Washington (AFP) - Twitter co-founder Jack Dorsey resigned Monday as the social media network’s CEO, after surviving an activist investor’s bid to oust him in 2020 and steering the firm during the tumult of Donald Trump’s presidency.

Dorsey – who also is chief executive of payments company Square – confronted during his tenure thorny freedom of speech issues, ways to make the platform profitable and pressure he had spread himself too thin.

With his recognizable look – shaved head and long beard, and his atypical style – Dorsey for years has embodied Twitter alone.

“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 in an email to Twitter staff.

“I want you all to know that this was my decision and I own it. It was a tough one for me, of course,” he added.

The company said Twitter’s chief technical officer Parag Agrawal will replace Dorsey in the top post, with Dorsey remaining a member of the board until his term expires at the 2022 meeting of stockholders.

- Trump era -

Like many Silicon Valley celebrities, from Mark Zuckerberg and Steve Jobs to Bill Gates or Michael Dell, Dorsey dropped out of college, never graduating from either of the universities he attended, one in his native Missouri and the other in New York.

Dorsey is credited with coming up with the idea for Twitter when eventual co-founder Evan Williams gave workers at blogging startup Odeo two weeks to work on fun new projects as a way to break up the daily routine.

He ran Twitter from 2007-2008 and returned later as CEO after Dick Costolo resigned in June 2015.

With Dorsey at the helm, Twitter reported its first profitable quarter for the last three months of 2017, and then two full years in the green, before slipping back into the red in 2020.

Twitter in March 2020 made a deal with key investors to end an effort to oust the chief, creating a new committee on the board of directors to keep tabs on company leadership.

Dorsey came under pressure in 2020 from Elliott Management amid concerns he had spread himself too thin by running both Twitter and Square.

Yet during Trump’s presidency, Twitter was widely seen as the medium used to broadcast America’s deepening political and cultural rifts.

- New CEO -

Dorsey took the controversial decision to permanently ban Trump from the platform, where the former president had amassed 88.7 million followers.

Dorsey made the decision days after Trump whipped up a mob of supporters who stormed the US Capitol, where they tried to prevent Joe Biden being confirmed winner of the 2020 election.

Supporters of the former president accused Dorsey and the social media giants of trying to curb free speech, and many quit to join new, far-right-friendly platforms.

But some also defended the hard decisions Dorsey had to make.

“People tend to conflate jack dorsey with twitter censorship, but my sense is he’s actually done what he could these past few years to keep the platform relatively open,” tweeted Mike Solana, head of the private equity firm Founders Fund.

“Things will be worse without him, not better. godspeed, bird king.” he added.

Twitter’s incoming CEO Agrawal joined the company in 2011 and has served as chief technology officer since October 2017, where he was responsible for the network’s technical strategy.

Agrawal holds a PhD in computer science from Stanford University and a bachelor’s degree in computer science and engineering from the Indian Institute of Technology in Bombay.

Nasdaq briefly suspended trading of Twitter on Monday, citing “news pending,” but the share was up 4.5 percent following the announcement.