Elon Musk accused Twitter of being a fraudster over his $44 billion deal for the social media company, which he claimed held back necessary information and misled his team about the true size of its user base.
The counter suit by the billionaire and Tesla CEO alleges that Twitter committed fraud, breach of contract and violation of a securities law in Texas, where Musk lives.
Musk's counterclaims were filed confidentially last week and un-sealed in a filing late Thursday at the Delaware Chancery Court.
Musk offered to buy Twitter earlier this year, but he tried to back out of the deal by claiming that the platform was infested with a larger number of spam bots and fake accounts than Twitter had disclosed.
Twitter sued to force him to complete the acquisition. Musk filed a countersuit.
Musk's attorneys argue in the countersuit that Twitter misrepresented or omissions distorted the company's value and caused Musk to agree in April to buy it at an inflated price. They said Twitter has 65 million fewer daily active users, who can be shown digital ads, than the 238 million that is claimed by Twitter.
The filing said most of Twitter's ads are shown only to a sliver of the company's user base.
Musk's team accused Twitter of making too many major changes in recent months without consulting Musk, including personnel decisions and allegedly disobeying the social media restrictions imposed by the government of India, which is Twitter's third largest market. Musk had pledged to make Twitter a haven for free speech, but he also said it must comply with local laws where it operates.
In an unexpected twist, Twitter filed a response denying Musk's accusations before Musk s own counterclaims surfaced.
Twitter called Musk's reasoning a story, a story that was imagined in an attempt to escape a merger agreement that Musk no longer found attractive. The company, citing Musk's estimate of fake accounts, took issue with the fact that the analysis relied on a generic web tool that identified Musk's own Twitter account as a likely bot.
Musk is hoping that the distortion will make waves, and that is what's going to happen, according to Twitter's response.
The case is scheduled to go to trial on October 17. The Delaware court handles high-profile disputes between businesses, such as Twitter.