Is the Exceptional Performance of US Stocks Sustainable? Key Takeaways for Investors

New research finds that valuation expansion—not stronger fundamentals—has fueled US stocks’ dominance since 2008.

The persistent outperformance of US equities over international developed markets since 2008 has left investors grappling with allocation decisions. AQR’s 2025 analysis, “Exceptional Expectations: U.S. vs. Non-U.S. Equities,” dissects this trend, offering data-driven insights into its drivers and implications.

AQR’s Antti Ilmanen and Thomas Maloney analyzed the drivers behind US equity outperformance by conducting a detailed decomposition of returns between US and non-US developed markets over the past 35 years.

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