Facebook shares have been on a tear, up more than 50 percent since the last quarterly report in July, when the company delivered on its promise of growth, especially in the all-important mobile space. With the stock up nearly 150 percent in the past 12 months, expectations are high, and in the past month, half a dozen analysts have boosted their earnings target. Will Facebook live up to heightened expectations and show mobile continuing to drive advertising growth?
More than 80 percent of the social network's revenue comes from advertising, and last quarter, 41 percent of that ad revenue was from mobile. Can that percentage tip above 50 percent this quarter?
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Based on ComScore data on Facebook's mobile use in the first two months of the quarter, the trend is positive: Unique mobile visitors grew 8.6 percent and total user minutes grew 97 percent. The negative story is on the desktop, where during that period Facebook suffered a 5.4 percent decline in unique visitors.
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Investors are weighing big questions.
Video ads are expected to be a big money-maker, but the company is holding off on them widely until next year. With the first ones launching next week, two questions dominate: How well will Instagram ads work, and will they alienate users?
Also, Facebook has talked a lot about its "mobile app install ads"—ads that drive people to click to download an app. How can the company build on that strength? And will Facebook suffer from growing competition from the likes of Snapchat, which is expected to raise up to $200 million at a valuation of up to $4 billion. And what about Twitter now that its IPO will help fuel its growth?
Wall Street analysts expect Facebook to increase its revenue 51 percent to $1.91 billion, while its earnings-per-share are projected to grow 54 percent to 18 cents. In addition to the mobile ad revenue, investors will be watching for revenue-per-user, and daily active user numbers. On the earnings call, expect questions about plans for Facebook to work more with TV advertisers as it builds its presence as a second-screen conversation about TV. Other hot topics: making money from search, video advertising, and a display ad network.
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Bank of America Merrill Lynch's analyst Justin Post warned that the fourth quarter and beyond the company faces tougher year-over-year growth comparisons, which Facebook could address by "discussing key growth initiatives."
"The street will be looking for commentary on engagement trends, ad inventory ratios, seasonality, advertiser adoption of FBX, app download activity, Instagram monetization and video advertising," he said.
Goldman Sachs' Heather Bellini, reiterating her "buy" rating on the stock, said over the next 12-18 months she sees powerful new product cycles in video ads, Instagram and graph search. "We believe advertisers [will] continue to be impressed with the ROI on their FB spending, which is helping to drive more dollars from offline to online."
Not everyone is so bullish: Forrester analyst Nate Elliott wrote an open letter to Mark Zuckerberg on Monday entitled "Facebook is failing marketers." Elliott cited a survey of 395 marketers and executives, hearing from them that "Facebook creates less business value than any other digital marketing opportunity." As it has in the past, we can expect to hear some stats on Facebook's ads' effectiveness, addressing these concerns.
—By CNBC's Julia Boorstin. Follow her on Twitter: @JBoorstin.