Instagram was the target of a storm of outrage on Twitter and other sites after the company announced a change in its user agreement that hinted that it might use shared photos in ads. Karly Domb Sadof/AP hide caption

itoggle caption Karly Domb Sadof/AP

Facebook CEO Mark Zuckerberg emphasized his company's mobile-centered future Tuesday, in his first public comments since Facebook's troubled IPO. Eric Risberg/AP hide caption

itoggle caption Eric Risberg/AP

A worker sits in the Facebook office in Menlo Park, Calif. The amount of information Facebook learns about its users seems to have entranced Wall Street. Jeff Chiu/AP hide caption

itoggle caption Jeff Chiu/AP

Investors will be betting that Facebook won't make its users so uncomfortable over privacy that they quit. Photo Illustration: Joel Saget/AFP/Getty Images hide caption

itoggle caption Photo Illustration: Joel Saget/AFP/Getty Images

A photo illustration shows the photo-sharing app Instagram's fan page on Facebook's website. Facebook is acquiring Instagram for some $1 billion. Justin Sullivan/Getty Images hide caption

itoggle caption Justin Sullivan/Getty Images

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