The benchmark Korea Composite Stock Price Index shed 5.58 points, or 0.23 percent, to 2,406.62 as of 11:20 a.m.
Automakers traded bearish with industry leader Hyundai Motor losing 1.41 percent and its sister affiliate Kia Motors declining 1.28 percent.
No. 1 steelmaker POSCO surrendered 2.62 percent and Hyundai Steel was down 1.3 percent.
Market kingpin Samsung Electronics, meanwhile, gained 0.38 percent.
SK hynix, a major chipmaker, jumped 2.48 percent, touching a record intraday high of 83,400 won at one point, following reports that Toshiba decided to pick a Japan-US-South Korean consortium, which includes the SK affiliate, as a preferred bidder to buy its chip business unit.
The South Korean won was changing hands at 1,132.70 won against the US greenback, down 4.40 won from the previous session's close. (Yonhap)