Facebook (NASDAQ:FB) reported better-than-expected Q4 results this afternoon, setting off an 8% surge at one point during late trading.

Both sales and earnings came in ahead of Wall Street's fourth-quarter targets. Revenue soared 63% to $2.59 billion while per-share profit zoomed 82% to $0.31. Analysts had been calling for $2.33 billion and $0.27, respectively, according to data compiled by Yahoo! Finance.

For the full year, revenue improved 55% to $7.87 billion. Adjusted profits grew 66% to $0.88 a share. Both figures handily beat the consensus -- $7.64 billion and $0.84, respectively -- as cash flow soared. Facebook's cash from operations more than doubled in 2013.

Costs also rose but at a much slower pace. Operating margins expanded 10 percentage points year-over-year as a result.

"It was a great end to the year for Facebook," Mark Zuckerberg, Facebook founder and CEO, said in a statement. "We're looking forward to our next decade and to helping connect the rest of the world."

Importantly, at 53% mobile ads now account for the majority of Facebook's revenue. That's up from 49% in Q3 and 23% in the fourth quarter of 2012. Mobile daily active users also jumped 49% year-over-year to 556 million in December. Overall, Facebook now counts 1.23 billion monthly active users of its sites.