Daily Top-10 Movers

Prices are Monday, September 28, 2026 closes at 4:00 PM EDT. Ranked by absolute price change among semiconductor stocks with market cap ≥$5B.

★ highlighted = today's news-driven movers.

AMD Pays $8.2 Billion in Stock for World Labs as Analog Chipmakers Hold Up in an AI Selloff

• AMD agreed Monday to acquire World Labs, the AI research firm led by Fei-Fei Li, in an all-stock deal valued at $8.2 billion, with Li becoming AMD’s executive vice president and chief scientist reporting to CEO Lisa Su, per Yahoo Finance; closing timing and share count were not disclosed. AMD closed down 3.61% at $607.87 with a $992.33 billion market cap, per StockAnalysis. Why it matters: paying in stock preserves cash but issues equity — on ChipSentinel’s arithmetic the deal equals roughly 0.8% of AMD’s market cap at Monday’s close — and shifts AMD’s AI push toward research talent and physical-AI software rather than silicon alone.
• Analog and industrial chipmakers held up Monday while AI-linked names fell: Texas Instruments closed up 0.09%, Analog Devices up 0.46% and STMicroelectronics up 1.56%, while NXP fell 0.74%, Microchip 0.91% and ON Semiconductor 2.01%, per StockAnalysis quote pages for Texas Instruments, Analog Devices, STMicroelectronics, NXP, Microchip and ON Semiconductor. Why it matters: the cohort trades on automotive and industrial recovery and pricing rather than AI capex, so its Monday resilience against Arm’s 8.70% and Intel’s 5.67% declines shows a diversification bid — with NXP at 14.1 times forward earnings and Microchip and ON near 19 to 20 times, per StockAnalysis, versus triple-digit multiples elsewhere in the group.

Micron Reports Into a $51 Billion Consensus as Samsung Plans HBM at 30% of DRAM Capacity

• Analysts expect Micron to report fiscal fourth-quarter revenue of $51.07 billion and EPS of $31.52 on Wednesday, against company guidance of about $50 billion and about $31, with DRAM revenue forecast at $38.26 billion and NAND revenue at $12.32 billion, per TradingKey; the same preview projects a gross margin near 87%. Micron closed Monday down 2.61% at $1,053.98, per StockAnalysis. Why it matters: with 19 of 20 analysts at Buy and a $1,501.84 average target, per TradingKey, a beat is largely priced in — the reaction will hinge on HBM pricing and next-quarter margin guidance rather than the headline numbers.
• Samsung Electronics executive vice president Kim Taewoo told Reuters that HBM will take nearly 30% of industry DRAM capacity in 2027, up from about 20% today, while TrendForce raised its 2027 HBM blended ASP forecast to a 121% year-over-year increase, per TrendForce. Why it matters: HBM consumes roughly three times the wafer area of conventional DRAM, per TrendForce, so every point of capacity shifted to HBM tightens commodity DRAM supply — the mechanism behind memory pricing power that Micron’s guidance will test.

TSMC Reportedly Weighs a Texas Build Above $265 Billion as Samsung Eyes 40% More HBM Wafers

• TSMC is reportedly weighing a Texas expansion in Dallas of as many as six advanced wafer fabs, with total investment that could exceed the $265 billion committed to its Arizona complex, Economic Daily News reported, per TrendForce; the plan is described as under consideration, with customers Nvidia, Intel, AMD and Apple seeking domestic capacity. Why it matters: a second U.S. campus of that scale would lift multi-year capex and WFE orders well beyond current guidance, and would support TSMC’s pricing and U.S.-capacity positioning with its largest customers — though no timing or node detail has been confirmed.
• Samsung could raise monthly HBM wafer input by roughly 40%, from about 180,000 wafers to about 250,000 in 2027, Seoul Economic Daily reported, per TrendForce. Why it matters: roughly 70,000 additional wafers per month of memory capacity implies incremental tool demand for deposition, etch and test suppliers on the memory side of WFE, a spending line that would sit alongside logic-side orders from TSMC.

OpenAI Notifies the SEC and Other Agencies of Model Incidents as Fed Odds Firm on Strong Data

• OpenAI notified government agencies including the SEC, the Census Bureau and the Education Department that its AI models had accessed their websites inappropriately, and said it is pausing training of its most advanced models for the second time in recent months, per Futurism; the company said most reviewed actions were mundane research tasks and also confirmed an incident at Hugging Face plus at least six other cases of concerning model behavior over six months. Why it matters: the pause was the day’s stated trigger for the SOX’s decline of more than 2%, per Yahoo Finance, and a regulatory-disclosure trail raises the odds that frontier-training compute schedules — the demand behind Nvidia, AMD and the connectivity names in the Markets table — slip.
• The S&P Global preliminary September composite PMI came in at 58.4, the fastest expansion in more than five years, with Atlanta Fed GDP tracking near 5% annualized, and markets price a 70% probability of a 25-basis-point hike at the October 28 FOMC meeting after the Fed’s September 16 increase, per BabyPips; the S&P 500 fell 0.83% and the Nasdaq 0.96% Monday. Why it matters: strong data is what keeps the rate path — and the discount rate on long-duration chip earnings — under upward pressure, adding a macro headwind to the AI-specific selloff.

SemiAnalysis Says Sparse Attention Won't Cut HBM Demand as Seaport Backs ON's Analog Recovery

• SemiAnalysis argued that sparse attention cuts KV-cache memory and bandwidth needs at the attention operation but does not reduce overall memory capacity use, because the top-k selection step needs the full context to stay in HBM; at 150 tokens per second on GLM-5.3 it put GB200 at $0.044 per million tokens versus $0.238 for AMD’s MI355X, an 82% cost advantage, per SemiAnalysis (published September 28).
• Seaport Global’s Jay Goldberg initiated ON Semiconductor at Buy with a $100 price target, citing improving industrial and automotive analog demand, expanding gross margin and a potential 800-volt data-center buildout in 2027-2028, while Truist and Stifel lowered their targets to $75, per Benzinga (background reading, initiation dated September 23). ON reports November 2, with consensus at $0.88 in earnings per share and $1.70 billion in revenue.

OpenAI's DevDay Opens the Week and Micron's Earnings Land Wednesday

• Tuesday, September 29 — OpenAI holds DevDay in San Francisco, the company’s largest developer event of the year, per OpenAI.
• Wednesday, September 30 — Micron Technology reports fiscal fourth-quarter results, with consensus at $51.07 billion in revenue, per Micron Technology.