The violent swings in South Korea's KOSPI, which are also spreading to the Nikkei 225, and the 2018 phantom-share incident have been reported. Semiconductor trends and the impact of foreign-currency settlements are also involved, and the market's future direction bears watching.
South Korea's KOSPI has been highly volatile, and the correlation coefficient between semiconductor export value and the 12-month forward expected earnings of KOSPI companies is said to be 0.9. A weaker won has weighed on share returns, while foreign investors' dollar settlements have had an impact. In 2026, a reverse rotation was also observed, with won selling swelling as the KOSPI rose, increasing the correlation between Seoul and the Nikkei.
In July 2026, the Nikkei 225 fell about ¥2,400 the day after Samsung Electronics and SK Hynix plunged by about 10%, with much of the decline concentrated in the electrical machinery sector. KOSPI volatility has affected Japanese stocks in real time, and was shown at 63% during the same period. Bitcoin, by contrast, was at 48% over the same period, and external institutions have used the KOSPI as a comparator.
In the phantom-share turmoil that severely shook the South Korean market, an input error at Samsung Securities on 6 April 2018 entered 1,000 shares instead of 1,000 won per share. Shares worth approximately KRW112 trillion at market value consequently appeared in the market. About 5 million shares were sold, with approximately KRW200 billion in transactions completed, and the share price plunged. The incident led to disciplinary action against employees and compensation lawsuits, prompting strong public backlash.
External analysis has also discussed South Korea's promotion to the MSCI World Index, with the possibility that market-structure reforms such as corporate-governance reform and mandatory cancellation of treasury shares could advance. Concerns have been raised that the foundations of the KOSPI could be undermined depending on the actions of Chinese memory-chip companies, and changes in the investment environment are drawing attention.