Mobile And Social Formats Steal RTB Share From ‘Big 3’ Ad Units

rtb-smorgasbordA new crop of ad units is on the rise as mobile and social inventory expands, independent trading desk Accordant Media reported in a Q1 analysis.

Although 70% of total real-time bidded (RTB) display media is attributed to the “Big 3” primary ad unit sizes, all three fell as a percentage of total programmatic impression volume. Simultaneously “non-standard” ad sizes are on the upswing. The percentage of impressions lumped under “all other” – a bucket that includes many mobile and social formats – increased by almost half (47%) compared to Q4.

“As more programmatic media buyers are targeting social and mobile environments, the overall share of the ‘Big 3’ has gone down,” said Arthur Muldoon, Accordant CEO.

Relatedly, publishers are surfacing more premium formats in exchanges. “We believe the growth of premium programmatic is contributing to the popularity of ad units like the 300×600,” Muldoon said.


During Q1, Accordant Media bid on display, social, mobile and video display ad impressions across 900,000 sites. It found overall volume of RTB ad inventory increased 31% sequentially, and 5% year-over-year.

Notably, CPM price increases in North America are outpacing supply growth.

“That is a really healthy sign for the marketplace, and it shows that there’s a broad based demand for programmatic media buying,” said Muldoon. “I think that’s also echoed by the growth of the numbers of participants in auction: more buyers bidding on media and that’s contributing to the stronger base of demand.”

The report also highlights how in Q1, auction volume in the US expanded only slightly vs. Q4, but demand drove prices up by 16% overall.

Enjoying this content?

Sign up to be an AdExchanger Member today and get unlimited access to articles like this, plus proprietary data and research, conference discounts, on-demand access to event content, and more!

Join Today!