The KOSPI surrendered early gains and fell for a third straight session after the Chuseok holiday, as foreign and institutional investors sold in tandem. Chip stocks opened higher on Anthropic's plans for massive artificial intelligence investment, but momentum faded amid caution ahead of Micron Technology's earnings release in the United States. Foreign investors sold a net 9 trillion won worth of KOSPI shares over the past three sessions, dragging the index lower.
The KOSPI closed at 6,838.04 on the 30th, down 32.77 points, or 0.48%, from the previous session. The index opened at 6,943.47, up 72.66 points or 1.06%, but turned lower as selling from foreign and institutional investors mounted.
Foreign investors sold a net 2.052 trillion won and institutions a net 768 billion won on the KOSPI. Retail investors bought a net 1.1667 trillion won but could not stem the decline. Foreign investors' cumulative net selling over the past three sessions reached 8.966 trillion won. Decliners outnumbered gainers, 513 to 352.
Early in the session, the market reflected expectations for expanded AI investment in the United States. Anthropic, which is pursuing a listing this year, disclosed in its initial public offering prospectus plans to spend at least $518 billion (about 700 trillion won) on AI computing and infrastructure over the next decade, lifting Micron and Meta on Wall Street overnight. SK hynix's (000660) American depositary receipts also rose 2.62%.
Large-cap chipmakers in Seoul, however, gave up intraday gains for mixed results. Samsung Electronics (005930) opened 0.73% higher at 274,500 won and rose as high as 276,000 won, but ended down 1.47% at 268,500 won. SK hynix climbed as much as 3.34% to 1.824 million won intraday before paring gains to close 0.62% higher at 1.776 million won. Combined net selling by foreign and institutional investors in the two stocks reached 2.062 trillion won.
Among the largest stocks by market capitalization, most fell, including Samsung Electronics preferred shares (005935), down 4.31%; Samsung Life Insurance (032830), down 2.93%; KB Financial Group (105560), down 2.71%; Hyundai Motor (005380), down 1.43%; and Samsung Electro-Mechanics (009150), down 0.98%. By sector, insurance fell 3.27% and financials 1.40%, while machinery and equipment gained 1.98%, chemicals 0.83% and metals 0.80%.
The KOSDAQ closed at 855.91, up 6.11 points or 0.72% from the previous session. Retail investors bought a net 11.8 billion won and institutions a net 48.8 billion won, while foreign investors sold a net 67.7 billion won. Gainers included EO Technics (039030), up 4.94%; Jusung Engineering (036930), up 4.73%; HLB (028300), up 3.11%; and EcoPro BM (247540), up 2.83%.
Market participants cited U.S. personal consumption expenditures (PCE) inflation data and Micron's earnings as the variables that will determine direction from here. "Domestic equities swung within a narrow range as caution ahead of major events set in, even with improving external conditions," said Lee Kyoung-min, an analyst at Daishin Securities. "Foreign investors extending net selling for a fourth straight session also weighed on supply and demand."
