The IAB has just released Q2 and first half 2013 online and mobile ad revenue figures. Total digital ad revenue in the US for 1H 13 was just under $20.1 billion (vs. $17 billion last year). Mobile represented 15 percent of the total.
Search revenues were up 7 percent in real dollars ($8.7 billion) vs. a year ago, though down as a percentage of total revenue. For the first six months of this year, search represented 43 percent of digital revenue vs. 48 percent in 2012. Display ad revenues were also up in real dollars though down in percentage terms.
Search remained the strongest ad category. However “decline in its overall share is attributed to growth in Mobile and Mobile Search, which is included in the Mobile category,” explained the IAB.
The IAB didn’t break out mobile ad revenues by format, unfortunately. In 2011 mobile search revenues were basically parallel (in percentage terms) to PC revenue distribution. However it’s very likely that mobile search revenues are more than 50 percent of total mobile ad revenue in the US and may be between 55 and 60 percent.