At the mid-point of $36, Facebook would raise $12.1 billion by selling 337.4 million shares. The company founded in a Harvard dorm room by Mark Zuckerberg, who turned 28 on Monday, had originally aimed for $28 to $35 a share.

Wall Street had expected the company to increase the price range, with investors keen to get in on Silicon Valley's largest ever IPO that eclipses Google Inc's 2004 debut. Its roadshow began last week and has drawn crowds.

The company plans to close the books on its IPO on Tuesday, two days ahead of schedule and in a signal that the landmark initial share sale is drumming up strong demand, a second source familiar with the deal told Reuters earlier.

The social network is scheduled on Thursday to price its shares, then begin trading on Friday.

The IPO is already "well oversubscribed," which is why the company is closing its books earlier than anticipated, the source said.

The raised price range marks an increase of 21 percent on the lower end. A hike of more than 20 percent typically means the company would have to file an amendment with the Securities and Exchange Commission.

Company spokesman Jonny Thaw declined to comment on Monday.

The IPO comes amid concerns from some investors that Facebook hasn't yet figured out a way to make money from an increasing number of users who access the social network on mobile devices such as smartphones.

Facebook will continue with its roadshow for the rest of the week, said a third source familiar with the deal, and investors who haven't yet attended a roadshow presentation will still be able to place orders.

Company executives met with prospective investors in Chicago on Monday and are slated to travel to Kansas City and Denver, before returning to Menlo Park, California, where Facebook is headquartered.

A host of Wall Street banks are underwriting Facebook's offering, with Morgan Stanley, JPMorgan and Goldman Sachs serving as leads. Facebook will trade on Nasdaq under the symbol FB.

CNBC reported the higher price range earlier, citing sources.

(Reporting by Olivia Oran; Editing by Richard Chang, Edwin Chan, Bernard Orr and Ryan Woo)

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