What Is a Stock Market Heatmap?
StockMapper is a free, live stock market heatmap. This page explains how treemaps work and how to interpret what you see on the map.
Heatmaps turn the market into a map
A stock market heatmap (or treemap) shows many companies at once as colored rectangles on one screen. Instead of scrolling through hundreds of tickers in a table, you see the whole index — usually grouped by sector — with the biggest names taking the most space.
How to read tile size
Each rectangle’s area represents something you choose: typically market cap, trading volume, or daily price change. Large tiles are the heavyweights in that view; small tiles are still visible but matter less for the metric you picked. On StockMapper you can switch size modes from the toolbar.
How to read tile color
Green means the stock is up for the selected period (usually today); red means it is down. Brighter or deeper shades often reflect larger moves. At a glance you can spot which sectors are leading or lagging — for example, when tech tiles are mostly green while energy is red.
Sectors and drill-down
Tiles are grouped into sectors (Technology, Health Care, Financials, and so on). Click a sector to zoom in and see every stock inside it. Click a stock to open a live candlestick chart. Use the breadcrumb to step back out to the full map.
Why use a heatmap?
Heatmaps are popular with traders and investors because they compress a lot of information into one visual. You can quickly answer questions like: Who moved the market today? Which sector is hot? Where is volume concentrating? StockMapper offers this for the S&P 500, Nasdaq 100, global indices, crypto, ETFs, and more — free, with no login required.