US small caps are set to outperform as capital rotates down the cap structure, as it does when a bull market broadens. After years of lagging megacaps, small caps historically run hardest in the back half of a bull, once megacap leaders are extended. Breadth is widening, with over 30% of S&P 500 members beating the index in 2025, the best since 2021. The Fed is easing into strength, and rate cuts that lower discount rates and cheapen financing especially help small caps and long-duration growth. x.com x.comÂ