Assets under management or AUM is a widely-tracked statistic in the mutual funds (MF) industry. It is the sum of all the money and value of securities that your fund house manages. The AUM moves on two factors--the sum of value of all the securities held by the scheme and the investor money flowing in or out. A rising AUM indicates good performance of the fund manager or popularity among investors or a combination of both. A scheme’s own AUM also dictates how much expenses it can charge to investors; higher the AUM, lower will be the expenses.