#KOSPIFallsMoreThan2% South Korea's benchmark stock index, the KOSPI, expanded its severe monthly routing on Tuesday, October 20, 2026, dropping 4.20% to close at 5,525.48. The index slid past an initial midday drop of 2.6% to reach a new multi-month low as a brutal combination of a tech-led semiconductor sell-off and heavy foreign capital flight continues to hammer Seoul's equity market.