The changes come almost three weeks after Ali Rowghani resigned as Twitter's chief operating officer following a power struggle with Chief Executive Officer Dick Costolo over responsibilities, according to people familiar with the matter. The San Francisco-social-media company has experienced decelerating user growth and has struggled to boost people's engagement with the service. "He definitely understands Wall Street, how investors value the company, what investors are focused on," said Neil Doshi, an analyst at CRT Capital Group in Stamford, Connecticut, who rates Twitter the equivalent of a hold. "Twitter has done a fantastic job in posting very good financial results, but they missed the mark on how important investors view the user growth at Twitter." The shares of Twitter rose 2.6 percent to $42.05 at the close in New York. The stock has declined 34 percent so far this year amid concern that user growth would continue to decelerate.