KOSPI Index Jumps 17% as SK Hynix and Samsung Lead Record Rebound

Key Takeaways

• South Korea’s KOSPI index rose as much as 17.06% during early trading on July 31, marking its largest intraday percentage gain on record.
• SK Hynix and Samsung Electronics led the rebound as stronger US semiconductor stocks revived confidence in artificial intelligence infrastructure demand.
• The rally recovered much of a three-day decline, but continued volatility means it may be too early to conclude that the market has entered a sustained recovery.

KOSPI Index Records Historic Intraday Gain

source:googlefinance

South Korean stocks rebounded sharply on Friday, July 31, as investors returned to semiconductor and artificial intelligence-related shares following three consecutive sessions of heavy selling.

The KOSPI index traded at 6,528.56 at approximately 10:10 a.m. Korea Standard Time, rising 935 points, or 16.72%. It reached an intraday high of 6,547.56, representing a gain of 17.06%.

The move exceeded the KOSPI’s previous record percentage increase of 11.95%, set in October 2008 during the global financial crisis.

The rally followed a decline of more than 17% over the previous three trading sessions. Investors had reduced exposure to technology shares amid concerns about expensive AI infrastructure projects, elevated valuations and growing competition from Chinese semiconductor manufacturers.

A buy-side “sidecar” was activated shortly after the market opened. The measure temporarily restricted program-buy orders for five minutes to limit disruption from sudden movements in index futures. Similar action was taken in the KOSDAQ market. The Korea Exchange uses the mechanism when futures prices move beyond specified thresholds.

SK Hynix and Samsung Electronics Lead the Rally

South Korea’s two largest memory-chip manufacturers accounted for a significant share of the KOSPI index rebound.

SK Hynix gained as much as approximately 28% during early trading, while Samsung Electronics rose nearly 25%.

At 9:27 a.m. local time, SK Hynix was trading at 1.629 million won, up 23.22%, while Samsung Electronics stood at 247,500 won, a gain of 19.57%. The companies’ share prices continued to fluctuate substantially as the session progressed.

The magnitude of the rebound reflected both renewed semiconductor optimism and the scale of the earlier correction. Despite strong earnings, Korean chip stocks had recently come under pressure as investors questioned whether rapid growth in AI-related spending could continue and whether current memory-chip profitability was sustainable.

US Semiconductor Rally Restores AI Confidence

The recovery followed a broad advance in US technology and semiconductor stocks.

Microsoft shares rose 15.5% on Thursday after its fiscal fourth-quarter results exceeded market expectations. The company reported quarterly revenue of approximately $90 billion, up 18% year on year, while Azure and other cloud-services revenue increased 43%.

Microsoft also said it added 31 data centres during the quarter and remained on course to roughly double its total capacity over two years. Capital expenditure reached $41 billion, with around two-thirds allocated to shorter-lived assets such as processors and graphics chips. The results suggested that demand for cloud computing and AI services remained strong despite the industry’s high investment requirements. Microsoft’s official results provided investors with a more constructive example of how AI infrastructure spending could support revenue growth.

The Philadelphia Semiconductor Index subsequently gained 8.19%. SanDisk advanced 25.99%, Micron Technology rose 18.36% and AMD gained 13%, strengthening sentiment toward Asian memory and semiconductor companies.

SK Hynix Record Earnings Provide Fundamental Support

SK Hynix’s latest financial results also helped support the rebound.

The company reported second-quarter revenue of 79.3187 trillion won, an increase of 257% from a year earlier. Operating profit reached 60.5426 trillion won, up 557%, while the operating margin expanded to 76%.

SK Hynix attributed the performance to higher DRAM and NAND prices and stronger sales of high-value products, including high-bandwidth memory, server DRAM and enterprise solid-state drives. The company began mass shipments of HBM4 products during the second quarter and plans to increase production in the second half of 2026. SK Hynix’s earnings release also said customer demand continued to exceed available supply.

Investor sentiment may have received an additional boost after SK Group Chairman Chey Tae-won purchased 3,620 SK Hynix shares. The transaction was valued at approximately 4.9 billion won based on the share price at the time, although the precise execution price was not disclosed. The purchase was interpreted as a signal of management confidence following the stock’s recent decline.

Can the KOSPI Rebound Continue?

The July 31 rally recovered a substantial part of the KOSPI’s recent losses, but the size and speed of the move also point to technical factors such as short covering, position rebuilding and reduced deleveraging pressure.

A single-session rebound does not necessarily establish a lasting upward trend. Whether the KOSPI index can stabilise may depend on future capital-expenditure guidance from Microsoft and other global technology companies, the direction of DRAM and NAND prices, demand for HBM products and competitive developments in China.

Investors may also watch whether SK Hynix and Samsung Electronics can retain their gains after the immediate effects of the US semiconductor rally fade. Given the extreme movements recorded during the week, short-term volatility is likely to remain elevated.

All market prices and percentage changes in this article refer to intraday trading on July 31, 2026, and may change before the market closes.