Alex DeGroote, a media analyst at Cenkos Securities, estimates that North America's advertising market represents about 40 percent of the global total or around $200 billion currently. He said Amazon is about $3 billion of this now, amounting to around a 1.5 percent market share. Given the growth DeGroote is expecting by 2020, Amazon could soon have an $8 billion share in North America, and globally that would equate to $20 billion.
Amazon's strength would be in search advertising rather than display, according to DeGroote. This is because of the massive amount of products it lists on its platform. Potential companies that sell through Amazon could pay the e-commerce giant to have their products featured prominently when someone searches for something.
"I think Amazon will do retail search and take Google to the cleaners on retail search using their estate," DeGroote told CNBC in a recent phone interview.
"Slowly over time you will use Amazon as your retail search engine rather than Google."
Google and Facebook currently rake in the majority of digital ad spending globally. Google is expected to have 80 percent of the U.S. search ad market in 2018, according to eMarketer data. But evidence is growing of Amazon's increasing interest in this space. CNBC reported in December that Amazon was looking to step up its ad products in search and video. Martin Sorrell, CEO of WPP, the world's largest advertising firm told CNBC in January, that it was increasing its spending on advertising on Amazon from $200 million in 2017 to $300 million this year.