Facebook’s Zuckerberg Says Mobile Shift Is His Biggest Challenge

Facebook’s Zuckerberg Says Mobile Shift Is His Biggest Challenge

David Paul Morris/Bloomberg

Mark Zuckerberg, chief executive officer and founder of Facebook Inc., right, and Andrew "Drew" Houston, founder and chief executive of Dropbox, during the Allen & Co. Media and Technology Conference in Sun Valley, Idaho, on July 12, 2012.