Key Highlights

  • SK hynix, the South Korean memory maker, saw its US-traded line rise about 8% in pre-market trading on Wednesday, October 28, 2026, after the company's release of that day reported third quarter revenue of KRW 104.6155 trillion, up 328%.
  • A market research estimate cited in a Korean report of Monday, October 19, 2026 gave SK hynix 50% of high bandwidth memory revenue in the second quarter of 2026, against 33% for Samsung and 18% for Micron.
  • The company's release said HBM4 shipments began in earnest and that HBM4 is expected to surpass HBM3E in shipment volume and revenue in the fourth quarter, which is the main mechanism behind operating profit of KRW 83.3338 trillion.
  • The release does not state an HBM revenue figure or unit volume for the third quarter, so the size of the HBM contribution is not quantified, and pre-market prices are thin.

Why the HBM Franchise Anchors the Rally

SK hynix, a South Korean memory maker, saw its US-traded line rise about 8% in pre-market trading on Wednesday, October 28, 2026, while Korean shares rose about 10%. High bandwidth memory (HBM) stacks several DRAM chips vertically and sits beside the processors that train artificial intelligence models. A market research estimate cited in a Korean report of Monday, October 19, 2026 put SK hynix at 50% of HBM revenue in the second quarter of 2026, ahead of Samsung Electronics at 33% and Micron Technology (NASDAQ:MU) at 18%. Those three shares sum to 101%, which indicates that the estimates are rounded. The company's release of Wednesday, October 28, 2026 reported third quarter revenue of KRW 104.6155 trillion.

How Vera Rubin Demand Feeds Into Earnings

The same Korean report tied HBM4 demand to the Nvidia Vera Rubin platform. The company's release of Wednesday, October 28, 2026 said HBM4 shipments began in earnest, and that HBM4 should surpass HBM3E in shipment volume and revenue in the fourth quarter and become mainstream. HBM4 is the latest generation of stacked memory and is understood to sell at a premium, so a shift in mix toward it lifts average selling prices and margin. Operating profit was KRW 83.3338 trillion, up 632% year on year, and the operating margin was 80%. The release does not split the result between HBM and conventional DRAM, so the HBM contribution is an inference from timing and not a reported figure.

Risks and What to Watch

The bull reading is that a leading share of HBM, combined with long-term agreements covering more than 50% of 2027 and 2028 production capacity with 14 major customers, gives SK hynix pricing power while the company expects demand to exceed supply through 2030. The bear reading is that a concentrated customer base, centred on Nvidia, ties earnings to a single platform cycle, and that the two competitors named hold a combined 51% of the segment. Three risks apply: the share data are second quarter estimates, the figures are preliminary and unaudited, and pre-market trading is thin. Investors should watch HBM4 volume commentary, the M15X plant reaching maximum capacity by year end and the open at 9:30 a.m. ET on Wednesday, October 28, 2026.

Where Things Stand

The answer is that Nvidia Vera Rubin demand appears to be a central driver, since a 50% HBM revenue share and HBM4 shipments beginning in earnest are consistent with a 632% rise in operating profit, although the HBM contribution is not quantified. The key number is the 50% second quarter share estimate. The next catalysts are the 9:30 a.m. ET open on Wednesday, October 28, 2026, the decision of the Federal Reserve due later that day, and the fourth quarter HBM4 volume crossover. Pre-market prices are snapshots and can change, and this is not investment advice.