Samsung and SK Announce 20,000 Trillion Won in AI Investment as South Korean Stocks Plunge in the Same Downturn—What Is the Market Worried About?

On June 29, 2026, the South Korean stock market experienced a severe jolt. The Korea Composite Stock Price Index (KOSPI) once saw its decline widen to 3%, trading at 8,148.69 points during the session. The Korea Exchange immediately launched the KOSDAQ index circuit breaker mechanism (Sidecar), pausing programmatic buy orders for 5 minutes.

At the individual stock level, the “twin giants” in semiconductors were hit hard—Samsung Electronics fell more than 5% intraday, while SK Hynix slid nearly 5%. Samsung Life dropped 5.2%, Hyundai Mobis fell 3.7%, and Hyundai Motor declined 2.91%. At the same time, Japan’s stock market also fell sharply: the Nikkei 225 dropped 1.82%, breaking below 69,000 points.

This was not an isolated market fluctuation. From Seoul to Silicon Valley, AI trading logic is undergoing a systemic repricing.

Why Did the KOSDAQ Circuit Break on the Morning of June 29?

The direct triggering mechanism for this KOSDAQ circuit breaker came from the sharp fluctuations in the index and related futures prices. According to an announcement from the Korea Exchange, at 09:28:31 local time on the morning of June 29, the Korea Stock Exchange—KOSDAQ market formally triggered the “Sidecar” trading mechanism, fully pausing buy quotes for programmatic trading. The trigger condition was that the KOSDAQ150 futures price surged to 1,650.50 points, up 96.20 points from the previous trading day’s closing price.

The essence of the circuit breaker mechanism is a systemic institutional reflection of extreme market sentiment. As the KOSDAQ market (Korea’s growth enterprise board market), it gathers a large number of technology and semiconductor-related companies, and its volatility is inherently higher than that of the main board. When programmatic buying is forcibly paused, it means that the panic at the algorithmic-trading level has already triggered the exchange’s risk-control thresholds.

Notably, since 2000, the KOSPI index has triggered circuit breakers 11 times, with 5 occurring in 2026. The frequency itself already says a lot: in 2026, South Korea’s stock market is in a high-frequency cycle of extreme volatility.

Why Did Samsung Electronics and SK Hynix Drop in Sync During the Session?

The synchronized selloff of Samsung Electronics and SK Hynix is first and foremost the result of sentiment transmission from the global semiconductor sector. On June 26 (last Friday), the Philadelphia Semiconductor Index fell 737.30 points throughout the day, a decline of 5.29%, with constituent stocks closing in the red almost across the board. The memory chip track was particularly brutal: Western Digital fell 13.20%, Seagate Technology dropped 12.24%, SanDisk slid 10.46%, and Micron Technology fell 6.70%.

The high linkage between the South Korean stock market and the U.S. semiconductor sector stems from South Korea’s deep reliance on the semiconductor industry. Samsung Electronics and SK Hynix together account for nearly 60% of the KOSPI index weighting. When the global semiconductor sector faces a selloff, the South Korean market can hardly stay immune. The Philadelphia Semiconductor Index’s single-day plunge of 5.29% directly sparked systemic panic in South Korea over chip stocks.

But the deeper problem is that the fundamentals of memory chips have not deteriorated. Trade statistics released by the Korea Customs Service on June 22 show that from June 1 to June 20, 2026, exports of major memory semiconductor products had already exceeded $23 billion. Aletheia Capital expects DRAM average selling prices in the third quarter of 2026 to rise by 30%, and the average selling price of HBM could double each year by 2027. Morgan Stanley noted that the shortage across the entire memory chip industry chain may persist—at least—until 2028.

Strong fundamentals coexisting with a sudden stock price crash indicates that the current decline is more about reconstruction of valuation logic than a reversal in the industry cycle.

Why Didn’t a 2000 Trillion Won Investment Plan Boost Stock Prices?

On the very same day as the stock market crash, Samsung and SK Group unveiled a capital expenditure plan of unprecedented scale at the South Korean presidential office. The combined total investment scale over the next decade for the two companies could be as high as 2,000 trillion won (about $1.3 trillion), focusing on semiconductors, AI computing data centers, and physical AI.

Under the plan, Samsung Electronics and SK Hynix will build 4 to 5 new semiconductor wafer fabrication plants in Gwangju, respectively. Samsung will increase investment in its chip packaging base in Chungcheongnam-do, while SK Hynix will continue expanding its NAND flash production lines in Chungcheongbuk-do. In parallel, the Chungcheong region will simultaneously carry the construction of the national core AI data center cluster, while the Yeongnam region will focus on industrializing physical AI for on-the-ground implementation.

This is a super investment plan worthy of being recorded in South Korea’s industrial history. But the market’s response was selling.

