Twitter CEO Dick Costolo has announced he is to resign from the company on 1 July, with founder Jack Dorsey taking over in the interim until a permanent replacement is found.
The move comes amid growing concerns from investors over slow growth of the platform's userbase since its IPO in 2013.
Costolo took the decision to leave himself, Reuters reported, and initially raised the idea at a board meeting last year.
Nate Elliott of Forrester Research told Reuters: "Unfortunately this news isn't surprising. The bottom line is that Twitter isn't very good right now at serving either its users or its marketers."
Dorsey will return as the fourth CEO the company has had in the space of nine years, having held the position from its founding until 2008, when he was allegedly fired for leaving work early to attend fashion and yoga classes.
He was succeeded by another of Twitter's co-founders, Evan Williams, then took over the reins for another two years, before handing the role over to Costolo, who had been COO.
Costolo sent out a tweet welcoming Dorsey back to the chief exec role and, in a statement, said: "I am tremendously proud of the Twitter team and all that the team has accomplished together during my six years with the company. We have great leaders who work well together and a clear strategy that informs our objectives and priorities."
He will remain as a member of the board and said he "[looks] forward to supporting Twitter however [he] can going forward".
