X Corp., the former Twitter Inc., was sued for infringing the “X” trademark in Florida federal court on Monday by X Social Media LLC, a company that helps connect law firms and clients through social media.

The Elon Musk-owned Twitter knew of X Social Media’s pre-existing rights to the trademark before launching an abrupt rebranding campaign in July, according to the complaint filed in the US District Court for the Middle District of Florida.

Twitter’s name change—driven by Musk’s push to create an “everything” app—is just the latest rebranding in the tech world to spawn a trademark lawsuit. In this case, Twitter’s shift to X has led consumers to incorrectly believe that X Social Media is associated with X Corp., the company’s filing said.

The complaint said the name change will be “financially and strategically harmful” to X Social Media, adding that the company has already lost revenue as a result.

X Corp. didn’t return a request for comment.

X Social Media, founded in 2015, credits itself in the complaint with being among the first companies to channel the power of social media platforms and advertising in its mission to “educate consumers about dangerous goods and services and to provide consumers with access to legal advocates who could give victims a voice.” It said the letter “X” signifies the “beginning of a life-changing journey towards justice.”

The company has invested over $2 million in building brand awareness and owns the website xsocialmedia.com, the complaint said. It obtained a federal trademark registration for “X SocialMedia” that it has used continuously for five years, according to the filing.

X Social Media sent X Corp. a cease-and-desist letter in August, according to the complaint, but Musk’s company refused. X Corp. has applied for seven trademark registrations with the US Patent and Trademark Office, the complaint said.

Other recent rebrands in the tech industry have triggered trademark lawsuits as well. Meta Platforms Inc.’s 2021 name change from Facebook to focus on metaverse products has spurred legal action from a VR company, an investment firm, a blockchain group, and another software service.

The financial technology company Block Inc., which rebranded from Square in 2021, faced a trademark battle with the tax preparation service H&R Block Inc., resulting in a settlement earlier this year.

Gerben Perrott PLLC represents X Social Media.

The case is X Social Media LLC v. X Corp., M.D. Fla., No. 6:23-cv-01903, complaint filed 10/2/23.