This example demonstrates data transformation by fetching a CSV file of stock data, parsing it with `d3.csvParse`, and grouping the records by industry using `d3.flatGroup`. It then counts the number of stocks per industry and displays the resulting summary as a JSON string in a `<pre>` element. The visualization uses D3 v7's selection and join APIs to render the computed counts, showing a simple text-based aggregation of the underlying dataset.