Seoul:Seoul shares experienced a significant surge of over 6 percent, driven by a strong performance in the chipmaking sector following SK hynix's announcement of record quarterly earnings and plans for additional shareholder returns. Meanwhile, the Korean won weakened against the U.S. dollar.
According to Yonhap News Agency, the benchmark Korea Composite Stock Price Index (KOSPI) climbed 374.1 points, or 6.63 percent, to close at 6,012.44, after peaking at 6,032.28 during the session. This rally prompted the Korea Exchange to activate a buy-side sidecar to temporarily suspend program trading buy orders for KOSPI-listed stocks. The sidecar measure is triggered when KOSPI 200 futures rise by at least 5 percent and sustain that level for a minute. This activation marked the second consecutive session for such a measure.
Earlier in the day, SK hynix reported record-high revenue and operating profit for the third quarter, driven by strong demand for memory chips amid the artificial intelligence (AI) boom. The company also announced a shareholder return program exceeding 100 trillion won (US$75.3 billion) for 2026. Investors are also closely watching the Federal Reserve's upcoming interest rate decision, expected early Thursday (Korean time), for insights into the future trajectory of U.S. interest rates.
Trade volume was relatively light, with 223.2 million shares valued at 19.83 trillion won changing hands. Advancers outnumbered decliners 580 to 288. Foreign investors and institutions purchased net amounts of 815.83 billion won and 960.79 billion won, respectively, while individual investors sold a net 1.8 trillion won.
Lee Jae-won, an analyst at Yuanta Securities, noted that SK hynix's performance underscored the strong demand for AI chips, which translated into solid operating profits and shareholder returns. This eased concerns about the sustainability of the AI-driven rally and potential peaks in the memory chip cycle.
Market heavyweights saw gains across the board, with Samsung Electronics rising 9.01 percent to 242,000 won, and SK hynix climbing 10.89 percent to 1.49 million won. SK Square, SK hynix's parent company, rose 11.23 percent to 921,000 won, while Samsung Electro-Mechanics, an affiliate of Samsung Electronics, increased 8.74 percent to 1.3 million won.
The Korean won was trading at 1,337.7 won against the U.S. dollar, down 10.7 won from the previous session's close.