Fraudulent operators using robots to impersonate people clicking on digital ads will rob the advertising industry of $6.3 billion in 2015, according to a report published on Tuesday.

The automated clicks, from entities known as bots, account for nearly one-quarter of the views on video ads and more than one in 10 on display ads across the Internet, according to the study, which was conducted by the Association of National Advertisers and White Ops, an online security company.

Although digital ad fraud has increasingly become an problem in recent months, the report found the bots were gaming not only bare-bones and unsophisticated websites, but also respected and established lifestyle and news publishers.

“The surprise was the ubiquity of the fraud,” said Bill Duggan, group executive vice president of the advertising association. “It is not just no-name websites but it also affects premium publishers.”

The legitimacy of clicks is crucial to publishers and the brands that advertise with them, because rates are set by the number of people who view ads.