Korea's memory makers and the AI boom: HBM, shares, risks

Samsung Electronics and SK hynix, both Korean, are two of the three companies that make high bandwidth memory (HBM), the stacked memory placed beside AI accelerators. In Counterpoint Research's second quarter 2026 data, SK hynix held 50 percent of HBM revenue and Samsung 33 percent. Both face new competition and a volatile market.

This post explains what HBM is in plain terms, how the Korean makers fit into the AI supply chain, what the 2026 numbers say, and which risks showed up in October. It is a factual summary with sources and as-of dates, not investment advice. For Korea's data centre and power plans, see our South Korea AI infrastructure overview.

Key numbers at a glance

• 50 percent, 33 percent and 18 percent: SK hynix, Samsung and Micron shares of global HBM revenue in the second quarter of 2026 (Counterpoint Research, 3 September 2026). The three add to 101 percent, which Counterpoint's data likely reflects as rounding.
• 64 percent and 15 percent: SK hynix and Samsung shares a year earlier, in the second quarter of 2025 (same source).
• 2,048: input and output connections per HBM4 stack, double the previous generation, with a JEDEC standard speed of 8 Gbps per connection (SK hynix, 12 September 2025).
• 12 layers and 36 GB: the HBM3E stack SK hynix said it began mass producing on 26 September 2024, with each DRAM die about 40 percent thinner than before (SK hynix, 26 September 2024).
• 12 September 2025: when SK hynix said it completed HBM4 development and readied mass production (SK hynix, 12 September 2025).
• 97.1467 trillion won revenue and 47.2063 trillion won operating profit for SK hynix in 2025, against 66.1930 trillion won and 23.4673 trillion won in 2024 (SK hynix results release, 28 January 2026).
• 333.6 trillion won revenue and 43.6 trillion won operating profit for Samsung Electronics in 2025 (Samsung results release, 29 January 2026).
• 21.8 percent: growth in Korea's nominal gross national income in the first half of 2026 compared with a year earlier, the fastest since 2000, with export prices up 19.9 percent (National Assembly Budget Office, 30 September 2026, as reported by Korea JoongAng Daily on 18 October 2026).
• 3.3 percent: IMF forecast for Korea's 2026 growth, up 0.7 percentage points from July, attributed by the article to strong chip exports (Korea JoongAng Daily, 18 October 2026).
• 800 trillion won: pledge by Samsung and SK hynix for a chip cluster in the Jeonnam and Gwangju region, and up to a combined 1.6 quadrillion won expected for the Yongin cluster (Korea JoongAng Daily, 19 October 2026).
• Down 17.8 percent and 24.3 percent: the one week moves in Samsung and SK hynix shares reported on 19 October 2026 (Financial News).

What HBM is, in plain words

Every processor needs memory. A graphics processor (GPU) or AI accelerator does arithmetic very quickly, but it can only work on data it can reach. If memory delivers data too slowly, the processor waits. Engineers call this the memory wall, and SK hynix uses the phrase in its October 2026 company post about memory-centric systems.

HBM is a way to widen the road between memory and processor. Instead of memory chips sitting at a distance on a circuit board, several memory dies, the individual slices of silicon, are stacked on top of each other and linked by tiny vertical electrodes that pass through holes in each die, called through silicon vias (TSV). SK hynix's September 2024 release describes the 12 layer HBM3E stack this way, and says each die was made about 40 percent thinner so that 12 layers fit in the height of the earlier 8 layer product. The stack then sits next to the processor in the same package, so the distance is very short and the connection very wide.

