SK hynix approved $38.1 billion in capital expenditure for two new memory fabrication plants, the largest single commitment in the company's history and a clear bet that AI-driven memory demand will sustain through the end of the decade. The facilities target high-bandwidth memory and NAND production, with first wafers expected in late 2028 and volume ramp in 2029.

The investment arrives as SK hynix captures roughly 50% of the HBM3E market, supplying Nvidia's H200 and B200 GPUs. Revenue from advanced DRAM grew 72% year-over-year in the most recent quarter, while operating margin exceeded 30% for the first time since 2018. The company now faces allocation pressure from every hyperscaler and three sovereign AI programs, all of which are competing for wafer commitments that won't materialize for four years.

The 2029 timeline creates a structural imbalance. Nvidia's Rubin architecture ships in 2026, Google's TPU v7 ramps in 2027, and Amazon's Trainium3 volumes arrive in late 2027. All three rely on HBM3E or its successor, and all three are currently negotiating multi-year supply agreements for capacity that does not yet exist. SK hynix is effectively preselling 2029 output to lock in pricing before competitors — Samsung and Micron — can match process node parity on HBM4. The four-year lead time also signals that the company does not expect memory demand to normalize, a reversal from the cyclicality that defined the industry for two decades.

The NAND portion of the capex targets enterprise SSDs for AI training clusters, where write endurance and power efficiency matter more than consumer-grade cost per gigabyte. Meta's Grand Teton and Microsoft's Maia both require NVMe drives with sustained write speeds above 14 GB/s, a specification that only 176-layer and higher NAND can meet. SK hynix ships 238-layer NAND today but has not yet disclosed the layer count for the new fabs, which suggests the company is waiting for yield data from its Icheon M16 pilot line before committing to a final process node.

Operators and allocators should watch three events. First, Samsung's HBM4 qualification timeline with Nvidia, expected in Q2 2025, will determine whether SK hynix retains monopoly pricing or faces margin compression. Second, TSMC's CoWoS-L packaging capacity expansion in Arizona, scheduled for mid-2026, could shift some HBM demand if substrate supply loosens. Third, any softness in Nvidia's data center revenue growth during 2025 earnings calls would indicate early saturation, though current order backlogs suggest that risk is minimal.

The $38.1 billion is not a hedge. It is a declaration that memory supply will remain the binding constraint on AI infrastructure for the next five years, and that SK hynix intends to capture the majority of margin expansion that follows. The fabs begin construction in Q3 2025.