On July 28, 2026, South Korea’s benchmark KOSPI (Korea Composite Stock Price Index) plunged 10.84%, its biggest one-day fall on record, after a selloff in artificial intelligence (AI)-linked semiconductor stocks. The fall was comparable to some of the sharpest one-day declines during the 2008 global financial crisis and the 2020 Covid-19 market panic, though still well below Wall Street’s 22.6% crash on Black Monday in 1987, the worst single-day stock market fall in modern history. Trading was halted for 20 minutes after a market-wide circuit breaker (an automatic trading halt during sharp market falls) was triggered. The AI selloff was merely the immediate trigger. As the questions below explain, the causes of the crash ran much deeper.
TIMELINE
Early 2026: The global AI boom drives a rally in semiconductor stocks.
First half of 2026: Samsung Electronics and SK Hynix lead gains on the KOSPI.
Mid-2026: Investors begin to worry AI-related shares have become overvalued.
July 28: Selling in chip stocks triggers margin calls and forced selling.
July 28: The KOSPI plunges 10.84%; trading is halted for 20 minutes.
In the aftermath of the crash, analysts and investors turn their attention to deeper structural weaknesses in South Korea’s economic model.
What triggered the crash?
The immediate trigger was a fall in semiconductor and AI-related shares led by Samsung Electronics and SK Hynix. Investors who had driven these shares sharply higher during the AI boom began to believe they had become overvalued and started selling to lock in profits.
Once confidence weakened, the selloff spread rapidly because many investors who had bought shares using borrowed money were forced to sell as prices fell.
Why is this really a story about power, not just AI?
The South Korean stock market crash may look like an AI story, but the real issue runs deeper.
South Korea’s market depends heavily on a few giant companies, especially Samsung Electronics and SK Hynix. They dominate the KOSPI, so when chip stocks fell, the whole market fell with them. Combined with the dominance of family-run business groups, the heavy concentration of investment in the same stocks, and a long-standing belief that Korean shares traded below their true value, the market became far more fragile than it appeared.
Why was AI only the trigger for the crash?
For most of 2026, investors saw South Korea as a big winner from the global AI boom because it makes many of the advanced memory chips used in AI.
That pushed Samsung Electronics and SK Hynix shares sharply higher. But as prices kept rising, many investors began to think the stocks had become too expensive. They started selling to lock in profits, and once that selling gathered pace, prices dropped quickly.
Why did concentration make the fall much worse?
The KOSPI isn’t evenly spread across lots of companies. A handful of big firms account for a large share of the index.
That meant when Samsung Electronics and SK Hynix fell, they dragged down the entire market. In a more balanced market, gains in other sectors can soften the blow. In South Korea, there were too few gains in other sectors to cushion the decline.
How did debt turn a market correction into a shock?
Many individual investors had borrowed money to buy shares during the AI rally.
When prices started falling, they were forced to sell to repay those loans or meet margin calls. Those forced sales pushed prices down even further, triggering more selling and making the decline much steeper.
Because so many ordinary investors had borrowed to invest, the losses spread far beyond professional investors.
Why did the crash affect ordinary citizens so deeply?
Many people lost money they had saved for a home, their family’s future, or retirement.
For them, investing wasn’t just about making a quick profit. It was a way to build a better future in a country with expensive housing, job uncertainty and growing worries about retirement. When the AI rally collapsed, many lost not only their savings but also confidence in their ability to build long-term financial security.
What is the deeper structural problem behind the crash?
South Korea’s economy was built around giant family-run business groups called chaebols, such as Samsung, Hyundai and SK.
These companies helped drive the country’s rapid growth, but the system also has weaknesses. Founding families often control huge business empires without owning much of them. Complex ownership structures let them stay in charge while giving ordinary shareholders little say.
That has led to long-standing concerns about weak corporate governance and whether all investors are treated fairly.
What does the “Korea Discount” mean?
The “Korea Discount” refers to the fact that South Korean companies often trade at lower prices than similar companies in other countries.
Investors worry about family control, weak shareholder rights, complicated ownership structures, low dividends, geopolitical tensions, and the economy’s heavy reliance on semiconductor exports. Together, these factors make investors less willing to pay a premium for Korean stocks.
Why does the 1997 Asian Financial Crisis still matter?
Before the 1997 Asian Financial Crisis, many chaebols borrowed heavily because they believed the government would step in if they got into trouble. When the crisis hit, that assumption proved wrong, exposing the risks of too much debt, weak oversight and an economy dominated by a few large business groups.
That experience still shapes investor thinking today. Whenever they see rising debt, heavy reliance on a few companies or weak corporate governance, they become much more cautious.
What reforms is South Korea trying to implement?
South Korea is trying to improve how companies are run through reforms such as the Value-Up Programme. The goal is to make companies more transparent, protect shareholders, improve returns and reduce the Korea Discount. But reform isn’t easy. The challenge is that the very chaebols requiring stronger governance are also the country’s principal drivers of exports, employment and economic growth. The task is to improve oversight without weakening the businesses that have powered South Korea’s growth.
What is the bigger lesson from South Korea’s 2026 stock market crash?
The AI boom may have triggered the crash, but it wasn’t the real cause. The broader lesson is that technological leadership alone cannot ensure market resilience. Long-term stability ultimately depends on sound corporate governance, a more balanced market and sustained investor confidence.