• by Tyler Loechner  @mp_tyler, February 5, 2014

Mobile real-time bidding (RTB) ad exchange Smaato on Wednesday released its global mobile RTB Insights Report for Q4 2013, a lengthy report detailing trends, growth and spend figures for the global mobile RTB space.

For the year as a whole, Smaato saw global spend on mobile RTB increase 466%, with steady growth each quarter. The U.S., UK, and Germany were the top three counties in terms of mobile RTB spend.

The U.S. dominated the field; 66% of mobile RTB spend on Smaato’s exchange in Q4 came from the U.S. The UK accounted for 8%, and Germany accounted for 3%. Every other country accounted for the remaining 12%.

Despite the heavy spending from U.S. advertisers, the strongest quarter-over-quarter growth rate belonged to Brazil. The up-and-coming country saw a 440% increase in mobile RTB spend last quarter. No other country had a spend increase greater than 142% (Netherlands) over Q3.

Mobile RTB fill rates increased by 106% in the U.S. last quarter, up to 23% from 11%.

In other words, 23 out of every 100 mobile ads requested in the U.S. were delivered via RTB on Smaato’s exchange last quarter, up from 11 out of every 100 the previous quarter.

Ad networks saw a 55% mobile ad fill rate in Q4 (up 72% over Q3). The “other” category, which included direct deals, had a fill rate of just 22% in Q4, lower than RTB. This is of note because the “other” category had a fill rate of 57% in Q3, which was by far the highest.

Even though the mobile fill rate in the U.S. more than doubled from Q3 to Q4, it lags behind the EMEA region, which had an RTB fill rate of 28% last quarter. The APAC region had an RTB fill rate of about 18%.

In Q4, advertisers targeted social networks (46%), games (16%), and entertainment channels (13%) for their mobile RTB needs. This is in line with the figures from Q3.