On June 23, 2026, the Korea Composite Stock Price Index (KOSPI) plunged 9.99%, closing at 8,203.84 points and triggering a circuit breaker — one of the largest single-day declines in South Korean market history. Samsung Electronics and SK Hynix each fell over 12%. Foreign capital fled en masse, and domestic leveraged positions were liquidated in cascade.
This crash was no isolated financial tremor. The underlying structure — the leveraged bubble born from the AI semiconductor super-cycle, the mass influx of retail investors into high-risk products, and the intrinsic relationship between industry concentration and market fragility — is worth dissecting, because the same logic lies dormant in other markets as well.
The Three Layers Driving the Crash
The first layer was the US factor. A tech-stock correction, rising expectations of Federal Reserve rate hikes driven by strong employment data, and growing global concerns over AI overheating — the resonance of these three forces first hit Wall Street, then travelled down the global ETF and program-trading transmission line to Seoul. South Korea's equity market carries an exceptionally high semiconductor weight, making it naturally sensitive to external shocks.
The second layer was the domestic leverage structure. Between May and June 2026, single-stock 2× leveraged ETFs tracking Samsung Electronics and SK Hynix drew enormous retail capital. Data showed that investors in their forties formed the highest proportion (approximately 29–31%), those in their thirties about 22%, and those in their twenties about 6.5% — investors under 40 collectively accounted for nearly 60% of participants. These products generated massive trading volumes, many used as ultra-short-term trading instruments. When the June 23 crash hit, the amplification effect of leveraged products meant same-day losses could exceed 20%, with some investors facing outright margin calls.
The third layer was the structural vulnerability of the retail investor base. The number of South Korean stock account holders surged from roughly 6 million in 2019 to over 14.5 million by the end of 2025, with a large proportion being first-time entrants — ordinary people and younger investors. Lee Chan-jin, head of the Financial Supervisory Service (FSS), later publicly stated that he regretted "not blocking the introduction of leveraged ETFs even if I had to lie down in front of the door" — an indirect acknowledgment of the regulator's misjudgment of the risk boundaries of new products.
Panic Transmission in the Age of Social Media
On South Korean live-streaming platforms such as Chzzk, many streamers traded while broadcasting live. The moment of a leveraged account being liquidated was recorded, edited into short clips, and rapidly disseminated across communities like DCinside, FMKorea, and Naver — producing what came to be called "despair compilations." Some of this was, of course, "performative exaggeration" — building followers, opening memberships, selling so-called practical manuals. But it also reflected a real structural problem: when social media transforms individual losses into public spectacle, panic spreads with a speed and intensity far beyond that of traditional information channels.
Korean media captured the mood with terms like "kaemi panic" (개미 패닉, "ant panic") — describing the mass retail investor stampede — fully reflecting the emotional state of the market.
The Rebound and Lingering Concerns
On June 24, the KOSPI rebounded approximately 4%, closing near 8,470 points. Individual South Korean investors stepped in heavily at lower levels, while foreigners and institutions continued their net selling. Some Korean media argued that the long-term demand for AI semiconductors remained unchanged — that this was merely "a correction after too rapid a rise."
But the structural issues exposed by this crash will not disappear with a rebound: the Korean equity market's near-total dependence on the semiconductor sector (Samsung Electronics and SK Hynix alone account for an enormous share of the index), the rapid expansion of leveraged ETFs within just months of regulatory approval, and retail investors' insufficient understanding of high-risk products — these factors will reassert themselves in the next global tech-stock adjustment.
This KOSPI crash is not the endgame of the AI bubble — the bubble is far from bursting. But it is an important structural stress test, revealing the chain of fragility in a market driven by AI semiconductors when external shocks hit: US tech correction → Korea's semiconductor weighting transmits the blow → leverage amplifies → retail investors margin-called → social media amplifies panic. The same chain could be triggered in other markets that are heavily reliant on AI narratives and retail capital.
The Fifth Circuit Breaker: Five in Seven Days
On June 26, 2026, the KOSPI plunged sharply again at the open, falling more than 8% intraday and triggering another circuit breaker — a 20-minute trading halt. This was the fifth circuit breaker triggered on the Korean exchange in 2026.
