Assets under management (AUM) is the total market value of the investments that a person or entity manages on behalf of clients. Assets under management definitions and formulas vary by company.You can use assets under management to assess how much money you need to invest in order to reach your financial goals. It's also an important metric for personal finance, because it shows how much money you have spent on investments over time and what the return was from those investments.The amount of assets under management is calculated by multiplying the total value of all your assets by their respective percentage values.