South Korea KOSPI crashes 12% triggering circuit breaker — worst single-day crash since 2008; Stoxx 600 -1.8%, Nikkei -1.3%; emerging markets in rout

South Korea’s KOSPI index crashed up to 12% on March 4, triggering an automatic circuit breaker — the worst single-day crash since the 2008 financial crisis. Bloomberg reports emerging markets broadly in rout as Iran war threatens global investment case. South Korea is particularly exposed due to near-total dependence on imported energy (99%) with significant Hormuz transit exposure. European Stoxx 600 fell 1.8%, Nikkei fell 1.3%. The circuit breaker indicates automated systems detected systemic risk beyond normal sentiment decline.