(The Hill) — Jack Dorsey announced Monday that he is leaving Twitter after co-founding the social media platform in 2006 and serving as its CEO since 2015.

He will be replaced by chief technology officer Parag Agrawal, according to a departure email shared by Dorsey on Twitter.

“I want you all to know that this was my decision and I own it,” Dorsey wrote. “It was a tough one for me, of course. I love this service and company… and all of you so much. I’m really sad… yet really happy.”

CNBC published a report on Dorsey resigning earlier Monday, sending Twitter stock up over 10 percent.

Dorsey appears set to stay on as CEO of his online payment company Square, a position he held concurrently with leading Twitter.

Agrawal, the new CEO, wrote in an email to staff also shared on Twitter that he sees “exciting opportunities ahead” for the company.

“Our purpose has never been more important,” he wrote. “Our people and culture are unlike anything in the world. There is no limit to what we can do together.”

Dorsey’s leadership of both companies led to concerns that his attention was divided. Activist investor Elliott Management tried to force Dorsey out using that argument in 2020, but ultimately struck a deal with another investor that allowed the CEO to stay on.