AUM (Assets Under Management)

A fund's AUM reflects how much money investors have collectively put into it - a larger, well-established AUM can signal investor trust and often better liquidity/lower per-unit operating costs, but an extremely large AUM in certain fund categories (particularly small-cap funds, where there are only so many genuinely attractive small companies to buy) can sometimes make it harder for a fund manager to deploy new money as effectively. AUM alone says nothing about a fund's actual returns, risk, or fit for your goal - it's a size metric, not a performance or quality metric.