US Stock Market Concentration Has Surpassed Its 1930s Peak. Should Investors Worry?

The US stock market is currently experiencing a level of concentration in its top 10 stocks that has surpassed its 1932 peak, drawing parallels to the “Roaring '20s” due to technological transformations, high wealth inequality, and increased credit. While this concentration doesn’t automatically signal a bubble and has historically led to strong returns, it does heighten risk by eroding diversification and making markets more sensitive to sentiment shifts. The author suggests investors consider diversification strategies, such as selective stock-picking, equal-weighting, or balancing US exposure with international equities and other asset classes, to mitigate these risks.