The IAB is out with its latest stats on digital advertising (download a .pdf here).
One thing that stands out from the report is the exploding growth of mobile advertisingIt's now 15% of all online advertising, up from 7% the year before. 
While it's growing, mobile is still pretty small overall. For the first half of this year, mobile ad revenue was $3 billion, up from $1.2 billion the year before.
When you consider all the major ad supported companies that are focused on mobile — Twitter, Facebook, Instagram, Google, pop to mind — it's sort of crazy to think about them splitting ~$6 billion in revenue this year.
chart of day online ad format share
Business Insider