On July 13, 2026, South Korea's stock market experienced a dramatic sell-off that many described as a "Black Monday." The KOSPI plunged nearly 9% in a single trading session, triggering a circuit breaker during the day. With this marking the seventh circuit breaker of the year, investor anxiety has continued to grow.

The sharp decline was led by major semiconductor stocks, which had previously driven much of the market's rally. As a result, many retail investors saw their recent gains disappear. Some even remarked that profits accumulated over several months had been wiped out within just a few weeks.


Why Did the KOSPI Fall Below 6,900?

The KOSPI closed at 6,806.93, down 8.95% from the previous trading day. Although the market opened with only modest losses, selling pressure intensified throughout the session.

The semiconductor sector was the primary driver of the decline. Samsung Electronics and SK Hynix both suffered steep losses, dragging the broader market lower. Heavy selling by both foreign and institutional investors further accelerated the downward momentum.

Market analysts also pointed to increased profit-taking in SK Hynix shares following the listing of its American Depositary Receipts (ADRs) in the United States, which added to the selling pressure in the domestic market.

Frequent Sidecar and Circuit Breaker Activations

Earlier in the day, a sidecar mechanism temporarily halted program trading. Later, a market-wide circuit breaker was triggered, suspending trading for a short period.

A circuit breaker is designed to temporarily stop trading during periods of extreme market volatility, giving investors time to reassess market conditions and helping to reduce panic-driven selling.

However, the fact that circuit breakers have already been activated seven times this year—and that sidecars have occurred even more frequently than during the 2008 global financial crisis—highlights the unusually high level of market volatility currently affecting South Korean equities.

Semiconductor Giants Led the Decline

The biggest losses came from leading semiconductor companies.

  • Samsung Electronics fell by approximately 10%.
  • SK Hynix dropped by roughly 15%.
  • SK Square and Samsung Electro-Mechanics also recorded double-digit declines.

Meanwhile, several companies in the battery, financial, and biotechnology sectors managed to post modest gains, demonstrating that market performance varied significantly across industries.

Although long-term expectations for artificial intelligence continue to support demand for semiconductors, investors remain concerned about near-term supply-demand conditions and corporate earnings.

Heavy Losses for Leveraged ETF Investors

Among those hit hardest were investors holding single-stock leveraged exchange-traded funds (ETFs).

Leveraged ETFs are designed to deliver a multiple of the daily return of an underlying asset. While they can amplify gains during rising markets, they can also magnify losses during periods of high volatility.

In addition, repeated market swings can produce what is commonly known as the "negative compounding effect," causing long-term returns to significantly underperform the underlying asset.

Following the sharp decline in Samsung Electronics and SK Hynix, several leveraged ETFs linked to these companies fell to record lows, once again highlighting the risks associated with highly leveraged investment products.

Concerns Over Margin Trading and Forced Liquidations

Investors who borrowed money to purchase stocks are also facing increased financial pressure.

Outstanding margin balances have risen substantially. If investors fail to meet repayment requirements within the specified period, brokerage firms may force the sale of their holdings through margin calls and forced liquidations.

The concern is that forced selling can create a vicious cycle. As stock prices fall, additional forced liquidations occur, generating even more selling pressure and potentially driving prices lower.

Key Factors to Watch Going Forward

Two major factors are expected to shape the direction of the market in the coming weeks.

The first is the outlook for the semiconductor industry. Investors will closely monitor whether continued investment in artificial intelligence translates into sustained demand for semiconductor products.

The second is the earnings season for major U.S. technology companies. Financial results and AI investment plans from firms such as Microsoft, Meta, and Amazon could significantly influence expectations for Korean semiconductor manufacturers.

In addition, investors will be watching whether the South Korean government introduces new regulations for single-stock leveraged investment products.

Conclusion

This "Black Monday" was more than just a one-day market correction. It highlighted the heightened volatility and fragile investor sentiment currently affecting the market. The simultaneous decline in semiconductor stocks and leveraged investment products served as a reminder of the risks that accompany periods of rapid market fluctuations.

Looking ahead, investors may benefit from focusing not only on short-term price movements but also on broader fundamentals, including corporate earnings, the outlook for the semiconductor industry, and the global pace of investment in artificial intelligence.