Kospi Surges Over 16% on AI Chip Rally

On July 31, 2026, South Korea’s benchmark Kospi index jumped more than 16% in a single session, the largest one-day gain on record. The surge was led by semiconductor giants SK Hynix and Samsung Electronics, whose shares rallied between roughly 20% and 30% after U.S. cloud-computing leaders Amazon and Microsoft reported stronger-than-expected earnings that revived optimism about artificial-intelligence (AI) spending.

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During the first half of 2026 the Kospi had more than doubled, driven by AI-related investment in memory chips. A three-day sell-off earlier in the week erased hundreds of billions of dollars in market value as investors feared an AI-valuation bubble and rising competition from Chinese chipmakers. The rally on July 31 followed Microsoft’s quarterly results, which showed faster-than-expected Azure growth and strong uptake of its AI-powered Copilot assistant, and Amazon’s after-hours earnings beat that lifted confidence in AI-infrastructure demand.

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• Kospi performance: Closed at 6,381.66, up 14.09% from the prior session (Korea Exchange).

Kospi jumps on U.S. chip rally as AI optimism returns

• Share gains: SK Hynix rose about 25%-30%; Samsung Electronics climbed roughly 21%-28%.

Korean stock market falls into bear market as chip stocks tumble

• Foreign net buying: Investors bought a net 4.86 trillion won (? $3.38 billion) in the main Kospi market during the morning session.

Kospi jumps on U.S. chip rally as AI optimism returns

• Sector breadth: Other chip-related stocks also rose sharply, including LG Innotek (+21.23%) and Seoul Semiconductor (+15%).

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• Volatility gauge: The Kospi 200 volatility index fell 2% to 84.46.

Kospi jumps on U.S. chip rally as AI optimism returns

• South Korean regulators: Authorities announced tighter rules on single-stock leveraged ETFs, raising the minimum deposit requirement from 10 million won to 30 million won to curb excessive leverage.

Kospi jumps on U.S. chip rally as AI optimism returns

• Corporate outlooks: Samsung’s earnings call highlighted an expected deepening of the global memory shortage into next year, while SK Hynix emphasized record quarterly earnings despite a revenue miss relative to forecasts.

Korean stock market falls into bear market as chip stocks tumble

• Magnitude of stock jumps: Reported gains for SK Hynix range from 24.6% to “almost 30%,” and for Samsung from 20.5% to 28%, reflecting differing calculations (closing versus intraday peaks).

Korean stock market falls into bear market as chip stocks tumble

• Index level at close: The Kospi was cited at 6,381.66 and earlier at 6,376.68 during midday trading, indicating a slight upward movement after the midday snapshot.

South Korea’s Kospi index jumps more than 16% on a surge of chipmaking stocks

• Foreign-buyer breakdown: Detailed net-buyer figures for institutional categories are provided by the Korea JoongAng Daily, but other reports do not specify the composition of foreign inflows.

Korean stock market falls into bear market as chip stocks tumble

• “The market went from throwing AI stocks overboard to fighting for the remaining seats before most traders had finished writing the obituary,” — Stephen Innes, SPI Asset Management

South Korea’s Kospi index jumps more than 16% on a surge of chipmaking stocks

The Kospi’s rebound underscores the market’s sensitivity to global AI-related earnings and highlights the concentration risk posed by the dominance of two semiconductor firms. Analysts warn that volatility could persist while investors reassess the profitability of AI infrastructure spending and the competitive threat from Chinese chipmakers. The rally also shows how foreign capital can quickly reverse a sharp sell-off, though reliance on leveraged ETFs may amplify future corrections.

Korean stock market falls into bear market as chip stocks tumble