U.S. display ad spending will more than double by 2017, to $37.36 billion in 2017 from $17.68 billion in 2013, according to new report by research firm eMarketer Inc. And, as the overall market is expected to grow, so is Facebook Inc.’s market share. 

Advertisers have increased their spending on Facebook’s display ads. The social network’s U.S. display ad revenue jumped 61.3% to $5.29 billion from $3.28 billion in 2013. That gain led Facebook’s share of the overall U.S. display ad market to increase from 18.6% to 23.8%. EMarketer expects U.S. marketers to continue moving more of their display ad dollars to Facebook, as it projects the social network’s U.S. display ad revenue will reach $10.03 billion by 2017. That would amount to 26.9% of that overall market.

Twitter Inc.’s market share also is growing, albeit it from a much smaller base. The social network’s U.S. display ad revenue reached $830 million last year, a 93% gain from $430 million in 2013. That meant its market share grew  to3.7% from 2.4%. EMarketer projects the social network’s display ad revenue will reach $2.54 billion by 2017, which would be about 6.8% of the overall market.

Meanwhile, Google Inc.’s market share is falling, a trend that eMarketer expects to continue even though Google’s overall U.S. display ad revenue continues to grow. Google’s U.S. display ad revenue grew 20% last year to $3.05 billion from $2.54 billion in 2013, as its market share fell from 14.4% to 13.7%. EMarketer projects the company’s U.S. display ad revenue will reach $4.13 billion by 2017, which would be 11.1% of the overall U.S. display ad market.

Facebook and Twitter’s growing market share is driven by advertisers shifting their display ad spending to mobile, eMarketer says, thanks in part to the social networks’ strong offerings in the space. EMarketer expects mobile display ad spending in the United States will surpass desktop ad spending for the first time this year. U.S. mobile display ad spending is expected to reach $14.67 billion this year, up 52.0% $9.65 billion in 2014. Meanwhile, U.S. desktop display ad spending is expected to dip 1.4% to $12.38 billion, from $12.56 billion last year.

Facebook is expected to generate $4.91 billion in mobile display ad revenue this year in the United States, up 38.7% from $3.54 billion last year. And eMarketer expects the social network to generate $7.53 billion in mobile display ad revenue by 2017. Similarly, Twitter is expected to generate $1.19 billion in mobile display ad revenue this year in the United States, up 71.5% from $694 million last year. EMarketer expects the social network’s mobile display ad revenue to reach $2.29 billion by 2017.