The S&P 500 on any given day is not telling you what American businesses are worth. It is telling you what millions of humans—reacting to headlines, narratives, and each other—are willing to pay for them at that moment.

When Bogle launched the first index fund in 1975, he wasn’t handing investors a scoreboard. He was handing them a compass. The S&P 500 was built to answer one question: “what is the market doing?”

The S&P 500 is 100% equities, 100% large and mega-cap, and 100% domestic. Zero cash. Zero bonds. Zero international exposure. Zero asset class diversification of any kind. It was built to measure one slice of one market in one country.