KOSPI Jumps Nearly 2% Toward 7,000 as Micron Blowout Revives Samsung and SK Hynix, Snapping Losing Streak

SEOUL, South Korea — South Korean stocks rallied nearly 2% on Thursday, snapping a three-day losing streak and pushing the benchmark KOSPI back toward the 7,000 mark as blockbuster results from U.S. memory chipmaker Micron Technology revived appetite for semiconductor shares.

The Korea Composite Stock Price Index rose 133.32 points, or 1.95%, to 6,971.36 as of 3:32 p.m. local time, near the end of the trading session. The index had closed Wednesday at 6,838.04.

The rally marked a sharp turnaround from the morning, when the KOSPI opened lower and briefly slipped as chip heavyweights Samsung Electronics and SK Hynix declined.

Weak start gives way to rebound

The index opened down 0.34% and fell 26.3 points, or 0.38%, to 6,811.74 in the first 15 minutes of trading, extending losses from a three-day slide. Samsung Electronics dipped 0.28% early in the session, while SK Hynix slipped 0.11%.

By mid-morning, the KOSPI was still hovering just below the previous close, trading in a range between 6,765.06 and 6,854.21.

But buying picked up as the session went on. Samsung Electronics and SK Hynix recovered after opening lower, as Micron's record results reinforced the view that the global memory chip shortage is tightening rather than easing.

Micron results lift chip sentiment

Micron, the largest U.S. memory chipmaker and a direct rival to Samsung and SK Hynix, reported fiscal fourth-quarter revenue of $54.23 billion after the U.S. market closed Wednesday, nearly four times the level of a year earlier and well above analysts' expectations. The company also forecast revenue of about $61.5 billion for the current quarter, again topping estimates.

"We expect FY27 to be even better," Micron said, adding that it expects memory and storage supply to be much tighter in 2027 and 2028 than in 2026.

The results matter for South Korea's market because Samsung, SK Hynix and Micron dominate the global memory chip industry and all three are benefiting from surging demand for high-bandwidth memory used in artificial intelligence systems. Micron said more than 75% of its fiscal 2027 shipment volume is already committed to customers.

Smaller chip-related stocks were among the strongest performers. Shares tied to high-bandwidth memory gained about 4% as a group in morning trading. SemiFive surged 12.8%, SFA Semicon climbed 8.2%, HPSP gained 6% and Wonik IPS rose 5.4%. Hanmi Semiconductor added 1.9%.

US investment package in focus

Investors also turned to energy and U.S.-linked stocks after Seoul and Washington outlined the first set of projects under South Korea's broader investment pledge to the United States.

The $200 billion commitment includes a framework for up to eight nuclear reactors, including six Westinghouse AP1000 units and two Korean-designed APR1400 reactors, along with a large gas power complex in Texas designed to supply AI data centers. Seoul said each project must pass commercial viability tests, and a proposed Alaska liquefied natural gas project remains under review.

Pharmaceutical shares also gained. Sam Chun Dang Pharm surged 9.7%, Celltrion rose 2.6% and Samsung Biologics added 2% in morning trading.

Bond yields and currency

Gains in Seoul came despite pressure from global bond markets. U.S. long-term Treasury yields climbed toward multi-decade highs overnight, with the 10-year yield rising to 5.29% and the 30-year yield to 5.63%, weighing on markets elsewhere in Asia.

Australia's benchmark S&P/ASX 200 fell nearly 2% to a four-month low on Thursday as rising yields and elevated oil prices hit investor sentiment.

On Wall Street, the S&P 500 slipped 0.25% and the Dow Jones Industrial Average fell 0.86% on Wednesday after a late sell-off, while the Nasdaq rose 0.24%.

The South Korean won weakened slightly against the dollar, trading at 1,358.7 won early in the session, down 3 won from the previous close.

Volatile year for Korean stocks

Thursday's gains add to a turbulent year for the KOSPI, which has been among the world's best-performing major stock markets on the back of the AI chip boom.

The index first crossed 7,000 in May and went on to set a record close of 9,114.55 on June 22, after hitting an intraday peak of 9,385.59 on June 19. It then plunged during a global semiconductor sell-off, including a 10.84% drop on July 28 that left it at 6,023.66, its steepest daily decline in more than four months.

The market has since recovered part of those losses but remains about 24% below its record close. The KOSPI reclaimed the 7,000 level on a closing basis on Sept. 21, ahead of the Chuseok holiday, before slipping again in recent sessions as rising global bond yields and concerns about chip valuations weighed on sentiment.

Samsung Electronics and SK Hynix together account for roughly 40% or more of the KOSPI's total market value, meaning swings in chip stocks have an outsized impact on the broader index.

Buyback support fading

Analysts have flagged one potential headwind for the market. Samsung Electronics and SK Hynix have completed about 80% of their combined 55 trillion won share buyback plans, raising the prospect that the purchases could end earlier than expected and reduce a key source of demand for KOSPI shares.

Investors will be watching Friday's U.S. jobs report for clues on the path of Federal Reserve interest rates and global bond yields. Upcoming Korean export data, closely watched as a gauge of chip demand, and the start of third-quarter earnings season will also be key for whether the KOSPI can firmly reclaim the 7,000 level.