Here’s another neat (and free!) portfolio analysis tool – PortfolioVisualizer.com. You can upload a custom asset allocation and get all sorts of backtest data and Monte Carlo simulation results from it. If you register for an account, it will remember your model portfolios for future use.
I created a custom portfolio “MMB Default” similar to my current portfolio asset allocation and below are selected charts that were produced. Here’s the summary:
Historical portfolio growth and annual returns. (Note that the time period shown was limited because the available data for Emerging Markets only went from 1995-2017. Apparently there are some ongoing issues with data licensing.)
Historical drawdowns during the same period. This provides a good feel of how “painful” it was to hold this portfolio. 2009 was certainly a stressful year when both our portfolio and future job prospects were being questioned.
Monte Carlo simulation of 4% withdrawal rate over a 30-year retirement period. I used my custom portfolio and had it simulate a withdrawal rate of $40,000 from a $1,000,000 portfolio (4%), adjusted annually for inflation, for a 30-year period. You can alter nearly all of these variables (withdrawal rate, inflation adjustments, period length, etc). Monte Carlo basically looks at many possible trajectories based on historical asset return characteristics. If things turn out well, you end up with a “runaway” portfolio, but if they don’t you can hit zero pretty fast.
The success rate looks at the percentage of simulated scenarios that end up with a positive value at the end of the period. At a 4% withdrawal rate for 30 years, it was 95%. At a 5% withdrawal rate for 30 years, it was only 84%. At a 5% withdrawal rate for 50 years, it was only 69%.
Here’s where I warn you that Monte Carlo simulations are not the end-all of portfolio safety. You can’t predict the next 50 years when you can barely look back 50 years. Living off a portfolio for decades involves not just a reasonable rate of withdrawal but planning as to how you could cut expenses or create additional income if conditions go sour for an extended time period. I’d rather have 90% theoretical safety and a flexible backup plan over 99% theoretical safety and no backup plan.
Portfolio Visualizer has several additional features that I may never use, but even the above is enough to make it a very interesting tool for the DIY investor. I hope they get their data source issues sorted out eventually. You can find all of my posts about portfolio tools in the Tools & Calculators category.