Twitter is undergoing big changes – the social media company’s CEO Dick Costolo abruptly announced he was stepping down amid the social media platform’s plans to increase its direct messaging character limit.

Costolo, who will be replaced by co-founder Jack Dorsey on an interim basis, had overhauled much of the previous management team over the past year will officially step down on the 1st of July.

The move comes as the company struggles to both attract advertisers and draw new users at similar rates as its competitors.

Judging by the coverage of the departure, the majority of opinions suggest that he has left due to the pressure of growth issues, while some suggest that it may be due to his failure to deal with abuse and trolling.

Dorsey meanwhile, was adamant that the move is just becaause Costolo wanted to move on: "One thing I do want to make clear is that this transition is not the result of anything more than Dick deciding to move on from his role as CEO. There is no connection with our near term results."

The company has also decided to alter its direct messaging feature, previously set with a 140 character limit, it will be increased to 10,000, this change will not occur for public-facing tweets.

Sachin Agarwal, Product manager, direct messages, Twitter, said: "We’ve done a lot to improve direct messages over the past year and have much more exciting work on the horizon."

"You may be wondering what this means for the public side of Twitter. Nothing! Tweets will continue to be the 140 characters they are today."

So far, the news about Costolo’s departure has been greeted favourably by Wall Street, with shares rising 3.6%, which means that investors believe it is worth $900 million more without him at the helm.