The South Korean stock market experienced another significant downturn on June 8, with the benchmark KOSPI index closing with a sharp drop exceeding 8%. Notably, the market triggered its circuit breaker mechanism twice within the same trading day. During the morning session, a decline of 8% in the KOSPI index activated the primary market-wide circuit breaker on the Korea Exchange (KRX), forcing a 20-minute trading halt.
Following the resumption of trading, the downward trend persisted. In the afternoon, the KOSDAQ index plummeted by 8%, triggering the circuit breaker once again. This occurrence of two circuit breaker events within a single day is an extremely rare event in the history of the South Korean stock market.
Post-Rally Risks Emerge in the Market
Within this year's global capital markets, the South Korean stock market has undoubtedly been a major focus of attention. Riding the powerful tailwind of AI semiconductors, the KOSPI has delivered an epic rally this year. The total market capitalization of South Korean stocks successively surpassed that of several developed markets, establishing it as one of the world's best-performing major markets.
In less than half a year, the KOSPI has nearly doubled in value; over the year from June 2025 to the present, it has surged more than 200%. By early June this year, the KOSPI index broke through the 8,800-point level intraday, setting yet another historical high.
Following this dramatic surge, the KOSPI has increasingly triggered circuit breakers for both sharp gains and losses within single sessions, indicating extreme market volatility. Data released by the Korea Exchange on June 3 shows that the total number of buy-side and sell-side temporary trading halts (Sidecar) triggered in the main board market this year has reached its highest level since the 2008 international financial crisis.
On June 5, the KOSPI opened significantly lower, with an intraday maximum drop exceeding 6%. This marked the 21st circuit breaker trigger of the year and the 10th activation of the sell-side pause order (Sidecar), reflecting unprecedented market turbulence.
Semiconductors Dominate the South Korean Market
In the South Korean stock market, nearly half of the total market cap weighting is concentrated in just two semiconductor giants: Samsung Electronics and SK Hynix.
Data from the Korea Exchange indicates that, benefiting from AI-driven chip demand, Samsung Electronics and SK Hynix together account for a staggering 54% of the KOSPI index's weighting. They also represent approximately half of the index's average daily trading volume from May, effectively transforming the benchmark into a "semiconductor-specific index."
Since the second half of 2025, DRAM prices have skyrocketed. South Korea's Samsung Electronics and SK Hynix collectively control over 70% of the global DRAM market share, making them the biggest beneficiaries of this semiconductor "super cycle." Their share prices have surged approximately 1.7 times and over 2.1 times, respectively, and together they have propelled the KOSPI index to its historical peak.
As the rally intensified, stock prices have severely disconnected from fundamental valuations, with future corporate earnings for many years being pulled forward and priced in. On June 5, the market sentiment abruptly reversed. The KOSPI index plunged over 5% in a single day. By the close, SK Hynix shares had fallen nearly 10%, and Samsung Electronics dropped over 6%.
Furthermore, despite the companies reporting solid earnings and recent positive news, they were powerless against the global market's reassessment of chip stock valuations. Last Friday, the Philadelphia Semiconductor Index recorded its largest single-day drop since 2020, as the sell-off in tech stocks transmitted across global markets.
On June 8, shares of Samsung Electronics fell more than 10%, while SK Hynix dropped over 7%.
Effectiveness of Market Rescue Measures Amidst Spreading Panic
In response to the spreading market panic, South Korean regulators have initiated market stabilization efforts.
On June 8, the Korea Exchange stated that it had convened an emergency market assessment meeting to address heightened stock market volatility. This urgent meeting was held at 8:00 AM local time, before the market opened. The meeting reviewed market conditions, including the sharp declines in U.S. stocks and overnight futures from the previous session, and discussed market control measures.
The Korea Exchange announced it would strengthen its institution-wide emergency response mechanisms, closely monitor global market trends, developments in the Middle East, and foreign exchange market movements. It also pledged to intensify supervision of unfair trading practices and expand the scope of inspections for illegal short-selling activities.
The exchange stated it would collaborate with financial regulatory authorities to continuously monitor global stock markets, Middle East tensions, and currency movements, while reinforcing emergency response systems, including information technology infrastructure. Additionally, the Korea Exchange plans to implement market stabilization measures such as circuit breaker-triggered trading halts as needed. It will also enhance preventive activities against potential unfair trading during periods of market uncertainty and increase scrutiny of illegal short selling.
Simultaneous Turmoil in Stocks and Currency
Concurrently with the stock market crash, the South Korean won also faced significant pressure. The won's exchange rate fell to its lowest level since 2009, rapidly intensifying concerns about capital outflows and the stability of South Korea's financial markets.
On June 8, in the Seoul foreign exchange market, the won opened at 1,555.2 per U.S. dollar, marking its weakest level in approximately 17 years and 3 months, since March 6, 2009 (1,590 won) during the international financial crisis.
The won's depreciation has acted as a signal for foreign investors to accelerate the selling of chip stocks. Data shows that foreign investors net sold over $10 billion worth of KOSPI constituent stocks in just the past week, a scale rarely seen in recent years. This foreign capital exodus directly impacted the won's exchange rate.
On the same day, South Korea's foreign exchange and financial authorities warned they would focus on inspecting for speculative trading and market-disruptive behavior taking advantage of the won's weakness. They stated that any such activities would be dealt with seriously and that excessive volatility or one-sided movements in the foreign exchange market would not be tolerated.
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