日韩股市“黑色星期二”：韩股熔断，日经重挫，AI热潮迎来阶段性调整

Original by Odaily (@OdailyChina)

Author: Qin Xiaofeng (@QinXiaofeng 888 )

Today, Asian stock markets experienced severe turbulence.

The Korea Composite Stock Price Index (KOSPI) plunged by over 8% during trading, triggering a market circuit breaker and a 20-minute trading halt. It ultimately closed down nearly 10% at 8203.84 points, marking the third-largest single-day decline of the year. The Japanese stock market also came under pressure, with the Nikkei 225 index falling about 3.5% to close near 69,788 points, ending its previous eight-day winning streak. The TOPIX index dropped approximately 2.6%.

This correction was heavily concentrated in technology stocks, particularly the semiconductor sector. Heavyweight stocks such as Samsung Electronics and SK Hynix led the decline, dragging down the entire market. Foreign capital accelerated selling, trading volume surged, and market panic sentiment was notably heightened.

Since June, both the Japanese and South Korean stock markets have experienced multiple sharp fluctuations. The South Korean market has triggered circuit breakers four times this year alone. The KOSPI, previously driven by the AI and semiconductor boom to near its all-time high of 9385 points, has retreated significantly. The Nikkei 225 also briefly stood above 70,000 points. In just a few weeks, the shift from record highs to a sharp correction highlights market fragility and profit-taking pressure. Odaily will analyze the situation from three perspectives: market performance, underlying causes, and future outlook.

1. Market Crash: From All-Time Highs to Circuit Breaker Alerts

At the opening on June 23, the KOSPI started high at 9083.54 points and briefly surged to 9175.45 points during the session. However, driven by foreign capital selling and follow-up sell orders, the index rapidly plunged. Around 2:33 PM, a decline exceeding 8% triggered the Korea Exchange (KRX) circuit breaker, halting trading of all KOSPI constituent stocks for 20 minutes. Similar mechanisms were activated on June 5 and 8, among other days, indicating that volatility has become the norm.

At the close, the KOSPI stood at 8203.84 points, recording a single-day drop of 9.99% with trading volume surging to 48.371 billion shares. Semiconductor giants like SK Hynix and Samsung Electronics led the decline, each falling over 12%. The KOSDAQ index proved even more fragile, falling over 6% in tandem, with small-cap tech stocks declining collectively. Net selling by foreign investors was significant, becoming the main source of selling pressure.

The Japanese market reaction was relatively moderate but still noteworthy. The Nikkei 225 fell over 3% intraday, closing at approximately 69,788 points, a single-day decline of about 3.47%. The TOPIX index also fell. Technology and semiconductor-related stocks performed the worst: SoftBank Group fell over 10%, chip manufacturer Kioxia plummeted 15.1%, and Tokyo Electron dropped 6.2%. The broad correction in AI and semiconductor sectors, which had previously driven the Nikkei's surge, ended an eight-day winning streak.

Compared to recent highs, the magnitude of this correction is staggering. The KOSPI has fallen over 12% from its mid-June peak, while the Nikkei 225 has significantly retreated from above the 70,000-point level.

Global market linkages were evident. US tech stocks came under pressure overnight, with the Nasdaq index falling over 1% and the S&P 500 edging lower. Rotation occurred among the "Magnificent Seven", with stocks like Amazon and Meta leading the decline. Other Asian markets, such as Taiwan's stock market, were also affected, creating a regional sell-off in tech stocks.

Overall, this is a rapid and sharp correction led by the technology sector, with the South Korean market falling much more than Japan's due to its higher concentration.

2. Cause Analysis: A Phase of AI Bubble Burst Under Multiple Factors

The sharp decline in Japanese and South Korean stock markets is the result of multiple factors interacting, which can be analyzed from dimensions such as direct triggers, macroeconomic policy pressures, and structural risks.

1. Direct Triggers: Overnight Weakness in US Tech Stocks and Profit-Taking Pressure

A significant pullback in the US tech sector during the previous trading session directly transmitted to Asian markets. The Nasdaq index fell over 1.2%, with notable rotation within the Magnificent Seven as some stocks came under pressure.

Lisa Shalett, CIO of Morgan Stanley Wealth Management, pointed out: "There's clear rotation in the Magnificent Seven, and news of some executives or researchers leaving has exacerbated market concerns about the progress of AI commercialization. Investors are beginning to demand more evidence that massive AI capital expenditures can translate into sustainable profitability."

This concern quickly spread to the Japanese and South Korean markets, which are heavily reliant on the global AI supply chain. South Korea's semiconductor exports consistently account for over 20% of its total exports, with Samsung Electronics and SK Hynix together comprising approximately 40% of the KOSPI's weight. On June 23, these two giants fell approximately 8%-12%, directly dragging down the index.

Furthermore, Japanese and South Korean stock markets had accumulated significant gains since June, resulting in very substantial unrealized profits. The KOSPI index surged from around 5000 points at the start of the year to over 9000 points by mid-June, with a maximum annual gain exceeding 80%. The Nikkei 225 also rose from around 40,000 points at the start of the year to over 70,000 points, hitting record highs. Valuations are at elevated levels (the KOSPI's forward P/E ratio briefly approached historical highs), making any negative catalyst prone to triggering profit-taking. The concentrated selling on June 23 was a natural correction following the excessively rapid prior gains.

