PANews, June 23 – According to Jinshi reports, amid a sharp shift in global AI market sentiment and the impact of macroeconomic events, South Korean and Japanese stock markets saw heavy sell-offs after recently hitting multiple all-time highs. In South Korea, the two memory chip makers that account for roughly half of the KOSPI index’s market capitalization — Samsung Electronics and SK Hynix — fell 7.4% and 10.1% intraday respectively, dragging the KOSPI index down more than 9% intraday and triggering a 20-minute trading halt, the fourth such occurrence this year. In Japan, the Nikkei 225 fell more than 3.0% intraday, led by SoftBank Group and chipmaker Kioxia, which dropped 10% and 14% respectively. Both the KOSPI and the Nikkei 225 had repeatedly hit all-time highs recently, mainly benefiting from market optimism over AI, progress in U.S.-Iran peace talks, and expectations of monetary policy tightening by the Bank of Japan. Investors continued to pour into the memory chip sector, which is seen as one of the most profitable products globally, with demand considered unlikely to cool in the short term. SK Hynix overtook Samsung on Monday to become South Korea’s most valuable company, after joining the AI chip frenzy in May and successfully entering the elite $1 trillion market cap club. The surge in share prices has made them more vulnerable to volatility, and analysts warn that valuations are already elevated and face risks from cyclical fluctuations in the semiconductor industry.