The moving average of a stock can be calculated using .rolling().mean(). The moving average will give you a sense of the performance of a stock over a given time-period, by eliminating "noise" in the performance of the stock. The larger the moving window, the smoother and less random the graph will be, but at the expense of accuracy.
The following sample calculates the moving average for MSFT over 30- and 90-day periods, using the daily close value. The difference in the reduction of noise can be easily determined from the visual: