COPENHAGEN: Adspend via real-time bidding (RTB) more than tripled in Europe last year and recorded growth of 32% in the fourth quarter alone, new data has shown.

According to the Adform RTB Trend Report Europe Q4 2013, RTB spending increased 366% in 2013 while mobile and tablet inventory grew at 518%, a development that Adform, the Danish digital advertising company, described as "astounding".

As reported by Campaign, this category of inventory accounted for more than 13% of all RTB impressions in Europe in December 2013, up from 2.65% in January 2013, and Adform expected mobile RTB to account for about 20% of all impressions in Q1 2014.

Even more significant, Adform stated, is growing evidence of a shift in programmatic campaign types – it identified a trend for the platform to be used increasingly for personalised and awareness-raising campaigns rather than just for performance and retargeting.

This was supported by data showing that the average engagement rate in Europe rose 5% from Q3 to Q4 2013 while the average engagement time increased by 42% to 15 seconds.

The report also found that programmatic ad trading generated record levels of CPMs (cost per thousand impressions) for publishers, who witnessed CPM growth of 15% from Q3 to Q4 2013 and an increase of 67% for the whole year.

"Higher CPMs will attract more publishers to participate in the real-time markets," the report suggested.

Turning to screen dimensions, the report noted that the 300 x 250-sized banner ad remained the most popular format while the 728 x 90 top banner, or leaderboard, was ranked second.

Adform said it was a "shame" that too many advertisers continued to rely on the 300 x 250 format for mobile ads, a situation which it described as "less than ideal".

Data sourced from Adform, Campaign; additional content by Warc staff