Facebook shares vaulted to their highest level in over a year Thursday as news of surging mobile revenues marked what some called a turning point for the social networking giant. The shares leapt 29.6 percent to close at $34.36, the highest since Facebook\'s first day of trade after its public offering in May 2012. Facebook shares had fallen sharply after the highly anticipated IPO last year and have yet to get back to the offering price of $38. Analysts have spotlighted doubts on mobile ad revenue growth as a major hurdle for the stock. But the company has aggressively changed its online format to enable it to follow its one billion members onto smartphones or tablets as lifestyles increasingly revolve around accessing the Internet from mobile devices. Facebook reported net income in the second quarter of $331 million compared with a loss of $157 million in the year-ago period. Revenue for the quarter that ended June 30 climbed to $1.81 billion, up 53 percent from the same period a year earlier. Some 41 percent of its ad revenues came from mobile, compared with 30 percent in the prior quarter and virtually nothing a year ago. \"Frankly, this was one of the strongest quarterly earnings reports for any Internet company we have seen since the financial crisis,\" said Jordan Rohan at Stifel Nicolaus. \"An inflection quarter. Facebook realized a massive acceleration in ad revenue growth... we believe Facebook is both under-owned and under-estimated.\" Arvind Bhatia at Sterne Agee said the results show that \"Facebook\'s mobile transition has been highly successful,\" and suggested there is more room for growth. \"We estimate Facebook\'s market share of online advertising is currently between five and 10 percent only,\" the analyst said. \"We believe Facebook is well positioned to grow its market share significantly.\" Jefferies analyst Brian Pitz cited \"impressive results that we believe ameliorate key investor concerns.\" Pitz also said the report showed that \"engagement\" by teens is holding up and advertisers are looking more at the social network. \"Importantly, e-commerce companies are increasingly becoming big advertisers on Facebook, setting the company up for a strong holiday,\" he said. Facebook last year directly integrated ads into user\'s newsfeed, whereas previously they had been segregated onto the right side of the screen and not visible on smartphones. Some observers have questioned whether the aggressive marketing could alienate customers. But Facebook officials said on a conference call that the shift is popular with advertisers and has not so far angered users. Of Facebook\'s 1.15 billion monthly users as of June 30, 819 million use a mobile device. Of Facebook 669 million customers who use the site daily, 469 million use a mobile device, according to Facebook. Since Facebook modified the format in 2012, ads now represent about five percent of the content on a user\'s news feed, company officials said. Facebook officials said they have been able to raise the \"cost per click\" when customers pick ads; this contrasts with Google, which troubled investors last week after acknowledging that the cost per click declined. \"News feed ads work,\" Facebook chief financial officer David Ebersman said on a conference call with analysts. The Facebook surge comes during a reporting quarter that has seen familiar names, including Microsoft and Google, struggle with various challenges associated with the shift from personal computers to mobile technology.