PR How Twitter announced its CEO’s departure Dick Costolo’s announcement that he was stepping down was one of two Thursday stories about top execs leaving; the other involved Rupert Murdoch of 21st Century Fox. By Matt WilsonJune 12, 2015 SHARE To read the full story, log in. Become a Ragan Insider member to read this article and all other archived content. Sign up today Already a member? Log in here. Learn more about Ragan Insider.