Online display advertising spend in the US will grow 70% from $42 billion this year to $72 billion by 2021, propelled mostly by social media ad spend, according to Forrester’s annual Online Display Advertising forecast, released Wednesday.
As mobile adoption continues to surge, Forrester predicted, social ad spend will reach $40 billion by 2021, and platforms like Facebook, Instagram and Snap will command more of marketers’ budgets.
Although Facebook controls the lion’s share of that ad spend, or close to 80% of total ad revenue in social in 2016, Forrester sees marketer dollars beginning to diversify as platforms like Snap add APIs and self-serve buying options, and as other walled gardens like Amazon launch audience-based offerings.
Forrester estimates Amazon will surpass $2.5 billion in ad revenue in 2021, further disrupting the Google-Facebook duopoly. (Other estimates are higher, but it’s unclear how much Amazon really makes because it doesn’t split out ad revenue.)
Platforms are going strong because they can measure ad deliverability, viewability and other key advertiser metrics, said Forrester research analyst Samantha Merlivat, the principal author of the report.
Even though Facebook has faced its fair share of concerns, from its US Census snafu to claims of overinflating video metrics, marketers still see Facebook as an inherently measurable and performance-driven environment, she said.
“We’re seeing more money spent in environments where there’s the perception that these issues are better monitored,” Merlivat said.
For advertisers, the ability for walled gardens to measurable performance trumps their disadvantages – namely, the difficulties of horizontal attribution or lack of data exportation.
Forrester also expects mobile to overtake desktop display ad spend by 2019 as advertisers increasingly invest in mobile video and other in-app formats.
“I would say a lot of advertisers still see desktop display as the foundation of everything they do and mobile as an add-on,” she said, “but it’s becoming clear that going forward, advertisers need to flip that around and really be mobile-first in the way they plan digital display.”
Forrester’s findings echo Zenith’s ad expenditure reports, which earlier predicted social, in-feed ads and other digital formats like native and mobile video would overtake standard display.
Zenith predicted total US display expenditures will grow from $84 billion in 2016 to $126 billion in 2019.