A year after IPO, Facebook aims to be ad colossus

FILE - In this May 18, 2012, file photo, provided by Facebook, Facebook founder, Chairman and CEO Mark Zuckerberg, center, rings the opening bell of the Nasdaq stock market, from Facebook headquarters in Menlo Park, Calif. Amid the hype and excitement surrounding Facebook's initial public offering, there were looming doubts. Potential investors wondered whether the social network could continue growing its advertising revenue without alienating users. One year later, much has changed at Facebook in a year, including the addition of mobile advertisements, the launch of a search feature and the unveiling of a branded smartphone.