SK Hynix’s HBM4 Certification for Nvidia’s Rubin Platform Does Little to Halt a 10% Stock Slide

Nvidia certifies SK Hynix HBM4 for Vera Rubin, but stock drops 10% on macro headwinds and Broadcom revenue miss. SK Hynix plans $67B capex and US ADR listing.

South Korea’s memory giant received exactly the endorsement the AI chip market had been waiting for — Nvidia formally certified its HBM4 chips for the upcoming Vera Rubin architecture — yet the stock still got hammered on Friday. Shares of SK Hynix closed at 2,070,000 KRW, down 9.92% in a single session and 11.27% lower on the week. The contrast between operational achievement and market reaction was stark: the equity has more than tripled from its October 2025 low and still shows a year-to-date gain of 205.76%.

Two forces converged to trigger the selloff. A stronger-than-expected US jobs report dimmed the prospect of early rate cuts, while Broadcom’s revenue forecast for AI chips came in roughly 7% below consensus. That was enough to spark a sector-wide rotation that hit Asian semiconductor names hard. Rumors also swirled that Nvidia may reduce the amount of storage per server rack in certain Rubin configurations, though the HBM4 memory allocation per chip is unchanged at 20.7 terabytes. Analysts were quick to distinguish between a design tweak that would affect total memory content and a cut in HBM4 demand itself — the latter remains intact.

Jensen Huang, Nvidia’s chief executive, confirmed in Seoul that SK Hynix, Samsung and Micron have all been qualified as suppliers of HBM4 for the Vera Rubin platform, marking the first time every major memory producer has met the requirements for a single Nvidia generation. Industry estimates give SK Hynix the lion’s share of volume at 60% to 70%, reflecting its entrenched lead in high-bandwidth memory. The company held 58% of the global HBM market in the first quarter. Deliveries of HBM4 are slated to begin in the third quarter of 2026, with Nvidia targeting a tenfold throughput improvement over Grace Blackwell.

To maintain that dominance, SK Hynix is embarking on an aggressive capacity buildout. The company aims to nearly double its DRAM wafer capacity from roughly 550,000 wafers per month today to around 1 million by the early 2030s. The centerpiece is the Yongin semiconductor cluster, where the first fab will house six clean rooms; equipment installation is scheduled to start in February 2027. Yongin alone is expected to contribute an additional 360,000 wafers per month by the first half of 2030. The M15X facility in Cheongju will begin with 40,000 wafers in the second half of 2026 and ramp to 80,000 by 2027. Management has earmarked $67 billion in capital expenditure through 2028 to fund the expansion, with an eye on what it sees as a looming global memory deficit later this decade.

Part of that funding will come from Wall Street. SK Hynix confirmed plans to list American depositary receipts in the US during the second half of 2026, potentially raising up to $14 billion by placing 2% to 3% of its shares. Institutional interest has been strong, and the move comes just after the company’s market capitalization briefly surpassed $1 trillion in early June. The firm is also building a plant in Indiana. On the competitive front, Chinese rivals CXMT and YMTC are expanding capacity — CXMT recently received approval for a multibillion-dollar IPO in Shanghai — but they remain years behind in cutting-edge HBM production.

Hwang Soo-wook of Meritz Securities characterised the recent drop as profit-taking after a massive rally, noting that fresh catalysts are scarce until second-quarter earnings are released in July. For SK Hynix, the certification itself was a necessary milestone, but the more critical metric will be how much volume it actually secures within Nvidia’s Rubin supply chain once shipments begin in late 2026. If the expected 60%–70% share materialises, Friday’s rout will look like a tremor rather than a signal of broken demand.