On Monday, SK Hynix's market capitalisation reached 2,080.4 trillion won ($1.35 trillion), edging past Samsung Electronics' 2,066.7 trillion won based on common shares. The shift ended Samsung's uninterrupted position at the top of South Korea's equity market since 2000. SK Hynix shares have surged more than 340% this year, while Samsung's have lagged. Samsung noted that including preferred shares would lift its valuation to around 2,252 trillion won, keeping it ahead on a fully diluted basis.

The reordering reflects the structural transformation of the global memory-chip industry. High-bandwidth memory (HBM), once a niche product, has become a critical component for AI accelerators made by Nvidia and Google. SK Hynix invested heavily in HBM during the industry's last downturn, securing a 61% share of the global HBM market by 2025, according to analysts, far ahead of Samsung's 17% and Micron's 21%. Unlike conventional DRAM, HBM chips are tightly integrated with AI processors, giving suppliers greater pricing power and eroding the commodity dynamics that long defined the sector.

The ascent caps a dramatic corporate turnaround. Two decades ago, the company—then Hynix Semiconductor—was on the brink of being sold to Micron under a mountain of debt, its shares collapsing to 135 won in 2003. It spent nearly a decade under creditor control. As recently as 2023, a memory-price slump pushed it to an annual operating loss of 7.73 trillion won. The AI investment wave that followed, led by Microsoft, Google and Meta, propelled a record operating profit of 23.5 trillion won in 2024. SK Group Chairman Chey Tae-won has described the strategy as a deliberate shift from interchangeable commodity memory to indispensable, system-critical components.

Seoul-based analysts say the milestone is more than symbolic; it signals that the economics of memory have been fundamentally altered by customised AI chips. Global brokerages, including Bernstein, see further upside for both stocks as HBM prices are expected to keep rising. SK Hynix is investing $12.9 billion in a new AI chip packaging and testing plant in Cheongju, due for completion by the end of 2027, while its parent SK Group has earmarked $75 billion for chip development and production by 2028, mostly directed at HBM. The next structural milestone will be the ramp-up of that new capacity, which will determine whether SK Hynix can sustain its lead as Samsung accelerates its own HBM push.