Stock Markets May 28, 2026 10:31 AM

Arm, Snowflake and a broad tech rally drive major market swings Thursday

Big-cap technology names and AI-related deals lead gains while storage and select mid-caps post sharp declines

By Sofia Navarro INTC LLY ARM MSFT IBM

Thursday's trading session produced significant volatility across market-cap tiers, with standout gains in Arm and Snowflake and notable declines at Pure Storage and several mid-cap names. Movers ranged from mega-cap technology and industrial stocks to AI-related software names and small-cap explorers, reflecting company-specific news such as acquisitions, product rollouts, earnings beats and guidance shortfalls.

Arm, Snowflake and a broad tech rally drive major market swings Thursday
INTC LLY ARM MSFT IBM

Key Points

  • Technology and AI-related stocks accounted for several of the largest gains, with Arm up 9.51% and Snowflake rising 35.08% on an announced acquisition for an AI agent governance platform.
  • Corporate-specific news drove much of the volatility: Microsoft flagged a new coding model release next week, Agilent reported stronger results and guidance, and AeroVironment won a $20M Air Force ceramics contract.
  • Not all sectors participated in the rally - storage and several mid-cap names fell sharply after weaker guidance or results, highlighting uneven market breadth across tech, industrials and small caps.

Stocks moved sharply on Thursday as company announcements and earnings-related guidance pushed some names substantially higher while others sank. Technology and AI-linked names accounted for several of the largest advances, while storage and certain mid-cap firms posted steep losses.


Session highlights

Among mega-cap names, Arm led gains, rising 9.51%, while other large-cap technology and healthcare stocks also advanced. Microsoft climbed after an announcement that it will release a new coding model next week, and Big Pharma showed strength as Eli Lilly added ground. Several industrial and semiconductor names posted modest declines.


Mega-Cap Movers (Market Cap: $200 billion USD or higher)

  • Intel Corp (INTC): -3.45%
  • Eli Lilly And Co (LLY): +5.72%
  • Arm (ARM): +9.51%
  • Microsoft Corp (MSFT); Microsoft to release new coding model next week: +3.1%
  • IBM (IBM): +4.24%
  • Palantir Technologies Inc (PLTR): +4.36%
  • Caterpillar (CAT): -1.97%
  • Kla-tencor Corp (KLAC): -1.83%
  • GE Vernova LLC (GEV): -2.88%
  • Lam Research Corp (LRCX): -1.12%

Large-Cap Stock Movers (Market Cap: $10-$200 billion USD)

  • Snowflake Inc (SNOW); Snowflake to acquire Natoma for AI agent governance platform: +35.08%
  • Dollar Tree Inc (DLTR): +17.49%
  • Agilent Tech (A); Agilent surges 8% on earnings beat and raised guidance: +16.32%
  • Best Buy (BBY): +14.72%
  • Kratos Defense & (KTOS): +14.29%
  • Heico Corp (HEI): +12.28%
  • MongoDB (MDB): +11.51%
  • Hormel Foods Corp (HRL); Hormel Foods stock rises nearly 4% on beating estimates as turnaround gains traction: +8.85%
  • Samsara (IOT): +5.85%
  • Pure Storage Inc (P); Everpure shares slide over 7% as guidance falls short of analyst expectations: -18.09%

Mid-Cap Stock Movers (Market Cap: $2-$10 billion USD)

  • Braiin (BRAI): +38.36%
  • AeroVironment (AVAV); AeroVironment wins $20M Air Force ceramics contract: +16.6%
  • Amprius Tech (AMPX): +15.3%
  • Ondas (ONDS): +20.05%
  • ICON Plc (ICLR): +10.78%
  • Ekso Bionics Holding (CHRN): +13.34%
  • American Superconductor (AMSC); AMSC falls as first quarter guidance disappoints: -11.08%
  • CECO Environmental (CECO): -8.05%
  • SVF Investment 3 (SYM): -7.96%
  • Photronics (PLAB); Photronics tumbles 32% on weaker-than-expected Q2 results, guidance: -34.69%

Small-Cap Stock Movers (Market Cap: $300 million - $2 billion USD)

  • Unusual Machines (UMAC): +49.02%
  • TimefireVR (RCAT): +25.77%
  • Corsair Gaming Inc (CRSR): +18.33%
  • Kohls Corp (KSS): +18.72%
  • Swarmer Inc (SWMR): +17.86%
  • Rotor Acquisition Corp (PDYN): +15.43%
  • Social Capital Hedosophia Hold III (CLOV): +10.82%
  • Sidus Space (SIDU); Sidus Space prices $100 million stock offering at $5.08 per share: -20.67%
  • ADTRAN Inc. (ADTN): -13.03%
  • MSTU (MSTU): -7.29%

Market context and breadth

The session was marked by pronounced dispersion: large percentage moves clustered in technology, software and AI-related names, while several industrial and semiconductor firms recorded modest declines. Company-specific developments - including an acquisition announcement, product/model release timing, contract awards and quarterly guidance - largely explain the individual stock movements.


Summary

Thursday's trading featured strong gains in AI- and software-linked companies, most notably Snowflake on an announced acquisition related to AI agent governance and Arm among mega-cap tech names. Conversely, several storage and mid-cap companies tumbled after issuing guidance or reporting results that disappointed analysts' expectations.

Risks

  • Earnings and guidance disappointments - several companies including Pure Storage, Photronics and American Superconductor posted weak guidance or results that corresponded with steep share declines, indicating company-specific downside risk for those sectors.
  • Concentration risk in tech and AI-related names - sizable gains in a handful of software and AI-linked stocks may leave portfolios exposed if sentiment shifts away from these areas.
  • Volatility among small- and mid-cap names - large percentage swings in smaller-cap stocks increase uncertainty for investors focused on those market segments.

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