Wall Street’s AI Sell-Off Spills Into Seoul, Sinking KOSPI Below 5,000

South Korea’s KOSPI fell below 5,000 Friday for the first time since February, and an 8% drop after the open triggered a circuit breaker that halted trading for 20 minutes at 9:03 a.m. The decline followed Thursday’s Wall Street sell-off, with the S&P 500 falling 4.36%, the Nasdaq 5.52%, and the Philadelphia Semiconductor Index 12.25%, its worst drop since March 2020. SK Hynix, a major supplier of high-bandwidth memory for AI accelerators, fell 11.71% to 1,116,000 won despite record quarterly sales, while Samsung Electronics dropped 9.98% to 181,400 won. The two chipmakers account for roughly half the index’s market value; the KOSPI had already lost 5.28% on Thursday as foreign investors sold more than 3.4 trillion won of shares.