"As proud as I am that a billion people use Facebook each month, I'm also really happy that over 600 million people now share and connect on Facebook every month using mobile devices," CEO Mark Zuckerberg said in the statement, adding that mobile users are more engaged than others.

"At the same time, we are deeply integrating monetization into our product teams in order to build a stronger, more valuable company," Zuckerberg said.

Facebook went public on May 18, but the stock so far has been a disappointment. Facebook's stock closed at $19.50 on Tuesday on the Nasdaq exchange. That's about half of its IPO price of $38, when the company was valued at around $100 billion.

Critics have said Facebook needs to provide a better mobile experience for its users and advertisers, and Zuckerberg admitted in a public appearance in September that the company's mobile strategy focused too much on HTML5 instead of on native applications.

In the third quarter, the company took a number of steps to improve on mobile, including a revamping of its iOS application, and the release of new software development kits for iOS and Android developers. It also closed its acquisition of the extremely popular mobile photo-sharing app Instagram.