AI stocks reweighted

Companies tied to artificial intelligence now account for roughly 45% of the S&P 500’s market value, up from about 25% in 2022. (spglobal.com) That shift sits mostly in a handful of sectors. S&P Global’s March 31, 2026 sector dashboard shows information technology at 42.8% of the index, communication services at 10.7%, and consumer discretionary at 18.2%, with many of the biggest artificial-intelligence names spread across those three groups. (spglobal.com) The biggest gains have come from chipmakers and cloud platforms. Nvidia was worth about $4.9 trillion in April 2026, while Microsoft was about $3.1 trillion, Alphabet about $4.1 trillion, Amazon about $2.8 trillion, and Broadcom about $2.0 trillion, according to CompaniesMarketCap’s daily rankings. (companiesmarketcap.com) Wall Street’s pitch has changed with the business mix. Instead of focusing only on one-time bursts of spending to train large models, investors are increasingly talking about inference — the steady computing work required every time a user asks a chatbot a question or an application runs an artificial-intelligence feature. (stanford.edu) That matters for revenue forecasts because inference looks more like recurring usage than a single build-out. FactSet said on April 20, 2026 that the “Magnificent 7” were expected to deliver 24.8% earnings growth in calendar 2026, but that falls to 13.2% without Nvidia, below the 15.9% projected for the other 493 companies in the index. (factset.com) The concentration risk has not gone away. MSCI said in a November 2025 stress test that a loss of confidence in artificial-intelligence growth assumptions could trigger a tech-led sell-off, with global semiconductors and other cyclical industries falling as much as 63% in its scenario analysis. (msci.com) The broader market is still leaning on a narrow group of companies for growth. FactSet’s first-quarter 2026 earnings outlook put expected S&P 500 earnings growth at 13.2% and revenue growth at 9.7%, while separate FactSet analysis showed how much that growth rate changes once Nvidia is removed from the largest tech cohort. (factset.com, factset.com) Artificial intelligence is no longer just a story about startups or software demos. In the S&P 500, it has become a question of how much of the index’s value can keep resting on chips, cloud capacity, and the promise that inference demand will stay high. (spglobal.com, msci.com)