South Korea's KOSPI slid more than 2 percent to the 6,600 level as foreigners and institutions sold heavily. Samsung Electronics released preliminary third-quarter results, but it failed to prevent weakness in heavyweight shares, including major chipmakers.

On Wednesday, the KOSPI closed down 177.97 points, or 2.62 percent, at 6,625.93. The index opened up 4.78 points, or 0.07 percent, at 6,808.68, but quickly gave up its gains.

Foreign and institutional selling weighed on the index. Foreigners net sold 1.99 trillion won on the main board and institutions net sold 1.67 trillion won. Retail investors net bought 2.90 trillion won, taking the supply.

Samsung Electronics' preliminary third-quarter results also failed to spark a rebound in the index. After the release, market focus shifted to the outlook for future earnings and changes in foreign investor flows, and Samsung Electronics closed down 2.42 percent at 262,000 won.

SK Hynix fell 2.44 percent to 1,681,000 won. Among semiconductor-related shares, SK Square slumped 8.06 percent, the steepest fall among top market-cap stocks.

Samsung Electro-Mechanics fell 3.62 percent, Hyundai Motor dropped 3.42 percent, KB Financial Group slid 3.38 percent, Samsung Biologics declined 4.54 percent and Samsung Life fell 4.27 percent. LG Energy Solution rose 2.56 percent to finish at 401,000 won.

The KOSDAQ closed down 6.16 points, or 0.69 percent, at 892.27. The previous session's close was 898.43.

In the Seoul foreign exchange market, the won-dollar exchange rate stood at 1,338.30 won, down 2.70 won from the previous session.

Local stocks showed weakness from early trading, but losses widened over time, led by the KOSPI. Selling pressure increased as foreigners and institutions posted large net sales at the same time and supply emerged broadly in top market-cap shares such as semiconductors, financials and biotech.

The KOSPI held the 6,800 level early in the session, but slid to the 6,600 level by the close, extending losses from the previous day. As the market, which had recently swung around the 7,000 level, underwent another sharp correction, whether foreign investor flows recover emerged as a variable that could determine the near-term direction.

Han Ji-young (한지영), a researcher at Kiwoom Securities, said investors should focus more on share-price moves and changes in foreign investor flows immediately after earnings releases, as well as changes in 2027 profit estimates, rather than on whether results beat consensus. She added that a meaningful shift in overall local market performance and foreign investor flows could appear from next week.