The benchmark Korea Composite Stock Price Index shed 7.98 points, or 0.34 percent, to 2,370.53 as of 11:15 a.m.
Market kingpin Samsung Electronics fell 1.49 percent.
SK hynix, a major chipmaker, declined 1.02 percent, and POSCO, the No. 1 steelmaker, was down 0.6 percent.
Naver, the country's top Internet portal operator, gained 0.5 percent.
Hyundai Motor, the No. 1 automaker, remained flat.
The local currency was trading at 1,121.45 won against the US dollar, up 6.75 won from the previous session's close. (Yonhap)