TradingKey - On September 28, Japanese and South Korean stock markets fell in tandem, with losses in the South Korean market widening significantly. The South Korea Composite Stock Price Index (KOSPI) closed down 2.70% at 6,889.75; Japan's Nikkei 225 Index (JPN225) closed down 0.73% at 65,877.62.

Source: TradingView

South Korean large-cap tech stocks came under noticeable pressure, with Samsung Electronics closing down 5.43% at 270,000 won (approximately $198) and SK Hynix falling 5.05% to 1.768 million won. In the Japanese market, Kioxia closed down 4.37% at 53,340 yen (approximately $339), while SoftBank Group bucked the trend, rising 1.53% to 6,244 yen.

News that SK Hynix's U.S. subsidiary Solidigm is considering an initial public offering (IPO) in the U.S. as early as next year became the focus of market attention. Following the news, investors began re-evaluating SK Group's relatively complex ownership structure, which also put some pressure on the South Korean semiconductor sector.

Meanwhile, after Trump rejected a proposal from Iran, market concerns over escalating tensions in the Middle East resurfaced. Tehran maintained its stance on a seven-day plan to reopen the critical waterway and stated that it would not ease the related conditions.

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