Key Highlights
- Artificial intelligence companies contribute over 80% of S&P 500 performance in 2026; without them, the benchmark index shows only 2% growth
- Wall Street firm Jefferies argues the surge stems from fundamental earnings expansion rather than speculative pricing, labeling AI stocks “the cheapest sector to own” based on PEG ratios
- Forward earnings projections for AI companies have surged over 30% since mid-2025, with anticipated EPS growth rate of 38.5% annually through 2027
- Samsung Electronics achieved $1 trillion market valuation, becoming the latest hardware manufacturer to reach this milestone alongside Nvidia, TSMC, and Broadcom
- Q1 2026 saw 86% of S&P 500 firms exceed earnings forecasts — the highest rate since the pandemic — driven primarily by AI and commodity sectors
The 2026 equity market performance tells a story dominated by one theme: artificial intelligence. Research from Jefferies reveals that AI-related equities have generated more than four-fifths of the S&P 500’s appreciation year-to-date. Remove these companies from the calculation, and the broader index shows a modest 2% advance.
Such extreme market concentration naturally raises concerns among portfolio managers and analysts. However, Jefferies presents compelling evidence that justifies this concentration.
The investment bank’s quantitative research division conducted a thorough analysis of the underlying factors propelling these returns. Their conclusion: fundamental earnings expansion, rather than multiple expansion, explains the outperformance. This differentiation is critical for assessing whether current valuations represent a speculative bubble.
The AI basket’s earnings projections for 2026 have climbed more than 30% since the middle of last year. Market analysts forecast a compound annual earnings growth rate of 38.5% for artificial intelligence companies through 2027. Meanwhile, sectors outside AI face expectations of merely 11.9% annual growth.
Despite this robust expansion, AI stocks trade at approximately 25 times forward earnings. This valuation sits beneath the sector’s one standard deviation band. The price-to-earnings-growth multiple stands at a remarkably low 0.6 times.
“AI is the cheapest sector to own in the U.S.,” Jefferies’ quantitative strategy team stated in their research report.
Performance Divergence Within the AI Ecosystem
The artificial intelligence investment landscape shows significant internal variation. AI server manufacturers, optical component producers, and memory chipmakers have delivered the strongest returns during 2026. Meanwhile, cloud hyperscalers and semiconductor designers have underperformed.
From a valuation perspective, memory and computing hardware stocks appear most compelling based on PEG analysis. Semiconductor manufacturing equipment and chip design companies carry relatively elevated multiples.
First-quarter 2026 earnings season provided additional insights. An impressive 86% of S&P 500 constituents exceeded profit expectations — the highest beat rate since the COVID-19 recovery period, rising from 75% in the prior quarter. Revenue beats reached 82%.
The surprise: these positive results largely failed to trigger stock price appreciation. Companies generally didn’t rally after reporting better-than-expected numbers, except within AI and select other segments. Earnings disappointments, however, triggered significant selloffs, suggesting elevated investor expectations market-wide.
Jefferies analyzed approximately 330 management earnings presentations using the AlphaSense analytics platform. Executive optimism registered at 95%. Analyst sentiment similarly improved, with 58% of conference calls reflecting positive tone versus 48% during Q4 2025.
One recurring concern emerged from these discussions: geopolitical tensions involving the United States and Iran. Roughly 44% of companies mentioned this situation as a headwind, specifically citing supply chain complications and deteriorating consumer confidence.
Samsung Achieves Trillion-Dollar Valuation Milestone
The artificial intelligence boom extends beyond software platforms and chip designers to encompass hardware infrastructure providers. Samsung Electronics recently surpassed $1 trillion in market capitalization, marking its entry into an exclusive group of mega-cap AI beneficiaries.
Samsung now stands alongside Nvidia, TSMC, and Broadcom — enterprises manufacturing the processors, memory modules, and infrastructure that enable AI deployment. Samsung’s valuation milestone stems largely from its high-bandwidth memory products, which serve as essential components in AI computing systems.
The trillion-dollar club previously consisted primarily of consumer-facing technology giants. Apple, Amazon, Microsoft, Alphabet, Meta, and Tesla achieved this threshold through smartphones, cloud services, e-commerce platforms, and enterprise software.
The current expansion wave tilts decidedly toward hardware infrastructure. Nvidia crossed $1 trillion in May 2023. TSMC reached this level in 2024. Broadcom joined before year-end. Samsung’s addition emphasizes memory’s critical role in AI infrastructure.
Berkshire Hathaway and Walmart have also achieved trillion-dollar valuations, alongside pharmaceutical giant Eli Lilly and energy behemoths Saudi Aramco and PetroChina. Yet the most dynamic membership growth currently centers on AI infrastructure providers.
Earnings estimate revisions across the S&P 500 have increased 6% during the past three months. Strip out AI and commodity sectors, and that figure collapses to a mere 0.3%.
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