S&P 500 - 1958

The following graph plots the year-to-date performance of the index for 1958 compared to the probability calculated by a random walk model.

Initial Value: 39.99 Hist. Volatility: 0.75% Annual Drift: 7% Final Value: 55.21 Percentile: 94%
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 1958 (what's this?).