Concentration
Firm
Author
Type
Concentration
March 2026
Stock Market Concentration Has Surpassed Its 1930s Peak. Should Investors Worry?
Morningstar
Dan Lefkovitz
Research
8 Pages
Morningstar's Dan Lefkovitz looks at the top-heavy nature of today’s US stock market and how it compares to the past 100 years.
Markets
March 2026
The Concentration Game
D.E. Shaw & Co.
Research
11 Pages
D.E. Shaw considers the impact of increased concentration on benchmark-relative equity portfolios, both in terms of overall risk and the potential to generate alpha.
Concentration
January 2026
The extreme weight of AI in the S&P 500: Measures of concentration for market cap, returns, earnings, and capex
Apollo
Torsten Slok
Research
39 Pages
Apollo updated their chart book documenting the extreme AI concentration within the S&P 500’s market cap, returns, earnings and capex.
Markets
October 2024
Updating our long-term return forecast for US equities to incorporate the current high level of market concentration
Goldman Sachs
David Kostin
Research
37 Pages
Goldman Sachs predicts that the S&P 500 will deliver an annualized nominal return of 3% over the next decade, placing it in the 7th percentile historically, with high market concentration significantly contributing to the lower forecast.
Markets
August 2024
Investor Memo Q2 2024
Cornell Capital Group LLC
Research
12 Pages
Cornell Capital Group explains why they’re cautious about the market given various valuation and economic indicators.
Markets
August 2024
CONCENTRATE! Is it like 2000 again?
GMO
Ty Cobb, Anthony Hene, Tom Hancock
Research
3 Pages
GMO compares the S&P 500 today to 2000, looking at market concentration, fundamentals and valuations.
Markets
July 2024
Warning Signs
Lyrical Asset Management
Research
6 Pages
Lyrical flags the extreme performance gap between the S&P 500 and its equal-weighted counterpart as a historic red flag.
Markets
June 2024
Stock Market Concentration
Morgan Stanley
Michael Mauboussin, Dan Callahan
Research
18 Pages
Michael Mauboussin looks at the concentration of global markets over the past 75 years and whether fundamental corporate performance supports the current increase in concentration.
Markets
May 2024
200 Years of Market Concentration
Finaeon
Bryan Taylor
Research
13 Pages
GFD looks at the rise of concentration in the U.S. stock market, analyzing 235 years of data.