Facebook mobile ad growth drives sales Facebook's aggressive mobile advertising push through the presidential election and holiday shopping season helped the social network report its first quarterly revenue growth since becoming a public company in May but still left investors wanting more. Revenues for the fourth quarter grew 40 per cent to $1.59bn compared with the same period last year. Revenue growth was flat for the previous two quarters and had declined the quarter before that. Net income was $426m on the pro forma basis by which Wall Street measures the company, and earnings per share were 17 cents. Wall Street had expected 15 cents on $1.53bn of revenue. Though mobile ad sales more than doubled to $306m compared with the third quarter, representing 23 per cent of overall ad revenues, some analysts had hoped for as much as $333m. "This represents a figure only slightly above the $3m per day the company was generating towards the end of the third quarter," said Brian Wieser, an analyst with the Pivotal Research Group. Still, we view the results as solid overall. Facebook's shares initially fell more than 10 per cent in after-hours trading before clawing back some ground to be 4 per cent lower at $29.98. The shares listed in May at $38. Mark Zuckerberg, Facebook's chief executive, defended the company's mobile efforts, pointing out that user engagement had fallen only 2 per cent since the company began introducing ads into the Newsfeed. Set against a 50 per cent increase in likes and comments from the company's adjustments to the algorithm last year, he said Facebook can now do even more to better target those ads, and even introduce new media formatssuch as video. "Today there's no argument, Facebook is a mobile company," he said. It allows us to reach more people, and we'll be able to make more money for each minute people spend with us on their mobile devices. Facebook finished the full year with earnings a share of 53 cents on $5.09bn in revenue, compared with estimates of 52 cents earnings a share on $5.03bn in revenue. Heading into 2013, Mr Zuckerberg said Facebook planned to incur more costs this year as it hired more people for its product development team. Advertisers will be watching Facebook in the coming year for the development of moneymaking products associated with new products released last year, particularly Graph Search, the social network's new social search feature. "Down the line, if we do this well, this could potentially turn into a meaningful business for us," Mr Zuckerberg said.