South Korea’s stock market triggered an emergency trading halt Monday after the KOSPI plunged more than 8% shortly after the open, turning Asia’s AI-stock selloff into a full market-stress event. The benchmark index fell nearly 9% before trading settled around 7,477.46, down 8.37% at 9:30 a.m. Seoul time. The Korea Exchange activated a 20-minute circuit breaker about three minutes after the open, while a sell-side sidecar also hit the KOSDAQ market minutes later.