The closing bell in Seoul had barely rung when the numbers did something that had not happened in twenty-six years. SK Hynix finished Monday’s session up 5.6 percent, pushing its market capitalization to 2,080.4 trillion won, about $1.35 trillion. Samsung Electronics, the company that had sat atop Korean equity markets since the late 1990s, closed down 0.1 percent at 2,066.7 trillion won. For the first time in a generation, the country’s most valuable listed company is a memory specialist that sells most of its output to American data-center operators.
Samsung disputed the ranking within minutes. Its market value, the company said in a statement, should include preferred shares, which would lift its figure to 2,246.4 trillion won. The arithmetic point did little to mask what investors already understood: in the high-bandwidth memory market that now sets the pace of Korean equities, Samsung trails badly. SK Hynix controls roughly 61 percent of global HBM supply, according to Reuters, with Micron at 21 percent and Samsung at 17 percent.
The reversal has been years in the making. SK Hynix bet early that AI training clusters would need memory stacked vertically and wired directly against the processor, a design that delivers bandwidth far beyond ordinary DRAM. That bet paid off when Nvidia and Alphabet’s Google began buying HBM in volume. SK Hynix shares have risen more than 340 percent this year alone, and the company now trades at a premium to Samsung despite earning a fraction of its revenue.
The gap between the two companies is also a gap between business models. Samsung spent the past decade defending its lead in smartphones, consumer appliances and conventional chips, while its foundry business lost ground to TSMC and its memory division managed the slow, profitable decline of commodity DRAM. SK Hynix, freed from the distraction of handsets and televisions, poured capital into HBM capacity and locked in multi-year supply deals with the largest buyers of AI compute. “The emergence of customized AI memory fundamentally changed the industry’s economics and allowed SK Hynix to establish itself as the market leader,” Kim Sunwoo, a senior analyst at Meritz Securities, said.
The leadership change is notable for how quickly it arrived. Samsung’s market value first crossed the trillion-dollar mark in 2021, when the global chip shortage made memory and foundry customers line up for allocation. Four years later, the memory cycle turned against it just as HBM demand exploded. Samsung’s HBM products took longer than rivals’ to pass Nvidia’s certification, and the delay cost it share in the one product category where growth remains dramatic. Nvidia Chief Executive Jensen Huang confirmed earlier this month that Samsung, SK Hynix and Micron had all passed qualification for HBM4, the next generation of the chip, but analysts said SK Hynix retains the capacity and the customer relationships to hold its lead.
SK Hynix’s rise carries risks of its own. The company runs major production sites in Wuxi and Dalian, China, which together account for a large share of its DRAM output, leaving it exposed to any escalation of U.S. export controls on Chinese semiconductor operations. Its fortunes are tied to a handful of hyperscale customers, and a slowdown in AI capital spending would hit its revenue harder than it would hit Samsung’s diversified portfolio. Valuation is a further question: SK Hynix now trades at a substantial premium to its historical average, and analysts have begun to ask whether HBM demand can keep growing fast enough to justify the multiple.
For Korean investors, the shift changes a familiar calculus. For decades, Samsung was the default large-cap holding, a stock that paid dividends, survived downturns and tracked the global economy. SK Hynix offers none of that comfort. Its earnings swing violently with the memory cycle, and its customers are concentrated in an industry whose spending plans can change in a quarter. Fund managers who built portfolios around Samsung are now forced to decide whether the new king deserves the same loyalty.
The broader signal is clearer. The top of the Korean market now belongs to a company whose growth depends on the buildout of AI infrastructure, not on consumer electronics. In 2021, when Samsung was Korea’s only trillion-dollar company, the market’s center of gravity sat in phones and televisions. Today it sits in HBM stacks bound for Nvidia and Google data centers. The trading desks of Seoul, long accustomed to reading Samsung’s earnings as a proxy for the global tech cycle, will now read SK Hynix’s instead.
Samsung is not standing still. The company is pushing its own HBM4 qualification and has signaled plans to expand foundry capacity for AI customers, and it retains the financial scale to outspend SK Hynix in a downturn. But the memory division, long the profit engine of the group, is now the part of Samsung most exposed to SK Hynix’s success. The two companies will compete for the same customers, the same engineers and the same government attention for years to come.
Whether SK Hynix holds the top spot depends on the durability of the AI spending boom. Bulls argue that HBM demand will remain tight through at least 2028 as every major cloud operator expands training capacity. Bears note that memory is a cyclical business and that SK Hynix is selling into the strongest up-cycle in its history. Monday’s closing bell settled the ranking for one day. The contest behind it, between a company that bet on AI memory and a conglomerate that hedged across everything else, is just beginning.
