NYSE AMEX Composite Index - 1998

The following graph plots the year-to-date performance of the index for 1998 compared to the probability calculated by a random walk model.

Initial Value: 684.61 Hist. Volatility: 0.54% Annual Drift: 7% Final Value: 688.99 Percentile: 29%
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 1998 (what's this?).