Twitter’s C.E.O., Dick Costolo, Is to Resign

SAN FRANCISCO — Dick Costolo, Twitter’s embattled chief executive, is stepping down, the company said on Thursday.

Jack Dorsey, the company’s co-founder and chairman, will serve as interim chief executive while the board searches for a permanent successor.

The change is effective July 1. Twitter shares were up more than 7 percent in after-hours trading immediately after the news was announced.

Since Twitter’s debut as a public company in 2013, Mr. Costolo has repeatedly disappointed Wall Street as the company struggled to attract new users, refine its products and develop new forms of advertising.