Elon Musk, chief executive officer of Tesla, said on Friday he was terminating his $44 billion deal to buy Twitter because the social media company had breached multiple provisions of the merger agreement.
Twitter's chairman, Bret Taylor, said on the micro-blogging platform that the board planned to pursue legal action to enforce the merger agreement.
"The Twitter Board is committed to closing the transaction on the price and terms agreed upon with Mr. Musk...," he wrote.
In a filing, Musk's lawyers said Twitter had failed or refused to respond to multiple requests for information on fake or spam accounts on the platform, which is fundamental to the company's business performance.
Musk also said he was walking away because Twitter fired high-ranking executives and one-third of the talent acquisition team, breaching Twitter's obligation to "preserve substantially intact the material components of its current business organization."
Musk's decision is likely to result in a protracted legal tussle between the billionaire and the 16-year-old San Francisco-based company.
Twitter, however, is hoping that court proceedings will start in a few weeks and be resolved in a few months, according to a person familiar with the matter.
Shares of Twitter were down 6% at $34.58 in extended trading. That is 36% below the $54.20 per share Musk agreed to buy Twitter for in April.
Twitter's shares surged after Musk took a stake in the company in early April, shielding it from a deep stock market sell-off that slammed other social media platforms.
But after he agreed on April 25 to buy Twitter, the stock within a matter of days began to fall as investors speculated Musk might walk away from the deal. With its tumble after the bell on Friday, Twitter was trading at its lowest since March.
The contract calls for Musk to pay Twitter a $1 billion break-up if he cannot complete the deal for reasons such as the acquisition financing falling through or regulators blocking the deal. The break-up fee would not be applicable, however, if Musk terminates the deal on his own.