A heat map is a graphical representation of price data where the individual values are shown in a matrix and prices are represented as colors. The darker the green color, the stronger the stock performance. The darker the red color, the weaker the performance. Stock shown in white have not moved from their previous close price.
You can click on any of the squares in the heat map and the symbol represented by the color will be shown in the Symbols List.
The symbols shown in the heat map represent those in the Symbols List. Filtering the symbols list results in a similar filter on the heat map.