Investors remain cautious ahead of a series of issues that could result in volatility for the rest of the year, analysts said.

The issues include Thursday's meeting of the Organization of Petroleum Exporting Countries, a 90-day deadline for U.S.-China trade talks and Britain's Dec. 11 parliamentary vote on a Brexit plan.

Foreigners and institutions sold a combined 206 billion won ($184 million) worth of stocks, but individuals bought a net 203 billion won stocks.

Tech and steel stocks led losses, with market leader Samsung Electronics Co. falling 1.93 percent, No. 2 chipmaker SK hynix Inc. declining 2.20 percent and leading steelmaker POSCO shedding 0.60 percent.

Among gainers, top carmaker Hyundai Motor Co. jumped 4.19 percent on news that the company's plan to invest in a local car manufacturing joint venture is set to suffer delays due to a lack of consensus among concerned parties.

Investors think Hyundai's investment in the car JV will increase its financial burden amid slowing sales globally.

The South Korean currency was trading at 1,117.20 won against the U.S. dollar as of 11:20 a.m., down 3.10 won from the previous session's close. (Yonhap)