Investors’ logic is not complicated: massive capital expenditures mean ongoing cash flow consumption for the coming years, while the visibility of AI commercialization revenue remains limited. Yardeni Research president Ed Yardeni said bluntly, “Investors seem to be experiencing AI fatigue. They are questioning whether the massive spending by hyperscalers on AI infrastructure will yield returns. They are worried that new technology will quickly make existing technology obsolete.”

How Does the Repricing of the Global AI Investment Return Cycle Feed into the Korean Market?

The KOSDAQ circuit breaker in the South Korean stock market is not an isolated event; it is part of the global reconstruction of AI investment logic.

In a research report released on June 24, Goldman Sachs pointed out that the AI investment boom has not yet peaked, but the market’s pricing of future returns is clearly running ahead of macroeconomic realization. The share of U.S. technology investment in GDP has already surpassed the peak reached during the late-1990s/early-2000s internet bubble era. The 2026 capital expenditure expectations for hyperscaler cloud vendors were revised upward by nearly 80% over the past six months. The four companies—Google, Amazon, Microsoft, and Meta—raised their 2026 capital expenditure to $725 billion, up 77% year over year from $410 billion in 2025.

Where is this massive capital flow going? Most of it has gone to AI computing infrastructure—GPU clusters, data centers, and high-speed interconnection networks. And as one of the core global suppliers of memory chips, South Korea is one of the biggest beneficiaries of this capital expenditure cycle. But the problem is: when the growth rate of capital expenditure continues to exceed revenue growth, the ROI inflection point becomes an issue the market must face.

The main line of trading is changing—from focusing on chip sales to examining AI application revenue and investment return efficiency. The backlash from soaring memory costs hitting end demand, combined with a slowdown in the capitalization process at leading AI companies, is forcing the market to reassess its capital expenditure assumptions for the AI infrastructure cycle and its long-term ability to monetize.

How to Understand the Logical Conflict Between Strong Memory Chip Fundamentals and a Stock Price Crash

This is the most notable contradiction currently in the market.

Based on all verifiable data, the memory chip industry is in one of the strongest upcycles in history. Micron Technology’s latest quarterly results show that the manufacturing capacity required for storage chips specifically optimized for AI is 3 to 4 times that of traditional computing products. Vivek Arya, a senior semiconductor analyst at Bank of America Securities, said bluntly, “Without memory chips, there is no AI.” He also pointed out that the recent surge in earnings far exceeded market expectations, reflecting a permanent shift rather than a typical cyclical upturn.

But stock prices are the result of expectation games, not a mirror of reality. When Samsung and SK announced the 2,000 trillion won investment plan, the market did not see room for future growth—it saw massive capital consumption over the next several years. A research report from CICC (China International Capital Corporation) noted that the current leverage multiples in South Korea’s stock market are around 2x to 5x, with absolute leverage at historical highs. In a high-leverage environment, any marginal negative development can be amplified into systemic selling.

The coexistence of strong fundamentals and a stock price crash indicates that the current market selloff is more of a trading-level issue than a reversal of industry logic. But this trading-level clearing in itself is also reshaping the pricing anchor for AI hardware assets.

How Do High Leverage and Programmatic Trading Amplify Volatility in the South Korean Stock Market?

The direct triggering factor behind this KOSDAQ circuit breaker was the suspension of programmatic buying, which reveals a structural characteristic of the current South Korean market: a high degree of coupling between algorithmic trading and leveraged funds.

An analysis by CICC suggests that the leverage multiple in South Korea’s stock market is around 2x to 5x, with absolute leverage at historical highs. High leverage amplifies volatility and can even bring liquidity pressure—such as declines of 16% to 36% that could trigger margin calls. The recent rise in forced liquidation pressure has further intensified the market’s downward spiral.

During this process, programmatic trading acts as an accelerator. When market declines trigger algorithmic stop-loss orders, programmatic sell orders further depress prices, which then leads to more stop-losses—forming a negative feedback loop. By suspending programmatic buying for 5 minutes, the KOSDAQ circuit breaker mechanism essentially aims to interrupt this loop and provide the market with a brief cooling-off period.

However, circuit breakers can only treat symptoms, not the root cause. As long as the coupling structure between leverage levels and algorithmic trading remains unchanged, the market will remain fragile in the face of negative shocks.

Has Crowdedness in AI Hardware Trading Reached a Tipping Point?

From multiple dimensions, crowdedness in AI hardware trading is indeed at historical highs.

The Philadelphia Semiconductor Index plunged 5.29% on June 26. But before that, the index had experienced sustained sharp rises over the preceding months. The memory chip track has become a core direction for capital chasing, and price expectations for AI-related memory products such as HBM and DDR5 have been repeatedly revised upward.

