Ad spending on sponsored content is growing at a faster clip than originally thought, according to a new forecast from eMarketer.

In June, eMarketer said advertisers would spend $1.88 billion on sponsored content this year, a 22.1% boost from 2012, and would get to $3.08 billion in spending on sponsored content by 2017. The new forecast predicts that marketers will spend $1.9 billion on sponsored content this year, a 24% hike from last year, and devote $3.2 billion to the tactic by 2017.

The uptick reflects publishers' attempts to create more bespoke advertising products for brands, according to eMarketer analyst Clark Fredricksen, partly in an effort to shore up ad rates.

Publishers are usually able to fetch higher prices for sponsored posts, a form of native advertising that seeks to more less mimic the editorial content around it, than for online display ads, the cost of which are being driven down by so-called "banner blindness" and real-time bidding, also known as programmatic buying.

"The growth of programmatic advertising is relatively severe," Mr. Fredricksen said. Nearly 20% of U.S. display ad spending will include real-time bidding this year, according to EMarketer, which said premium publishers see their growing emphasis on sponsored content as a way to offset losses from programmatic.

Publishers likely to gain the most traction from sponsorships are digital-only publishers, eMarketer's forecast said, because these publishers are more willing "to experiment with the customized executions heavily integrated with editorial."