South Korean and Japanese equities plunged after a sudden reversal in global AI
sentiment and macro developments. In Seoul, Samsung Electronics fell 7.4% and SK
Hynix dropped 10.1% intraday; the two memory-chip makers account for roughly
half of KOSPI market capitalization. KOSPI slid more than 9% intraday and
triggered a 20-minute trading halt — the fourth such pause this year. In Tokyo,
the Nikkei 225 fell over 3%, led by SoftBank and Kioxia, down about 10% and 14%
respectively. Both markets had recently hit multiple record highs on AI
optimism, progress in US–Iran talks and expectations of BOJ tightening; analysts
warn the chip names’ rapid run-up has left valuations elevated and exposed to
semiconductor cyclical risk.
