Last week I investigated Amazon's dominance of overall ecommerce sales. Following that, I thought it would be interesting to investigate the details of this dominance. As you can see, Amazon's sales are buoyed by its dominance of Computer and Consumer electronics sales. Amazon has a majority of sales in one other market - books/music/video, where it has 83.2% of all ecommerce sales. This makes sense, as this is the very category that Amazon began with.