Mike Nudelman/Business Insider
Jack Dorsey will be returning as interim CEO. This isn't Dorsey's first time in this post. He cofounded Twitter with Biz Stone and Evan Williams back in 2006, but left the company in 2008. He returned in 2010 to lead product, but ended up scaling back his responsibilities.
He will stay on as CEO of Square, the mobile payments company he founded in 2010, while managing new responsibilities at Twitter.
Dorsey first became a billionaire in 2012, and he is currently worth $2.4 billion.
Rebecca Borison wrote an earlier version of this story.