Twitter Co-Founder, Jack Dorsey, has resigned as Chief Executive Officer, CEO, of the firm after 16 years at the social media company, to be replaced by chief technology officer, CTO, Parag Agrawal.
Meanwhile, Twitter's shares rose 11% after the news broke.
The company said Dorsey would step down immediately, but remain on the board until Twitter's stockholder meeting in 2022.
Dorsey said: "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 Dorsey.
Agrawal has been with Twitter for a decade and served as CTO since 2017.
"I want to thank the board for their confidence in my leadership and Jack for his continued mentorship, support, and partnership," said Agrawal.
In his most recent tweet on the site, posted Sunday, Dorsey wrote: "I love Twitter."
In an email to staff on Monday Dorsey wrote that after 16 years at the company, it was time to leave.
"There's a lot of talk about the importance of a company being 'founder-led'.
"Ultimately I believe that's severely limiting and a single point of failure," he wrote.
"I've worked hard to ensure this company can break away from its founding and founders."
Dorsey said Agrawal was his preferred choice for CEO. "My trust in him as CEO is bone-deep," he wrote. "I want you all to know this was my decision and I own it."
Dorsey, 45, co-founded the microblogging site in 2006 and posted the world's first tweet: "Just setting up my twttr."
He co-founded Square in 2009 after being pushed out of the top job at Twitter before returning as chief executive of the social media company in 2015