PALO ALTO, Calif. (


) --


, the world's most popular social networking site, has set up a dual-class stock structure emulating


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strategy in perhaps a sign that it is preparing for an initial public offering.

Facebook, however, said an IPO wasn't imminent.

"We did introduce a dual-class stock structure because existing shareholders wanted to maintain control over voting on certain issues, to help ensure the company can continue to focus on the long term to build a great business," said Larry Yu, a Facebook spokesman, told


. "Facebook has no plans to go public at this time."

Facebook has converted all shares held by existing shareholders, common stock options and restricted stock units to Class B stock, which carry 10 times the voting power of Class A stock, the

Wall Street Journal

reports, citing a person who has seen documents outlining the plan.

The use of a dual-class of shares helps protect the voting control of a narrow group of investors, in this case Facebook founder Mark Zuckerberg. Google adopted this practice in 2004 before it went public when Class B shares were issued to co-founders Larry Page and Sergey Brin.

Zuckerberg said in May that an IPO was "a few years out,"



Dual-class shares also have been adopted by media houses such as

New York Times

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, the

Financial Times