Hong Kong Exchanges and Clearing (HKEX) will push ahead with talks on extending stock market trading hours by releasing a discussion paper, even as it faces brokers’ concerns over a longer trading time and cancellation of the trading lunch break, according to two sources with knowledge of the matter.The paper may well pave the way for the first change to the city’s market opening time in 14 years. The bourse operator would first initiate the discussion paper due to the mixed reaction to the...