After a devastating advertiser exodus last week involving some of the world’s largest media companies, X owner Elon Musk is suing the progressive watchdog group Media Matters over its analysis highlighting antisemitic and pro-Nazi content on X — a report that appeared to play a significant role in the massive and highly damaging brand revolt.

The lawsuit filed Monday accuses Media Matters of distorting how likely it is for ads to appear beside extremist content on X, alleging that the group’s testing methodology was not representative of how real users experience the site.

“Media Matters knowingly and maliciously manufactured side-by-side images depicting advertisers’ posts on X Corp.’s social media platform beside Neo-Nazi and white-nationalist fringe content and then portrayed these manufactured images as if they were what typical X users experience on the platform,” the complaint filed in the US District Court for the Northern District of Texas said. “Media Matters designed both these images and its resulting media strategy to drive advertisers from the platform and destroy X Corp.”