The tech behemoth, formerly known as Twitter, claims the companies illegally plotted to boycott the site, causing it to lose “billions of dollars” in revenue.
The complaint was launched in Texas against the World Federation of Advertisers and its members, which include British multinational Unilever, food behemoth Mars, CVS Health, and Danish renewable energy corporation Orsted.
Musk commented on X, “We tried peace for two years, and now it is war.”
It comes after advertising revenue at X plummeted after Musk purchased and relaunched the social network for $44 billion (£35 billion) in 2022.
Within days of taking over, Musk dismissed thousands of employees, including numerous moderation personnel.
Companies also stopped advertising on the site in November 2023 due to worries that their content was appearing alongside pro-Nazi messages, with X’s owner also accused of fostering hate speech.
Musk later apologized for embracing an antisemitic conspiracy theory, but also advised advertisers to “go f*** yourself”.
The software billionaire has faced increased criticism for controlling the site, which was recently condemned for failing to combat disinformation propagated during the English riots.
