NYSE AMEX Composite Index - 2008

The following graph plots the year-to-date performance of the index for 2008 compared to the probability calculated by a random walk model.

Initial Value: 2409.62 Hist. Volatility: 2.64% Annual Drift: 7% Final Value: 1397.53 Percentile: 15%
Click on the image for the high resolution version.

The high to date and low to date prices of the stock plotted against a random walk model for 2008 (what's this?).