Indeed, in the first half of 2025, non-US equities posted their strongest relative start to the year in decades, with several global markets outperforming the US. While the US was ranked the best-performing market consistently between 2010 and 2022, it had slipped to 11th place by May 2025. This rotation in performance leadership, Acadian notes, is not an anomaly but rather a return to the norm. “The prior run of US market dominance is the historical exception, not the rule,” the firm explains.
After more than a decade of exceptional performance by US equities, global leader in systematic and quantitative investing Acadian Asset Management believes the tide has turned. The asset manager argues that the case for global diversification — once side-lined in the shadow of American market dominance — is now stronger than it has been in years. Slowing earnings growth, stretched valuations, a weakening dollar and reduced financial market integration all point to a world where US equities may no longer justify their outsized presence in global portfolios.
“For many years after the Global Financial Crisis, US equity markets enjoyed tailwinds that led asset owners to wave the white flag on global diversification,” says Acadian. “But these tailwinds have abated.”
