Facebook's IPO already oversubscribed: source

Reuters reports:

Facebook Inc's record initial public offering is already oversubscribed, a source familiar with the share listing said, days after the world's largest social network embarked on a cross-country roadshow to drum up investor enthusiasm.

Despite concerns about slowing growth, a lofty valuation and signs the company is having trouble ramping up revenue from mobile advertising, institutional investors have so far indicated demand for more shares than Facebook has available, the source told Reuters.