SK Hynix jumps as AI demand tightens HBM supply

SK Hynix shares rose about 5% on Wednesday, taking the stock’s gain to roughly 17% for the week after OpenAI released GPT-6 Astra. Investors pointed to stronger demand for high-bandwidth memory, or HBM, and falling inventories at SK Hynix and Samsung that left supply below 10 days.

KB Securities estimated inventories at the two companies had dropped to under 10 days. KB’s head of research, Kim Dong-won, projected that 2027 could bring the “tightest supply conditions in history” as hyperscaler investment in AI infrastructure rises toward $1.3 trillion.

KB calculated that HBM4 requires roughly three times the wafer capacity of conventional DRAM. Manufacturers shifting more production to higher-margin HBM reduces the wafer capacity available for standard DRAM.

Analysts noted the GPT-6 Astra release reinforced expectations that larger, longer-running AI models and agentic systems will increase compute workloads. Those workloads require GPUs, custom accelerators, server DRAM and advanced HBM used in AI servers.

Han Ji-young, an analyst at Kiwoom Securities, commented: “Earnings momentum across the AI industry has remained intact since OpenAI released GPT-6.” Han added that KOSPI resistance around 7,000 looked like consolidation rather than a breakdown.

Investment banks adjusted price targets on SK Hynix this week. Mirae Asset raised its target to 3.1 million won from 2.8 million won, and DB Securities increased its target to 2.3 million won from 2.0 million won.

Mirae Asset analyst Kim Young-gun noted that broader HBM adoption among developers of application-specific integrated circuits would expand SK Hynix’s potential customer base beyond traditional GPU makers.

DB Securities analyst Seo Seung-yeon expects HBM4 shipments to accelerate from the third quarter and noted resilient server demand will help offset pressure from a stronger Korean won.

HBM is a stacked memory design that delivers higher bandwidth and lower power per bit than standard DRAM, making it suited for AI accelerators and high-performance computing. HBM4 requires greater manufacturing resources and increases pressure on wafer supply.

Investors cited the combination of rising HBM demand and constrained wafer capacity as a factor behind SK Hynix’s recent share gains.