Stats › Concentration and breadth › Index concentration
Ten companies hold 38.5% of the S&P 500
The ten largest constituents hold 38.5% of the S&P 500's market capitalisation. The remaining 493 hold 61.5%. Source: S&P Dow Jones Indices factsheet, 30 April 2026.
The S&P 500 weights its five hundred American companies by market value, so the largest carry the index. The ten biggest now hold 38.5% of it, against about nineteen percent in 1990. An index fund is a far narrower holding than the name suggests.
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