Rich Privorotsky, a strategist in Goldman Sachs’ Global Banking & Markets division, described the current AI market as a “rubber band stretched too far,” warning that over the past few weeks investors have nearly ignored all negative signals appearing in AI capital expenditure trades. This “selective inattention” is itself a typical characteristic of crowded trades—when everyone firmly believes in the same narrative, any marginal change can trigger a collective expectation adjustment.

AI hardware and semiconductor crowded trades are facing a logical reconstruction. The market has started to question AI capital expenditure and monetization assumptions. This is not a call for bearishness on AI’s long-term trend; it is a warning about fragility arising from overly optimistic short-term pricing.

From Seoul to Silicon Valley: The Long-Term Impact of Rebuilding AI Trading Logic

The KOSDAQ circuit breaker in South Korea is a signal. It marks a paradigm shift in AI hardware trading—from “narrative-driven” to “ROI verification.”

Over the past two years, the market’s AI pricing logic has been relatively simple: whoever controls computing power controls the future. GPU makers, memory chip makers, and data center operators became targets of capital chasing, and valuations kept expanding. But entering 2026, every link in this logic chain is undergoing pressure testing: computing power rental prices have pulled back from their peaks, technology giants are collectively tightening AI budgets, electricity and engineering delivery expose physical limits, and the capital market has begun using ROI to evaluate each AI company.

From an industrial strategy perspective, Samsung and SK’s 2,000 trillion won investment plan is necessary—without continued capital investment, they cannot maintain competitive advantages in the global memory chip market. But from a capital market perspective, the investment return cycle, cash flow pressure, and execution risk of this investment are variables that need to be priced.

When industrial logic conflicts with capital logic, pricing power temporarily shifts to the latter. This is the deep meaning of the June 29 circuit breaker in South Korea’s stock market: the AI investment cycle is still continuing, but the market is no longer willing to pay for “expansion at any cost.”

Summary

On June 29, 2026, South Korea’s KOSDAQ triggered a circuit breaker, with the KOSPI once falling by more than 3%, and Samsung Electronics and SK Hynix dropping by more than 5% intraday. The core driver of this market event was not a deterioration in semiconductor fundamentals, but a valuation reconstruction triggered by a global repricing of the AI investment return cycle.

The fundamentals of the memory chip industry remain strong—record exports, continued price increases, and supply-demand gaps lasting at least until 2028. However, the 10-year 2,000 trillion won investment plan announced the same day by Samsung and SK led the market to begin reassessing the return cycle and cash flow pressure of large-scale capital expenditures. Under the amplifying effects of high leverage and programmatic trading, this expectation correction was quickly transformed into systemic selling.

From Seoul to Silicon Valley, AI trading logic is shifting from “narrative-driven” to “ROI verification.” This is not a reversal of AI’s long-term trend, but a correction to the market’s pricing mechanism—capital expenditures can expand indefinitely, but valuations cannot.

Frequently Asked Questions (FAQ)

Q: What is the KOSDAQ circuit breaker mechanism?

The KOSDAQ circuit breaker mechanism (Sidecar) is a risk control measure set by the Korea Exchange for the growth enterprise board market. When the KOSDAQ150 futures price experiences a large move compared with the previous trading day’s closing price, the exchange will pause programmatic buy orders for 5 minutes to interrupt the negative feedback loop of algorithmic trading.

Q: What specific areas will Samsung Electronics and SK Hynix’s 2,000 trillion won investment plan be directed to?

The plan runs for ten years, with a total investment scale potentially reaching up to 2,000 trillion won (about $1.3 trillion). It focuses on three major areas: semiconductor manufacturing (4 to 5 new wafer fabs in Gwangju), AI computing data centers (the Chungcheong region), and the industrial rollout of physical AI (the Yeongnam region).

Q: Has there really been a problem with the fundamentals of memory chips?

Based on the available data, the fundamentals of memory chips have not deteriorated. In the first 20 days before June 2026, the major memory semiconductor export value already exceeded $23 billion. Institutional expectations are that the average DRAM price will rise 30% in the third quarter of 2026, and that the average HBM price may double every year by 2027. The current decline in stock prices is more about a reconstruction of valuation logic rather than a reversal of the industry cycle.

Q: What impact does the repricing of the AI investment return cycle have on the crypto market?

The logic reconstruction in AI hardware trading may indirectly affect crypto mining—there is competition between mining-chip and AI-chip needs within the supply chain. But the specific impact must be judged independently using Gate’s real-time market data.

Q: How long will volatility in the South Korean stock market last?

An analysis by CICC suggests that high leverage will amplify short-term volatility, but the longer-term trend depends more on fundamentals. The supply-demand landscape in the memory chip industry and the sustainability of AI demand will be key variables determining the South Korean stock market’s medium- to long-term trajectory.