KOSPI halts trading after 8% plunge

South Korea’s Korea Exchange halted trading in KOSPI-listed shares for 20 minutes on July 28 after the benchmark fell 8.02% to 6,213.51.

The Level 1 circuit breaker took effect at 10:13 a.m. local time after the decline remained above 8% for one minute. It was the eighth KOSPI circuit-breaker activation of 2026 and the 14th on record.

Selling continued after trading resumed. Yonhap placed the index 8.59% lower at 6,175.71 at 11:20 a.m., while Reuters reported a decline of about 9.4% by 12:41 p.m. Korea time. The figures were intraday and may differ from the eventual closing level.

The KOSPI circuit breaker stopped the full market

The Level 1 mechanism suspended trading and order-taking in shares on the main KOSPI market for 20 minutes. The exchange then reopened trading through a 10-minute single-price call auction. The measure followed sell-side “sidecar” curbs earlier in the session, which temporarily stopped program trading as futures and cash shares fell.

The two controls serve different purposes. A sidecar pauses program orders, while a circuit breaker stops most trading across the market. The July 28 halt followed earlier 2026 activations on March 4 and 9, June 8, 23 and 26, and July 7 and 13, according to Korean market reports citing the exchange.

The latest decline extends a period of unusually sharp moves in South Korean equities. As previously reported, KOSPI volatility in June was intensified by margin calls, high retail leverage and the heavy index weight of Samsung Electronics and SK Hynix.

SK Hynix ADR fell below its $149 offer price

SK Hynix’s Nasdaq-listed American depositary receipts closed the previous U.S. session at $143.02, down 7.5%, according to Reuters. That was their first close below the $149 offering price since regular trading began in July. Market data showed an intraday low near $139.10, explaining reports that the ADR had briefly fallen below $140.

The verified closing figure differs from the $139.45 quote circulated in some early reports. That lower number appears to reflect an intraday or extended-hours quote rather than the official regular-session close. The ADR opened at $159.61, reached $164.30 and fell as low as $139.10 before closing at $143.02.

SK Hynix priced 177.9 million ADRs at $149 and raised about $26.5 billion in the U.S. offering. Each ADR represents one-tenth of a Korean common share. The company said the listing was intended to broaden its U.S. investor base and strengthen its position in AI memory markets.

Chip concerns drove the KOSPI selloff

SK Hynix shares in Seoul fell as much as 14%, while Samsung Electronics dropped as much as 13.4%, Reuters reported. The two chipmakers together account for nearly half of the KOSPI, so their declines exerted heavy pressure on the benchmark.

The selloff followed another decline in U.S. semiconductor shares. Investors were reassessing the scale and financing of AI infrastructure spending, including questions around whether chip suppliers and technology companies are supporting customer demand through large financial commitments. Those concerns remain market interpretations rather than evidence that orders have been cancelled.

China-related developments added pressure. Reuters cited analysts who pointed to the stock-market debut of Chinese memory producer ChangXin Memory Technologies and reports of progress in domestic deep-ultraviolet lithography equipment. Details about the equipment’s performance and commercial timeline had not been disclosed, so the competitive threat remains uncertain.

In related coverage, concerns around AI valuations had already pushed SK Hynix and Samsung lower during earlier July sessions. Another report examined how Bitcoin traded alongside technology shares during a prior KOSPI-led risk-off move.

Earnings and tighter ETF rules come next

SK Hynix is scheduled to publish its second-quarter results at 9:00 a.m. Korea time on July 29. The release will give investors updated figures for high-bandwidth memory sales, margins, capital spending and demand from major AI customers.

In April, the company reported first-quarter revenue of 52.58 trillion won and operating profit of 37.61 trillion won. SK Hynix attributed the results to strong demand for AI memory, high-capacity server DRAM and enterprise solid-state drives.

July 29 is also the scheduled KOSPI listing date for the newly issued common shares underlying the U.S. ADR sale. The additional shares may affect short-term supply and index positioning, although the company has not forecast a specific price effect.

South Korea’s Financial Services Commission is also accelerating restrictions on single-stock leveraged exchange-traded products. From July 31, retail investors must hold at least 30 million won in cash to make new or additional purchases. The previous 10 million won requirement allowed some securities to count towards the minimum.

The FSC has already suspended new listings and advertising for single-stock leveraged products. Further changes covering premium controls and watchlist rules are scheduled for August 19. The regulator said it would continue monitoring demand and consider more measures if volatility remains elevated.

For markets, the next confirmed events are SK Hynix’s earnings, the additional share listing and the July 31 leverage restrictions. Investors will also watch whether the KOSPI recovers after the halt and whether SK Hynix’s ADR can reclaim its $149 offering price.