Stock Markets April 28, 2026 02:02 PM

Stocks Swing Widely on Tuesday; Rambus Plunges as Centene, Sanmina and Several Small Caps Rally

Mega-caps broadly slide while selected large-, mid- and small-cap names post sharp moves tied to earnings, analyst actions and trial data

By Caleb Monroe ARM AMAT ANET AVGO MU
Stocks Swing Widely on Tuesday; Rambus Plunges as Centene, Sanmina and Several Small Caps Rally
ARM AMAT ANET AVGO MU

Tuesday's trading session featured pronounced shifts across market-cap segments. Large-cap technology and semiconductor names led declines among mega-caps, while healthcare and selected small- and mid-cap companies posted double-digit gains after earnings beats, analyst ratings and early-stage trial news. Rambus fell sharply on an analyst downgrade tied to DRAM shortage concerns, even as Centene and Sanmina jumped following stronger-than-expected results and guidance.

Key Points

  • Mega-cap technology and semiconductor stocks led the declines, with Arm, Applied Materials, Arista and others posting double-digit or mid-single-digit drops.
  • Rambus plunged about 20% after a Baird downgrade citing DRAM shortage concerns; several large- and mid-cap companies including Centene and Sanmina rallied after earnings beats and raised guidance.
  • Small-cap winners included Kforce and Omnicell, while Erasca suffered a steep drop despite reporting positive early trial data.

Tuesday's U.S. equity session saw a wide dispersion of performances across market-cap brackets, with several notable losers among mega-cap technology and semiconductors and outsized winners among some large-, mid- and small-cap names driven by earnings reports, analyst moves and clinical trial updates.


Mega-cap movers (market cap $200B+)

  • Arm (ARM) - The stock fell sharply, down 7.57% in the session.
  • Applied Materials Inc (AMAT) - Shares declined 5.48%.
  • Arista Networks (ANET) - The stock eased 5.19%.
  • Avago Technologies (AVGO) - Declined 4.72%.
  • Micron Technology (MU) - The stock moved lower by 3.48%; DA Davidson initiated coverage with a buy rating citing AI memory demand.
  • Lam Research Corp (LRCX) - Shares slid 3.65%.
  • GE Vernova LLC (GEV) - The stock dropped 3.68%.
  • Kla-tencor Corp (KLAC) - Declined 3.55%.
  • Coca-Cola Co (KO) - One of the exceptions among mega-caps, KO rose 5.45%.
  • UnitedHealth Group (UNH) - Also an outlier, UNH climbed 3.77%.

Large-cap movers (market cap $10B-$200B)

  • Rambus Inc (RMBS) - The biggest decliner in this group, Rambus fell 20.71% after Baird downgraded the stock, citing concerns tied to a DRAM shortage.
  • Spotify Technology (SPOT) - The stock slipped 13.46%.
  • Pentair (PNR) - Shares dropped 11.09%.
  • Zimmer Holdings (ZBH) - Although ZBH beat Q1 estimates and raised guidance, the stock was listed with a 10.75% move to the downside in the day's movers list.
  • Vicor Corp (VICR) - Fell 8.79%.
  • Iris Energy (IREN) - Declined 9.25%.
  • FormFactor (FORM) - Down 7.90%.
  • Sanmina-SCI Corp (SANM) - Moved higher sharply, with the firm noted as soaring 12.5% on a Q2 earnings beat and strong guidance; the movers list shows a 13.64% gain.
  • Centene (CNC) - The stock rose after an earnings beat and raised guidance, listed with a gain of 13.93%.
  • Revolution Medicines Inc (RVMD) - Advanced 10.84%.

Mid-cap movers (market cap $2B-$10B)

  • Erasca (ERAS) - The company reported positive early trial data for a pan-RAS drug; its shares plunged 47.81% in the session.
  • Live Oak Acquisition (NVTS) - Fell 16.72%.
  • Relay Therapeutics Inc (RLAY) - Down 11.44%.
  • Qiagen N.V. (QGEN) - Shares declined 10.50%.
  • Sportradar (SRAD) - The company named Sameer Deen as chief operating officer, but the stock was down 13.6% in the movers list.
  • Commvault Systems (CVLT) - Bucked the downtrend in mid-caps, rising 11.26% after reporting a fourth quarter earnings beat.
  • Hertz Global Holdings (HRI) - Noted as up 11.7%, reflecting better-than-expected revenue and earnings at a related holding.
  • CECO Environmental (CECO) - Jumped 12% on an earnings beat and an outlook raise; movers list shows an 11.26% gain as well.
  • Kiniksa Pharmaceuticals Ltd (KNSA) - Advanced 20.5%.
  • Puyi ADR (MAAS) - Gained 19.46%.

Small-cap movers (market cap $300M-$2B)

  • Kforce (KFRC) - One of the largest percentage winners, KFRC rose 43.41%.
  • Omnicell (OMCL) - The stock climbed after a strong Q1 beat and a raised profit outlook, listed up 19.48%.
  • Doubledown Interactive Co Ltd (DDI) - Advanced 19.04%.
  • Agencia Comercial Spirits Ltd (AGCC) - Up 17.27%.
  • First Tracks Biotherapeutics (TRAX) - The stock moved higher after H.C. Wainwright initiated coverage with a buy rating, rising 12.43% in the movers list.
  • Kopin Corp (KOPN) - The company was noted for a product and funding update, with the stock up 11.99%.
  • LITX (LITX) - Declined 16.21%.
  • Adlai Nortye ADR (ANL) - Fell 12.98%.
  • Aevex Inc (AVEX) - Down 12.27%.
  • Cree Inc. (WOLF) - Declined 14.86%.

The list of movers in the session also included a set of additional percentage changes that appeared across market-cap segments and repeated within aggregated tables of intraday moves. Those listed include, among others: KO +4.6%, QIA -10.76%, AMAT -4.93%, LRCX -3.01%, RMBS -20.9%, KLAC -3.18%, ZBH -10.55%, MU -3.15%, UNH +3.45%, AVGO -4.27%, WOLF -14.91%, CECO +15.02%, FORM -7.44%, KFRC +43.71%, KOPN +10.11%, OMCL +20.45%, SANM +15.53%, VICR -7.52%, PNR -11.09%, CNC +14.23%, and others that were highlighted in aggregate intraday tables.


Market takeaways

Tuesday's broad-based session underscores the divergence between large-cap tech and semiconductor weakness and select pockets of strength in healthcare, outsourcing and small-cap names that reported better-than-expected earnings, raised guidance, or received analyst attention. Analyst actions and corporate earnings and guidance were primary drivers noted for many of the daily moves.

Risks

  • Analyst downgrades and sector-specific supply concerns - exemplified by Rambus and DRAM shortage worries - can trigger steep share price declines in the semiconductor and memory supply chain.
  • Earnings outcomes and guidance changes create volatility across market caps, particularly for companies in healthcare and manufacturing that reported mixed results or raised guidance.
  • Early-stage clinical data can produce outsized stock moves in biotechnology and mid-cap pharma, as seen with Erasca's large decline despite its trial news, reflecting investor sensitivity to nuanced developments.

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