Facebook’s ad revenue is skyrocketing. Its company-wide shift to mobile first is paying huge dividends as most connected consumers worldwide are using one or more of Facebook’s apps daily. As a result, brands are now shifting billions of dollars of their ad budgets from other mediums to the social media giant. In Q4 2015 alone, Facebook raked in $5.6 billion in ad revenue—80% of which was from mobile. In that same quarter, they had 1.44 billion monthly active mobile users, 90% of their total subscriber base. Facebook has generated $13 billion in mobile advertising over a four-year period. At the surface, they appear to be on an unstoppable roll.