S&P 500
The 45% Fragility: S&P 500 Concentration Hits Historic Peak as 'SaaSpocalypse' Looms
The S&P 500, once the ultimate symbol of American industrial diversification, has reached a point of unprecedented structural vulnerability. As of March 13, 2026, the index’s top 20 stocks now account for nearly 45% of its total weight, a level of concentration that surpasses the peak of