city's bourse operator Hong Kong Exchanges and clearing eased 0.6% by lunch break. That compared to a 0.2% slip in the benchmark Hang Seng Index.

(Reporting by Jessie Pang and Summer Zhen; Editing by Farah Master, Christopher Cushing and Miral Fahmy)