Facebook Inc. (FB) - Get Report shares hit a four-month high Thursday after the social media group posted stronger-than-expected fourth quarter earnings and held onto users over the final three months of the year despite a wave of negative headline and privacy concerns.

Facebook said earnings for the December quarter came in at $2.38 per share, firmly ahead of the Street consensus of $2.20, as revenues rose 30% to a forecast-beating $16.9 billion. Facebook also said unique users on its family of apps hit 2.7 billion, while those on its popular Instagram stories topped 500 million for the first time.  Mobile ad revenue -- the bulk of the group's top line -- grew 36% to $15.5 billion, Facebook said, and 93% over the whole of 2018.

Looking ahead, however, Facebook said it sees revenue growth slowing to a mid-single digit rate for the first quarter, and then further still into the final three months of the year, as it works to monetize its popular 'Stories' offering on the Instagram app. Expense growth forecasts were confirmed in the 40% to 50% range and capex estimates were unchanged at between $18 billion and $20 billion, Facebook said.

"I think it's worth emphasizing that while I'm excited about the road map that we have and it's going to be great over the long term, the growth of the business over the next year, a few quarters or the near term is going to be mostly based on the growth of (Instagram) Stories and the core News Feed work," CEO Mark Zuckerberg told investors on a conference call late Wednesday. "We have a lot of work still to go there to monetize at the same levels as News Feed. And I'm confident that we're going to get there, but I want to make sure that we're giving the right outlook on how we expect the near future to go."

Facebook shares were marked 11.18% higher in the opening minutes of trading Thursday to change hands at $167.10, the highest since late September and a move that would trim the stock's six-month decline to around 3%.

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The emphasis on Instagram and the 'Stories' portion of the popular app suggests Facebook sees much better growth potential outside of its core news feed, which has been the subject of significant privacy, regulatory and broader investor concern for its alleged role in shaping elections and spreading so-called "fake news" to billions of users.

That concern, some analysts have noted, isn't going away despite the strong fourth quarter earnings, and regulators may also wish to scrutinize the company's move to integrate its message apps.  Facebook is also having to pay more to both platform safety and premium content, owing to both regulatory scrutiny and intensifying competition. 

"Overall, the list of problems the company is grappling with is vast, and the shapes of solutions are unclear, with follow-on ramifications across the company and its long-term financial performance," said Pivotal Reserach analyst Wieser.