NEW YORK (AP) — Facebook's stock is trading up 8 percent Friday, as investors seek to put a dollar value on the company that turned online social networking into a global cultural phenomenon.

That means Facebook is worth about $112 billion, more than Amazon.com and McDonalds.

But as many people looked for a big first-day pop in Facebook's share price, the single-digit increase was somewhat of a letdown.

"It wasn't quite as exciting as it could have been," said Nick Einhorn, an analyst with IPO advisory firm Renaissance Capital. "But I don't think we should view it as a failure."

Indeed, the small jump in price could be seen as an indication that Facebook and the investment banks that arranged the IPO priced the stock in an appropriate range.

Earlier Friday the company's 28-year-old CEO, Mark Zuckerberg, smiled as he rang the opening bell from Facebook's headquarters in Menlo Park, Calif. Surrounded by cheering Facebook employees and wearing his signature hoodie, he pushed the button that signals the opening of the stock market in New York. The morning's events followed an all-night "hackathon" at the company, where engineers stayed up coding software and conjuring up new ideas for Facebook and its 900 million users.

"Right now this all seems like a big deal. Going public is an important milestone in our history. But here's the thing, our mission isn't to be a public company. Our mission is to make the world more open and connected," Zuckerberg said. "In the past eight years, all of you out there have built the largest community in the history of the world. You done amazing things that we never would have dreamed of and I can't wait to see what you guys all do going forward."

On Thursday, Facebook and the investment bankers settled on a price of $38 per share. The company and its early investors raised $16 billion in the offering, which valued Facebook at $104 billion. That makes Facebook the most valuable U.S. company to ever go public.

Now, the stock market will assign a dollar value to Facebook that will rise and fall with investor whims. It will be subject to broad economic forces and held accountable for profit it earns —or loses— from one quarter to the next.

But Facebook is one a rare companies whose IPO transcends Wall Street's money lust. It is a cultural touchstone for the way technology reshapes our lives. Since its start as a scrappy network for college students, Facebook has come to define social networking by getting people around the world to share everything from photos of their pets to their deepest thoughts.

It has done so while becoming one of the few profitable Internet companies to go public recently. It had net income of $205 million in the first three months of 2012, on revenue of $1.06 billion. In all of 2011, it earned $1 billion, up from $606 million a year earlier. That's a far cry from 2007, when it posted a net loss of $138 million and revenue of $153 million. The company makes most of its money from advertising. It also takes a cut from the money people spend on virtual items in Facebook games such as "FarmVille."

Facebook's public debut marks a new milestone in the history of the Internet. In 1995, Netscape Communications' IPO gave people their first chance to invest in a company whose graphical Web browser made the Internet more engaging and easier to navigate. Its hotly anticipated IPO lit the fuse that ignited the dot-com boom. That explosion of entrepreneurial activity and investment culminated five years later in a devastating bust that obliterated the notion that the Internet had hatched a "new economy".

It took Google Inc.'s IPO in 2004 to prove that an Internet company with a disruptive idea could be profitable. In the process, the Internet search leader is forcing other industries to adapt to a new order where people have come to expect to be able to find just about anything they want by entering a few words into a box on any device with an Internet connection.

Facebook's IPO heralds a new phase of the Internet's evolution. This social era makes connections among people as important as Google's massive index of Web links. Still, the IPO will raise new pressures for Facebook to generate more revenue, perhaps by digging further into the trove of revealing information that people share on the network to sell even more targeted ads.

Facebook's IPO almost certainly will enrich other up-and-coming entrepreneurs as Zuckerberg uses the company's cash and stock to buy other startups in an effort to being in other talented engineers and promising technology. That's what has been doing for years. Since it went public in 2004, Google has spent $10.2 billion buying nearly 200 other companies. Those figures don't include Google's still-pending $12.5 billion acquisition of cellphone maker Motorola Mobility Holdings Inc., which is still awaiting regulatory approval in China.

Zuckerberg's biggest deal so far came when he agreed to buy Instagram, a maker of a popular mobile app for photos, for $1 billion. Because most of the deal is being paid for in stock, Instagram is already getting richer. Based on Facebook's IPO price of $38 per share, Instagram is in line to receive nearly $1.2 billion.

Though Zuckerberg rang the Nasdaq opening bell from California, people outside the stock market in Times Square snapped photos of a big blue Facebook sign that lit up the building. Some of them used their smart phones to check in to the Nasdaq on Facebook. Frederick Nolde, who was visiting from Richmond, Va., said he bought 100 shares through the online brokerage eTrade.

He thinks the company is worth $100 billion. "I think Google is a good comparison and it's worth $200 to 300 billion. The real question is how they do in mobile. If they can figure that out they'll do well."