A third of the revenue come from co-op budgets, where Amazon promotes a brand's products based on how well an item is selling.
Amazon's ad business continues to fascinate brands as an alternative to the duopoly of Facebook and Google.
Amazon is proving to be the sleeping giant of advertising.
Amazon made roughly $9 billion from advertising spending in 2018 (bucketed as "other" revenue in the company's earnings) and is expected to hit $38 billion in the category by 2023, more than quadrupling in five years.
Read more: Amazon wants to give Facebook and Google a run for their money in advertising — here are the 6 execs making it happen
Retailers are putting sales dollars into advertising