ETFs and indices · updated October 21, 2026
What assets under management (AUM) mean for an ETF
Assets under management (AUM) are the total money invested in a fund by all its investors. They tell you how big and widely used the fund is, not how good it is.
How it works
AUM is calculated by multiplying the number of fund units by the value of one unit. It grows when new money comes in or when the stocks in the fund rise, and shrinks the other way round.
How to read assets under management (AUM)
Large funds usually have lower costs and a smaller gap between the buy and sell price.
When assets under management (AUM) can fool you
Big does not mean good: a fund can be big just because it is old or heavily marketed.
Related terms
Questions about assets under management (AUM)
What happens if a small ETF closes?
The fund sells its holdings and pays you out at that day's value. You do not lose the money, but you may owe tax on the gain and you have to reinvest.
These explanations are for information only. They are not a recommendation to buy or sell.
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