<prompt> Human: I owned my home. Bought a new home and just sold the old one. What is the best use of the funds? My primary debt is the mortgage on the new house which cost about twice what the old one did. No credit card debt, no car loans or other loansdebt of any type so nothing else to pay down. I also already maximize my retirement savings so that is kind of in order as well.Should I just put all of the money into the new mortgage, invest in something all in index funds? Maybe a split of things with varying levels of risk?, buy a few hundred thousand lottery tickets kidding!... what is the best approach? The total I have to work with is in the low 6 figures.  <response>: A thought experiment. The mortgage assuming 4 interest is basically a 4 guaranteed return. The question is this:If you didnt have a mortgage, would you take out a 100K loan at 4 in order to invest the money?If yes, go for it. If no, get the mortgage down.In reality, the answer is probably a happy medium based on your age, similar to how your normal investments would be divided between high and low risk. If youre 50, you probably want to put more towards mortgage to insulate yourself from the volatility of the market. if youre 25, you probably want to put more towards risky investments. 