South Korea's KOSPI plunges 7.6% as AI doubts and US inflation hit chipmakers

South Korea’s KOSPI index plunged 7.57 per cent on Thursday to close at 5,554.22, its lowest since April 7, as a semiconductor selloff and US inflation data triggered a trading halt. Samsung Electronics fell 9.5 per cent and SK Hynix dropped 11.1 per cent, with the index losing 454.59 points over seven straight sessions. US consumer inflation rose 3.7 per cent in September, exceeding expectations and reviving rate-hike fears that raise AI infrastructure financing costs. The selloff triggered a 20-minute circuit breaker, the first since July 29. Foreign investors sold 3.6 trillion won ($2.68 billion) in shares, while South Korean authorities held an emergency meeting to pledge market stability measures.