Jack Dorsey has stepped down as CEO of Twitter, effective immediately. Current Chief Technology Officer, Parag Agrawal, will take over the CEO role. This ends Dorsey’s second stint as CEO after he returned in 2015 to take over the company he co-founded in 2006. Dorsey was originally forced out of the company in 2008; however, the reasons for his recent departure are uncertain. Since his return in 2015, Twitter’s stock (TWTR) has gone up 85%.

“I’ve decided to leave Twitter because I believe the company is ready to move on from its founders. My trust in Parag as Twitter’s CEO is deep. His work over the past 10 years has been transformational. I’m deeply grateful for his skill, heart, and soul. It’s his time to lead,” said Jack Dorsey in a statement.

Dorsey will remain on the Twitter Board of Directors until his term expires in 2022. He will also remain the CEO of Square. The news brought an immediate surge to Twitter’s stock.