Investors are closely examining the financial details disclosed in LinkedIn Corp's IPO filing, trying to determine how much the company is worth.

LinkedIn, which filed to raise up to $175 million in an IPO on Thursday, is attracting significant interest as the first social networking company to start the process of becoming publicly traded. But exactly how attractive it is, is an open question.

It's only recently that their earnings have turned positive, said Jay Ritter, a professor of finance at the University of Florida.

LinkedIn has posted sequentially increasing revenue in each of the past seven quarters. It has posted several quarterly losses during that period -- $2.9 million in the March 2009 quarter -- but has been profitable for the past two quarters, according to its filing with the U.S. Securities and Exchange Commission.

Right now, some privately held shares are traded on secondary markets such as SharesPost. But their value so far has depended more on buzz than fundamental knowledge of the company's finances.

You're talking about the secondary markets, which are like the wild west, said David Menlow, president of IPOfinancial.com, an independent research firm. Who's to say what they are really worth?

Investor interest in privately held Web companies such as Facebook, Zynga and Groupon, which recently rejected a takeover bid from Google Inc, is surging.

Facebook, a social networking site that has more than 500 million users, has been valued at $50 billion.

Earlier this week Demand Media Inc, which publishes articles online, saw its shares gain by more than a third.

LinkedIn's investors include Greylock Partners, Bessemer Venture Partners, Goldman Sachs Group Inc and Sequoia Capital, a venture capital firm that has backed Yahoo Inc, Google, Apple Inc, Cisco Systems Inc and Oracle Corp.

Morgan Stanley, Bank of America and JPMorgan are among the bookrunners for the LinkedIn offering. The company, co-founded in 2002 by ex-PayPal executive Reid Hoffman, has not yet decided how many shares to sell or determined a price range.

(Reporting by Brenton Cordeiro in Bangalore and Clare Baldwin in New York; writing by Ian Geoghegan; editing by Gopakumar Warrier and Andre Grenon)

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