Social Media advertising revenue is expected to surpass $8 billion by 2015, according to BIA/Kelsey’s U.S. Local Media Annual Forecast. BIA/Kelsey predicts that ad spending will rise from $2.1 billion to $8.3 billion in the next five years, representing a compounded annual growth of 31.6%. BIA/Kelsey states that $7.7 billion of that will go to display ads, the most popular form of social media advertising, with Facebook leading the charge. The other $600 million will come from non-displayed formats, such as Twitter’s “promoted products.”