Twitter Co-founder Jack Dorsey is stepping down as chief executive of the company, and he will be replaced by the current chief technical officer Parag Agrawal. In a written statement, Dorsey said that it was finally time for him to leave, adding that he had deep trust in his replacement. While the reason for his departure remains unclear, many suspect that it has something to do with the fact that a number of Twitter investors felt that the co-founder, who also serves as chief executive of the payment firm Square, was not giving the social media platform the attention that it needed.