Now the company's $190 billion market value makes it bigger than such bellwethers as Coca-Cola and AT&T. It's not a member of the Dow industrials, but if it were, it would be larger than two-thirds of that index's 30 members.
Shares of the world's No. 1 social network touched a record high of $76.74 on Thursday after earnings and revenues easily topped analysts' forecasts, boosting its market value to nearly $194 billion. That ranks it 15th in the Standard & Poor's 500 benchmark index, just below the $196 billion market cap of International Business Machines Corp.
"A 100-year-old company with real assets versus a company admittedly with virtual assets and they are trading at the same market cap - crazy," said Kim Forrest, senior equity research analyst at Fort Pitt Capital Group in Pittsburgh.
The speed of Facebook's rise to mega-cap status is what's notable. It took Apple Inc nearly three decades to achieve such a market value; Google Inc needed five years.
Facebook has only been public for a little more than two years, and only joined the S&P 500 seven months ago. Since S&P Dow Jones Indices announced the addition on Dec. 11, Facebook shares have risen 54 percent.
The gains represent a reversal of fortune for the social media company. After a botched IPO that infuriated investors in May 2012, the stock slumped, underperforming for 15 months before finally eclipsing its offering price of $38 in August 2013. Since then, Facebook shares have been unstoppable, doubling in less than a year.
"People understand the world is moving to mobile, and when you look at the time spent on mobile, Facebook has the lion's share," said Walter Price, senior portfolio manager and managing director of the AllianzGI Global Technology fund, which owned more than a million shares as of June 30.
The firm has leveraged its position by selling put options, or negative bets on the stock, and buying more call options, or bets on the shares rising further. "This is a momentum stock you can put a P/E on," Price said.
Facebook's rally has left e-commerce giant Amazon Inc in the dust. That company's value peaked around $187 billion in January, but closed Thursday at $165 billion. Amazon reported disappointing results afterwards, which dragged down its stock by 7 percent, valuing the company around $153 billion.
Facebook's market cap is still dwarfed by the roughly $403 billion in combined market cap for the two classes of Google shares, arguably the most similar in terms of revenue generation. However, Facebook tops The Coca-Cola Co by about $15 billion and Disney by more than $40 billion.
SHORT, QUICK TRIP
Apple, the S&P 500's most valuable company, needed nearly three decades before its market value finally rose to more than $190 billion, surpassing that level in late December 2009.
Google's move was swifter. The company went public in August 2004, and posted a closing market value of more than $190 billion for the first time in October 2007, right around the S&P's peak before the financial crisis.
That's not to say there aren't detractors. StarMine, a Thomson Reuters company, sees Facebook as more overvalued than 95 percent of the companies in its stock universe. Using expected growth rates over the next decade, StarMine puts an intrinsic value of $29 on the stock. It has a high price-to-earnings ratio of 42, more overvalued than 90 percent of the stocks StarMine tracks.
However, the stock's relentless march has left few willing to stand in its way. Investors betting on the stock falling have dried up. In August 2012, more than 80 percent of shares available for short bets were being borrowed by investors expecting the stock to drop, according to Markit. Now, just 0.4 percent of shares available are being used for short bets.
Of the 43 analysts with recommendations on the stock, 37 are "strong buy" or "buy" ratings, with six "hold" ratings.
"If you were looking to short names that were ridiculously overvalued and people were not even thinking the growth was going to continue, I wouldn't put Facebook in that category," said Stephen Massocca, managing director at Wedbush Equity Management LLC in San Francisco.
"That being said, do I buy Facebook here From my perspective, I am a value investor - I wouldn't get anywhere near it with a 10-foot pole."
That acceptance of Facebook's legitimacy as a successful and viable company makes the comparison to the classic names that now surround it on the market cap list more palatable.
"In some respects, Facebook speaks to a demographic shift in the way retailing, social media and virtually every other component of people's lives is being bundled," said Peter Kenny, chief market strategist at Clearpool Group in New York.
"Investors are starting to see the brilliance of this platform in ways that haven't to date really captured the imagination of many."