Two and a Half Months of Gains Erased: HBM Supply Bottleneck Bears Price Responsibility
Both Micron (MU) and SK Hynix (000660.KS) recorded one-month declines around -22%. That both fell by the same magnitude in the same period is no coincidence. Both sit at the front lines of the HBM (high-bandwidth memory) supply bottleneck, and market confidence about when that bottleneck clears is wavering.
HBM Supply-Demand Imbalance and the Two Players’ Position
HBM is memory adjacent to AI accelerators (GPUs, TPUs), determining the performance of high-end chips like Nvidia’s H100 and H200. As AI model training and inference accelerate, HBM demand grows exponentially. Micron recorded 379.3% year-over-year revenue growth, while SK Hynix achieved 47.2 trillion won in operating profit on 97.1 trillion won in 2025 revenue, yielding a 70.3% net margin. Both companies enjoy historic prosperity. Yet stock prices are falling because markets detect omens that the boom is ending.
Why the Decline Now: Four Pressure Factors
1. Insatiable AI accelerator demand growth: As generative AI proliferates, data center construction races intensify. The required HBM quantity per accelerator is rising, and bandwidth competition is driving standardization on next-generation chips (120+ layer stacks). Even with growing supply, if demand growth outpaces supply gains, the bottleneck persists.
2. Incomplete expansion plans: Both players have announced HBM production line expansions, but real completion timing carries large uncertainty. New process introduction, yield stabilization, and equipment delivery delays can push schedules. Markets hold a vague hope for “relief around 2027,” but the probability of delay is substantial.
3. Rival entry threat: Samsung Electronics and JEDEC standard participants are also accelerating HBM development. If Micron and SK Hynix’s duopoly breaks, price-cut pressure becomes vertical freefall. Current prosperity rests on shortage economics; the moment supply surplus is dated, futures markets begin price collapse.
4. Narrative shift timing: Markets have already moved from “HBM is the bottleneck” to “when does it clear?” The instant the first chips roll off expansion lines, even if supply merely shifts from “shortage to adequate,” price risk materializes. Stock prices react not to boom continuation but to the moment boom termination becomes visible.
Why the Two Players Nevertheless Persist: Structural Strength
Proprietary technology and process mastery: Micron closing price 833.59 dollars (as of 2026-11-02), a 63.8% net margin, evidences cost competitiveness. SK Hynix sustained ultra-premium profitability with 42.9 trillion won net income in 2025. Rivals need minimum 2–3 years of development to enter; in that window, these two leap ahead with next-generation tech (HBM3e, HBM4).
Capital-intensive industry moat: HBM processes require extreme ultraviolet (EUV) lithography, precision etching, and intricate contact design. Hynix and Micron possess 10+ years of accumulated expertise across every dimension. New entrants must endure the long valley between technology acquisition and yield stabilization.
Summary
When the HBM supply bottleneck clears is markets’ paramount concern. The two companies’ ultra-high margins are temporary; once supply transition to surplus becomes visible, price declines are unavoidable. Yet firms that survive until that inflection point stand a strong chance of reasserting supply advantage through next-generation technology. Stock price short-term volatility emerges from this uncertainty.
This article is for informational purposes and does not constitute investment advice.