Short-seller Hindenburg Research warned on Monday that Elon Musk's $44-billion deal to take Twitter Inc private could get repriced lower if the Silicon Valley billionaire walked away from the deal.

"Musk holds all the cards here," Hindenburg, which has a short position on Twitter, said in a report. "If Elon Musk's bid for Twitter disappeared tomorrow, Twitter's equity would fall by 50% from current levels. Consequently, we see a significant risk that the deal gets repriced lower."

Shares of the social media platform were down as much as 4% amid a broader market decline and touched $47.76, their lowest level since Musk made his $54.20 per share offer in April, calling it "best and final".

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Twitter was not immediately available for a comment.

"We are supportive of Musk's efforts to take Twitter private and see a significant chance the deal will close at a lower price," Hindenburg said.

The short-seller said the deal has seen a number of developments, from financing to board approval, which could have weakened the company's position.

Hindenburg said Musk could walk away paying the $1 billion breakup fee and has leverage to renegotiate if he chooses to.

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Last month, Twitter secured a $44 billion cash deal to sell itself to Tesla Inc chief executive and received over $7 billion in funding from high-profile investors, including Oracle's co-founder Larry Ellison and Sequoia Capital.