Twitter's share price took a dive today even as the tech-heavy NASDAQ Composite index rose by nearly four percent.
The social-media company's shares plunged 9.67 percent to close at US$40.72 in the wake of a tweet by Elon Musk.
Last month, the Tesla CEO announced that he was buying Twitter in a US$44-billion deal.
Musk offered US$54.40 per share and planned to take the company private.
But early today, he said that this takeover is "temporarily on hold".
Musk said that the delay is pending details to support a calculation that spam and fake accounts represent fewer than five percent of Twitter users.
This evening, he followed that up by declaring: "The bots are angry about being counted."
Some are speculating that Musk may be trying to back out of the deal because of a recent sharp decline in Tesla's share price.