Slideshows have been hurt by growing demand for viewable inventory, as readers rarely scroll down and often click to the next slide before ads load.
Topix, which buys traffic to slideshows that rack up tons of page views, was affected by this shift. Four months ago, the site’s viewability hovered around 40%, so programmatic buyers optimized away from it.
Topix started improving viewability, first by removing its worst ad units – the 40% of ad impressions that averaged just 5% viewability.
Other ad units were highly viewable in some browsers or devices, but nonviewable elsewhere. Topix removed those units more selectively. Some ad units now load dynamically based on whether a user is viewing from Chrome, Firefox, an iPhone or an Android device, for example.
Dealing with the fact that readers wanted to browse through slides faster than ads could be called and loaded required another approach.
Topix didn’t want to get rid of slideshows, which would send its average of 70 page views per user plummeting. Those page views made Topix’s traffic-buying strategy viable.
Instead, Topix made fewer ad calls by holding bids and using them for subsequent page views. Topix no longer had to initiate a separate ad call for each of the 70 page views.
When a reader starts a slideshow, Topix makes ad requests to all its header bidding partners and serves ads normally. Then, when the user clicks to the next page, it serves the next-highest bid, avoiding a duplicate ad call.
By using this technique, Topix lowered overall bid requests by 80%.
Bid caching is often considered a no-no by buyers, because they’re getting something different than what they paid for.
But Topix said its partners are okay with the technique because it holds bids for only 20 seconds, and only while the user stays on the same URL – which ensures the ad won’t show up on another slideshow that the buyer doesn’t consider brand-safe.
If the user clicks to another slideshow, Topix throws out all the bids and starts over.
“For our site, it works well, because the user is in the same place,” Topix CEO Chris Tolles said. “If you were a more traditional news site, that would be more difficult.”
Plus, Topix said its technique also helps out slower exchanges – like Facebook Audience Network, which hasn’t always returned bids quickly.
If slow exchanges return a bid after its two-second timeout, Topix will let those buyers’ bids through on subsequent page views, giving them access to inventory they would have missed.
And if a reader scrolls too quickly through a slideshow, Topix holds the same ad over a few page views, refreshing only after it hits a viewability threshold.
All of Topix’s techniques raised average viewability from 40% to 80%, which increased CPMs 50% above their previous levels.
As a bonus, holding bids made the slideshows load faster – and used up less mobile data, since the slideshows no longer made dozens of ad calls.
“For every page view, there would be 30 header bidding partners because there were three ads per page,” said engineering VP Mike Sawka. “There was a huge amount of data going back and forth.”
And faster load times mean more engaged audiences. Because pages load up to 50% faster with the held bids, users consume 10% more page views than before, according to Topix.
Topix plans to continue to optimize for ad viewability in the months ahead, finding smaller tweaks to make that will turn the dial up on viewability and save the slideshow.