This is a tool for tracking cost basis of stocks. Brushing the range chart at the bottom recalculates the cost basis for having purchased $1 of each of the displayed stocks. It is also good for comparing the performance of different stocks over a specified period of time.
The data is pulled from Yahoo finance through a herokuapp I forked from Rob Wu‘s cors-anywhere. I also added sound by attaching oscillators to each of the stocks when they are drawn, that fluctuate along with the stock when you mouseover the chart or click the play button.
You can manually enter a stock that isn’t in the select menu, but not while viewing it through the Bl.ocks.org interface, you have to go here or here.