This interactive donut chart visualizes the distribution of market capitalization across sectors for top Chinese companies, using CSV data on 30 firms. Users can click pie slices or legend items to filter by sector, hover to see tooltips with market cap and percentage shares, and view a summary panel detailing sector statistics. Built with React and D3 v7, it uses the `pie` and `arc` generators, `scaleOrdinal` for color mapping, and a ResizeObserver for responsive dimensions.