The benchmark Korea Composite Stock Price Index fell 0.9 points, or 0.04 percent, to 2,092.61 in the first 15 minutes of trading. The main index ended in positive territory in the past 12 sessions.
At the United Nations General Assembly on Sept. 23 (local time), US Treasury Secretary Steven Mnuchin said the trade talks would resume next week and the US asked Chinese officials to delay their planned trip to US farms after working-level talks last week.
US President Donald Trump said he doesn't feel he needs to secure an agreement before next year's election. But investors still expect the world's two biggest economies to come up with progress in the upcoming talks.
Tech stocks were lead decliners, with market bellwether Samsung Electronics falling 0.3 percent and No. 2 chipmaker SK hynix declining 0.4 percent. No.1 refiner SK Innovation shed 0.3 percent.
Among gainers, top carmaker Hyundai Motor rose 0.8 percent, No. 1 auto parts maker Hyundai Mobis climbed 2.2 percent and leading steelmaker POSCO gained 0.4 percent.
The local currency was trading at 1,193.00 won against the US dollar, up 1.00 won from the previous session's close. (Yonhap)