Assets under management (AUM) are the overall market value of assets that a mutual fund holds. The fund manager manages these assets and takes investment decisions on behalf of investors. AUM is an indicator of the size and success of a fund house. AUM fluctuates on a daily basis, depending on the flow of investor money in and out of a particular fund and asset performance. Increased investor flows, capital appreciation and reinvested dividends will increase the AUM of a fund. Adversely, decreased investor flows, investment pullout and market losses will decrease the AUM of a fund.