[Young Journalist JunKi Shin] The KOSPI index finished with its largest gain in history, fueled by massive buying from foreign investors. SK Hynix finished the trading session at its Daily Cap. Analysts attribute the increase largely to SK Group Chairman Chey Tae-won directly purchasing 4.8 billion won worth of SK Hynix shares (3,620 shares) on the open market on July 30.

Data from the Korea Exchange shows that on July 31, the KOSPI finished at 6,595.45, surging 1,001.89 points (17.91%) from the previous trading day, setting a new record for both the largest single-day point gain and percentage increase.

The second-highest daily percentage gain was 11.95%, recorded on October 30, 2008, during the global financial crisis.

On the same day, Samsung Electronics jumped 26.81% to finish at 262,500 won, while SK Hynix hit its daily limit, soaring 29.95% to 1,718,000 won. Both companies recorded their highest single-day percentage gains in history.

SK Hynix’s surge to its daily limit is interpreted as being heavily influenced by Chairman Chey's open-market stock acquisition. On the previous day, Chairman Chey bought common shares of SK Hynix at 1,322,000 won per share.

This marks the first time Chairman Chey has held SK Hynix shares under his personal name.

SK Hynix stated that Chairman Chey's purchase reflects his confidence in the semiconductor firm's value and his view that the stock was significantly undervalued, positioning the move as part of responsible management.

Investors viewed Chairman Chey’s open-market purchase as a clear signal of confidence in the company's mid-to-long-term growth and corporate value, which positively impacted overall market sentiment.

Previously, at the Korea Chamber of Commerce and Industry (KCCI) Jeju Summer Forum on July 17, Chairman Chey commented on investing in SK Hynix: "Because memory chips will always be in demand, the trajectory will trend upward over time. Rather than buying and selling frequently, holding onto shares steadily is a better way to preserve wealth."

Foreign investors led the index's record rally through aggressive buying, posting a net purchase of 7.2196 trillion won. Institutional investors also bought a net 1.1782 trillion won. In contrast, retail investors sold a net 8.2543 trillion won.

Both foreign net purchases and retail net sales reached a record high in the history of the South Korean stock market.

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