Our chart of the week looks at how the makeup of the largest U.S. companies has shifted dramatically over the past four decades. In earlier decades, the top names in the S&P 500 index were dominated by blue-chip companies in energy, consumer staples, and financials. Today, that list is led by technology and growth-oriented businesses such as Apple, Microsoft, and Nvidia, representing nearly 40% of the S&P 500 index. Only one company, Microsoft, was among the top names 20 years ago. While it may seem hard to imagine these companies being dethroned given their relevance to our everyday lives, history shows that leadership changes are inevitable. This evolution underscores that disruption has always been part of investing and will continue to shape market leadership in the years ahead.