Going public: Key developments in Facebook's IPO - Article Photos 4/4

FILE -In this Tuesday, Oct. 2, 2012, file photo, Facebook CEO Mark Zuckerberg, center, addresses students of Moscow's State University in Moscow, Russia. Facebook's third-quarter results released Tuesday, Oct. 23, 2012, inched past Wall Street's expectations, offering evidence that the company is making inroads in mobile advertising, a longtime concern among investors. (AP Photo/Alexander Zemlianichenko)