Analysts say that to succeed, Facebook needs to figure out how to sell ads on mobile platforms. Saeed Khan/AFP/Getty Images hide caption

itoggle caption Saeed Khan/AFP/Getty Images

Facebook co-founder and CEO Mark Zuckerberg at Facebook headquarters in Palo Alto, Calif., in 2007. The company is expected to file papers for an initial public offering this week. Paul Sakuma/AP hide caption

itoggle caption Paul Sakuma/AP