--- title: "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%" type: "News" locale: "en" url: "https://longbridge.com/en/news/296282882.md" description: "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." datetime: "2026-08-19T00:44:41.000Z" locales: - [zh-CN](https://longbridge.com/zh-CN/news/296282882.md) - [en](https://longbridge.com/en/news/296282882.md) - [zh-HK](https://longbridge.com/zh-HK/news/296282882.md) --- # 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 - 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%. Find out more ### Related Stocks - [07709.HK](https://longbridge.com/en/quote/07709.HK.md) - [EWY.US](https://longbridge.com/en/quote/EWY.US.md) - [03121.HK](https://longbridge.com/en/quote/03121.HK.md) - [YCS.US](https://longbridge.com/en/quote/YCS.US.md) - [9984.JP](https://longbridge.com/en/quote/9984.JP.md) - [.DJI.US](https://longbridge.com/en/quote/.DJI.US.md) - [.SPX.US](https://longbridge.com/en/quote/.SPX.US.md) - [.IXIC.US](https://longbridge.com/en/quote/.IXIC.US.md) - [STX.US](https://longbridge.com/en/quote/STX.US.md) - [SNDK.US](https://longbridge.com/en/quote/SNDK.US.md) - [MU.US](https://longbridge.com/en/quote/MU.US.md) - [WDC.US](https://longbridge.com/en/quote/WDC.US.md) - [WDCVV.US](https://longbridge.com/en/quote/WDCVV.US.md) ## Related News & Research - [Jim Cramer warns of a looming 'nightmare' for tech stocks as US and Korean markets now handcuffed to each other](https://longbridge.com/en/news/295657692.md) - [Bond selloff slows but stocks sink](https://longbridge.com/en/news/296310132.md) - [The Biggest Bounce Most Missed](https://longbridge.com/en/news/296091645.md) - [Société Générale sees more room for KOSPI recovery despite rebuilding leverage](https://longbridge.com/en/news/296029764.md) - [SK: Record profit and revenue growth driven by semiconductors and AI, with major asset divestment](https://longbridge.com/en/news/295896541.md)