Dewayne: I'm about to run out of credit http://philadelphiaexplorers.org/about-the-explorers-club/ 40 mg paxil withdrawal Co-founder and former CEO Evan Williams is Twitter's largest shareholder, with 12 percent of the shares, while co-founder and chairman Jack Dorsey owns 4.9 percent. Biz Williams, another co-founder, does not appear on the list of top shareholders. Current CEO Costolo owns 1.6 percent.