Tech billionaire Elon Musk put his deal to buy Twitter on hold on Friday. Musk wrote on Twitter that he first wanted to wait for calculations to show that accounts without real users actually accounted for less than five percent. The online service published this estimate earlier in the week. Musk had previously stated that he wanted to ban accounts that are used to send spam messages from the platform.

Twitter stock quickly fell nearly a quarter in premarket trading after Musk’s tweet, to trade at around $34.50. That’s a far cry from the $54.20 a share Musk had promised shareholders. The paper went out of business on Thursday at $45.08 – a sign of investor skepticism that Musk is actually going through with the deal.

The boss of the electric car manufacturer Tesla had agreed with the Twitter board of directors on a deal worth around 44 billion dollars. But he is still dependent on enough shareholders wanting to sell him their shares. Twitter and Musk previously wanted to complete the acquisition by the end of the year. In the past few months, he has already bought a good nine percent stake in Twitter on the stock exchange.