alt Hacker NewsIf a significant percentage of the market is excluded from the index because they don't meet index inclusion criteria, then then index stops being a useful benchmark.
If you change a benchmark whenever you think it'll be 'wrong', then it becomes a measure of the heuristics you use to predict what'll impact the benchmark rather than a benchmark in its own right.
S&P claims their S&P 500 product is the "best single gauge of U.S. large-cap equities". For this benchmark to be accurate, at a fundamental level, this benchmark has to follow the market and reflect current market conditions.
The market decides what the large-cap U.S. equities are, not S&P. If S&P excludes some of the largest U.S. companies, which based on their current rules, will exclude all of Anthropic, SpaceX, and OpenAI; then they do a poor job reflecting the benchmark they claim to follow.
It's not S&P's fault that market conditions have changed.