This article is more than 2 years old.

January 27, 2016 This article is more than 2 years old.

The story of Facebook right now is its mobile dominance—all the more interesting because four years ago investors were wary of the company for its seeming lack of a mobile strategy.

In that period of time, Facebook has created a $13 billion mobile-advertising business. That’s how much revenue it generated from mobile ads in 2015. For the fourth quarter, Facebook reaped 80% of its ad revenue from smartphones and tablets.

Facebook passed a new milestone in the final quarter of the year, with 90.6% of all its active users accessing the social network from a mobile device. Of its 1.59 billion monthly active users, 1.44 billion come from mobile, a 21% rise year-over-year. As of Dec. 31, it made $4.83 in ad revenue per mobile user.

The company is also closing in on another mark: 1 billion users who check its flagship app everyday. At the rate it’s growing, about 25% each quarter year-over-year, it could pass the threshold as soon as this quarter. It reported 934 million daily active mobile users at the close of 2015.

Overall, Facebook reported $1.56 billion in profit on $5.84 billion in revenue, up 52% year over year. In 2015, it made $3.69 billion in net income on $17.93 billion in revenue.

Investors are loving the results, with shares up nearly 9% in after hours trading.