Market Concentration Has Reached Historic Levels
New research shows that just 10 companies now account for 25 percent of developed market equity indices.
Updated on Sept. 25, 2026 in Investing
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Scientific Beta released data showing unprecedented market concentration in global equity indices. The findings indicate that 10 companies now represent 25 percent of a 1400-stock developed markets index.
Why it matters
High market concentration poses significant challenges for investors who rely on traditional market cap weighting for portfolio diversification. This trend leaves many standard benchmarks heavily dependent on the performance of a select few firms.
A 1400-stock developed markets index is now 25 percent concentrated in just 10 companies. Additionally, the United States equity market now accounts for 70 percent of the total global market share.
The players
Scientific Beta
This is a global index provider that offers smart beta and factor-based investment solutions for institutional investors.
The details
The report highlights that the effective number of stocks in US market cap benchmarks has dropped to its lowest level since the 1960s. Scientific Beta suggests five alternative weighting frameworks to help investors reduce concentration risk while maintaining exposure.
Timeline
The research findings were published on September 25, 2026.
US market concentration levels reached a previous low in the 1960s.
Market Dynamics
This research follows a pattern of increasing global index concentration that complicates the Your Future Your Super performance tests for Australian funds. It marks a departure from traditional diversification strategies as US markets grow to dominate 70 percent of global equity.
Retail and institutional investors may face higher portfolio volatility as benchmark performance becomes increasingly tied to a handful of firms. This shift requires investors to assess whether their current index-tracking funds provide adequate protection against sector-specific downturns.
The takeaway
Investors should re-evaluate their reliance on traditional market-cap-weighted indices that may no longer offer expected levels of diversification. Consider exploring alternative weighting strategies to mitigate the risks associated with current equity market concentration.
Further reading
For more context on how market shifts affect long-term strategy, explore our Investing section.
Source note: This article includes information reported by Financial Standard.
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