Facebook Inc. (FB) and Alphabet Inc.’s Google (GOOG) aren’t players in ecommerce, but they still have to worry about Amazon.com Inc. (AMZN) and its growing advertising reach that could eat away at their ad revenue.

That’s the assessment of BMO Capital Markets analyst Daniel Salmon, who said in a research note Tuesday that Amazon’s advertising business is “gaining significant momentum” that will result in Amazon taking share from Google and Facebook. The analyst is projecting that Amazon’s advertising segment has the potential to boost sales by 65% this year, hitting $3.5 billion.

"A key point of differentiation for Amazon [from competitors] is the massive amount of consumer purchase data it possesses," Salmon said in the note to clients covered by Yahoo Finance. "While Google knows what people are searching for and Facebook knows what people are interested in and who they are connected to, Amazon knows the specific products that customers are purchasing and how frequently they are purchasing these products." On Monday, BMO cut its investment rating on Google parent Alphabet to market perform from outperform.  (See also: Google and Facebook Run 57% of All Digital Advertising Worldwide.)

New Area for Domination?

While Amazon has long been the dominate force in ecommerce, turning the retail industry on its head, it hasn’t been a juggernaut in online advertising like Google and Facebook are. But with that area of its business growing, it could create pain for the two going forward. After all, Amazon has a reputation for entering a market, disrupting it and eventually dominating.

For now, Google and Facebook seem to be more than OK from an ad revenue perspective. Last month, market research firm eMarketer predicted the amount of money going to U.S. digital advertising in 2017 will increase nearly 16%, reaching $83 billion, with Google and Facebook the main beneficiaries of the increased spending. eMarketer is forecasting Facebook’s display-ad business in the U.S. will increase 32.1% this year, hitting $16.33 billion, with Facebook accounting for 39.1% of the market share. eMarketer said the growth in ad spending on Facebook can be attributed to an increase in the number of users and the time the users are spending on the social network, which in turn draws more advertisers. What’s more, eMarketer said Instagram is driving growth in advertising for Facebook, its parent. eMarketer said Google’s market share will increase 16.1% to $28.55 billion in 2017, with Google claiming close to 78% of the total search ad revenue in the U.S. this year. Wall Street has been getting even more bullish on Facebook because of its advertising prospects with one analyst recently saying Facebook could monetize its WhatsApp messaging app and Oculus, its virtual reality unit, via ads.