South Korea's KOSPI benchmark surged 5.61% to 8,945.95 on Thursday, closing within striking distance of the psychologically key 9,000 level for the first time, as memory chip shares rallied sharply following stronger-than-expected quarterly results from U.S. chipmaker Micron Technology.
The move reinforced the standing of SK Hynix (000660.KS), which just three sessions earlier—on June 22—had unseated Samsung Electronics from its 25-year-and-seven-month reign as KOSPI's most valuable listed company. As of that session, SK Hynix's common-share market capitalization reached approximately KRW 2,084.65 trillion (USD 1.4 trillion), edging past Samsung Electronics' common-stock market cap of KRW 2,084.2 trillion—a gap of roughly KRW 5.7 trillion (USD 3.7 billion) by early afternoon. Samsung had held the top position continuously since November 2000.
On Thursday, SK Hynix extended those gains by as much as 11.6% in early trade, while Samsung Electronics added 6.2%, as both chipmakers benefited from Micron's upbeat results and guidance that reinforced investor confidence in sustained AI-driven demand for high-bandwidth memory (HBM).
A Reshaped Index
The transfer of KOSPI's crown reflects a fundamental reshaping of Korea's equity landscape. SK Hynix now commands roughly 61% of the global HBM market—memory purpose-built for AI accelerators such as Nvidia's H100 and H200 GPUs—and has secured the majority of Nvidia's next-generation HBM4 orders. It also supplies HBM3E chips to Microsoft for its in-house Maia processor line.
Year-to-date, SK Hynix shares have gained 347.7%, against Samsung Electronics' still-formidable 192.77% advance. Because the two chipmakers together account for more than 55% of KOSPI's total market capitalisation, strength in both names is quickly transmitted to the broader index, helping push the gauge toward its latest milestone.
Samsung Electronics' more diversified business—spanning semiconductors, displays, smartphones, and home appliances—has historically justified its premium valuation, but analysts say that very breadth has become a relative drag. "Samsung's diverse portfolio versus SK Hynix's concentrated focus on semiconductors is the key factor behind the stock price divergence," one analyst told KED Global.
Micron as the Catalyst
Thursday's rally was triggered by Micron's fiscal-third-quarter earnings report, which beat consensus estimates on both revenue and guidance, with management citing strong and sustained AI infrastructure demand as the primary driver. Bank of America subsequently raised its Micron price target to USD 1,500, reinforcing the view that the AI memory cycle has further room to run.
The Micron print carries particular weight for Korean chipmakers: because Micron competes directly with SK Hynix and Samsung in DRAM and NAND markets, its upside guidance acts as a real-time proxy for Korean chip demand and pricing power heading into the second half of 2026.
What 9,000 Would Mean
If KOSPI closes above 9,000—a level it has never reached—it would mark its second hundred-point centenary milestone in 2026 alone. The benchmark has roughly doubled so far this year, driven overwhelmingly by the AI-semiconductor tailwind that has also fuelled SK Hynix's historic market-cap overtake.
Retail participation has surged alongside the rally: the number of Korean stock-trading accounts hit a record 108.7 million as of Wednesday, up more than 10 million from year-end levels, underscoring the degree to which the bull market has drawn in new investors.
Sources
- KED Global — S.Korea's stock market crowns new king: How SK Hynix rewrote Kospi history
- Korea Herald — Seoul shares surge on tech gains led by Micron earnings
- Benzinga — Micron: BofA Lifts Price Target to USD 1,500
- MarketScreener — South Korean chip shares surge after Micron flags strong AI-related demand
