Update: Facebook shares rise as trading begins

 

After all the buildup, Facebook's long-anticipated initial public offering arrived today as the company's shares began trading on the Nasdaq Stock Market shortly after 11 a.m. ET.

 Facebook began trading at more than $42 a share, with some 82 million shares traded in the first 30 seconds.

 "Having Facebook operating as a public company is very important in terms of really gauging the role of social media," said Ezra Gottheil, an analyst with Technology Business Research. "We will really get to see how Facebook, the dominant social medium, is performing. How much money they can earn is a reflection of their value in the economic world."

 On Thursday, Facebook set its initial share price at $38. With the company offering 421 million shares, it could raise upwards of $18.5 billion in its IPO.

The company had a valuation of about $104 billion before trading began.

Facebook employees welcomed the IPO with an all-night hackathon last night in its Menlo Park, Calif., offices, the BBC reported.

 While the IPO is an important milestone for Facebook and its 28-year-old co-founder and CEO Mark Zuckerberg, it's also a bellwether for the entire social networking world.

Facebook is the largest social network in the world, with about 900 million active monthly users. According to Experian Hitwise, Facebook became the top-ranked website in the U.S. in March 2010. One in every five Web page views in the U.S. is on Facebook.

 If Facebook's IPO is wildly successful, other social networks, such as Twitter, are likely to gain more investor backing. However, if investors aren't as eager to buy Facebook shares as expected, or if they buy shares and the price dropsin the coming months, the likelihood of IPOs from other social networking companies becomes more tenuous.