$100,000 in the Stock Market According to Monte Carlo

If you have a $100,000 to invest in the stock market, what amount can you expect to have in 10 years?

Average Growth

One way to proceed is to assume you will earn its average historical performance every year. That is a bit shy of 10% growth per year the S&P 500 experienced from 1926 to 2010. Let’s round it to 10%. You can expect to have $259,374 at the end of ten years.

Chart of Growth at 10% per year, the historical average

This is a pleasant chart to contemplate, but we know the stock market can down for entire years. The above chart removes that reality from your consideration.

Monte Carlo Simulation

Another method to look at the future value of a $100,000 portfolio is called Monte Carlo simulation. With it, the chaotic nature of growth and drop the market experiences over the years is brought into play. I segmented the 85 years of market performance (as reflected in the S&P 500) into 9 ranges. There are some years with very bad losses. As the chart shows, in three of those 85 years, the stock market fell between 30% and 50%

Chart of Changes into Intervals
Among these nine intervals, I randomly select a return for the first year, then the second year, and so on until the ten years are done. That is simulation one. I do the same procedure, of course starting with the same $100,000 portfolio for simulation 2 through simulation five.

In the chart below, you can see the variability that your $100,000 goes through in five different scenarios. Poor returns in the early years results in Sim5 only having $51,000 after ten years, while Sim 2 has over $500,000.

Chart of 5 Simulations Range after 10 years is from $51,000 to $503,000

  3 comments for “$100,000 in the Stock Market According to Monte Carlo

  1. Robert Hamill
    June 12, 2011 at 3:11 am

    The simulation doesn’t have a specified starting year. Any year will do.

    The way it works is that the $100,000 ‘pot’ is the starting condition. Then random annual returns are applied year after year.

  2. Aaron Hartson
    June 11, 2011 at 10:29 pm

    Do you have the starting years for the 5 simulations?

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