FILE - In this Wednesday, Nov. 17, 2010, file photo, Twitter co-founder and former CEO Evan Williams speaks at the Web 2.0 Summit in San Francisco. Williams, a Twitter co-founder who was CEO for two years until Costolo took over in 2010, owns a 12 percent stake in the company, which means he is in line for the biggest jackpot once the company goes public. (AP Photo/Paul Sakuma, File)