Shares of social media platform Snap Inc. (SNAP) are trading down 1.9% at $14 on Thursday afternoon following a bearish research note from a team of analysts who expect Instagram, Facebook Inc.’s (FB) rival platform, to continue to dominate its share of advertising dollars. (See also: Facebook’s TBH Buy Is a Bet Against Snap: Cramer.)

Cowen & Co. downgraded Venice, Calif.-based Snap to underperform from market perform in a note published on Thursday, ranking the company the lowest relative to other social media networks. SNAP sank over 6% in early trading as analysts cited a survey of 50 “senior U.S. advertising buyers” suggesting that the company should expect only “modest share gains” in social and video ad buying in 2018 and 2019.

'Lowest Rated' Relative to Other Social Networks 

Blackledge reduced his 2018 revenue expectations for SNAP to $1.1 billion from $1.3 billion, warning investors that the video sharing app, popular among Millennials, is likely to disappoint in the fourth quarter. He foresees the stock falling 21.4% over the upcoming 12-month period to $11.

“On the whole, Snap was the lowest rated relative to other Social networks, given low relative marks on return on investment; targeting; and data, analytics and measurement,” wrote Cowen analyst John Blackledge. “Ninety-six percent of ad buyers would prefer to advertise on Instagram Stories vs. Snap Ads (4 percent), but underscoring the opportunity ahead, more than 50 percent has yet to purchase Instagram Stories ads or Snap Ads."

The analyst also cut his user forecast to “account for a slightly more conservative view” given app redesign and various challenges such as problems with Android devices and penetration in rest of the world (ROW) markets.  

The Wall Street firm wrote that digital ads are positioned to take a larger share of traditional ad budgets through next year. The analysts found that buyers expect digital budget share to rise from 44% of total ad spend in 2017 to 54% by 2019 at the expense of traditional ad mediums. (See also: Snap Has Monetization Challenges: Morgan Stanley.