After 2018's artificial growth spike, eMarketer expects increases of more than 50 per cent per year through at least 2020, when Amazon will enjoy 7 per cent of all US digital ad spending. For more than a year now there's been a steady murmur about Amazon's encroachment on the territory of the Facebook-Google duopoly. This year, 57.7 per cent of US digital ad spending will go to one of those two platforms. Amazon may be in third place, but 4.1 per cent is far behind Facebook's 20.6 per cent or Google's 37.1 per cent of market share. In 2020, Amazon's 7.0 per cent share will compare with Facebook's 20.8 per cent and Google's 35.1 per cent of US digital ad spending. So while the gap may be narrowing, the duopoly pillar still stands. Amazon has the ingredients for a truly powerhouse digital ad business, the key to which is doing more than just selling ad impressions. It's impossible to say how much of Amazon's business comes from selling ads on its own properties vs. facilitating ad transactions across the web.