Are ETFs index funds?

Some are, many aren’t.

An index fund is defined by its strategy: it aims to track an index (like the S&P 500). An ETF is defined by its wrapper and trading mechanics: it’s a fund that trades on an exchange. Those two ideas overlap a lot, which is why many of the biggest ETFs are index-tracking ETFs.

But ETFs can also be:

Actively managed (a manager makes ongoing decisions about holdings)

Rules-based but not “classic index” (smart beta, factor strategies)

Focused on specific exposures (bonds, commodities, sectors, themes)

So the clean mental model is:

Index fund = strategy

ETF = vehicle You can have index ETFs, active ETFs, and you can also have index mutual funds (index strategy inside a mutual fund wrapper).