It may be used as a benchmark, but that’s not actually the purpose of it. The purpose is to serve as a way for people to invest in a representative sample of the market. It can still be a representative sample with safeguards. If you want a benchmark without safeguards, you can calculate one without risking millions of people’s life savings.

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tristanj 3 hours ago | parent [-]

You have your history backwards. The S&P 500 was created in 1957 as a benchmark. The first investable index fund tracking it (Vanguard's) wasn't created created until 1976. Vanguard created their fund to track the benchmark, not the other way around.

And if you need a second, different index to function as the true market benchmark because the S&P 500 no longer reflects the actual market, then you just agreed the S&P 500 is no longer an adequate benchmark. You just agreed with my point.

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phlakaton 2 hours ago | parent | next [-]

Because it's selective, the S&P by definition does not reflect the actual market. It reflects a subset of it.

If you're comfortable with this notion of what the S&P does, then you ought to be comfortable with S&P applying the same methodology they've always used. There are other indexes you can reference if this particular sampling of the market isn't to your personal liking.

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tristanj an hour ago | parent [-]

The S&P's historical inclusion criteria were designed to filter out unstable, illiquid questionable companies to get a view of large-cap US equities. That logic worked when every major American company was public and profitable.

That's not true any more. Today we have multiple giga-caps (SpaceX, Anthropic, OpenAI) vying to IPO, all of which potentially in the top 20 largest companies in the US market, all ineligible for S&P 500 inclusion because of the 12-month profitability rule.

You claim S&P can "apply the same methodology they've always used" but this is just factually wrong. The inclusion criteria are not sacred rules set in stone and S&P has rewrote them multiple times. For example, they banned dual-class share structures in 2017 to stop SNAP from joining the index, but reversed it in 2023 because they excluded too many companies. The rules get rewritten when the market changes, and it's clear the current market environment has changed.

Meanwhile, Nasdaq changed their rules to handle this situation. And S&P changed the inclusion criteria for the S&P Total Market Index so SpaceX would be included.

It's clear these inclusion rules are changing.

	▲	ywvcbk 36 minutes ago \| parent [-]
		> out unstable, illiquid questionable So Space X, OpenAI, Anthropic? Those are perfect examples. It's unlikely their valuations could survive the IPO if their float wasn't extremely low. > top 20 largest companies in the US market You do know that S&P weights are based on the free float and not the market cap. So based on that SpaceX etc. will not be in the top 20. The total value of shares of Johnson & Johnson available on the public market will be much higher than that of SpaceX/etc. based on their current valuations.

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ywvcbk 42 minutes ago | parent | prev [-]

> the S&P 500 no longer reflects the actual market

Well it was never intended to reflect the full "actual market".

> no longer an adequate benchmark

According to your definition it never was. However there were and are plenty of other index benchmarks which serve different purpose. Its just that S&P 500 managed to become the most popular one, why did it happen if it was always inherently flawed?

Like they didn't even add Microslop for 8 years...