Post-modern portfolio theory is a way to think about how to build an investment portfolio. It helps you make choices about which investments to include in your portfolio and how much of each investment to put in. In post-modern portfolio theory, you look at how each investment will work together with the other investments in the portfolio and how they could affect each other. You want a portfolio that is diversified, meaning you want different kinds of investments that are not all the same. Diversification will help you spread out your risk of losing money. Post-modern portfolio theory can help you build an investment portfolio that is balanced and that has the right mix of investments for you.