NASDAQ Composite Index - 1973

The following graph plots the year-to-date performance of the index for 1973 compared to the probability calculated by a random walk model.

Initial Value: 133.73 Hist. Volatility: 0.42% Annual Drift: 7% Final Value: 92.19 Percentile: MIN
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 1973 (what's this?).