South Korea's KOSPI index has surged roughly 200% year-on-year as Samsung and SK Hynix ride the AI chip boom, but concentration risk looms large.

South Korea's KOSPI index plunged nearly 10% as SK Hynix and Samsung sell-off triggers circuit breakers, raising doubts about AI-driven stock valuations.

South Korea's KOSPI index doubled in 2026, driven by retail investors betting on Samsung and SK Hynix. But concentration risk and AI chip demand concerns