EquitiesDeep DiveS&P 500 Growing Concentration: What Has Changed and Why It Matters?The S&P 500 includes hundreds of companies, yet its ten largest holdings accounted for over 40% of the index's total weights in 2025, more than double their share a decade earlier. What does this growing concentration mean for market performance, diversification, and investors?28 October 2026 · 12 min read