The overall global mobile advertising market more than doubled in 2013 to almost $18 billion, and is set to grow another 75% this year.
See also: Study: Mobile Ad Spending to Hit $42 Billion in 2017, Eclipsing Radio
Twitter was the only major player other than Facebook to log an increase in its share of the mobile ad market, up from 1.5% to 2.4%.

Image: eMarketer
Increasing share in a growth market can do wonders for a company. More than half of Facebook’s fourth-quarter earnings in 2013 came from mobile ad revenue.
The social network’s ability to quickly pivot from being a desktop-focused product — Facebook had no mobile ad revenue as recently as 2011 — to the second-largest player in the space has sent shares in the company up more than 150% in the past year. The income also provided the financial footing for the $16 billion acquisition of WhatsApp, another major mobile play.
eMarketer’s study of global mobile ad share is also notable for the names not on the list. While Google and Facebook take the top two spots, other notable US. digital companies are missing such as Microsoft, Yahoo and AOL.

Image: eMarketer
Yahoo CEO Marissa Mayer has been particularly vocal about the company’s need to make inroads in the mobile market. She recently told the 4A Transformation Conference that Yahoo now has 500 mobile-focused employees, a significant increase since she joined the company.
AOL, meanwhile, is heavily investing in online video advertising, another growing market in the overall digital ad industry.