Seoul shares fell more than 1 percent Monday, hit by declines in semiconductor stocks. The local currency fell against the US dollar.
The benchmark Korea Composite Stock Price Index (Kospi) tumbled 31.95 points, or 1.14 percent, to close at 2,763.51.
Trade volume was slightly moderate at 456.1 million shares worth 10.3 trillion won ($7.42 billion), with losers outnumbering winners 673 to 211.
Institutions and foreign investors dumped local shares worth a combined 105.3 billion won, while retail investors bought 137.8 billion won worth of shares.
Market uncertainties grew as US President Joe Biden ended his reelection campaign.
Han Ji-young, an analyst at Kiwoom Securities, said the market "could transition to a phase in which it is unknown who will win the US presidential election, from the recent so-called 'Trump trading' sentiment predicated on the assumption of a Trump victory in November."
Most blue chips suffered from weak trading, with market heavyweight Samsung Electronics falling 1.66 percent to 83,000 won and smaller chip rival SK hynix falling 2.15 percent to 205,000 won.
Leading battery firm LG Energy Solution tumbled 4.92 percent to 328,500 won following news that it has recently suspended construction of its joint US plant with General Motors amid stagnation in the growth of the electric vehicle market. Smaller rival Samsung SDI also dropped 4.2 percent to 342,500 won.
Energy-related stocks also went south. Leading refiner SK Innovation fell 3.93 percent to 107,600 won and LG Chem declined 4.05 percent 320,000 won. Leading automaker Hyundai Motor also slipped 1.35 percent to 255,000 won.
The local currency had been trading at 1,388.2 won against the greenback as of 3:30 p.m., down 1.5 won from the previous session.
Bond prices, which move inversely to yields, rose. The yield on three-year Treasurys fell 0.3 basis point to 3.071 percent, and the return on the benchmark five-year government bonds dropped 0.8 basis point to 3.091 percent. (Yonhap)