THE ENTIRE KOREAN STOCK MARKET WENT DOWN BECAUSE OF ONE LEVERAGE ETF: KORU
This is a research and educational article on market structure, not investment advice. It is not a recommendation to buy or sell any security. Figures are drawn from public reporting (Direxion, Korea Exchange, Goldman Sachs, HSBC, Reuters, Bloomberg, CNBC) and rounded; some figures vary by source and are noted as approximate.
This not merely a correction of South Korea’s stock market value.
The fact is, the entire market just got margin-called and wipe out.
In five weeks the KOSPI erased a rally that took fourteen months to build, and the country’s favorite leveraged ETF wrapper went from the best trade of 2026 to a 70% drawdown. SK Hynix posted the best quarter in its history in the middle of the crash. The stock fell anyway.
This is not a story about bad companies — it’s a story about what leverage does to a market when everyone is levered the same way, into the same two stocks, through the same fragile plumbing.
SO WHAT IS KORU, REALLY?
Before we explore the underlying mechanism of the KOSPI stock crisis, we need to know about KORU, the leveraged ETF causing the massive margin call.
KORU is the ticker for the Direxion Daily MSCI South Korea Bull 3X ETF, issued by Direxion and managed by Rafferty Asset Management. It has traded on NYSE Arca since 2013. It does not hold Korean stocks directly in the way a normal fund does — it invests at least 80% of its net assets in swap agreements and other derivatives designed to deliver, in combination, three times the daily return of the MSCI Korea 25/50 Index, a benchmark covering roughly 85% of the free-float market cap of large- and mid-cap South Korean companies.
There is only about 14 positions and is explicitly non-diversified, which matters here because the underlying index is itself dominated by Samsung Electronics and SK Hynix.
Do not be fooled by the literal meaning of 3X LEVERAGE ETF
Holding this leverage ETF,
IT DOES NOT ALWAYS GRANT YOU 3 TIMES OF RETURN
BUT YOU WILL EXPOSE TO MORE THAN 3x of RISKS.
Essentially, the KORU isn't built to deliver 3x your return over a year, a month, or even a week — only over a single trading session, after which it resets.
Direxion says so plainly in its own materials:
the fund "should not be expected to provide three times the return of the benchmark's cumulative return for periods greater than a day."
It is designed and marketed as a short-term trading tool for people who actively manage a position, not something to buy and hold through a cycle.
And that single design choice — reset the leverage ratio every 24 hours, forever — is the entire reason this story is possible.
KORU — FOR QUICK REFERENCE
Full name: Direxion Daily MSCI South Korea Bull 3X ETF
Issuer: Direxion / Rafferty Asset Management, LLC
Exchange: NYSE Arca · Inception: 2013
Benchmark: MSCI Korea 25/50 Index (large- & mid-cap South Korea, ~85% free-float coverage)
Target exposure: 300% of the benchmark's daily return, reset every trading day
Structure: ≥80% of net assets in swap agreements & derivatives, not direct equity holdings
Holdings: ~14 positions, non-diversified; heavily correlated to Samsung Electronics + SK Hynix
Net expense ratio: 1.32%
Intended use: Short-term trading tool for investors who actively manage the position — not a buy-and-hold vehicle
THE KOREAN CASINO
The KOSPI gained roughly 297% from its April 2025 low to an all-time high of 9,385.59 on June 19, 2026 — its strongest run since the 1980s.
The whole stock market driver was memory chips: Samsung Electronics and SK Hynix, riding the AI infrastructure boom, saw their combined weight in the index balloon from roughly a quarter of KOSPI value a year earlier to somewhere between half and 60%, depending on the week you measured it.
This is MORE THAN EXTREME,
THE ONLY TWO STOCKS HAVE FUELED IN THE ENTIRE MARKET UPSIDE.
Retail investors didn’t just buy in — they borrowed to buy in.
Margin loan balances hit a record high in the tens of trillions of won during the rally, with HSBC estimating roughly $23 billion in margin lending outstanding by mid-July. Margin trading accounted for an estimated 35% of retail activity, at average leverage of around 3x.
Then, on May 27, 2026, regulators let the industry go one step further:
The single-stock leveraged ETFs on Samsung and SK Hynix (2x daily), sold out on day one. Korean retail bought roughly 14 trillion won worth against 2 trillion won from foreign investors.
Approving a 2x single-stock leverage product at the top of a fourteen-month parabolic run is a choice.
Regulators later acknowledged as much — South Korea’s finance minister publicly apologized in late July, conceding the products had been allowed onto the market without adequate vetting.
[CHART 1 — Why 3x Doesn’t Mean 3x: Volatility Decay in a Choppy Market]
THE MECHANISM: WHY 3X DOESN’T MEAN 3X
The 3x leveraged ETF like KORU doesn’t promise triple the return of its index over any period you choose — it promises triple the daily return, reset every single day. That distinction is everything.
