Twitter CEO Dick Costolo will step down and the social media powerhouse's co-founder and Chairman of the Board Jack Dorsey will take over as interim head, the company says.

In a statement, Twitter Inc. says: "Costolo will continue to serve on Twitter's Board of Directors, and Dorsey will continue to serve as CEO of Square, Inc., the payments and financial services company he co-founded in 2009. Twitter's Board has formed a Search Committee to lead the search for a permanent CEO."

In April, Twitter missed Wall Street analysts' revenue forecasts, posting a first quarter net loss of $162 million and prompting a tumble in Twitter's share price. The company also lowered its full-year growth projections.

No explanation was given for Costolo's decision to step down as CEO, but Reuters says it is a result of "pressure from investors frustrated by the Internet company's slow growth and seemingly constant shake-ups in its upper ranks."

In the statement, Costolo said he was "tremendously proud of the Twitter team" and felt that he and the company had accomplished much during his six years at the helm.

Dorsey said: "The future belongs to Twitter thanks in large part to Dick Costolo's dedication and vision. Dick has put a world-class team in place and created a great foundation from which Twitter can continue to change the world and grow."

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