Sites with a large proportion of pirated content took in an estimated $111 million in ad revenue in the U.S. last year, including $36 million from premium advertisers, according to a new study released by the ad industry's Trustworthy Accountability Group.

The total ad revenue on sites with infringing content would have been even higher had the ad industry not taken steps to reduce piracy, according to the study, which was commissioned by TAG and conducted by Ernst & Young LLP’s Media & Entertainment Advisory. That organization found that absent anti-piracy initiatives like TAG's program, operators of piracy sites may have garnered around twice as much ad revenue.

For the study, Ernst & Young examined ads that ran from November 15 to December 15 on 672 sites with a large proportion of infringing material. Most of those impressions -- 83% -- were deemed non-premium, including ads for gaming and dating services, and ads served to users of virtual private network services. The remaining 17% were premium ads.

Ernst & Young concluded that without "quality control" measures, more premium advertisers would have appeared on those sites, which would have resulted in more ad revenue for the operators. Researchers estimated that premium advertisers paying $5 per thousand display impressions, and $14 per thousand video impressions. Non-premium advertisers paid an estimated $2.50 per thousand display impressions and $7 per thousand video impressions; advertisers who ran ads served through virtual private networks paid an estimated $1 per thousand impressions.

Several years ago, TAG rolled out a voluntary anti-piracy initiative that requires participants to promise to take commercially reasonable steps to prevent digital ads from appeaing on sites associated with copyright infringement. More than 50 brands and agencies participate in that program.

Agencies can meet that promise by hiring TAG-validated companies that provide anti-piracy services or using TAG-certified ad placement services, among other measures.

Mike Zaneis, CEO of TAG, says the organization hopes to see a bigger drop in premium advertising on piracy sites. "What's needed is more participation," he says. "That's certainly a push of ours."

He adds that monthly reports from the analytics shop Pathmatics have shown recent drops in premium brand advertising on piracy sites.

Wow, didn't think those ads paid much but I guess it all adds up.