Facebook: Bear vs. bull

Facebook's stock hit an all-time high this week, and shares have more than doubled since the company went public in 2012. But how much more room does Facebook have to grow? CNBC's "Power Lunch" asked a bear and a bull for their takes on Friday.

Bearish on FB

CNBC contributor Jon "DRJ" Najarian said the uncertainty in the mobile ad space, where Facebook is growing substantially, could be a problem. The companies who tend to buy these ads are the "unicorns," or the companies with "billion-dollar valuations just out of nowhere," as Najarian explained.

"That could dry up if things turn south at all, so that's a concern if you are on the bullish side of Facebook," he said.

He does like the payment plan that will allow messenger users to make payments through the app, although he was concerned it only allows for debit cards at this point in time.

Disclaimer: Najarian does not own any Facebook stocks or options.

Bullish on FB

Emmanuel Dunand | AFP | Getty Images

James Cakmak, equity analyst at Monness, Crespi, Hardt, is optimistic that the messenger app will be successful in attracting more users.

"Right now I don't think [the messenger's payment option is] about making money as much as it is getting people engaged on the platform in more ways than one," he said. "This is just the first step towards a much more immersive experience."

Cakmak's price target is $95. He added that Facebook's targeting of users is getting better than that Instagram's revenue will increase.

Disclaimer: Neither Cakmak nor his firm owns share of Facebook. The company is not an investment banking client of Monness, Crespi, Hardt.