Which stocks are in play for the day, attracting significant volume--and hence movement? This heatmap from FinViz organizes stocks within sectors and color codes them based upon their relative volume: the proportion of volume traded today relative to its normal volume at that time of day. Light blue means that we're trading much above average relative volume; black means much below average. The sizes of the boxes correspond to the weighting of each stock within the sector. Excellent tool.
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