The controversial case against Facebook

Facebook shares are up strongly this year—but one analyst is saying the stock already hasgone about as far as it can go.

In a note to investors, Janney's Tony Wible downgraded Facebook from "buy" to a "neutral," saying he believes top line growth, engagement and monthly average user growth will decelerate (though not decline).

To clarify, that doesn't mean Wible is negative on Facebook. He just doesn't think it will continue to soar.

Since this time in 2012, Facebook's stock has risen 291 percent, to $75. Janney has a price target of $82.50 per share – which is just 9 percent from Tuesday's close – though it still has some positive things to say about the social media giant.

"We suspect we are already seeing some of this as the stock has started to react less to earnings upside," Wiblewrote. "The company has tremendous monetization opportunities beyond its massive core mobile ad market as it finds ways to make more through video advertising, new online assets (e.g. Instagram), and new products (e.g. search). Many investors already expect this to happen."

Yet, one money manager doesn't believe investors should walk away from Facebook just yet.

"Facebook is as growthy [of] a growth stock as you can get," said Chad Morganlander, portfolio manager at Stifel Nicolaus' Washington Crossing Advisors. "But investors have to be cautious about the volatility of the company and know what they're getting into."

Morganlander notes his firm maintains a "buy" rating on the stock with a price target of $95 per share. They see Facebook's revenues hitting $22 billion by 2016, more than twice what it took in over the last four quarters.

"This is an investment that you have to be pragmatic [with]," Morganlandersaid. "You have to put a small portion of your money in there. If you are a growth investor, you're going to have to ride out the volatility."

Ari Wald, head of technical analysis at Oppenheimer & Co., is also quite positive on Facebook based on the stock's chart and is confounded by Janney's recent downgrade.

"It looks good, and that's why the downgrade based on stock performance is a bit of a head-scratcher for me," Wald said. "A stock coming off a new high isn't a reason to sell it when it's got a lot of other great things going for it."

Wald is reassured by the fact that Facebook's stock has remained well above its 200-day moving average, and enjoys stronger volume during rallies. "It has been a leader within a very strong big cap sector," he said. "These are all very good things."

Wald sees the $72 level as an important one to watch with Facebook. It broke above it a month ago. He sees that former resistance level now serving as support, with a move toward $90 per share.

"If you look at second-quarter correction, dropped $17" from $72 before, Wald said. "I think we can get that $17 on the upside. That would measure to about $90"

"Overall, strong trend," added Wald. "Buy it. It's going higher."

To see the full discussion on Facebook, with Morganlander on the fundamentals and Wald on the technicals, watch the above video.

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