The visualization animates the stock prices of Microsoft, Amazon, and IBM from 2000 to 2010, first drawing line charts that sequentially reveal price movements over time, then transforming each chart into a series of stacked horizon areas. The animation uses `d3.timer` to progressively draw the lines, followed by `transition` to shift the line charts into layered horizon plots with varying fill opacities. The code relies on `d3.svg.line`, `d3.svg.area`, `d3.csv`, and `d3.nest` to parse and structure the dataset, while `d3.time.scale` and `d3.scale.linear` handle the axes.