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SEOUL, Oct. 20 (Yonhap) -- South Korean shares plunged by nearly 4 percent Tuesday, as investors attempted to cash in recent gains in major chip shares amid persistent concerns over the artificial intelligence (AI) value chain. The Korean won was trading higher against the U.S. dollar.
The benchmark Korea Composite Stock Price Index (KOSPI) fell 215.27 points, or 3.73 percent, to 5,552.74 after declining as low as 5,493.24.
The index opened 0.6 percent lower and extended its losses amid deepening woes over AI-related sectors as well as escalating protests in France, which sharply reduced appetite for risky assets.
The KOSPI had risen for two consecutive sessions after a sharp sell-off fueled by concerns over AI-related investments. It had plunged by around 21 percent over seven trading sessions from Oct. 6 through Thursday.
Overnight, U.S. stocks ended mixed as technology shares rebounded from their steepest weekly drop since June.
Financial data is shown on a screen inside the dealing room of Hana Bank in central Seoul on Oct. 20, 2026. (Yonhap)
"Concerns over credit risks and profitability surrounding AI investment have yet to be fully resolved, limiting the sustainability of the rebound," said Lee Kyoung-min, an analyst at Daishin Securities. "Profit-taking emerged following the previous session's gains, sending the market back into negative territory."
Trade volume was light at 259.75 million shares worth 16 trillion won (US$12.97 billion), with decliners far outnumbering advancers 771 to 117.
Foreigners and institutions sold a net 535.4 billion won and 1 trillion won, respectively, while individuals bought a net 900 billion won.
Market heavyweights fell across the board, led by a sharp sell-off in technology shares.
Market bellwether Samsung Electronics fell 2.98 percent to close at 211,500 won, while rival chipmaker SK hynix declined 4.23 percent to 1.22 million won, heading for its lowest close since April.
SK Square, the parent firm of SK hynix, dipped 5 percent to 741,000 won, while Samsung Electro-Mechanics, an electronics component affiliate of Samsung Electronics, went down 1.28 percent to 1.16 million won.
The Korean won was quoted at 1,328.1 won against the U.S. dollar as of 3:30 p.m., up 2.2 won from the previous stock trading session's close.
Bond prices, which move inversely to yields, closed higher. The yield on three-year Treasurys lost 3.7 basis points to 3.840, and the return on the benchmark five-year government bonds went down 2.4 points to 3,990.
khj@yna.co.kr
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