The world’s richest man, Elon Musk, has completed his $44bn (£38.1bn) takeover of Twitter, according to US media and an investor in the firm.
He tweeted “the bird is freed”, in an apparent reference to the deal closing.
A number of top executives, including the boss, Parag Agrawal, have reportedly been fired.
It brings to a close saga that saw Twitter go to court to hold the multi-billionaire to the terms of a takeover deal that he had tried to escape.
Twitter has not yet confirmed the takeover, but an early investor in the company told the BBC that the deal had been completed.
Mr Musk, a self-styled “free speech absolutist”, has been critical of Twitter’s moderation policies and the news will be greeted with mixed feelings by Twitter users and employees.
Many people on the right of US politics will celebrate the exit of Mr Agrawal as chief executive. They view people like Mr Agrawal, and his predecessor, Jack Dorsey, as liberals who are curtailing free speech.
They also think that under their stewardship, Twitter has censored conservative voices – an accusation that Twitter denied.
Mr Agrawal, chief financial officer Ned Segal, and the firm’s top legal and policy executive, Vijaya Gadde, are no longer with the company, according to US media reports.
Mr Agrawal and Mr Segal were escorted out of Twitter’s San Francisco headquarters after the deal closed, the Reuters news agency reported.
Twitter co-founder Biz Stone thanked Mr Agrawal, Mr Segal and Ms Gadde for their “collective contribution” to the business.
Meanwhile, Bret Taylor – who had served as Twitter’s chairman since last November – updated his LinkedIn profile to indicate that he was no longer in the post.