KOSPI Slides 10.84% as Samsung Electronics and SK Hynix Tumble

Easing oil-related pressure was outweighed by concern about semiconductor competition. Samsung Electronics and SK Hynix fell by double digits, foreign net selling in the KOSPI market expanded to KRW 4.9666 trillion, and the index closed 10.84% lower.

Foreign selling was concentrated in the KOSPI

The KOSPI opened at 6,400.27, fell as low as 5,992.91 and closed at 6,023.66. Sell-sidecar measures, which temporarily curb program selling, and circuit breakers were triggered in both the KOSPI and KOSDAQ markets, but the losses persisted through the close.

• KOSPI: Retail +KRW 4.334tn; foreign -KRW 4.9666tn; institutions +KRW 630bn
• KOSDAQ: Retail +KRW 51.5bn; foreign +KRW 85.9bn; institutions -KRW 134.5bn

Foreign investors’ heavy net selling was concentrated in the KOSPI market, while retail investors bought a net KRW 4.334 trillion. In the KOSDAQ market, foreign investors were net buyers and institutions were net sellers, leaving the two markets with different investor-flow patterns.

Semiconductor concerns outweighed the drop in oil prices

Overnight, the Philadelphia Semiconductor Index fell 2.23%, Nvidia lost 4.99%, and SK Hynix’s US depositary receipts dropped 7.47%. News that China was developing deep-ultraviolet lithography equipment, along with concern about intensifying competition after ChangXin Memory Technologies’ listing, added to selling pressure on Korean semiconductor shares. Specific equipment performance and mass-production schedules have not been disclosed, but Samsung Electronics fell 13.39% and SK Hynix lost 14.65%.

TodayNote’s morning briefing highlighted both easing oil pressure and weakness in US semiconductor shares. By the close, the declines in Samsung Electronics and SK Hynix were driving the index lower. The USD/KRW reference rate was 1,465.4, below the morning’s 1,466.3, even as foreign net selling in the KOSPI market grew to KRW 4.9666 trillion; the day’s selling therefore did not coincide with a rise in USD/KRW.

Next-session checkpoints

• Whether SK Hynix’s July 29 earnings and commentary ease concerns about competition from China
• Whether KOSPI foreign net selling slows and Samsung Electronics and SK Hynix begin recovering ahead of the broader index
• Whether foreign net buying and institutional net selling in the KOSDAQ market continue to diverge

Sources

• Naver Pay Securities KOSPI, 새 창에서 열림 and KOSDAQ, 새 창에서 열림, checked at 16:32 KST on July 28, 2026
• Bank of Korea Economic Statistics System USD/KRW reference rate, 새 창에서 열림, checked at 16:32 KST on July 28, 2026
• Yonhap News Agency on KOSPI circuit breakers and the semiconductor selloff, 새 창에서 열림, July 28, 2026
• Newsis on the KOSPI and KOSDAQ close and major stocks, 새 창에서 열림, July 28, 2026
• TodayNote morning briefing, July 28, 2026