Twitter announced Monday morning that Jack Dorsey, its co-founder and interim CEO, has become the company’s permanent CEO. The news was made official on Sept/ 30, per an SEC filing. As part of the announcement, the company said Dick Costolo, Twitter’s former CEO, stepped down from Twitter’s board last Wednesday. Likewise, Adam Bain, the company’s chief revenue officer and a promising candidate for the CEO role, has been promoted to COO.