The result is more bandwidth, meaning more data per second, per stack. SK hynix's release of 12 September 2025 says HBM4 doubles the number of input and output connections to 2,048, and that this doubling is what doubles bandwidth over the previous generation. It gives the JEDEC standard operating speed as 8 Gbps per connection and says its own parts run above 10 Gbps. JEDEC is the industry body that writes memory standards. Multiplying 2,048 connections by 8 Gbps and dividing by eight bits per byte gives roughly 2 terabytes per second per stack at the standard speed; that is simple arithmetic on the company's figures, not a measured result. An accelerator carries several stacks, so the memory bandwidth of a single card is a multiple of that. SK hynix lists the generations in order as HBM, HBM2, HBM2E, HBM3, HBM3E and HBM4, which is why HBM3E is called the fifth generation and HBM4 the sixth.

HBM is harder to make than ordinary memory. It needs thinned dies stacked precisely, heat that has to escape from the middle of the stack, and packaging next to the processor. That difficulty is one reason Counterpoint's market data, covered below, tracks just three suppliers: SK hynix, Samsung Electronics and Micron Technology. It is also why HBM supply is discussed together with advanced packaging capacity. Our explainer on HBM and CoWoS packaging limits covers that side.

One more detail is useful. The bottom die of the stack, the base die, is a logic chip made on a foundry process. Samsung's results release of 29 January 2026 says its foundry business began shipping 4 nanometre HBM base die products in the fourth quarter of 2025. Base dies can also come from an outside foundry, so the memory in an AI accelerator can link several companies and countries, which is why a single national share figure never tells the whole story.

Where the Korean makers stand in 2026

The most recent share data cited here is from Counterpoint Research's Memory Tracker, published 3 September 2026. It reports revenue shares, which means each company's HBM sales as a fraction of the total, not the number of chips shipped.

In the second quarter of 2026:

• SK hynix: 50 percent, down from 64 percent a year earlier and 58 percent in the first quarter.
• Samsung: 33 percent, up from 15 percent a year earlier and 21 percent in the first quarter.
• Micron: 18 percent, against 21 percent in each of the previous four quarters.

Read the path rather than one number. Samsung's share rose in the third quarter of 2025 to 23 percent, eased to 21 percent in the first quarter of 2026, then jumped by 12 points in the second. SK hynix stayed the largest supplier but lost 14 points over the year. Counterpoint notes that most current HBM revenue still comes from HBM3E, the fifth generation, and expects HBM4 shipments to become significant from the second half of 2026. It also expects Samsung's share to keep growing gradually as it ramps HBM4.

Different trackers use different methods, such as shipped bits, so another firm's shares can differ. This post relies on that one tracker, so treat the exact percentages as one analyst's estimate, not an official count.

On the product side, the companies describe themselves as ready for the next generation. SK hynix's own October 2026 press release from the Open Compute Project Global Summit in San Jose says it displayed HBM4 and HBM4E, its seventh generation, as physical products and let visitors mount HBM4 onto an Nvidia Vera Rubin server model. It also says its Advanced MR-MUF packaging process lets it stack chips 40 percent thinner without warping, while improving heat dissipation. That is a company claim and the post gives no bandwidth or power figures. Korea JoongAng Daily reported on 19 October 2026 that Samsung unveiled HBM5, its eighth generation, at the same summit. No Samsung release on HBM5 is cited here, so treat it as a press report.

The wider memory business around HBM

HBM is only part of the Korean makers' memory output. SK hynix's October post also lists server DRAM, including a 192 GB SOCAMM2 module, a low power DRAM module for AI servers, and a second generation CXL memory module with 256 GB capacity and 80 GB/s bandwidth. CXL, short for Compute Express Link, is a standard for pooling memory across servers. The company says it moves cached data for AI models over pooled memory faster than over a network in demos with partners, without giving a figure. These are vendor demonstrations, not independent tests.

Why does it matter? Because AI memory demand is not only HBM. Long conversations and large models need memory to hold intermediate data, and that pushes up demand for ordinary server DRAM too. A Financial News article of 19 October 2026 quotes a Hana Securities analyst as saying third quarter DRAM prices came in better than expected and that he expects the fourth quarter increase to be revised upward. That is one analyst's view, but it shows memory pricing is currently rising, which is good for the makers and a cost for their customers.