In a smooth, trending market, daily compounding works in your favor and the leveraged product can outrun a simple 3x multiple.
In a much volatile market — exactly the environment a margin-call cascade produces — the same daily reset mechanically bleeds value, even if the underlying index round-trips back to where it started.
This is exactly what happened in real time.
KORU fell from roughly $1,090 to $610 between May 29 and June 5 — a 44% drop in a single week — while its unleveraged sibling, iShares MSCI South Korea (EWY), fell about 15% over the same stretch.
On the worst single day of that stretch, EWY fell 14% and KORU fell roughly 42%, well beyond a simple 3x multiple, as swap counterparties rebalanced into the decline intraday. By mid-July, KORU had fallen about 70% from its June 1 high.
In July alone it posted its worst monthly decline on record, down nearly 64%.
The leverage that multiplies your upside in a trend is the same leverage that multiplies your losses the moment the trend becomes noise.
THE SELF REINFORCING MARGIN CALL
The unwind started slipping in late June and accelerated on July 13, when SK Hynix crashed 15.37% — its largest single-day drop since listing — and Samsung fell 10.7%, as leverage-driven selling in both stocks began overwhelming the market’s ability to absorb it.
Here’s the feedback loop:
Three days later, on July 16, the KOSPI fell 6.4% and tripped circuit breakers on both the Kospi and Kosdaq.
The Bank of Korea raised its base rate to 2.75% that same day — its first hike in more than three years — explicitly to lean against speculative leverage, and the Financial Services Commission suspended new single-stock leveraged ETF listings and sharply raised margin requirements. None of it stopped the mechanism already in motion.
Two weeks later, on July 29, SK Hynix reported a 557% year-over-year jump in quarterly operating profit — the best quarter in its history — and its stock still fell 9.6%, as results missed analyst estimates and management offered no timeline on shareholder returns.
The KOSPI fell almost 6% that same day and the Kosdaq more than 6%, tripping circuit breakers on both exchanges for a second consecutive day — the first time that had happened in the market’s history.
The record earnings beat and a fresh market-wide circuit breaker landed on the same afternoon, because by that point the stock price had stopped reflecting the business and started reflecting the leverage sitting on top of it.
Underneath all of it, the same reflexive loop kept turning:
falling prices triggered margin calls, margin calls forced broker liquidations, forced liquidations pushed prices lower, and the leveraged ETFs’ own daily rebalancing sold into the decline right alongside the panicked retail accounts.
By the time it was done, KOSPI had fallen as much as 44% from its June peak, and July’s monthly decline — more than 33% — became the worst month in the index’s history, worse than the 27% drop in the 1997 Asian Financial Crisis and the 23% drop in the 2008 Global Financial Crisis.
[CHART 2 — The KOSPI Round Trip: From All-Time High to Worst Month on Record]
THE BILL: WHO GOT LIQUIDATED
Goldman Sachs estimated that by July 13, more than 1.2 million retail leveraged accounts in South Korea had triggered margin calls, and somewhere between 320,000 and 360,000 had been forcibly liquidated — roughly one in every thirty Korean adults.
Retail investors are estimated to have lost around $39 billion in the crash overall.
The single-stock products were hit hardest of all:
the KODEX SK Hynix leveraged ETF fell more than 80% from its June 23 peak, and the KODEX Samsung equivalent fell nearly 75% from its June 3 peak.
One widely reported case: a retail trader who built roughly 300 million won (about $202,500) on a 500% margin loan watched it evaporate in four weeks — and said he planned to borrow and re-enter the market again.
That instinct, multiplied across a million accounts, is the real story here.
[TABLE — Peak-to-Trough: The Leverage Cascade, June–July 2026]
REGULATORS ARE ALWAYS LATE FOR PARTY
South Korea’s finance minister publicly apologized in late July, acknowledging that single-stock leveraged ETFs had been allowed onto the market without adequate vetting.
The FSC is now weighing whether to restrict these products to professional investors only.
Yes, they are still ‘discussing’ the matter.
Not to mention the late apology.
THEN The apology only arrived after the liquidations, not before the leveraged ETF listings — which is roughly the pattern regulators follow everywhere leverage gets democratized right as an asset class goes parabolic.
THE LESSON FOR INVESTORS
Leverage doesn’t multiply your view of the market — it ONLY multiplies the market’s ability to force you out of your view before you’re proven right or wrong.
Daily-reset leveraged products are trading vehicles, not investments. Holding period matters more than direction; volatility decay works against you even when you’re eventually right about the trend.
Concentration compounds leverage. When two stocks are 50%+ of the index and everyone is levered into the same two names, the exit door is one lane wide for everyone at once.
Margin calls are reflexive, not incidental. The same mechanism that amplified the upside — daily rebalancing into the trend — amplifies the downside just as mechanically once the trend reverses.
Regulators tend to approve first and apologize later. Product approval timing tells you more about where you are in the cycle than any chart does.