SAN FRANCISCO — Facebook shares shot up 12% after the giant social network said it earned 79 cents a share on revenue of $5.84 billion in the fourth quarter, easily topping Wall Street estimates. Facebook's dominance in mobile advertising helped to allay Wall Street concerns over its heavy investments in messaging service WhatsApp and virtual reality unit Oculus, which have not yet generated profits.
Chief Executive Mark Zuckerberg, who returned from two months of paternity leave on Monday, has said virtual reality represents the next major computing platform. The company has also begun monetizing some of its other units, such as photo-sharing app Instagram, which surpassed 400 million users last year and began selling ads in September. Facebook said mobile ads accounted for 80 percent of