What is an ETF's AUM?

AUM, or assets under management, is the total value of all assets held by an ETF. It grows or shrinks based on market performance and investor inflows/outflows.

AUM can be a proxy for popularity and stability. Larger ETFs often have better liquidity and tighter spreads, though that's not guaranteed.

Small AUM isn't automatically a dealbreaker, but very small ETFs are more vulnerable to closure. If you want to reduce closure risk and improve trading quality, higher AUM can be a helpful signal.