Elon Musk 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.
Musk said he was waiting for information “supporting (the) calculation that spam/fake accounts do indeed represent less than 5 percent of users”.
He has been vocal on cleaning up spam accounts.
However, analysts speculated that he could be seeking to re-negotiate the price or even walk away from the takeover.
Following Musk’s tweet, Twitter shares fell as much as 25 per cent in pre-market trading.
Under the terms of the deal, if either Twitter or Mr Musk walk away they must pay the other side a termination fee of $1bn.
Twitter reported over two weeks ago that fake accounts accounted for fewer than 5 per cent of its daily active users during the first three months of this year.
However, the company said in determining the amount of spam accounts, “it applied significant judgment, so our estimation of false or spam accounts may not accurately represent the actual number of such accounts”.
“The actual number of false or spam accounts could be higher than we have estimated. We are continually seeking to improve our ability to estimate the total number of spam accounts,” it said.
Musk, who is the richest person in the world according to Forbes magazine, is now examining that figure.
Twitter has long had an issue with automated, fake accounts being used to relentlessly post content.
Musk has called for “defeating the spam bots” on Twitter as well as several other changes, including bringing back some banned accounts such as that of former US President, Donald Trump.
Dan Ives, a tech analyst at investment firm Wedbush Securities, said Musk’s tweet would “send this Twitter circus show into a Friday the 13th horror show”.
He said Wall Street would now “view this deal as 1) likely falling apart, 2) Musk negotiating for a lower deal price, or 3) Musk simply walking away from the deal with a $1bn break-up fee”.
Mr Ives said if Mr Musk did still decide to go ahead with the deal, a “clear renegotiation is likely on the table”.
He added many would view him highlighting the number of spam accounts “as a way to get out of this deal in a vastly changing market”.
“The nature of Musk creating so much uncertainty in a tweet (and not a filing) is very troubling to us… and now sends this whole deal into a circus show with many questions and no concrete answers as to the path of this deal going forward. BBC