Twitter shares rose as much as 4.8 percent after the messaging service announced its latest upper-management shake-up. The previous CFO, Mike Gupta, was named senior vice president of strategic investments on Tuesday. Twitter has reported lackluster user and usage growth for the last couple of quarters and its stock price has nearly halved in the last six months. Last month, Twitter Chief Operating Officer Ali Rowghani departed after clashing with Chief Executive Dick Costolo over whether he should continue to oversee product innovation, according to a person familiar with the matter.