AI stocks push S&P 500 to records as ex‑AI Index stalls
S&P 500 hit record highs in 2026 driven by gains in AI-linked stocks, while an S&P 500 ex-AI index has been essentially flat since February as AI firms make up about 45% of the index.
The S&P 500 reached fresh record highs in 2026, driven by strong gains in AI-linked stocks and large cloud providers. An S&P 500 ex-AI gauge has been essentially flat since February, reflecting a concentration of market gains in a subset of companies.
The headline index has risen nearly 7% since early February and about 15.5% since March 30, with the late-March to April rally led by major cloud and AI-related firms. Investors have focused on those companies on expectations of sustained revenue growth from AI applications.
A version of the index that excludes AI enablers, the US 500 Excluding Artificial Intelligence Enablers Price Return Index (SPXXAI), has shown little net movement since its February launch and is down about 1.84% over that period, according to Google Finance data. Over a three-year window through early 2026, the headline S&P 500 returned roughly 76% while an ex-AI version gained about 32%.
The sector mix of the S&P 500 has shifted: AI-linked firms now account for about 45% of the benchmark’s market capitalization. That weighting means strong performance from a few large names has a disproportionate effect on the headline index while many other stocks have lagged.
Fabien Yip, a market analyst at IG International, noted that outside the AI cluster there is a lack of clear catalysts, and many companies have paused spending plans and updated margin forecasts pending greater clarity on recent geopolitical tensions.
Market participants are monitoring whether the leading AI firms can sustain revenue and profit growth. Continued outperformance by those companies would likely keep the headline index elevated; if momentum slows, the gap between the headline S&P 500 and the ex-AI gauge could widen further.
