What was filed
Reuters and Fashion Law report a complaint filed on September 15, 2026, in the U.S. District Court for the District of Massachusetts. The case is New Balance Athletics, Inc. v. Decathlon America LLC et al., No. 1:26-cv-14235. It is a new trademark suit. Those reports do not describe a judgment.
What the complaint alleges
The complaint alleges that a KIPRUN logo is likely to be confused with New Balance's N mark, and it pleads Lanham Act claims. Reuters reports that the complaint describes a mirrored K on Kiprun running shoes as resembling that N. Fashion Law likewise reports the claims as allegations in the complaint, including trademark infringement and related theories.
Do not read any of that as a holding. The public reports describe the filing. They do not describe a court finding that Decathlon infringed.