This is an interactive visualization of today's (5/31/2016) stock trading volume of all NYSE stocks with 1-million+ shares being traded (full screenshot), using Power BI. Click on the expand button at the bottom of the chart to expand the treemap view to full screen.
The information visualized here is interesting, e.g. I never realized that Alibaba (BABA) is the 2nd heaviest traded stock on NYSE today. But the real interesting thing here is how easy it is for anyone to visualize data in interesting ways, using Power BI. It took me only a few minutes to build a chart like this and share it out. I will use this as a starting point, and gradually build out a fully featured stock market visualization app using Power BI.