S&P 500 - 1971

The following graph plots the year-to-date performance of the index for 1971 compared to the probability calculated by a random walk model.

Initial Value: 92.15 Hist. Volatility: 1.3% Annual Drift: 7% Final Value: 102.09 Percentile: 60%
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 1971 (what's this?).