South Korea's AI-Driven KOSPI Slumps to World's Worst Stock Market in Third Quarter

South Korea's AI-driven stock market has gone from global standout to the world's worst third-quarter performer, as the KOSPI's semiconductor-led surge unwound under pressure from AI-spending doubts, oil prices and higher yields. The benchmark closed at 6,870.81 on Sept. 29, down about 19% from its 8,476.48 close on June 30, after a rally that made Seoul one of the clearest public-market proxies for the AI infrastructure boom.