Elon Musk has said his $44bn (£35bn) deal to buy Twitter is on hold after he queried the number of fake or spam accounts on the social media platform.
He said he was waiting for information “supporting [the] calculation that spam/fake accounts do indeed represent less than 5% of users”.
Mr Musk added later that he was “still committed to [the] acquisition”.
However, analysts speculated he could be seeking to renegotiate the price or even walk away from the takeover.
Mr Musk’s tweets sent Twitter’s share price plunging 10% in morning trade in New York.
Even before his comments, the company’s stock had been selling for less than the $54.20 per share Mr Musk has offered, a sign that the markets were not convinced he would complete the buyout.