Dick Costolo was the CEO of which company before the co-founder took over in 2015?
Dick Costolo:  He took over as CEO from Evan Williams in October 2010. Dick Costolo:  On June 11, 2015, it was announced that Costolo would step down as CEO on July 1, 2015 and would be replaced by Twitter co-founder and chairman Jack Dorsey on an interim basis until the Board of Directors could find a replacement. Jack Dorsey: Jack Dorsey (born November 19, 1976) is an American computer programmer and internet entrepreneur widely known as a co-founder and CEO of Twitter, and as the founder and CEO of Square, a mobile payments company.
Twitter