UK publishing's £1billion problem: non-viewable ads

Just over half (52 percent) of display ads served in the U.K. throughout the third quarter of 2015 were viewable, a sluggish 3 percent increase from the previous quarter.
The figures come from ad verification firm Meetrics, which tracked billions of impressions across Europe, and pinpointed the U.K. as the weakest on viewability rates compared to Austria, France and Germany.
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The main reason ads aren’t viewable is they take too long to load, with about 20 percent of ads served not loading before a viewer has moved elsewhere.
http://digiday.com/agencies/viewability-uk-lags/