Twitter has announced chief executive Dick Costelo has stepped down.
Co-founder Jack Dorsey will take over as interim chief on the 1st July and stay until a replacement can be found.
It was said Mr Costelo had been under pressure from investors who were unhappy with the firm's growth.
In a statement he said he was "tremendously proud" of the Twitter team.
Following this announcement from Twitter, shares in the company jumped by more than 7% in trading after US markets had closed.
Back in April the firm missed Wall Street's forecast for revenue growth and posted a net loss of $162m. Its share price has also declined nearly 30% since then and is currently trading below the price it debuted in 2013.
Analysts are pessimistic about the firm's ability to grow.
On announcing his resignation, Mr Costelo said: "I am tremendously proud of the Twitter team and all that the team has accomplished together during my six years with the company."
He added that he had decided to leave now because he felt the continued scrutiny if he remained would be a "distraction" and "no help to the company".
Mr Dorsey said the search team would take as long as necessary and the candidate could come from inside or outside the company.
He added that he knew one thing for certain: he or she must be a Twitter user.
He said the most important attribute was that they "really use and love the product in every single way".
Analyst at Forrester research, Nate Elliot, said the news of his departure wasn't surprising.
He added: "Twitter has never been great at giving its users reasons to come back.
"While other social sites have introduced new features and functionality the past few years, Twitter has mostly stood still. The result has been excruciatingly slow user growth."
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