The S&P 500’s recent six-week rally has been led by a small group of large-cap stocks, narrowing market breadth and sparking pullback risks.
The S&P 500 has surged over the past six weeks, but the gains are concentrated in a handful of large-cap stocks, raising questions about the rally’s sustainability. The cap-weighted index has outperformed its equal-weighted counterpart, which assigns equal influence to all companies, highlighting the dominance of mega-cap names in driving returns.
Earlier this year, the equal-weighted S&P 500 outperformed the cap-weighted version, with the latter down nearly 8% year-to-date through late March. However, the cap-weighted index has since rebounded sharply, overtaking the equal-weighted measure. Historical data since 1975 shows that such narrow leadership often precedes market pullbacks.
Analysts are examining whether this pattern signals potential weakness ahead, as similar periods of low relative strength in the equal-weighted index have historically led to corrections.