In an email sent to staff and later tweeted out, Jack Dorsey announced on Monday that he is resigning as CEO of Twitter, effective immediately.

In the email, he disagreed about the importance of companies being “founder-led,” calling that belief  “severely limiting and a single point of failure.” He posted the email in its entirety with the caption, “Not sure anyone has heard but, I resigned from Twitter.”

Dorsey named his successor Parag Agrawal, who up until now was Twitter’s Chief Technology Officer starting at the company in 2011 as an engineer. Parag formally held leadership positions at Yahoo! Research and Microsoft Research.

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Dorsey also named Salesforce president and COO Bret Taylor as chairman of the board. Dorsey said he would assist Agrawal and Taylor during their transition and would continue to serve on the board until his term is completed around May 2022.

Dorsey expressed confidence in Parag, saying he had been considering him as his replacement for some time due, in part, to his ability to lead with his “heart and soul.” As for his last wish for Twitter, he said he hopes the platform is the “most transparent company in the world.”

According to the Wall Street Journal, shares of Twitter were halted on Monday, with the shares jumping as much as eleven percent upon reports that Dorsey was expected to step down.

Dorsey was called to step down last year after Elliott Investment founder and billionaire investor, Paul Singer, voiced concerns about Dorsey being the CEO of both Twitter and the digital payment company Square, asking that he step down from one of them. Eventually, Elliott Investments and the management of Twitter reached a deal on the matter.

After Dorsey’s resignation announcement on Monday, Elliott issued a statement, saying, “Having gotten to know both incoming Chairman Bret Taylor and incoming CEO Parag Agrawal, we are confident that they are the right leaders for Twitter at this pivotal moment for the company.”