If you want to model a change in the return on your investments, there's an option to click future change of return.

Of course if this is something you know will happen, just move your money to the Total Bond fund (AGG index) which earned 11%, 8.5%, and 8.25% in 2000-2002 when stocks were earnings, respectively, -11%, -11%, -20%. In 2008 it was 5% vs -37%. That said, I realize you are just asking how to model a "what if."

In the new MaxiFi Planner with its new Monte Carlo, it will run risk analysis on the variance and return features of your asset classes.

Best,

Dan

See post titled "How to input possible market fluctuations" dated 3/3/18 for comment on creating your own asset classes with specified rate of return assumptions. I'm hoping the new Monte Carlo feature in MaxiFi will allow this.