Stocks making the biggest moves midday: Workday, Generac, Vital Farms, Vicor, Tower Semi & more

Generac surged 19% after securing an Amazon data-center backup-generator supply agreement expected to generate $2.4B of initial deliveries in 2027-28, alongside Amazon receiving rights to buy up to $340M of Generac stock. AI-related names also advanced, with Vicor up 15%, SiTime nearly 10%, Tower Semiconductor about 9% and Arm 9%, while Lucid rose almost 9% after ending restructuring work with advisors. The major negative outlier was Fluence Energy, down 14% after reducing FY2026 revenue guidance to $2.4B from $2.9B-$3.1B and forecasting a $200M EBITDA loss versus prior guidance of a $30M loss to $10M loss.

Analysis

GNRC’s AI-data-center exposure changes its earnings mix more than AMZN’s economics: contracted deliveries create a visible 2027-28 revenue bridge, but the market is likely extrapolating a single-customer award before pricing, service obligations, working-capital needs, and capacity commitments are known. The equity component aligns Amazon but also creates dilution/overhang risk; the key read-through is whether GNRC can turn this into a repeatable hyperscaler qualification. Near-term, Cummins (CMI), Caterpillar (CAT), and Eaton (ETN) face modest competitive narrative risk, while electrical-distribution bottlenecks could preserve their broader data-center pricing power.

The AI hardware moves are not interchangeable. VICR and TSEM offer higher operating leverage to a genuine architecture transition in power delivery and optical interconnects, respectively, but both need design-win conversion into volume production before estimates can move materially. ARM’s demand confidence is supportive of server-CPU share expectations, yet its valuation remains unusually sensitive to royalty-rate evidence and customer deployment cadence; a broad AI-capex slowdown would hit high-multiple enabling names before hyperscalers. SITM’s rating-driven move has the weakest fundamental catalyst absent evidence that AI/server timing content lifts unit growth or gross margin.

FLNC’s reset is more consequential than a one-quarter execution miss: lower revenue and substantially worse EBITDA imply either project mix deterioration, delayed awards, or cost-to-complete pressure. That raises the probability of cash consumption and weakens its ability to bid aggressively against Tesla (TSLA), Wärtsilä and private integrators. Conversely, falling battery-cell costs and grid reliability needs remain structural supports over 6-18 months, but FLNC requires independently verifiable backlog quality, margin recovery, and liquidity disclosure before becoming investable.

Take-private speculation in WDAY and VITL should be treated as event-driven optionality rather than a fundamental rerating. Financing availability, sponsor return hurdles, and any strategic buyer’s antitrust or valuation discipline determine downside once rumors fade. For WDAY, a sustained premium requires credible debt capacity and a bid above the public-market value of its durable subscription cash flows; without that, the most likely outcome is premium decay within weeks.

Key Decisions for Investors

• Initiate a 1-3 month relative-value position: long GNRC / short ETN in equal beta-adjusted dollars only after GNRC holds above the post-announcement breakout for 3-5 sessions. Target 10-15% relative outperformance on follow-on hyperscaler validation; exit if GNRC discloses materially dilutive equity issuance, weak contract margins, or no capacity/booking update by the next earnings call.
• Maintain a watchlist long in VICR and TSEM rather than chase the initial move. Enter on pullbacks only if management identifies production timing, expected revenue contribution, and customer qualification milestones; size for high volatility. The upside is 20%+ on estimate revisions, while failure to convert licenses/agreements into volume orders would likely reverse the momentum premium.
• Avoid FLNC longs and consider short exposure versus long NEE or XLU over the next 1-3 months if updated guidance reveals backlog cancellations, negative operating cash flow, or incremental financing needs. Cover on evidence of stable gross margin and sufficient liquidity through the next project-completion cycle; the risk is a strategic investment or unexpectedly large grid-storage award.
• For WDAY and VITL, do not underwrite rumor premiums as standalone longs. Event-driven desks can use defined-risk call spreads only where implied takeover probability remains below credible deal odds; otherwise, wait for named financing sources, board process confirmation, or a filed bid before acting.