The benchmark Korea Composite Stock Price Index shed 3.33 points, or 0.14 percent, to 2,359.86 as of 11:15 a.m.
Bourse heavyweights traded mixed, with market kingpin Samsung Electronics up 0.39 percent.
SK hynix, a major chipmaker, fell 0.44 percent, and POSCO, the No. 1 steelmaker, declined 0.58 percent.
Naver, the country's top Internet portal operator, lost 0.26 percent, while Hyundai Motor, the No. 1 automaker, dropped 0.71 percent.
LG Chem, the country's top chemical firm, surrendered 1.19 percent, and SK Innovation, the leading oil refiner, advanced 0.80 percent.
The local currency was trading at 1,122.25 won against the US dollar, up 5.85 won from the previous session's close. (Yonhap)