It may come as a surprise to many, but Amazon tops the list of companies spending the most on programmatic ad buys, according to a recent study.

MediaRadar, which offers detailed analysis on brands, released the results of a new study, analyzing the top programmatic spenders.

Amazon accounted for 10% of funds spend on programmatic when analyzing the top 50 companies spending on programmatic advertising in first-quarter 2018. The company spent about 1.5 times more than the next-biggest programmatic spender, Microsoft.

Marketers will spend more than $46 billion on programmatic advertising in the U.S. in 2018, with 86.2% of all digital display ads bought programmatically by 2020, estimates eMarketer. The research firm forecasts mobile programmatic ad spending will reach $32.78 billion, or 70.4% of all programmatic digital display outlays in the U.S. — this year.

To determine how much companies spent, MediaRadar used its platform to examine thousands of brands placing ads across the web programmatically in the first quarter of 2018. Then it compared those numbers to the year-ago quarter to determine annual changes across the category.

MediaRadar found that 75% of all brands buy online advertising programmatically

Wayfair took the No. 3 spot, followed by TaxAct, Charles Schwab, Weight Watchers, Spring, Coors Light, Geico, and Dell.

MediaRadar’s analysis also notes that 94% of the companies in the top 50 ran programmatic ad placements in the first quarter of 2018. Those companies include Walmart, Microsoft, and Verizon.  

The amount spend on native placement of programmatic ads continues to rise too. Of the brands that ran native ads in the first quarter of 2018, 42% placed all of their native programmatically — up 10% compared with the year-ago quarter.