3. The rule of 100: This thumb rule suggests that the percentage of equity in your portfolio should be 100 minus your age. So, when you are 30, the equity portion of your portfolio should be 70 per cent. When you are 40, it should be 60 per cent and when you are 50, it should be 50 per cent, and so on. This thumb rule is based on the fact that equity investments deliver good returns over a longer time period as market volatilities even out. So at the start of your career, you should have a higher proportion in equity and reduce your equity exposure as you near retirement.