U.S. stock market breadth has hit a three-month low, with only a handful of major stocks driving market gains. The S&P 500 and Nasdaq saw strong gains driven by tech giants like Meta, Apple, Google, Microsoft, Amazon, Nvidia, and Tesla (MAG7) — while the majority of stocks remained weak. This dynamic raises concerns about the sustainability of current market trends. 100-day moving average crossing is at its lowest point in three months and indicates a potential weakening in broader market momentum. A closer look reveals that this rally is primarily fueled by just these handful of large-cap stocks, leaving many other companies lagging. This narrow participation often triggers concerns from analysts and investors who see a potential lack of underlying market strength behind the impressive headline gains.