Facebook's Status: Improving Facebook Inc. is making progress squeezing more money from advertisers on mobile devices—but not enough to shake the burden of Wall Street expectations. The world's biggest social network on Wednesday posted a 40% fourth-quarter revenue jump to $1.59 billion and reported its strongest quarterly advertising growth for all of 2012, as it ramped up its mobile business and offered new tools to advertisers to better target consumers. Facebook's profit fell 79%, weighed down by spending on new initiatives and charges related to employee stock. The results were roughly in line with Wall Street projections.facebook proxy Facebook's mobile advertising results particularly stood out. Over the quarter, Facebook's overall ad revenue rose 41% to $1.33 billion from a year ago, with mobile ads making up 23% of the total. In the prior quarter, mobile revenue was $153 million, or 14% of total advertising revenue. "Today there is no argument Facebook is a mobile company," said Chief Executive Mark Zuckerberg on a conference call Wednesday.unblock facebook Still, investors were lukewarm on Facebook's results after a recent run-up in expectations. Facebook's stock initially fell around 5% in after-hours trading following its earnings report, but selling tapered, with the stock later down 3.8% to $30.05. Shares had earlier closed at $31.24, up 1.5%, before the report. The company's shares have been on a recent tear, rising more than 70% since September.get on facebook For some analysts, Facebook's growth on mobile was a bit underwhelming. Richard Greenfield, a BTIG Research analyst, noted that Facebook was making about $3 million per day on mobile ads at the end of the third quarter, and made a little bit more than that in the fourth quarter. "Despite the fact that they significantly increased the ad load in the mobile news feed, the growth rate seemed to slow," Mr. Greenfield said. On the earnings call, the company noted that it's mobile business was still in the early innings. "It didn't show upside to the most bullish expectations," said Jordan Rohan, a Stifel Nicolaus analyst. However, Mr. Rohan added that he was encouraged by Facebook's progress thus far. Since its rocky initial public offering last May, Facebook has been on a mad dash to improve its presence on mobile—long seen as a weakness for the company—and to sell more ads on smartphones and tablets. The Menlo Park, Calif., company has unleashed a flurry of new products, including messenger applications for smartphones and several ad formats. Earlier this month, Facebook unveiled a social search engine called Graph Search, which it has described as a key pillar for the business. Facebook said that as of late December, 680 million users were actively accessing the social app on smartphones every month, up 57% from a year earlier. Facebook continues to face challenges, including whether its aggressive push to make money from so many angles will eventually turn off consumers. Users may tire of advertisements, particularly on their pocket-size smartphones where screen real estate is limited. "One question is how far can they go without hurting user experiences," said Mr. Kinsella.