What slowdown? Thanks once again to mobile ads, especially video ads, Facebook Inc. today managed to beat back worries that running fewer ads on its pages might finally bring the social network’s advertising business down to earth.

Facebook said it earned a net profit of $3.06 billion, or $1.04 a share, up 76 percent from a year ago. Revenue jumped 49 percent in the first quarter, to $8.03 billion. Analysts polled by Thomson Reuters had forecast an 87-cent profit on revenue of $7.84 billion.

Facebook’s shares, which are up 32 percent from the start of the year, were falling about 2.5 percent in after-hours trading. It wasn’t immediately clear why. There may be some confusion over the numbers because Facebook no longer is providing the metric analysts like, which removes certain costs such as stock compensation. But the company also reiterated its expectation that ad revenue growth would slow in the second half of the year, which also might have spooked investors.

In regular trading today, shares were down less than 1 percent, to $151.80. That gave the company a market cap of $440 billion, fifth largest on the S&P 500 index.

In the last couple of quarters, Facebook has been warning that growth would slow “meaningfully” by the second half of this year as the company laps rapid growth last year and also reduces the ad load on its site. In the fourth quarter, admittedly before the slowdown was supposed to kick in, the company beat back worries with a 51 percent jump in revenue. Still, Chief Financial Officer David Wehner said growth would slow in coming quarters, mostly because of lower ad loads.

Mobile advertising again drove much of the upside in the first quarter, with revenues up 58 percent, to $6.7 billion. Mobile revenue now comprises 85 percent of total ad revenue, up from 82 percent a year ago. “Increasingly the question is whether you can do without mobile, not whether you can do without TV,” Chief Operating Officer Sheryl Sandberg said.

“The revenue growth in the quarter is all the more remarkable considering the concerns that came to light late last year around measurement issues,” Pivotal Research Inc. analyst Brian Wieser wrote in a note to clients. “While the large brands who would have cared most about these issues likely account for less than a third of the company’s revenue base, the absence of any obvious impact can still be viewed favorably.”

The company has been in the news lately less for its business, which remains nearly all advertising, than its own impact on news and culture, in particular the recent furor over people livestreaming killings, suicides and rapes on the site and ongoing concerns about Facebook’s role in fake news influencing the presidential election.

But those concerns could hurt its bottom line. “It’s clear we have more to do here,” Facebook Chief Executive Mark Zuckerberg (pictured) said on the earnings conference call. Earlier Wednesday, he said Facebook would add 3,000 people to its 4,500-person staff to monitor for violent videos more closely. Facebook said its headcount of 18,770 was up 38 percent from a year ago.

Zuckerberg said in response to a question that artificial intelligence eventually will be able to do a better job of finding the most important video for the team to monitor, but he added, “That will take a period of years to reach the level of quality we want.”

Beyond potentially higher overhead expenses, which concerns Wieser, advertisers and agencies are watching for whether that monitoring will affect ad loads. “It will be interesting to see if increased controls around ‘brand safety’ have an impact on ad load,” Ian Schafer, founder and chairman of Deep Focus, part of the Engine ad agency group, told SiliconANGLE.

Still, some analysts were already confident Facebook remains on the growth track, partly thanks to rapidly increasing ad revenues at its Instagram photo and video sharing app. EMarketer predicts that Instagram will generate $3.9 billion in ad revenue worldwide this year, more than double 2016. 

High expectations about Instagram’s potential prompted Deutsche Bank analyst Lloyd Walmsley to raise his target price from $155 to $180 a share. “We think the rapid growth in monthly active users at Instagram puts the asset on track to be the next $1 billion-plus user product at Facebook and a highly monetizable one at that,” he wrote in a research note to clients. Instagram recently said it now has 700 million monthly users, double two years ago.

“It’s no coincidence that Instagram is a primary driver behind Facebook’s better-than-expected earnings in Q1,” Caitlin McDaniel, associate director of social media at the agency GSD&M, said in an email. “Instagram has taken care to implement new features and ad units to capture greater share of users’ time without alienating existing loyal users and more advertisers are implementing dual-channel buys that include Facebook and Instagram for greater reach, frequency and impact.”

Facebook didn’t immediately provide estimates for full-year 2017, but analysts had forecast an adjusted profit of $6.25 a share on revenues of $27.6 billion.

Facebook and Alphabet Inc.-owned Google Inc. jointly dominate online advertising, as Google also reported better-than-expected results last week. The pair accounted for 99 percent of the growth in online advertising last year, according to Pivotal Research Inc.

“Facebook continues to be a juggernaut and half of a duopoly,” Schafer said. “It’s nearly impossible to avoid advertising on Facebook and its owned properties.”

Photo: Robert Hof