US stock market wealth concentration revealed in century-long study

An analysis of US stock market performance from 1926 to 2025 reveals extreme wealth concentration driven by a small number of highly successful companies. Research by Hendrik Besenbinder of Arizona State University shows that while the US stock market created $91 trillion in net wealth over this century, the vast majority of this gains came from a tiny fraction of total stocks.

Data indicates that only 27.6% of stocks outperformed the broader market, while nearly 60% of stocks actually destroyed shareholder wealth, with a median lifetime return of -6.9%. The distribution follows a power law: just 46 companies contributed half of the total net wealth created. In recent years, the concentration of wealth creation has accelerated, with top tech companies like NVIDIA, Apple, Microsoft, Alphabet, and Amazon contributing significantly more to market gains than the industrial giants of the previous century.

While the historical average annual return is often cited around 7% when adjusted for inflation, the expected annual return is approximately 9.15% due to the mathematical distribution of returns. The study notes that the winners in the market are often characterized by their ability to sustain high returns through compounding, whereas the highest annual growth rates are often unsustainable over long periods.