The HBM Oligopoly — Three Companies Make the World's AI Memory · The Memory Wall — HBM, DRAM, NAND & the AI Memory Cartel
000660.KS
SK HynixForeign listing — not directly tradable in a US brokerage. Editorial detail only.
~57% of global HBM revenue, ~70% of NVIDIA Rubin HBM4 allocation — the single most important memory company in the AI buildout.
What they do
The Korean DRAM and NAND maker that invented HBM in 2013 and has dominated the category ever since. They won the AI lottery by being first to mass-produce 8-high and 12-high HBM stacks at high yield, using a proprietary packaging process called MR-MUF (Mass-Reflow Molded Underfill) that runs cooler than Samsung's competing approach. Market cap crossed $1 trillion USD in May 2026. NYSE ADR listing confidentially filed with the SEC March 2026, targeting 2H 2026 debut.