# HBM memory is the next AI bottleneck, and SK hynix just showed why

- **Published:** 2025-10-31
- **Updated:** 2026-10-12
- **Category:** Hardware & Infrastructure
- **Author:** Sinthetix
- **URL:** https://sinthetix.com/blog/hbm-memory-supply-sk-hynix

> SK hynix's record quarter and its 2026 supply talks, plus OpenAI's memory letters of intent, show high-bandwidth memory as a constraint on AI capacity.

Discussion of AI hardware focuses on GPUs, but every accelerator depends on high-bandwidth memory (HBM) stacked beside the processor. This week's results from the largest HBM maker show that supply of that memory is committed well ahead.

**Key takeaways**

- SK hynix reported record third-quarter revenue of KRW 24.45 trillion and operating profit of KRW 11.38 trillion [1].
- It has completed its 2026 HBM supply negotiations [1], and Blocks & Files describes its HBM, DRAM and NAND output as "effectively sold-out through 2026" [2].
- HBM4 shipments begin in the fourth quarter of 2025, with full-scale sales in 2026 [2].
- Per The Register, OpenAI says its Korean memory partners will be tasked with around 900,000 DRAM wafer starts a month, under letters of intent [3].

## The numbers

SK hynix, reporting on October 29, posted quarterly sales of KRW 24.45 trillion, up 39% year over year, and operating profit of KRW 11.38 trillion, up 62% with a 47% margin. It was the first quarter in which operating profit exceeded KRW 10 trillion [1]. Net profit was KRW 12.6 trillion [2].

| Metric (3Q 2025) | Value |
| --- | --- |
| Sales | KRW 24.45 trillion, +39% YoY [1] |
| Operating profit | KRW 11.38 trillion, +62% YoY [1] |
| Operating margin | 47% [1] |

Blocks & Files attributes the results to sales of 12-high HBM3E and DDR5 server memory [2]. TrendForce reports that all 2026 HBM supply negotiations with key customers are complete [1], and Blocks & Files characterizes SK hynix's HBM, standard DRAM and NAND output as "effectively sold-out through 2026" [2]. That phrase is the publication's wording, not a company statement. HBM4 finished development in September [1], with shipments starting in the fourth quarter and full-scale sales planned for 2026 [1][2]. The company also plans to raise 2026 capital spending significantly, with a new Cheongju fab line (M15X) slated to begin production next year [1].

## Demand signals upstream

In the first days of October, Samsung and SK hynix each signed letters of intent with OpenAI tied to its Stargate project, according to The Register's October 2 report. The article says OpenAI expects the Korean partners to be tasked with around 900,000 DRAM wafer starts a month, a scale only "the biggest fabs on the planet" can support [3]. Letters of intent are not purchase orders, so treat this as a statement of ambition rather than contracted volume.

## Why it matters

When memory is committed a year ahead, new accelerator capacity is gated by more than GPU availability. For buyers, that means constrained supply and firm pricing in memory-heavy configurations are plausible planning assumptions, though none of the sources here forecast prices.

## Practical implication

If you plan to buy or lease GPU servers for 2026, lock in memory-inclusive delivery dates with suppliers early, and confirm which HBM generation the system uses. For API-based AI, expect the effect to show up as capacity limits more than as list-price changes.

## Sources

1. [SK hynix posts record 3Q profit: three highlights spotlight HBM4, soaring capex and 2026 outlook](https://www.trendforce.com/news/2025/10/29/news-sk-hynix-posts-record-3q-profit-three-highlights-spotlight-hbm4-soaring-capex-and-2026-outlook/), TrendForce, 2025-10-29
2. [HBM gold mine sends SK hynix revenues to a new high point](https://www.blocksandfiles.com/ai-ml/2025/10/30/hbm-gold-mine-sends-sk-hynix-revenues-to-a-new-high-point/1587272), Blocks & Files, 2025-10-30
3. [OpenAI ropes in Korean giants Samsung and SK Hynix to feed its AI megaproject](https://www.theregister.com/2025/10/02/openai_ropes_in_samsung_and/), The Register, 2025-10-02

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