The money and the economy

Memory is now large enough to move Korea's national numbers. SK hynix's results release of 28 January 2026 reports 2025 revenue of 97.1467 trillion won and operating profit of 47.2063 trillion won, a 49 percent operating margin, with net profit of 42.9479 trillion won. Its 2024 figures were 66.1930 trillion won of revenue and 23.4673 trillion won of operating profit, so operating profit roughly doubled in a year. The company says its HBM revenue more than doubled over the same period.

Samsung's release of 29 January 2026 reports 2025 revenue of 333.6 trillion won and operating profit of 43.6 trillion won. Its fourth quarter was a record, with 93.8 trillion won of revenue and 20.1 trillion won of operating profit, and its chip division, Device Solutions, contributed 16.4 trillion won of that quarter's operating profit. Samsung credits expanding HBM sales and higher memory prices, and said it was on track to begin delivering HBM4 in the first quarter of 2026. On these company figures, SK hynix earned more operating profit in 2025 than the whole of Samsung Electronics, on less than a third of the revenue, which shows how concentrated the memory gains were. These are company reported results, not audited annual reports.

The national picture is supported by Korea JoongAng Daily reporting. On 18 October 2026 it cited the National Assembly Budget Office as saying nominal gross national income rose 21.8 percent in the first half of 2026, the fastest since 2000, an increase of 284 trillion won. Of that increase, 224 trillion won, 78.7 percent, went to gross operating surplus, which is business income, and 47 trillion won, 16.5 percent, to wages and employee pay. Export prices rose 19.9 percent. The article's headline argues that the chip boom leaves workers with little to show, which is the paper's framing. This post uses the numbers, not the conclusion.

The same paper reported on the same day that the IMF raised its 2026 growth forecast for Korea to 3.3 percent, attributing the change to strong chip exports driven by AI infrastructure demand. An IMF office director quoted in that article said AI data centre projects could take about 10 years and that investment "has only just begun". He also listed downside risks if the boom falters, including a stock market correction and adverse effects on businesses. The article says the government plans a Future Fund next year, funded by windfall revenue from the chip boom, with no amount given.

Investment: where the money is going

Korea JoongAng Daily reported on 19 October 2026 on where the two companies are investing. Its figures:

• Samsung and SK hynix pledged 800 trillion won, about 600 billion US dollars, for a chip manufacturing cluster in the Jeonnam and Gwangju region.
• The two companies are expected to spend up to a combined 1.6 quadrillion won at the Yongin cluster in Gyeonggi province, which is separate from the Jeonnam plan.
• Samsung's first foundry plant in Taylor, Texas is scheduled to go online next year, with a combined 37 billion dollars going into the site, and it is building a 4 billion dollar chip testing and packaging plant in Vietnam.
• SK hynix recently began construction on a 4 billion dollar packaging plant in West Lafayette, Indiana, and is looking at sites in Japan and the United States.

The same article says the United States ended the validated end user waiver for Samsung and SK hynix's China operations in 2025. Before that, the companies could import controlled US chip equipment into China without per shipment approval. Now they must renew licences annually. SK hynix said it has no plans to expand capacity in China beyond its existing base, and Samsung said it will keep its China facilities with no significant new investment planned. These are company statements, and the article's point is that investment is moving toward the United States, India, Vietnam and Japan.

The pledges are large, and pledge sizes are not construction. Forecast figures such as 800 trillion won are announcements over many years, and they depend on prices, demand and policy staying favourable.

Risks that appeared in October 2026

The October reports show how quickly sentiment can change. These are market events, not forecasts.

