If Everyone Buys Index Funds, Who Sets the Price?

If everyone just buys the index, who's left to actually set the price? That's the question no one selling you index funds wants to answer — so I went looking. The honest answer surprised me. What the evidence actually says: - Index funds now hold 55%+ of all the money in U.S. stock funds (2025) — but they're only about 5% of the trading that happens each day. Out of every $21 that changes hands, roughly $1 comes from an index fund. - Owning isn't pricing. The active investors still fighting over price are the ones who set it — the index just copies the number they land on. - Why "everyone just indexes" can't actually happen: the Grossman–Stiglitz paradox (1980). A perfectly efficient market can't exist — because then no one would bother paying to find the price. - The strongest case against all this — price-blind buying, like Tesla's ~$70B forced index inclusion in December 2020 — and the one question I honestly couldn't answer. 📄 Full write-up, with every source you can check yourself: https://medium.com/@moneymindnumbers/if-everyone-buys-index-funds-who-sets-the-price-7c8d4ccf6822 The series so far: ▸ Ep 1 — How Much Does a 1% Fee Really Cost You? https://youtu.be/UIbSfU1E1Zo ▸ Ep 2 — Why Do Index Funds Beat Almost Every Fund Manager? https://youtu.be/p-16zMd5t-4 #indexfunds #investing #pricediscovery #passiveinvesting #stockmarket #personalfinance