An additional five million shares have been acquired by private equity firm, Elevation Partners in Facebook Inc. for $120 million, according to a reliable source. The investment gave the firm a 1.5% stake in the world's largest Internet social network. It was Elevation's second round of investments in shares of Facebook.

Facebook, being one of the world's most popular Web sites, next to established Internet giants like Google Inc. and Yahoo Inc., is closely looked at by investors keen for a blockbuster initial public offering.

About $700 million and $800 million in revenue were generated by Facebook in 2009. The privately held, Facebook has managed to develop a vibrant market for shares in the past year.

Facebook had banned its employees from selling their shares in the company to outside investors, except during particular periods. Presently, its employees would not be permitted to sell shares, as Facebook is not in that period.

The technology blog, TechCrunch, reported the news of funding. Among Facebook's backers are Digital Sky Technologies, Microsoft Corp Corp, Hong Kong tycoon Li Ka-shing, as well as venture capital firms, Accel Partners, Greylock Partners and Meritech Capital Partners.

Elevation Partners will invest up to $100 million in an online review site, Yelp in January. Earlier, the firm invested $460 million in smartphone maker, Palm for a number of years. Hewlett-Packard announced plans to obtain the struggling Palm for an amount of $1.2 billion.