South Korea's stock market has been experiencing wild swings, with more than half of all circuit-breaker triggers in the history of the KOSPI index occurring in just the last six months. The culprit, according to Reuters, is a surge in leveraged single-stock exchange-traded funds (ETFs) tied to the country's two biggest chipmakers: Samsung Electronics and SK Hynix.
These products amplify daily moves in the underlying stocks, and when combined with the outsized weight of those two companies in the index, they are creating a feedback loop that can turn ordinary trading days into volatile events. Regulators are now stepping in to slow the growth of these ETFs, blocking new launches and raising the minimum cash balance required to trade them.
How leveraged ETFs amplify market moves
Leveraged ETFs are designed to deliver a multiple—often 2x or 3x—of the daily return of a single stock or index. To maintain that leverage, the funds and their counterparties must rebalance their positions every day. After a day when the stock rises, they buy more shares to keep the leverage ratio constant. After a drop, they sell. This mechanical buying and selling can overwhelm normal liquidity, especially when the ETF is large relative to the underlying stock.
Reuters reports that a Hong Kong-listed 2x leveraged SK Hynix ETF has grown more than 20-fold this year to $7.78 billion. Amundi, a global asset manager, notes that some single-name leveraged ETFs trade at four times the average volume of the underlying stock. That means the daily rebalancing flows can be large enough to move the stock itself, creating a self-reinforcing cycle.
In a market where two stocks—Samsung Electronics and SK Hynix—now account for more than half of the KOSPI's value, the effect can ripple into the broader index. When leveraged ETFs force buying on up days and selling on down days, the index can experience sudden "air pockets" that trigger circuit breakers. The KOSPI's circuit breakers kick in if the index drops more than 8% for at least one minute.
From global growth proxy to flow-driven market
South Korea's stock market has historically been seen as a bellwether for global economic growth, given its heavy exposure to exports of semiconductors, automobiles, and ships. But Reuters says the market is increasingly behaving like a "flow" story, where large, borrowed-money positions can move prices regardless of fundamentals.
The concentration in AI-related chip stocks is a key driver. Both Samsung Electronics and SK Hynix are seen as major beneficiaries of the global spending cycle on artificial intelligence infrastructure, which has drawn in speculative capital. The leveraged ETFs amplify that speculative flow, turning what might be a modest daily move into a sharp intraday swing.
This dynamic is not unique to South Korea. Leveraged single-stock ETFs have grown rapidly in markets around the world, including the United States and Hong Kong. But the extreme concentration of the KOSPI makes it particularly vulnerable. For context, the two chip giants now represent more than half of the index's total market capitalization, according to Reuters.
What it means for investors
For everyday investors, the rise of leveraged single-stock ETFs introduces a new layer of risk. These products are designed for short-term trading, not long-term holding. The daily rebalancing means that over time, the performance of a leveraged ETF can diverge significantly from the underlying stock's performance, especially in volatile markets.
The broader lesson is that market structure matters. When a small number of stocks dominate an index, and when leveraged products tied to those stocks become large, the entire market can become more fragile. The KOSPI's circuit breakers are a safety valve, but they are being tested more frequently than ever before.
South Korean regulators are responding by trying to slow the growth of these products. They have blocked new launches of leveraged single-stock ETFs and raised the minimum cash balance required to trade them. These measures aim to reduce the potential for disorderly trading, but they may not eliminate the underlying concentration risk.
For investors with exposure to South Korean equities, either directly or through broad market ETFs, it is worth monitoring the regulatory landscape and the size of leveraged ETF flows. The same forces that have driven the KOSPI higher on AI optimism could also amplify a downturn if sentiment shifts.
Elsewhere in Asia, similar dynamics are at play. In Taiwan, chip stocks have also been volatile, with the market tumbling 6% despite TSMC's record profit, as AI optimism fades. See our coverage: Taiwan Chip Stocks Tumble 6% Despite TSMC's Record Profit as AI Optimism Fades.
The South Korean experience is a reminder that leverage, concentration, and market structure can combine to create outsized moves. For now, regulators are trying to put the genie back in the bottle, but the leveraged ETF boom shows no signs of slowing.
