Evan Williams Out As Twitter's CEO

Twitter Inc. has replaced Evan Williams as its CEO with Costolo chief executive, the company said on Monday. Costolo was previously Twitter's COO. Williams, who co-founded the company, will now be "completely focused on product strategy," according to a statement made on the company website Monday. "Given Dick's track record as a three-time successful CEO, I'm confident we can make this a smooth transition," Williams wrote on the site.