Suno, an AI music generation company, has raised a $400 million Series D round, valuing it at $5.4 billion. Despite facing copyright lawsuits from major labels like Universal Music Group (UMG) and Sony, Suno continues to thrive. The company argues its use of copyrighted material falls under fair use, but legal battles persist as the number of songs used for AI training has ballooned to over 61,000.

Despite the litigation, Suno's popularity remains high; users generate over seven million songs daily on the platform. The Series D round was led by Bond Capital, alongside existing investors Matrix, Lightspeed, and Union Square Ventures. However, the company has not named any artist endorsements, leaving some to wonder about its relationship with the music industry.

The legal troubles highlight a broader issue: as AI increasingly integrates copyrighted material, fair use doctrines may face new challenges. Suno's continued growth suggests that investors remain optimistic despite the ongoing legal battles and the increasing number of songs involved in their training process.