AP Business Writers

Twitter co-founder Jack Dorsey, who was the social platform’s first CEO in 2007 until he was forced out the following year, then returned to the role in 2015, is once again out of the job — this time, he says, by choice.

It’s the end of six tumultuous years at the social platform, during which Twitter has been plagued with slow growth, weathered an investor revolt, grappled with accusations of failure to deal with problems of hate speech, harassment and other harmful activity and finally took the extraordinary step of banning a sitting U.S. president for creating a danger to public safety during the Jan. 6 insurrection at the U.S. Capitol.

In a letter posted on his Twitter account, Dorsey said he was “really sad…yet really happy” about leaving the company and that it was his decision. Dorsey offered no specific reasons for his resignation beyond an abstract argument that Twitter, where he’s spent 16 years in various roles, should “break away from its founding and founders.” Dependence on company founders, he wrote, is “severely limiting.”

Twitter named its current chief technology officer, Parag Agrawal, as CEO effective Monday. Dorsey will remain on the board until his term expires in 2022. Agrawal joined Twitter in 2011 and has been CTO since 2017. By mid-afternoon, Twitter shares were down almost 2% at $46.38.

Dorsey defended the ban of former President Donald Trump, saying his tweets after the Capitol riot endangered public safety and created an “extraordinary and untenable circumstance” for the company. Trump sued Twitter, along with Facebook and YouTube, in July for alleged censorship.

“If he’s actually stepping away from Twitter this time, Dorsey leaves behind a mixed legacy,” said Paul Barrett, deputy director of the NYU Stern Center for Business and Human Rights. “A platform that’s useful and potent for quick communication but one that’s been exploited by a range of bad actors, including former President Donald Trump, who did his best on Twitter to undermine democracy — until Dorsey’s people finally had enough and shut him down.”

Dorsey has faced several distractions as CEO, starting with the fact that he’s also founder and CEO of the payments company Square.