• by Gavin O'Malley  @mp_gavin, February 1, 2017

Driven again by mobile, Facebook saw revenue reach $8.81 billion in the fourth quarter, the social giant said Wednesday. Beating analysts’ expectations, that sum represented a 51% rise compared to the same period a year earlier.

Year-over-year, quarterly profit also increased from $1.56 billion to $3.57 billion.

In the fourth quarter, mobile ad revenue represented approximately 84% of total ad revenue -- up from about 80% of ad revenue in the fourth quarter of 2015.

On a Wednesday earnings call, Facebook CEO Mark Zuckerberg sounded unmoved by the impressive results. “This was another good quarter,” he remarked.

On a sentimental note, however, Zuckerberg did mention that Wednesday marked the five-year anniversary of the day Facebook filed to go public.

Consistent with earlier comments, he again reiterated his commitment to video. “I see video as a megatrend, on the same order as mobile,” Zuckerberg said.

To that end, he said users can expect to see “much more video” in the News Feed over the coming months and years.

Among other video-related efforts, Facebook is reportedly eyeing investments in long-form content. Yet asked about these reports on Wednesday, Zuckerberg said he remains focused on short-form video, for the time being.

“We’re focusing more on shorter-form content to start,” Zuckerberg said.

With regard to video monetization models, Facebook CFO David Wehner said the company remains committed to sharing revenue with content publishers.

Despite the impressive earnings, Facebook experienced its share of turbulence, during the fourth quarter. For one, it confessed to several metrics miscalculations, eMarketer principal analyst Debra Aho Williamson noted earlier this week.

“In the fourth quarter, Facebook revealed several errors in the metrics that marketers use to measure marketing and advertising, and some advertisers are starting to express concern,” Williamson remarked.

“While I don’t believe ad revenues are being impacted as of yet, I do think that marketers should be vigilant in tracking the effectiveness of their advertising on Facebook and not rely solely on what Facebook is telling them,” suggested Williamson.

As noted by Williamson, Facebook also appears to be having trouble monetizing its messaging platforms, including WhatsApp and Messenger.

In December, Facebook saw an average of 1.23 billion daily active users (DAUs) -- an increase of 18% year-over-year. On average, mobile DAUs reached 1.15 billion in December -- an increase of 23% year-over-year.

Facebook recorded 1.86 billion monthly active users (MAUs) in December -- up 17% year-over-year. Mobile MAUs reached 1.74 billion -- an increase of 21% year-over-year.

This year, 171.4 million U.S. consumers will use Facebook -- a jump of 2.7% over last year -- eMarketer expects. In addition, 150.2 million U.S. consumers will access Facebook via smartphone, while 79.2 million will do so via a desktop or laptop, according to the research firm.

In 2017, 45% of Facebook's total ad revenue will come from the U.S., while it will capture 14.7% of the worldwide digital ad market -- making it the second ad publisher behind Google, which has a 31.7% worldwide share.    

Meanwhile, Facebook will net $29.71 billion in mobile Internet ad revenue globally -- up 35.2% from last year -- eMarketer predicts.

Overall, Facebook will capture 20.7% of the worldwide mobile ad market, by eMarketer’s reckoning.