I want to design a hypothetical portfolio containing a large number of stocks with widely varying position sizes, and I would like to be able to determine as I am designing the portfolio precisely what percentage of the portfolio each stock occupies without having to do the math myself. So I am looking for a spreadsheet that will display (and automatically update) position size percentages when I enter, or change, the number of shares for each stock in the portfolio. I've been searching the web but so far I haven't been able to find a spreadsheet that displays or updates percentages of position sizes. But this seems like such a basic and useful function that I imagine one must exist?? Is anyone familiar with software or a spreadsheet that can do this?