Twitter and Elon Musk may have gotten more than they gambled for with the company’s rebrand, with Microsoft owning the “X” trademark.

Twitter began the process of rebranding to X Sunday, with the rebrand well underway on Monday. In addition to all the other challenges that come with a major rebrand, there may be a trademark issue.

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According to the US Patent and Trademark Office, Microsoft filed for a trademark for “X” on May 3, 2000, and was granted the trademark on March 4, 2003. The trademark has the following description:

Providing on-line chat rooms for transmission of messages among computer users concerning video and computer games; providing on-line electronic bulletin boards for transmission of messages among computer users concerning video and computer games

Entertainment services, namely, providing interactive multiplayer game services for games played over computer networks and global communications networks; providing computer games and video games downloadable over computer global communications networks; providing information on the video game and computer game industries via the Internet; and providing information on computer games, video games, video game consoles and accessories therefor via the Internet

While Microsoft’s trademark is clearly in the context of its Xbox gaming console and service, the reference to “on-line electronic bulletin boards for transmission of messages among computer users” certainly could be stretched to apply to Twitter, especially since Twitter is a popular place for gamers to post videos and discuss their favorite games.

Microsoft is likely considering its legal options, and we will continue to monitor and report on any developments.