Here’s why SK Hynix stock is skyrocketing today

SK Hynix stock surged again on Wednesday, extending one of the sharpest rallies among Asian semiconductor stocks as investors doubled down on the idea that the next phase of the AI boom will require far more memory.

The stock was up nearly 5% to 1.87 million won during morning trading, taking its gain to roughly 17% in a week.

The main catalyst came from OpenAI’s GPT-6 Astra launch, but investors are also responding to exceptionally tight memory inventories and stronger demand for HBM from custom AI chips.

Astra has revived the AI memory trade

Astra has strengthened the argument that more capable AI models will not necessarily reduce computing demand through efficiency.

Agentic systems that run for longer and handle more complicated tasks can increase total workloads, lifting demand for accelerators, server DRAM and high-bandwidth memory.

That matters disproportionately for SK Hynix, already one of the industry’s leading HBM suppliers.

Kiwoom Securities analyst Han Ji-young told Seoul Economic Daily on Wednesday that earnings momentum across the AI industry has remained intact since OpenAI released GPT-6.

Han said the KOSPI’s resistance around 7,000 looked more like consolidation than a breakdown in the trend.

The resilience is notable because Korean shares are also dealing with higher oil prices, Middle East tensions and weaker US equities.

The bigger catalyst may be vanishing supply

The more powerful part of the SK Hynix story may be physical scarcity.

KB Securities estimates that memory inventories at Samsung Electronics and SK Hynix have fallen below 10 days of supply.

Kim Dong-won, head of research at KB Securities, told Korea JoongAng Daily that 2027 could bring the “tightest supply conditions in history” as hyperscaler AI infrastructure investment rises towards $1.3 trillion.

HBM4 makes that constraint harder to solve.

KB estimates HBM4 requires roughly three times the wafer capacity of conventional DRAM.

As manufacturers devote more production to higher-margin HBM, less capacity remains for ordinary DRAM, potentially tightening the broader memory market at the same time.

That changes the investment case, as investors are not simply betting on stronger AI demand, but also on demand rising into a supply base with very little short-term cushion, allowing memory makers to preserve unusually strong pricing.

HBM demand is spreading beyond Nvidia

SK Hynix’s HBM opportunity increasingly extends beyond Nvidia-linked GPUs as Meta, Microsoft and other hyperscalers develop proprietary AI accelerators that also require large amounts of advanced memory.

Mirae Asset analyst Kim Young-gun said that broader HBM adoption among ASIC developers is favourable for SK Hynix because it expands its customer base.

Mirae raised its price target to 3.1 million won from 2.8 million won this week.

DB Securities separately lifted its target to 2.3 million won from 2 million won. Analyst Seo Seung-yeon expects HBM4 shipments to accelerate from the third quarter, while resilient server demand helps offset pressure from the stronger won.