### How to figure out whether it was profitable to invest in S&P 500.

Let's say You made a choice to buy shares in funds, such as iShares or Vanguard.
And you already have looked at the graphs of hypothetical index growth.
But nobody knows whether the next few years will be boom years or crisis' years.
All we can do now is to try to predict the most likely outcome.

There are two ways to see the future. The first one is to visit a fortune teller.
The alternative approach is to use historical data.

The following is the service that evaluates the past, but it's not a prediction.
The algorithm generates a lot of scenarious by using historical prices and different start dates
(see the chart "Input data for calculation"). You can set the historical period and investment period.
After you start calculation algorithm will select different start dates throughout the history
and on that basis calculate return on investments.

The result panel contains two fields: average historical income and lower limit of confidence interval.
The graph below shows historical probabilities of different investment returns. The higher bar, the higher probability.
The level of return you want to get probability see along the x-axis.