NYSE AMEX Composite Index - 1999

The following graph plots the year-to-date performance of the index for 1999 compared to the probability calculated by a random walk model.

Initial Value: 688.99 Hist. Volatility: 0.8% Annual Drift: 7% Final Value: 876.97 Percentile: 90%
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 1999 (what's this?).