Social Media

The big 'if' for buying Facebook shares

Two reasons FB can sustain growth: Mahaney
Facebook Street check
Why Facebook can power even higher

At nearly $120, Facebook shares are far from cheap, but after a gangbusters earnings report, there may still be a case for getting in now, analysts told CNBC.

"If — it's a big if — if Facebook continues to execute at this level, you could see a tripling in their revenue growth over time, the growth rate is sustainable, and you could buy the stock even today," Mark Mahaney, analyst at RBC Capital Markets, said Thursday on CNBC's "Squawk Alley."

Shares of the social network soared Thursday, up more than 7 percent after it reported earnings that were well above analyst estimates.

Mark Zuckerberg
Facebook shatters Wall Street estimates, proposes new share structure

"There's definitely been a rotation in," said John Blackledge, managing director and senior equity research analyst at Cowen and Co. "No doubt investors are riding this horse, they had a great quarter. And if you look over the last three years, they've had the best earnings in internet, maybe all of tech," he said Thursday, also on "Squawk Alley."

Facebook posted better active usership than expected, with people sharing more and spending on average more than 50 minutes per day on Facebook, Instagram and Messenger.

Fifty minutes may only be the beginning, one investor said. Even if Facebook is no longer cool, it's still useful, and almost a necessity, said Morris Mark, founder of Mark Asset Management and a Facebook shareholder.

"it's almost essential that you participate," Mark told CNBC's "Squawk on the Street" on Thursday. "It's a very, very powerful franchise."

Kevin O'Leary
Kevin O'Leary is scared that Facebook will be like Yahoo

And that could be good news for Facebook's main revenue stream, advertising, Blackledge said.

"We definitely think there's more upside from here," he said. "We think they are going to continue to gain ad share. We have Facebook's share pull for digital advertising rising from 11 percent this year to 26 percent by 2021, driven by rising users, rising engagement and more advertisers."

To be sure, Facebook has a behemoth competitor in the ad space, Google, who Mahaney said is "slightly better positioned" for advertisers with YouTube. Plus, it's unclear when Facebook's push for chatbots n Messenger can be scaled and monetized in the U.S. and Europe, said Raymond James analyst Aaron Kessler.

But while Facebook faces tough comps later this year and may not trade at a 40 or 50 times multiple, compared to traditional companies, it is still reasonably priced for its growth, Kessler said Thursday on CNBC's "Fast Money: Halftime Report."

"They have 200,000 advertisers on Instagram today versus 3 million on Facebook," Mahaney. "That looks like a gap-up opportunity."

— CNBC's Everett Rosenfeld contributed to this report.