NEW YORK (TheStreet) -- Social media giant Facebook (FB) - Get Report will "become a tremendous short once the engagement numbers slip," Citron Research head Andrew Left said on CNBC's "Halftime Report" on Tuesday afternoon.  

The engagement numbers will miss in the next few years, Left predicted. "Every piece of research on Facebook has an asterisk on the bottom and everything's based on engagement levels," he explained. 

Previously, Left was short on Facebook based on the thesis, "How much better can its story really get?" noted CNBC's Scott Wapner. 

After releasing that previous short view on Facebook, the company "turned around and blew out earnings, completely destroyed every estimate," yet was only up 1.5% to 2% the next day, Left noted. "What would have happened if they came in in-line?" he asked. 

The stock market needs new buyers and new sellers daily, Left said. So the short thesis is based on, "Who's left to buy [Facebook stock] tomorrow?" he said. 

"It has nothing to do with Mark Zuckerberg. Nothing to do with the company," Left said. 

Facebook's story could turn out very similar to Apple's (AAPL) growth story, he predicted. 

Three to four years ago, everyone knew shares of Apple would hit $1,000, they just didn't know when, Left said. But then it suddenly turned into a value stock from a growth stock and went lower and lower over the next two years. "So nothing's to say that can't happen to Facebook too," he concluded.

Shares of Facebook were lower in mid-afternoon trading on Tuesday. 

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Separately, TheStreet Ratings objectively rated this stock according to its "risk-adjusted" total return prospect over a 12-month investment horizon. Not based on the news in any given day, the rating may differ from Jim Cramer's view or that of this articles's author.

TheStreet Ratings team rates Facebook as a Buy with a ratings score of A-. This is based on the convergence of positive investment measures, which should help this stock outperform the majority of stocks the team rates.

You can view the full analysis from the report here: FB

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