Shares of SK Hynix jumped as much as 11% on Wednesday, lifting the South Korean chipmaker's market capitalisation above US$1 trillion as investors continued to pile into artificial intelligence-linked semiconductor stocks.
At its intraday peak, the stock climbed 14.9% before pulling back, with the chipmaker's total market value hitting a record 1,680 trillion won - equivalent to roughly $1.12 trillion.
SK Hynix pared gains to close 9.21% higher, while compatriot Samsung Electronics ended up 2.68%.
The memory chipmaker's 250% year-to-date rally underscores how tightly the Kospi's fortunes have become bound to the global AI infrastructure build-out.
Samsung Electronics had first cleared the $1 trillion threshold on May 6, and Micron Technology followed just one day earlier, on Tuesday, meaning SK Hynix, Samsung, and Micron now form the three dominant suppliers of high-bandwidth memory, each sitting at the centre of the global AI infrastructure buildout.
Counterpoint Research data show that as of the fourth quarter of last year, SK Hynix commanded 57% of global HBM revenue, leaving Samsung and Micron with 22% and 21% respectively.
Full-year 2026 HBM capacity is already sold out, with supply shortages expected to extend through 2027.
KOSPI concentration
The two Korean memory giants account for more than 40% of South Korea's benchmark Kospi, underscoring how closely the index's performance has become tied to global demand for AI-related semiconductors and memory chips.
Buoyed by the chipmaker surge, the Kospi touched an intraday high representing a 5.1% advance before settling at a 2.3% gain by the close, and the index has now risen 95% so far this year.
Analysts have warned that the concentration could heighten market volatility and leave the benchmark more exposed to risks, including supply chain disruptions and a slowdown in global data centre investment.
Valuations still have wiggle room
SK Hynix's rally may still have room to run, according to Peter Kim, global investment strategist at KB Financial Group, who highlighted that earnings upgrades are outpacing even the stock's gains.
"Fundamentals and valuations of the two twin towers … are still very much intact," KB Financial Group global investment strategist Peter Kim said, referring to SK Hynix and Samsung Electronics.
Kim said SK Hynix's valuation has become "cheaper" as analysts have raised earnings forecasts faster than share prices have increased.
Nomura analysts predict SK Hynix's book value may hit 296 trillion won by 2027, with operating profits rising to 99 trillion won in 2026 and 128 trillion won in 2027, driven by strong demand.
The company has filed confidentially with the U.S. Securities and Exchange Commission for an American Depositary Receipt listing, targeting completion within 2026, with local Korean media reporting the company aims to raise between 10 trillion won and 15 trillion won - roughly $6.7 billion to $10 billion at current exchange rates.
Proceeds are earmarked for AI-focused expansion, including its HBM cluster in Yongin, South Korea, and its Indiana packaging facility.
The planned U.S. ADR listing is anticipated to attract further global capital, with the market now viewing SK Hynix as a structural AI infrastructure beneficiary with pricing power expected to persist until 2027.
What to watch:
- HBM4 ramp timeline and whether SK Hynix can maintain its supply lead over Samsung and Micron into late 2026
- Progress on the U.S. ADR listing and final offer sizing
- Any signs of data centre capex moderation from hyperscalers, given Kospi concentration risk
- Samsung labour negotiations and any knock-on order-flow effects for SK Hynix
- Nomura's operating-profit forecasts versus actuals through H2 2026
