SK Hynix overtook Samsung Electronics on Monday to become South Korea's most valuable listed company, after a surge in its shares pushed the chipmaker past a rival that had held the top spot since 2000. The move put a new name at the top of South Korea's market and underscored how fast AI memory has reshaped the value of the country's biggest chip businesses.
The search interest around DRAM stock is being driven by a simple market fact: SK Hynix has become the dominant supplier of high-bandwidth memory chips used in AI systems, and its shares have rallied more than 340% this year. On Monday, the stock closed up 5.6%, lifting the company's market capitalisation to 2,080.4 trillion won, or about $1.35 trillion. That was enough to edge above Samsung Electronics on an ordinary-share basis, even as Samsung's stock eased 0.14%.
Kim Sunwoo said the change came down to economics, not just momentum, arguing that the emergence of customised AI memory fundamentally changed the industry's economics and allowed SK Hynix to establish itself as the market leader. That shift matters because SK Hynix supplies high-bandwidth memory chips to Nvidia and Alphabet's Google, placing it at the centre of the boom in AI processors and the memory stacks they require.
HBM is a specialised memory chip stacked vertically to deliver faster performance and lower power consumption, and it is tightly integrated with AI processors. SK Hynix's rise has also been reinforced by the broader semiconductor rally, but the company's leadership in this segment is what gave the stock its edge. Analysts say it kept investing in HBM during a memory-industry downturn, a bet that now looks like the difference between a cyclical rebound and a lasting revaluation.
The friction is in the accounting. Samsung said its market capitalisation should include preferred shares, which would put its value at 2,246.4 trillion won at the market close, above SK Hynix's 2,080.4 trillion won. Excluding preferred shares, Samsung's value was 2,066.7 trillion won. That leaves the headline ranking intact for now, but the comparison itself is contested, and that means the lead may not be as clean as the trading screen suggests.
The deeper story is how far SK Hynix has come. In 2002, then-Hynix Semiconductor was on the verge of being sold to Micron after years of debt from an aggressive expansion drive. The deal fell through, the company stayed under creditor control for nearly a decade, and its shares later plunged as low as 135 won in 2003. It reported an annual operating loss of 7.73 trillion won in 2023, then swung to a 23.5 trillion won operating profit in 2024. For Samsung, which also makes logic chips and consumer electronics such as smartphones and TVs, the question now is not whether memory matters. It is whether the market has decided which memory maker matters most.
