Korea Exchange said on Tuesday it has postponed the launch date for the securities market pre- and after-market to Sept. 14 from June 29, a delay of 2.5 months.

The move reflects securities industry views that the exchange needs to improve the completeness of system development for longer trading hours and secure sufficient time for testing. As a result, a mock market that had been scheduled to open in March will operate for 23 weeks from April 6 to Sept. 13. The previous schedule was 15 weeks from March 16 to June 28.

The exchange said the change in timing was decided after considering capital market stability as well as views from the industry and labor circles. It said longer trading hours are needed to secure the competitiveness of the domestic stock market, but sufficient development time and market stability take priority.

The operating hours for the premarket will also be adjusted in part. The premarket end time will be shortened by 10 minutes to 7:50 a.m. from 8 a.m.

The change is intended to secure a 10-minute preparation window between the end of the KRX premarket and the start of the NXT premarket, supporting the cancellation of unfilled orders and the release of margin.

The premarket start time will remain at 7 a.m. The exchange said it considered investor demand to quickly reflect information from the U.S. stock market in the domestic market.

It also aims to minimise IT system load and operational risk at securities firms by operating in non-overlapping time slots with an alternative trading system.

The extension of trading hours will be based on voluntary participation by securities firms. The exchange plans to allow firms to join in stages after sufficient testing, rather than forcing schedules when system stability is not sufficiently secured.

Securities firms can choose to operate all of the pre- and after-market or only certain time slots.

Short selling of borrowed shares will be permitted during the extended hours. Regulatory devices such as the NSDS for short selling, overheating rules and price regulations will be applied in the same way as in regular sessions. The exchange also plans to strengthen and apply volatility mitigation devices, including static volatility interruptions, and to operate a market-maker system.

The exchange said it plans to restrict branch orders during the pre- and after-market time slots to minimise social costs. It said some types of branch orders, including wrap account orders, will be allowed.

The exchange has gathered industry views through 54 one-on-one meetings with member firms, 95 rounds of telephone feedback, surveys and briefings for all member firms, and executive-level meetings with member firms planning to participate. It also held three rounds of talks with the securities union and continued consultations with related institutions including Koscom, the Korea Securities Depository, Korea Securities Finance and NXT.

A KRX official said it plans to advance capital market infrastructure, including longer trading hours, to improve the international consistency and competitiveness of the domestic capital market.