Kospi slid 4.9% to 6,490.97 on Monday, sharply underperforming mostly firmer Asian markets as investors dumped South Korean AI-linked shares.
Samsung Electronics fell 4.4% and SK Hynix lost 3.3% as bubble fears in AI deepened after Moonshot AI's new Kimi K3 model renewed pressure from lower-cost Chinese rivals.
Taiwan's Taiex was little changed, Hong Kong's Hang Seng rose 2.1% and Shanghai gained 1.2%, showing the selloff was concentrated in AI-heavy pockets rather than across the region.
Brent crude rose 2.6% to $90.40 and U.S. crude gained 2.2% to $83.58 as U.S.-Iran strikes entered a ninth straight night and tanker traffic in the Strait of Hormuz nearly stalled.
The drop extended a broader tech retreat after the S&P 500 lost 1% and the Nasdaq 1.4% on Friday, with investors reassessing AI spending and geopolitical risk at the same time.