Facebook REUTERS

Facebook shares are hot, but they're starting to behave like publicly-traded shares, which has attracted the scrutiny of the Securities and Exchange Commission (SEC).

Shares of the social-networking giant have been traded in the secondary market as employees and former employees sell their shares to eager investors. These shares can then be resold and traded similar to the way public stocks are traded.

SecondMarket is a part of the secondary market that offers a platform to trade Facebook shares. In addition to Facebook, it also has allowed the trading of Twitter, LinkedIn, Zynga, and Tesla shares.

But the SEC's main concern is about something else.

Ever since Facebook gained traction among internet users, institutional investors have been itching to get their hands on a piece of the company's bright future. Microsoft (Nasdaq: MSFT), Goldman Sachs (NYSE: GS), Interpublic Group (NYSE: IPG) and a whole bunch of venture capital/investment firms all own a part of Facebook.

What alarmed the SEC, however, is that Goldman Sachs is setting up a special-purpose vehicle to allow some of its wealthy clients to invest as much as $1.5 billion in Facebook shares, reported the Wall Street Journal.

In order to protect public investors, the SEC requires companies that publicly raise money through equity offerings to disclose certain financial information. For public companies, required disclosures include quarterly and annual earnings reports. For companies wishing to issue initial public offerings, they are required to draft up prospectuses.

Back when corporate and professional entities were investing in Facebook, the SEC had no problem. Now, as wealthy individual clients of Goldman Sachs invest in the company, the line between the public investors and sophisticated private investors is blurred.

Combine that blurred line with the fact that one can get price quotes for Facebook shares from the secondary market, Facebook is starting behave more and more like a publicly-traded company.

If Facebook is indeed being treated as a public company, the SEC may also force it to make financial disclosures like any other publicly traded company.

Currently, Goldman Sachs' latest investment in Facebook and the value of Facebook shares traded on the secondary market indicate that the company has a total value of around $50 billlion, placing it above Yahoo! (Nasdaq: YHOO) and eBay (Nasdaq: EBAY), but below Amazon.com (Nasdaq: AMZN) and Google (Nasdaq: GOOG).

Email Hao Li at hao.li@ibtimes.com