Sharp Decline Triggers Circuit Breaker

South Korea’s KOSPI index recorded a steep decline on July 28, falling nearly 11% to close at 6,012.68 in its most severe daily drop since April. The selloff prompted a Level 1 circuit breaker that halted trading in KOSPI-listed shares for 20 minutes after the index dropped more than 8% early in the session. Trading stopped at 10:13 a.m. local time once the decline exceeded the threshold for one minute, marking the eighth such activation in 2026 and the 14th on record.

Earlier in the day, sell-side sidecar measures had already limited program trading. After the halt, the exchange reopened via a single-price call auction. Intraday figures showed the index down as much as 10.5% at one point, with reports placing it between 8% and more than 9% lower at various stages before the final close. The move erased hundreds of trillions of won in market value.

Chipmakers Drive the Losses

Samsung Electronics and SK Hynix stood at the center of the downturn. Samsung shares fell as much as 13.4%, while SK Hynix declined between 9.7% and 14% across reports. Together the two companies represent a substantial share of KOSPI market capitalization, amplifying the index-level impact.

Investors reacted to growing questions about the sustainability of heavy artificial intelligence infrastructure spending. Recent U.S. semiconductor weakness, including declines in related stocks and exchange-traded products, added to the pressure. Concerns also centered on Chinese advances, including the strong market debut of memory producer ChangXin Memory Technologies, whose shares surged hundreds of percent on the STAR Market, and reports of progress in domestic deep ultraviolet lithography equipment that could intensify competition in advanced chip production.

SK Hynix’s U.S.-listed American depositary receipts had closed the prior session below their recent offering price for the first time, heightening caution ahead of the company’s second-quarter earnings release scheduled for July 29.

Regional Markets and Crypto Feel the Pressure

The selloff extended across Asia. Japan’s Nikkei 225 fell about 3.9%, Taiwan’s Taiex declined roughly 4% to 4.6%, and other regional benchmarks posted losses as semiconductor-related names came under pressure. Japanese chip-linked shares such as Kioxia, Tokyo Electron and Advantest also registered sharp drops.

Cryptocurrency markets experienced milder but noticeable declines. Bitcoin fell around 2.8%, Ether dropped about 3.6%, and overall digital asset market capitalization declined by approximately 2%. South Korea’s significant role in global retail crypto trading volumes contributed to the spillover. Margin calls on leveraged tech equity products and exchange-traded funds often prompt traders to sell more liquid crypto holdings, transmitting volatility beyond local equities.

Upcoming Events in Focus

Attention now turns to SK Hynix’s earnings results on July 29, which will provide updated figures on high-bandwidth memory demand, margins and capital spending. The same day also brings the KOSPI listing of additional common shares linked to the company’s recent U.S. ADR offering. From July 31, South Korean regulators will tighten rules on single-stock leveraged exchange-traded products, raising the cash requirement for retail investors making new purchases.

Digital assets have so far shown greater relative resilience than Asian equities, consistent with a sector-driven move rather than a broad risk-off event. Further developments in U.S. technology and semiconductor shares will be watched closely for any additional transmission of pressure.