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Japan and South Korea Stocks Plunge as Kospi Drops Over 6% to Trigger Circuit Breaker; Kioxia Falls Over 10%, SK Hynix Over 9%, Samsung Over 7%

TradingKey
Aug 19, 2026 at 12:44 AM
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On August 19, Japanese and South Korean stock markets plunged due to a sharp overnight drop in U.S. stocks. The KOSPI fell over 6%, triggering a circuit breaker, while the Nikkei 225 dropped 2.82%. Semiconductor giants SK Hynix, Samsung, and Kioxia saw significant declines of over 7-10%. This sell-off was driven by cooling risk appetite for tech stocks, with U.S. indices also falling for three consecutive days.

TradingKey - On August 19, Japanese and South Korean stock markets weakened in tandem in early trading. The Korea Composite Stock Price Index (KOSPI) opened down 5% at 6,528.77 points, before losses widened to 6.39%, last standing at 6,430.93 points. Meanwhile, the Korea Exchange activated a Sidecar mechanism to suspend program sell orders for the KOSPI. Japan's Nikkei 225 Index (JPN225) also opened lower and continued to decline, with its drop expanding to 2.82% at 65,558.27 points.

Source: TradingView

South Korea's semiconductor sector was the main drag on the broader market. SK Hynix fell 9.03% to 1,512,000 won (about $1,073), while Samsung Electronics dropped 7.26% to 249,000 won.

Japanese tech stocks also faced noticeable selling pressure, with Kioxia tumbling 10.32% to 51,250 yen (about $321) and SoftBank Group dropping 6.17% to 5,470 yen, putting heavy-weight tech stocks in Japan and South Korea under broad pressure.

The weak performance in Asian markets was impacted by a sharp overnight drop in U.S. stocks. The three major U.S. stock indices fell for a third consecutive trading day, with the Dow Jones Industrial Average dropping 0.22% to close at 53,343.40 points, the S&P 500 Index sliding 0.69% to 7,691.76 points, and the Nasdaq Composite Index tumbling 1.33% to close at 26,289.71 points, as overall risk appetite for tech stocks cooled noticeably.

The memory chip sector saw particularly prominent declines, becoming the hardest-hit area of the overnight U.S. market sell-off. SK Hynix (SKHY), Seagate Technology (STX), and SanDisk (SNDK) all fell by over 9%, while Micron Technology (MU) and Western Digital (WDC) also dropped over 7%.

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