 Amazon's two-day shopping extravaganza, Prime Days, is now underway. It's expected to reinforce Amazon's dominant position in e-commerce and retail. In just the first seven hours of the deals, sales were up 12% over last year at the same time. That's according to Momentum Commerce. And Adobe estimates that Amazon is not the only company benefiting. Estimated online sales across all retailers over the two-day event are expected to total $14 billion, up almost 11% from last year.