The 4 Core Underlying Root Causes of Frequent Circuit Breakers in the Korean Stock Market (The trigger is just a symptom; the root causes were already in place)

1. Extremely Distorted Index Structure: Semiconductors Hijack the Entire Market with No Buffer



The Korean stock market is an extreme, single-chip-dependent market: Samsung Electronics and SK Hynix, two memory leaders, along with Samsung-affiliated companies, together account for over 50% of the KOSPI index weight. The entire market trend is entirely tied to the AI memory chip cycle.

When the AI boom is up, the index surges; once global memory demand cools and chip price hike expectations fade, a 10%+ drop by either giant alone can send the broader index crashing over 8% with no offset from consumer, healthcare, or financial sectors. The index inherently carries a "crash gene"—a congenital defect that makes Korean stocks prone to circuit breakers.



2. Widespread High Leverage Among the Public Is the Core Accelerator of Circuit Breakers (Fatal Risk)



This is the most critical culprit behind the recent crash: At the end of May, South Korea approved 16 single-stock 2x leveraged ETFs in bulk, all linked to the two chip leaders Samsung Electronics and SK Hynix. Retail investors don’t need to open margin accounts or meet collateral requirements—they can buy 2x leveraged products with one tap on their phones.

In just over a month, the size of these leveraged ETFs surged from $3 billion to $9.1 billion, with over 90% of holders being ordinary retail investors and a weekly turnover rate as high as 200%. It’s equivalent to the entire nation gambling on chip prices with leverage.

Once stock prices fall slightly, the 2x leveraged products trigger a chain reaction of forced liquidations: price drops → leveraged positions blow up, forcing selling → prices fall further → more leveraged accounts blow up, creating a vicious downward spiral. Within an hour, massive sell orders flood in, directly driving the index to the circuit breaker line. Regulators later publicly regretted approving these leveraged products.



3. Excessively High Foreign Ownership Ratio, Making the Market Prone to Mass Exodus Under High Fed Rates



Foreign investors hold over 35% of the total South Korean stock market, and over half of the semiconductor leaders are foreign-held, making it a foreign-dominated pricing market.

With the Fed maintaining high interest rates and expectations of another rate hike this year, the U.S. dollar continues to strengthen, causing global risk capital to flow back to U.S. Treasuries. If foreign investors collectively turn bearish and dump Korean stocks without sufficient buying support, the index can plummet rapidly. Plus, with the Korean won depreciating simultaneously, foreign sellers have a stronger incentive to convert proceeds and exit, further amplifying the decline. This is the external driver behind the frequent circuit breakers in Korean stocks in recent years.



4. Extreme Retail Sentiment: Greed During Surges and Panic During Crashes Amplify Volatility



Retail investors account for over 60% of trading volume in the Korean market, making them the absolute trading force: During rallies, they blindly chase highs, pumping up bubbles with mass buying; during declines, panic-driven selling creates a stampede, and negative rumors are amplified infinitely (a draft tax notice that hasn’t even been enacted can crash the index by 10%). Additionally, retail investors’ tendency to buy the dip with a delay only slows down the clearing process, prolonging the downtrend, turning circuit breakers from occasional events into the norm.