The benchmark Korea Composite Stock Price Index lost 4.09 points, or 0.17 percent, to 2,414.12 as of 11:20 a.m.
Most large caps traded mixed, with tech shares in negative terrain.
Market kingpin Samsung Electronics lost 0.57 percent, and SK hynix, a major chipmaker, was down 0.5 percent.
The local currency was trading at 1,130.5 won against the US dollar, 3.9 won lower than the previous session's close. (Yonhap)