South Korea's Kospi Index Records Largest Single-Day Gain

The benchmark Kospi index in South Korea recorded its largest single-day percentage gain in history on July 31, 2026, closing up between 17% and 18%. The rally followed a severe monthly slump where the index plummeted nearly 40% from its June peak, driven by investor anxiety over the returns and infrastructure costs of artificial intelligence spending.

Microsoft triggered the recovery with stronger-than-expected quarterly earnings, which bolstered global tech sentiment and confidence that aggressive AI investments are yielding profits. This shift led to massive surges in semiconductor giants Samsung Electronics and SK hynix, both of which rose over 23%. SK hynix specifically saw a 30% jump after SK Group chair Chey Tae-won made a $3 million personal share purchase.

The recovery extended to other firms, including Hyundai Motor, Naver, and Hanwha Aerospace, while Taiwan Semiconductor Manufacturing Co. gained 10%. In response to the trend, the South Korean government announced plans to invest nearly $14 billion into its sovereign wealth fund for AI investments and data centers. The rebound contrasted with Apple, whose shares slipped due to supply chain warnings, and Indian IT firms like TCS and Infosys, which face pressure as generative AI reduces demand for traditional outsourcing.