Random Fractals and the Stock Market

Surrogates of the Stock Market - Graphs in Three Dimensions

The problem of determining the Trading Time generator from Price vs Clock Time data remains open, though several promising directions are being explored.

This picture illustrates the conversion process in a single 3-dimensional graph.
(We use a simple Price-Clock Time graph for clarity.)
Note how the Clock Time-Trading Time curve compresses the flat regions and expands the steep regions of the Price-Clock Time graph.
Thus the long tails of the Price-Clock Time graph are absorbed into the multifractal time measure.
In addition, the dependence of increments is uniformized to fractional Brownian motion in the Price-Trading Time graph.
That is, the conversion to Trading Time decomposes long tails and dependent increments into different aspects of the graph.
This diagram was designed by the Math 190 class in the autumn, 1998 semester. Energetic discussions with the class transformed our original unclear representation into this.
Originally, the Scientific American editors decided to use this picture for the cover of the February, 1999, issue, advertising the article "A Fractal Walk Down Wall Street." Instead, they selected this.
But what about other applications?
Could biological data, from cardiac arrhythmias to the spread of epidemics, be better understood through conversion to the equivalent of Trading Time?
Almost all complicated systems exhibit irregular time behavior.
Perhaps rescaling in multifractal time will provide important new insights.

Return to Trading Time.