South Korea's KOSPI rose 133.31 points, or 1.95%, to 6,971.35 on October 1, closing within reach of the 7,000 mark as Samsung Electronics and SK Hynix led a semiconductor-led rally. The KOSDAQ index climbed 4.48%, gaining 38.38 points to close at 894.29.

Samsung Electronics advanced 2.79% to 276,000 Korean won, while SK Hynix — the country's two largest listed companies — rose 3.21% to 1.833 million Korean won. The surge followed two catalysts landing within 24 hours of each other: Micron's fiscal fourth-quarter earnings beat and a record month for Korean semiconductor exports.

Micron's fivefold revenue jump

Micron reported revenue of $54.23 billion for its fiscal 2026 fourth quarter, covering June through August — roughly five times the figure from the same period a year earlier. The result exceeded the $51.07 billion consensus compiled by the London Stock Exchange Group (LSEG) by more than $3 billion.

The numbers alone moved markets, but the guidance moved them further. Speaking at the earnings announcement on September 30 local time, Micron CEO Sanjay Mehrotra said: "Supply and demand will become even tighter in 2027 and 2028 than this year," and added, "It is difficult to predict when supply and demand will regain balance."

That statement matters directly for Korea's two memory giants. If the global memory shortage — driven substantially by AI-related demand — persists and tightens into 2028, Samsung Electronics and SK Hynix stand to benefit from both sustained pricing power and shipment growth. Investors read Mehrotra's comments exactly that way, treating the day's move as a rebound for the sector after a period of digestion.

Record $60.3 billion export month

The second catalyst came from Seoul. The Ministry of Trade, Industry and Resources released its September Export and Import Trends report on October 1, showing semiconductor exports of $60.3 billion for the month — up 26.28% year-on-year and the first time in history the monthly figure has surpassed $60 billion.

The scale is striking. A single month of Korean chip exports at $60.3 billion now exceeds the annual export totals of many countries, and a 26% growth rate on top of an already elevated base signals that demand, not just pricing, is expanding.

Lee Kyung-min, a researcher at Daishin Securities, connected the export data to the market mechanics behind the rally. "Institutions turned to net buying today, pushing the KOSPI index above the 6,900 mark," he said. "As major events were digested, sectors with improving investment sentiment and earnings improvement expectations showed a rotational rally."

KOSDAQ's broader surge

The KOSDAQ's 4.48% gain outpaced the main board, led by the index's largest companies. Alteogen, the top KOSDAQ company by market capitalization, rose 4.13%. Battery materials suppliers EcoPro and EcoPro BM gained 5.58% and 5.13% respectively, and semiconductor equipment maker Jusung Engineering added 3.66%, extending consecutive increases.

Jusung Engineering's inclusion among the leaders is notable for the chip supply chain: equipment makers tend to track capital expenditure expectations, and a tightening memory market through 2027-2028 typically pulls fab investment forward.

What to watch

The rally rests on two verifiable data points — Micron's confirmed $54.23 billion quarter and Korea's confirmed $60.3 billion export month — plus one forward-looking claim from Micron's CEO that supply will remain tighter in 2027 and 2028 than it is now. If Mehrotra's tightness forecast holds, Samsung Electronics and SK Hynix enter the coming quarters with pricing leverage in a market where, by his own words, no one can yet say when balance returns.