The interval from the first circuit breaker on June 19 to the fifth on June 26 was just seven days. The circuit breaker had shifted from "a one-off extreme event" to a "weekly routine" market feature. The structural problems — semiconductor dependence, leverage amplification, retail panic — had not only failed to ease but were accelerating. The index had rebounded about 4% on June 25, only to plunge even more sharply on June 26, demonstrating that the rebound had not altered the underlying downward drivers.
The consequences of five circuit breakers were twofold. In the short term: massive forced liquidation of leveraged positions, the systematic destruction of retail capital, further compressing the market's buying power. In the longer term: accumulating policy pressure on the South Korean government — the credibility of the circuit-breaker mechanism itself was being depleted (when a market halts five times in seven days, circuit breakers no longer trigger calm; they amplify anxiety), while the regulatory cost of delay on the leveraged-ETF issue was rising.
The Seventh Shock: Technical Bear Market
On July 8, 2026, the KOSPI closed down over 5% at 7,246.79 points — a cumulative drop of more than 20% from its June high, officially entering a technical bear market. The direct triggers were twofold: an overnight sharp decline in US tech stocks, intensifying fears of a global AI investment slowdown and a semiconductor industry peak; and simultaneously, escalating US–Iran conflict in the Strait of Hormuz, driving risk aversion higher.
Korea's unique fragility was exposed once again. Market professionals noted that the KOSPI's decline was significantly larger than that of other major Asian markets — directly linked to the extreme semiconductor sector weighting and the amplification effect of single-stock leveraged ETFs. The Korea Exchange that day initiated a "temporary halt" on program trading for KOSPI200 index futures.
The July 8 decline layered a "geopolitical risk premium surge" on top of "industry-cycle-peak anxiety" — a double squeeze. Samsung Electronics and SK Hynix faced not only the prospect of peaking AI demand but also the risk that a Hormuz Strait blockade would drive up costs and disrupt supply chains.
The Full Picture: From 135% Surge to 40% Plunge in 40 Days
On July 30, the South Korean government announced that individual investment limits in single-stock leveraged ETFs would be capped at 20% of total investment. The news exploded on Korean social media — not because of the policy itself, but because it came far too late. SK Hynix had already fallen 60%. The KOSPI had lost over 40% from its peak. More than 1.2 million leveraged accounts had triggered margin calls, with 320,000 to 360,000 accounts forcibly liquidated. Imposing leverage restrictions at this point was like reinforcing a house that had already collapsed in an earthquake.
The 135% Bull Run
Between December 2025 and June 2026, the Korean stock market surged 135%, vaulting into the ranks of the world's sixth-largest equity market, surpassing even India. But the truly fatal factor was the concentration of the rally: SK Hynix soared 1,900% in one year, Samsung rose 600%, and the combined weight of these two stocks in the Korean market briefly reached 50%. The National Pension Service (NPS) played an unspoken supporting role: to avoid being forced to sell because its holdings were passively exceeding its target allocation, the NPS sharply raised its year-end target allocation from 14.9% to 20.8% in May 2026 — an operation that objectively reduced selling pressure and added fuel to an already overheated market.
The Final Leverage Step
On May 27, 2026, South Korean financial regulators approved and officially listed single-stock 2× leveraged ETFs tracking Samsung Electronics and SK Hynix — the first time such products had ever been permitted in Korea. Retail investors flooded in. The total assets under management for the two leveraged ETFs peaked at roughly US$19–23 billion (for the Hynix ETF) and US$8–12.4 billion (for the Samsung ETF) — many times the average daily trading volume of the underlying stocks. The options market also spiraled out of control: the notional open interest of call options on the EWY ETF tracking Korea surged to a record US$5.5 billion in May.
From any angle, the combination of these three indicators — extreme market concentration, record retail trading volumes, and unprecedented leverage — was a textbook definition of "possessing all the conditions for a crash."
Collapse in Six Weeks
The KOSPI hit an all-time high near 9,114 points around June 22, then began its slide. Trading defaults surged 300% within two months. By mid-July, more than 1.2 million leveraged retail accounts had triggered margin calls — equivalent to about 3.4% of the South Korean adult population. Of these, roughly 320,000 to 360,000 accounts were forcibly liquidated by brokerages, with some accounts losing their entire principal or even ending up in debt. SK Hynix fell about 60% from its June 25 peak. The broader market lost over 40% in roughly 40 days, erasing more than US$2 trillion in market capitalization.