New competition in ordinary DRAM. Korea JoongAng Daily reported that Micron fell 3.88 percent on 12 October and Samsung and SK hynix fell more than 6 percent and more than 9 percent intraday on 13 October, after China's memory maker CXMT said it had made key progress on a cell design called 4F2 and planned server memory using it by the end of 2026. Compared with the current 6F2 layout, 4F2 reduces cell area by about 33 percent, the article says, which in theory allows about 50 percent more cells on a chip. The article also notes CXMT's DDR5 products appeared on the market in earnest in late 2024 and that observers reported yield and reliability problems with newer chips in 2025. SK Group Chairman Chey Tae-won was quoted warning that Korean market share could fall if China or Micron expands capacity faster. CXMT's statement is a plan, not shipped product, and the article cannot say how it will turn out.

Doubts about AI spending. Financial News reported on 19 October 2026 that Samsung had fallen 17.8 percent and SK hynix 24.3 percent in the week before, with the KOSPI index down 14.5 percent. It attributes part of the fall to higher interest rates raising the cost of funding data centres, which raises doubts about how long AI investment will last. The same analyst argued that demand fears may be overpriced into memory stocks because supply remains tight, and that long term supply contracts ease pressure on customers and improve visibility on future demand. Those are one analyst's views. Share prices change daily, so check current data.

Customer cost pressure. Rising memory prices are good for makers and costly for buyers. The same article says customers appear uneasy about price rises. That tension is typical of a market with a few suppliers.

Cycles. Memory has a long history of boom and bust. SK hynix's operating profit doubled between 2024 and 2025 on its own figures, and swings of that size can run in either direction. A single year of strong results says little about the next.

What is firm and what is uncertain

Firm:

• HBM is a stacked memory that gives accelerators far more bandwidth, and three makers dominate it.
• In Counterpoint's second quarter 2026 data, SK hynix led with 50 percent and Samsung followed with 33 percent.
• Korean chip exports are credited by the IMF and Korean reporting with lifting 2026 growth.
• Samsung and SK hynix have announced very large investments in Korea and abroad.

Uncertain:

• Exact shares. One tracker, revenue based, and it contains a rounding gap.
• HBM4 volumes and which supplier wins which customer. Counterpoint expects volume in the second half of 2026, and no customer split has been confirmed publicly.
• The scale of the Chinese challenge in ordinary DRAM and whether it reaches HBM.
• The durability of AI spending, which the October reports show markets are debating.
• How much of each company's profit comes from HBM specifically, since neither results release gives an HBM revenue figure.

What to watch next

• Counterpoint's third quarter 2026 share data, and whether Samsung's rise continues.
• HBM4 and HBM4E shipments and which accelerators carry them.
• CXMT's server memory launch at the end of 2026 and any yield data.
• Company earnings releases and long term supply contracts.
• Progress of the Yongin and Jeonnam clusters and the Texas and Indiana sites.
• Any change to US licences for Korean fabs in China.

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Quick check

Sources

• Counterpoint Research, Global HBM market share Q2 2026 (3 September 2026)
• SK hynix newsroom, Memory-Centric Server Systems Are the Future, OCP Global Summit 2026 (16 October 2026)
• Korea JoongAng Daily, Global chip stocks tumble as China's CXMT unveils next-generation DRAM plans (October 2026)
• Korea JoongAng Daily, Korean manufacturers redraw China playbook as U.S. pressure escalates (19 October 2026)
• Korea JoongAng Daily, Korea's chip boom swells national income, but leaves workers with little to show (18 October 2026)
• Korea JoongAng Daily, AI boom to sustain Korea amid global headwinds, says senior IMF official (18 October 2026)
• Financial News, DRAM prices rise, but semiconductor stocks plunge (19 October 2026)
• SK hynix, SK hynix Announces FY25 Financial Results (28 January 2026)
• SK hynix, Completes World's First HBM4 Development and Readies Mass Production (12 September 2025)
• SK hynix, Begins Volume Production of the World's First 12 Layer HBM3E (26 September 2024)
• Samsung Electronics, Fourth Quarter and FY 2025 Results (29 January 2026)

Last reviewed: 19 October 2026.