What Happened?

A number of stocks fell in the afternoon session after a report that South Korea's SK Hynix is slowing its high-bandwidth memory (HBM) expansion rattled the AI-chip complex. 

The selling started in Asia as SK Hynix and Samsung each dropped more than 12%, dragging the KOSPI down about 10% and triggering a 20-minute market-wide circuit breaker, then carried into Europe (ASML −5%, Infineon, ASM International and STMicroelectronics down 5–8%) and the U.S., where the Philadelphia Semiconductor Index opened down roughly 7% a day after closing at a record high.

The headline sounds bearish for AI, but the underlying report is a margin story, not a demand story. SK Hynix is deliberately slowing its HBM4 ramp to redirect capacity into conventional DRAM, where shortages have pushed operating margins above HBM's. Korean analysts pegged the margin gap at more than 15 points. 

HBM is the memory bolted onto Nvidia's AI accelerators, so any "slowing HBM" signal instinctively sparks fears the AI build-out is cooling which is why the reflex was to sell. The more accurate read is that all three memory makers are running the market tight (Samsung flagged a 146% DRAM ASP jump in Q1, SK Hynix mid-60%), keeping pricing power with sellers.

The bigger driver appeared like profit-taking after a parabolic run. Micron rose ~300% since the start of the year, colliding with a hawkish rate shift: traders pricing 50bps of Fed hikes by December under new Chair Kevin Warsh, making debt-funded AI capex harder to justify at record valuations. The divergence confirmed it: memory names took the brunt (Micron −11%) while logic-heavy Nvidia fell only ~3.6%. Wedbush framed the drop as a buying opportunity with enterprise demand intact.

The stock market overreacts to news, and big price drops can present good opportunities to buy high-quality stocks.

Among others, the following stocks were impacted:

• Semiconductor Manufacturing company KLA Corporation (NASDAQ: KLAC) fell 9.1%. Is now the time to buy KLA Corporation? Access our full analysis report here, it’s free.
• Analog Semiconductors company onsemi (NASDAQ: ON) fell 9.4%. Is now the time to buy onsemi? Access our full analysis report here, it’s free.
• Semiconductor Manufacturing company Nova (NASDAQ: NVMI) fell 8.8%. Is now the time to buy Nova? Access our full analysis report here, it’s free.

Zooming In On onsemi (ON)

onsemi’s shares are very volatile and have had 28 moves greater than 5% over the last year. In that context, today’s move indicates the market considers this news meaningful but not something that would fundamentally change its perception of the business.

The previous big move we wrote about was about 21 hours ago when the stock gained 6.6% on the news that the Philadelphia Semiconductor Index hit a fresh record high even as the broader Nasdaq slipped as NVIDIA unveiled its next-generation Vera Rubin platform at the ISC High Performance 2026 conference in Hamburg, which set off a chain reaction across the chip and AI-server supply chain. 

NVIDIA introduced it as a platform for "world-class supercomputers for science," delivering more than 7 exaflops of AI performance, 5 petaflops of native FP64 compute, and up to 144 GPUs per rack, succeeding the Blackwell Ultra generation. CEO Jensen Huang called it "a new instrument for science." Critically, NVIDIA named its system-builder partners (Bull, Dell, GIGABYTE, HPE, and Supermicro) to bring Vera Rubin NVL4 racks to market, and those partners moved hardest. Super Micro surged 11-16% after detailing a liquid-cooled blueprint scaling to 1,152 Rubin GPUs per unit. Dell rose approximately 5% on its PowerEdge XE8812 server, which will power Doudna, the next flagship US Department of Energy supercomputer at Lawrence Berkeley National Laboratory. 

The memory side added a second leg. Micron rose nearly 5% ahead of its earnings later in the week, extending a run that lifted the stock close to 300% year-to-date, supported by a wave of analyst price target increases (Needham to $1,550, Bernstein to $1,300) that framed the report as the key test of AI memory demand. SanDisk gained 4%, and Intel rose 3.8%, the latter continuing to benefit from the previous week's Trump-Apple foundry news. 

What stood out was the internal contradiction in the tape. NVIDIA itself was essentially flat to slightly lower, and the Nasdaq actually fell, dragged by a 5.6% drop in Alphabet and a 1.4% decline in Microsoft on regulatory and software-disruption concerns. So this was not a broad tech rally, it was a targeted rotation into the semiconductor and AI-hardware supply chain specifically. Investors are distinguishing sharply between the companies building AI infrastructure, which they are rewarding, and the software and platform companies they fear AI will disrupt, which they are selling. The chip rally and the software selloff happening on the same day are two sides of the same thesis.

onsemi is up 109% since the beginning of the year, but at $118.63 per share, it is still trading 11.4% below its 52-week high of $133.93 from June 2026. Investors who bought $1,000 worth of onsemi’s shares 5 years ago would now be looking at an investment worth $3,214.

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