Korean media dug up old records from months earlier: around March, the government had fostered a pro-investment atmosphere; in May, the FSS had approved individual-stock leveraged ETFs; on June 8, newly inaugurated President Lee Jae-myung publicly stated that "the KOSPI still looks somewhat undervalued" — with the index already near the 9,000-point cycle peak.
The leverage restriction announced on July 30 drew polarized reactions on Korean social media. Some condemned the timing — "imposing limits just as SK Hynix is down 50% and the KOSPI is repeatedly halting amid extreme volatility is pulling away the recovery ladder." Others praised the government for "moving swiftly to reduce stock investment leverage." Both sides acknowledged the same fact: the restrictions themselves could no longer undo the damage already done.
South Korea's complete trajectory from bubble to crash offers a textbook case study in how market concentration, retail leverage, and regulatory lag amplify one another. As Shen Yi observed in analyzing this case: Korean retail investors now have no idea whether they should be short or long.
The Ninth Wave: Mirror Image of the Surge — The 15% Rebound After the Circuit Breaks and the Bubble's Second Validation
On the third day after the bubble burst, the Korean stock market delivered the exact opposite answer: in early trading on July 31, the KOSPI surged — at one point more than 14% — with SK Hynix jumping 27% and Samsung Electronics up 20%. The Korea Exchange triggered the sidecar mechanism for both the KOSPI and the KOSDAQ, suspending program trading for five minutes each. By noon, the gain had widened further to 15% — a 15% rally the day after circuit breakers had fired on two consecutive days. Using the same circuit-breaker machinery, the Korean market first hammered out a crater of 40% down in 40 days, then pulled up the largest single-day bullish candle in its history.
Reactions on Korean forums were mixed: "A giant bullish candle appeared, setting a historic first with a 15% gain... Circuit breakers two days in a row, then a 15% rally the next day — should we be happy?" Some joked that "the entire market is flailing around like a junk stock," while others calmly observed: "Maybe they've just run out of ammunition."
This surge shared the same structure as the eighth wave of the plunge: extreme concentration in just two stocks — SK Hynix and Samsung. After leveraged ETFs were restricted, the market did not return to rationality; it merely switched volatility from a one-directional collapse into violent two-way swings. The same market participants who lost 40% in 40 days now face a 15% single-day rebound — Shen Yi's closing line from the previous section finds its confirmation here: Korean retail investors genuinely do not know whether to short or to go long.
That the circuit breaker has now been triggered twice in opposite directions shows that Korea's problem lies not in direction but in volatility itself. During the crash, regulators were condemned for arriving late; during the surge, leverage restrictions were accused of pulling away the ladder of recovery — the same policy tools, in the same market, were given two diametrically opposed readings. In a market after the bubble has burst, even policy becomes a hedging instrument for sentiment.
The July Roller Coaster — Real Prosperity and False Frenzy
The July monthly observation supplies the other half of the picture — industrial fundamentals — for the Korean stock market's roller coaster: this was not pure concept speculation. In the first twenty days of July, Korean semiconductor exports grew 180.6% year on year, exports to China rose 94.1%, and exports to the United States grew 39.6%. SK Hynix had bet early on HBM, becoming one of NVIDIA's key suppliers, and its market capitalization at one point surpassed Samsung's. The factories, the technology, the orders, the profits — all of it was real.
But real prosperity and false frenzy can coexist. The Lee Jae-myung government's indulgence of the financial carnival kept ordinary Koreans borrowing to pile on leverage — one college student lost 300 million won amid the volatility, then said he would keep borrowing to invest. This was compared to Argentine fans maxing out four credit cards to attend the World Cup — two sides of the same coin in the absurd era of late capitalism: social channels are narrowing, the pressure of life is mounting, and everyone is looking for their own exit.
One more detail is worth recording: the US Deputy Trade Representative publicly stated that the United States should share in the enormous profits of Samsung and SK Hynix. Korea does the manufacturing but lacks full technological sovereignty — it needs the Chinese market, and it must accept American management of equipment, chips, and supply chains. The position of being squeezed between violent surges and violent crashes is, in essence, a refraction of this structural location: US tech companies decide the scale of AI investment, the Chinese market provides vast demand, Korea manufactures — and yet someone shows up demanding a share of the profits.
The Korean stock market is not a mirror of the Korean economy; it is a cross-section of the high-leverage spectacle of the US AI capital cycle.