This visualization displays multiple time-series lines as filled areas, each representing a stock symbol over time, with overlapping semi-transparent regions stacked by date. It uses D3 v4 to fetch CSV data from an external gist, parse dates with `d3.timeParse`, and nest records by symbol. The chart draws smooth areas via `d3.area` with a basis curve, maps dates to an ordinal time scale, and values to a linear scale, including axes and a color-coded legend with opacity. A custom calculation sets each point’s lower price based on the maximum lower value among other symbols.