24/7 Wall St.

In a stock move that is starting to defy gravity, social media giant Facebook Inc. (NASDAQ: FB) has eclipsed the market value of two of the longtime stalwart members of the Dow Jones Industrial Average. In climbing to almost $70 a share, the stock has moved by AT&T Inc. (NYSE: T) and Coca-Cola Co. (NYSE: KO). For investors who bailed out of the stock at the market low in September of 2012, this must be a very bitter pill to swallow.

In addition to blowing past former market leaders, the stock has also jumped into the top 20 of the largest American companies listed by market cap. A spectacular move for a company that was heavily criticized for upsizing and up-pricing what became a very dismal initial public offering (IPO). After the highly anticipated IPO debuted in May of 2012 at $38, the stock proceeded straight down. Disappointment over initial earnings hammered the stock to a low in September of that year to $17.72. Three straight quarters of blowout earnings, mobile advertising revenues that are skyrocketing and an installed base of well over a billion users have turned the tables.

The question that challenges many investors is starting to gain traction. Is this gigantic market cap justified? With the recent stock move, Facebook has leapfrogged tech giants like Amazon.com Inc. (NASDAQ: AMZN) and Oracle Corp. (NASDAQ: ORCL). While Amazon trades at an incredible 578 price-to-earnings multiple on a trailing basis, Oracle trades at a more reasonable 16 times earnings, and it pays shareholders a 1.25% dividend. Facebook currently trades at 110 times trailing earnings.

Recent reports have indicated that Facebook is starting to lose some of its core younger users. Facebook itself admitted last fall that it had lost younger users. “We did see a decrease in [teenage] daily users [during the quarter], especially younger teens,” Facebook chief financial officer David Ebersman said during a call with analysts. Estimates are that 11 million teenage users have left Facebook since 2011. Advertisers covet younger audiences because their taste in products are more varied and changing, so this data could have a significant effect on the ad rates Facebook can charge.

One thing is for sure. Investors that are buying Facebook at these levels could be in for a big surprise if any of the metrics that are so crucial, like mobile advertising, start to turn down. In addition, hitting a critical mass wall with unique users also becomes a huge metric to watch. While the fate of Facebook is probably not going the way of MySpace, at these lofty levels investors better hope that the company keeps putting out the best possible numbers each and every quarter.