Sp500 biggest 100 years of structural changes

A lot of people treat the S&P 500 like it is a passive, mathematical law of nature. It isn't. It is an actively managed, rules-based product run by a committee, and they change the rules whenever the market threatens to break their methodology. Right now in mid-2026, they are quietly rewriting the rulebook to accommodate the incoming wave of massive IPOs like SpaceX and Anthropic. I wanted to break down exactly what is happening now, and rank the most impactful structural changes the index has m