Tesla CEO Elon Musk is threatening to walk away from his $44 billion bid to buy Twitter. Musk reportedly accused the company of refusing to give him information about its spam bot and fake accounts.

Lawyers for the Tesla and SpaceX CEO made the threat in a letter to Twitter dated Monday that the company disclosed in a filing with the US Securities and Exchange Commission.

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The lawyers wrote that Musk has repeatedly asked for the information since May 9, about a month after his offer to buy the company, so he could evaluate how many of the company’s 229 million accounts are fake.

Twitter CEO Parag Agrawal has said that Twitter has consistently estimated that fewer than 5% of its accounts are spam. But Musk has disputed that, contending in a May tweet, without providing evidence, that 20% or more are bogus.

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Shares of Twitter Inc. slid 1.5% Monday, likely incensing Twitter shareholders who filed a suit against Musk late last month for deflating the price of the stock. Shares of Twitter are down more than 20% in the last month.

Twitter said in a statement Monday that it has been cooperatively sharing information with Musk “in accordance with the terms of the merger agreement” and noted that the deal is in “the best interest of all shareholders.”

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“We intend to close the transaction and enforce the merger agreement at the agreed price and terms,” it added.

Musk agreed to buy Twitter for $54.20 a share back in April. A number of Musk’s actions since, including a public spat with Twitter’s CEO about the fake accounts — on Twitter — has led some experts to question whether the billionaire wants to use his loud complaints to negotiate a lower deal price or even walk away entirely.

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Musk’s lawyers wrote in the letter that Twitter has offered only to provide details about the company’s testing methods. But they contend that’s “tantamount to refusing Mr. Musk’s data requests,” and constitutes a “material breach” of the merger agreement that gives Musk the right to scrap the deal if he chooses.

“This is a clear material breach of Twitter’s obligations under the merger agreement and Mr. Musk reserves all rights resulting therefrom, including his right not to consummate the transaction and his right to terminate the merger agreement,” the letter says.

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Musk wants underlying data to do his own verification of what he says are Twitter’s lax methodologies.

The Twitter sale agreement allows Musk to get out of the deal if there is a “material adverse effect” caused by the company. It defines that as a change that negatively affects Twitter’s business or financial conditions. Twitter has said all along that it’s proceeding with the deal, although it hasn’t scheduled a shareholder vote on it.