Vanguard Sht Term Govt Bond ETF - 2015  (Inactive Symbol)

The following graph plots the year-to-date performance of the stock for 2015 compared to the probability calculated by a random walk model.

Initial Value*: $60.2 Hist. Volatility: 0.06% Annual Drift: 7% Final Value*: $60.5 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 2015 (what's this?).