Using established guidelines is a way for many people to simplify their financial lives. For example, when they don't know how to divide up their assets in a portfolio, they'll use the "rule of thumb" of "100% - your age" to decide the portion of their assets that they should have in stock. (Your age would be the fixed income portion.) For example, if you were 60 years old, you might hold 40% of your assets in stocks and 60% in bonds. Search This Site: