A trader stands in front of an electronic display board showing Kospi in Hana Bank's trading room in central Seoul, on Oct. 14.YONHAP
Stocks fell for the sixth consecutive session on Wednesday on persisting concerns over excessive spending on AI as investors remained cautious ahead of U.S. inflation data.
The Korean won strengthened against the dollar.
After choppy trading, the benchmark Kospi lost 26.54 points, or 0.44 percent, to 6,008.81.
The Kospi has dropped since Tuesday last week, including a 5.46 percent plunge the previous day.
After opening 0.44 percent higher, the index rose 2.57 percent around 9:34 a.m. following New York Fed President John Williams' media interview that he saw no need for further monetary tightening next year.
However, the gains were erased following Dutch tech giant ASML's lower-than-expected sales outlook.
ASML, which provides chip manufacturing machines to major chipmakers, including Samsung Electronics, reported strong earnings for the third quarter, but its revised 2026 sales outlook failed to meet market expectations, considering a yearly 84 percent surge in its stock price.
"The Kospi erased all of its gains after ASML's earnings report," said Seo Sang-young, a senior analyst at Mirae Asset Securities. "Investors are also awaiting U.S. consumer prices data later in the day."
Trade volume was moderate at 350.8 million shares worth 19.9 trillion won ($14.9 billion), with gainers beating decliners 502 to 369.
Foreigners and individuals sold a net 1.18 trillion won and 309.3 billion won worth of stocks, respectively, offsetting a net 808.3 billion won purchased by institutions.
Semiconductor shares closed in negative territory as SK hynix fell 1.66 percent to 1.42 million won and Hanmi Semiconductor, a chip equipment manufacturing company, tumbled 5.02 percent to 217,500 won.
Samsung Electronics' headquarters in Suwon, Gyeonggi, on Oct. 8.YONHAP
Industry leader Samsung Electronics stayed flat at 232,000 won.
Bank shares were also weak as Hana Financial Group retreated 2.25 percent to 121,600 won and KB Financial Group declined 1.97 percent to 159,200 won.
Major retailer Lotte Shopping sank 4.47 percent to 89,800 won, and Samyang Foods, best known for its Buldak ramyeon series, dropped 2.47 percent to 1.14 million won.
In contrast, leading battery maker LG Energy Solution rose 2.93 percent to 422,000 won, and top oil refinery SK Innovation jumped 4.08 percent to 163,200 won.
CJ ENM, a top production studio, soared 6.9 percent to 37,950 won, and cosmetics manufacture APR climbed 4.06 percent to 294,500 won.
The Korean won strengthened 6.8 won from the previous stock trading session's close to trade at 1,338.3 won against the U.S. dollar as of 3:30 p.m.
Bond prices, which move inversely to yields, closed lower. The yield on three-year Treasurys added 2.6 basis points to 3.883 and the return on the benchmark five-year government bonds rose 1.7 basis points to 4.047.
