By Caitlin McCabe
When the S&P 500 was introduced nearly 70 years ago, it was designed to represent a wide swath of the U.S. economy. These days, it's feeling a lot less balanced.
Call it the AI-fication of the S&P 500, in which a handful of companies now exert outsize influence over the benchmark index. According to Dow Jones Market Data, the 10 largest companies in the S&P 500 now represent 43.2% of the index's total market value.
That's a sharp change from even just a few years ago. At the end of 2020, that figure stood closer to 29%, according to a report from RBC Wealth Management earlier this year. Back in 1990, when the 10-largest list included companies like General Electric and Philip Morris, that share was 19%.
The growing concentration is a function of AI enthusiasm in financial markets.
RBC noted in its report that, unlike during past stock-market booms, "the largest constituents of the S&P 500 are highly profitable businesses with strong balance sheets, durable competitive advantages and substantial free cash-flow generation." It added that elevated concentration alone isn't sufficient evidence of a bubble.
Still, it's something worth watching, RBC said. One reason why: If AI enthusiasm reverses, "there are fewer offsetting exposures within the index to absorb the impact," the report said.
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(END) Dow Jones Newswires
June 01, 2026 09:15 ET (13:15 GMT)
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