The eye-catching performance of some of the world’s largest stocks has led to them becoming fixtures in investors’ portfolios. Whether that exposure comes via market-cap-weighted funds or direct ownership, the stocks' collective gains have overshadowed the roughly 2,500 other U.S.-listed stocks that do not meet the criteria for inclusion in the S&P 500.
But this year, a dramatic and structural shift in the markets has favored smaller, more nimble firms whose stocks have generated gains that have markedly outpaced their larger peers.
