South Korean chip shares rally after Micron’s upbeat earnings

South Korean chip stocks rallied on Thursday after Micron Technology reported a record quarter and an upbeat outlook, reviving optimism that demand for AI memory will stay tight well into next year.

The benchmark KOSPI rose about 4.1%, with the country’s two memory makers, which together account for more than 55% of the index, doing most of the lifting.

Samsung Electronics climbed 5.3% to 358,500 won. SK Hynix, the smaller but now more valuable of the pair, rose 9.2% to 2.818 million won, according to Reuters. Foreign buyers led the move, reversing two days of chip-sector weakness in a single session.

The catalyst came from across the Pacific. Micron, the largest US maker of computer memory and a key supplier to Nvidia, posted fiscal third-quarter revenue of $41.46bn for the March to May period, far ahead of the roughly $35.84bn analysts polled by LSEG had expected.

The company guided fourth-quarter revenue above Wall Street estimates and said demand for AI memory would keep supply tight through at least 2027. For two memory houses whose fortunes track the same cycle, that was read in Seoul as a forecast about their own order books.

The 💜 of EU tech

The latest rumblings from the EU tech scene, a story from our wise ol' founder Boris, and some questionable AI art. It's free, every week, in your inbox. Sign up now!

SK Hynix had a second reason to rise. A day earlier the company filed to raise up to 45.45 trillion won, about $29bn, through a Nasdaq listing of American depositary receipts, tentatively set for July 10.

At the top of its range, the deal would be the largest ADR offering on record, ahead of the $21.8bn Alibaba raised in 2014, and the company has earmarked the entire sum for chip capacity rather than shareholders or debt.

The listing comes days after SK Hynix passed Samsung in market value on a common-stock basis, the first change at the top of the Korea Exchange since November 2000.

Samsung had a catalyst of its own, though a softer one. Local media reported the company is weighing a share buyback of as much as 90 trillion won, roughly $58.6bn, to fund employee stock bonuses agreed in recent wage talks.

Samsung said no decision had been made on the timing or scale, and that it would provide an update within a month. The figure helped sentiment even without a board sign-off.

The optimism spread across Asia. In Tokyo, the Nikkei rose about 4%, led by the equipment and memory names that sit upstream of the same demand.

The chip-tester Advantest jumped 11.4%, Tokyo Electron added 7.8%, and Kioxia, the memory maker, gained 8.8%, as investors chased the read-through from Micron’s numbers into the wider supply chain. Analysts cited a familiar mix of fundamentals and fear of missing out.

Underneath all of it sat high-bandwidth memory, the stacked DRAM that feeds Nvidia’s accelerators and now carries the highest margins in the business.

SK Hynix supplies the bulk of it and has turned that lead into the strongest earnings of any Korean company.

Samsung, still qualifying its own HBM for Nvidia and expected to win a larger share of next-generation HBM4 orders, has spent the same stretch playing catch-up. Micron’s results, read in Seoul, suggested the demand pulling both along had not yet peaked.

The concentration that powered Thursday’s rally cuts both ways. With Samsung and SK Hynix making up more than half the KOSPI’s value, a single strong quarter from a US peer can lift the entire index, and a single soft one in memory demand can take it back down.

The market has spent the past year treating that risk as remote, on the bet that hyperscaler spending keeps the memory supercycle running.

For now, the buyers are betting it does. SK Hynix has booked its high-bandwidth memory capacity through 2026, with shortages forecast into 2027, and Micron has just told the market the same story from the other side of the trade.

The next test is procedural rather than narrative: SK Hynix’s ADR pricing on July 10, and whatever Samsung decides about its buyback in the weeks after. Thursday answered the mood question. It did not answer the cycle one.