What's New

Add hints on initial screen and Monte Carlo tab screen to give new users an idea of what to do without reading too much. Color-code the Plot/Traces/Report mode switcher button red for noticability, to indicate its importance; and code the Run Monte Carlo button green, because green means go. Add an app preview video for the video mavens in the audience. Change the default "days back to sample" to 252 trading days ~(1 year) to avoid digging too deep into the past for data. After all, the past is past. You may adjust this of course.

App Description

Don't just multiply volatility by root(t), do a monte carlo study and cover the extreme bases. Give the symbol-pushers a run for their money. Can your equation throw in random, out of the ordinary shocks of different magnitude and probability? Well, this app can. MCarloRisk3D: with 3D viewing options for better understanding of the estimated probability surface.

Stock price risk analyzer app for the common man. Now with optional Black Swan events and tunable forward volatility.

Estimates future price distribution using random walk theory.

Background discussion: E. Fama article on early random walk studies from the 1960's:


New model calibration tutorial:


Example use case & training guide for studying "AAPL to $320" can be found at:


The app uses prior data from the stock in question for volatility estimates. 

User can control how far back in time to use historical data to capture only the current "epoch" of a company or of the market as a whole if desired.

Built-in backtesting, verification, and model tuning tools.

-- Details --

This app models daily stock returns as a stable stochastic process and estimates a future price distribution by Monte Carlo re-sampling from an "empirical distribution" of a user-specified subset of prior (known) daily returns. 

Be sure to press the Run Monte button on the Monte Carlo tab after changing settings or downloading a new data set. 

This app downloads historical data from Yahoo Finance as base data to resample. Prices are converted to daily returns [P(t)/P(t-1)] before resampling. The user can choose how far back to resample. By estimating a probability distribution of future prices at the user-specified investment horizon in this manner, we can give risk-of-loss estimates in thumb-rule fashion. 

Reports out estimated price and %loss estimates at the commonly used levels of 1st percentile and 5th percentile (1% and 5% risk). Also reports out median (50th percentile) price estimates at the given number of days forward. Calculations may be performed on Yahoo daily Closing or Adjusted daily Closing price data. An artificial shock filter is provided, which can be used to reject the resampling of prior returns that are artificially large (due to splits or other artificial re-valuations that do not affect the underlying value of the asset).

The stochastic model may be tuned or calibrated only by adjusting the maximum number of days backwards to sample or adjusting the black swan parameters.

Model Validation features:

On the Monte Carlo tab, you can withhold any number of recent days from the model and then plot the results of the stochastic risk forecast as lower-bound envelopes at 1% and %5 estimated probability (risk) levels. 

Validate tab:

This allows you to perform an exhaustive validation on your model by withholding several points, computing the model, comparing the forward prediction of the model versus the actual reserved data, and repeating this in increasing time sequence for all withheld points.

A vertical "Cursor Beam" is provided that you can drag across the new plots in the Monte Carlo tab and the Validate tab to show the plotted values from several curves at once, with the values color-coded to the curves.

Show the full price probability plot linked to the days-forward setting of the Monte Carlo graph. This is a slice thru the probability surface generated by the Monte Carlo procedure.

The app provider makes no claims as to the suitability of this app for any purpose whatsoever, and the user should consult an investment advisor before making investment decisions.

iPad Screenshots

(click to enlarge)

MCarloRisk3D screenshot 1 MCarloRisk3D screenshot 2 MCarloRisk3D screenshot 3 MCarloRisk3D screenshot 4 MCarloRisk3D screenshot 5

App Changes

  • May 03, 2013 Initial release
  • May 09, 2013 New version 2.0
  • May 15, 2013 New version 2.1
  • May 20, 2013 New version 2.2
  • June 07, 2013 Price increase: FREE! -> $0.99
  • June 11, 2013 Price decrease: $0.99 -> FREE!
  • June 23, 2013 Price increase: FREE! -> $1.99
  • June 29, 2013 Price decrease: $1.99 -> $0.99
  • July 04, 2013 Price decrease: $0.99 -> FREE!
  • July 18, 2013 Price increase: FREE! -> $1.99
  • July 21, 2013 Price decrease: $1.99 -> FREE!
  • September 17, 2013 Price increase: FREE! -> $4.99
  • October 10, 2013 Price decrease: $4.99 -> $0.99
  • October 18, 2013 Price decrease: $0.99 -> FREE!
  • June 02, 2014 Price increase: FREE! -> $0.99
  • June 04, 2014 Price decrease: $0.99 -> FREE!
  • June 28, 2014 New version 2.3
  • January 05, 2015 Price increase: FREE! -> $1.99
  • January 27, 2015 Price decrease: $1.99 -> FREE!
  • March 17, 2015 Price increase: FREE! -> $1.99
  • May 02, 2015 Price decrease: $1.99 -> $0.99
  • May 08, 2015 Price decrease: $0.99 -> FREE!
  • November 08, 2016 New version 2.5
  • December 20, 2016 Price increase: FREE! -> $1.99
  • December 28, 2016 Price decrease: $1.99 -> FREE!

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