2. Macro and Policy Factors: Rising Fed Rate Hike Expectations and Economic Data Impact

The latest strong US employment data has further fueled market expectations that the Federal Reserve will maintain high interest rates or even raise them further. According to Reuters, non-farm payrolls increased by 172,000 in May, far exceeding the 85,000 forecast by economists, while the unemployment rate held steady at 4.3%. This data prompted some institutions (like Goldman Sachs) to push back their initial rate cut expectations to 2027. More critically, the Fed's FOMC meeting on June 16-17 decided to keep the federal funds rate unchanged in the 3.5%-3.75% range. The meeting statement emphasized that economic activity is expanding at a solid pace, but uncertainties arising from the Middle East conflict have increased, and inflation remains above the 2% target.

The Fed's latest dot plot released a clear hawkish signal: the median forecast for the federal funds rate at the end of 2026 was raised to 3.8% (significantly higher than the 3.4% forecast in March), implying at least one rate hike is possible within the year. Simultaneously, the FOMC raised its inflation forecasts for 2026: the median Core PCE inflation forecast rose to 3.3%, and the median Headline PCE forecast rose to 3.6% (compared to around 2.7% previously). The GDP growth forecast was slightly revised down to 2.2%.

Consequently, interest-rate-sensitive growth stocks, especially in the tech and semiconductor sectors, bore the brunt. The South Korean stock market, previously considered a typical "high-beta" asset due to the AI boom, is extremely sensitive to changes in global liquidity. The Japanese stock market is also constrained by global liquidity expectations, although domestic wage growth data improvements provided some support.

A series of macro signals significantly pushed up US Treasury yields, exerting pressure on global risk assets and directly exacerbating the selling pressure on Japanese and South Korean tech stocks.

3. Structural Risks: High Market Concentration and Capital Outflows

South Korea's stock market has particularly prominent structural vulnerabilities. The KOSPI is heavily dependent on the two semiconductor giants, Samsung Electronics and SK Hynix, making it highly susceptible to sharp fluctuations when the semiconductor cycle or global AI demand wavers.

Continued foreign capital outflows are another key factor. Foreign investors reaped substantial profits during the earlier rally and have shown net selling multiple times since June, particularly in the South Korean market, with some funds possibly rotating into US IPO stocks (like SpaceX) or other assets. On June 23, net selling by foreign investors increased significantly, becoming the primary source of selling pressure.

In comparison, while the Japanese market was also dragged down by tech stocks, its sector diversification is relatively higher, limiting the Nikkei 225's decline to around 3.5%.

Additionally, specific company developments intensified market pressure. According to market sources, SK Hynix recently adjusted its AI chip (specifically HBM) memory capacity allocation, shifting some production lines towards higher-margin traditional DRAM to optimize short-term profitability. This move raised investor concerns about the short-term supply-demand balance of HBM, triggering selling.

3. Future Outlook: Short-Term Volatility Inevitable, Long-Term AI Narrative Still Resilient

Looking ahead, the Japanese and South Korean stock markets will likely exhibit characteristics of "volatile consolidation and structural divergence". Short-term market volatility will remain high, but medium-to-long-term fundamental support persists, with the correction potentially offering a window for positioning in quality assets.

Short-term volatility dominates; recovery depends on US stocks and Fed signals. In the near term, the market remains in a highly volatile adjustment phase. The trend of US tech stocks is a key barometer. If the Nasdaq stabilizes or sees a technical rebound, the Japanese and South Korean markets may follow with a recovery. Conversely, if the Fed releases further hawkish signals or Q2 earnings reports from Japanese and South Korean companies disappoint, the correction could extend or deepen. Key events to watch include:

• US inflation (CPI/PCE) and employment data for June-July;
• The Fed's next FOMC meeting (July);
• Q2 earnings results from heavyweight stocks like Samsung Electronics, SK Hynix, and Tokyo Electron.

Strong medium-to-long-term fundamental support makes corrections potential opportunities. Global AI capital expenditure is still growing rapidly, and the underlying logic of the semiconductor super-cycle remains unchanged. According to forecasts from Goldman Sachs and other institutions, global AI-related capital expenditure (compute, data centers, power) is expected to total approximately $7.6 trillion between 2026 and 2031. AI CapEx alone is projected to be nearly $765 billion in 2026, increasing annually to $1.6 trillion by 2031. New capacity additions for data centers are estimated at nearly 100GW from 2026 to 2030, with total investment reaching around $3 trillion.

South Korea holds a solid leading position in HBM and advanced process technology. SK Hynix's HBM market share has consistently been between 50% and 62%, and its supply share for the NVIDIA Rubin platform in the HBM4 era is expected to reach around 70%. Samsung Electronics is also accelerating capacity expansion, planning to increase HBM capacity by approximately 50% in 2026. Long-term orders for these two giants are largely secured until 2027, indicating that the AI memory demand super-cycle is still in its early stages.

From a long-term perspective, AI remains a transformative productive force for the world, and periodic adjustments struggle to reverse the overarching trend of technological progress. Just like corrections following every tech bubble in the past, they ultimately leave substantial rewards for genuine infrastructure builders and innovators. This "Black Tuesday" could perhaps mark the turning point for AI investment – moving from frenzy to rationality, from concepts to real-world application. The resilience and potential of the Japanese and South Korean stock markets still warrant anticipation.