Under Armour is investigating claims of a data breach. Here's what customer info may have been compromised.

By Bill Peters

The incident occurred in November and swept up 72 million email addresses, according to a website that tracks data breaches

Shares of Under Armour are down almost 20% over the past year.

Under Armour Inc. is looking into a possible cyberattack that may have left millions of users vulnerable, although the company disputed claims of a massive heist of "sensitive" data, and said there was no evidence yet showing that its payment-processing or password-storage systems had been hit.

An Under Armour (UA) spokesperson, in a statement to MarketWatch late Thursday, said the athleisure-wear company was "aware of claims that an unauthorized third party obtained certain data" and that it was working with outside cybersecurity experts to learn more.

According to the website Have I Been Pwned, which tracks data breaches and users affected by them, the incident occurred in November, sweeping up 72 million email addresses. Information related to names, birthdates, gender, geographic locations and some purchase details may have also been compromised.

"In November 2025, the Everest ransomware group claimed Under Armour as a victim and attempted to extort a ransom, alleging they had obtained access to 343GB of data," the site said, adding that consumer data from the breach was published on a hacking forum this month.

The Associated Press reported on the matter earlier in the day, and cited the account from that website.

Under Armour's statement did not directly address a question about whether the site's account was accurate. But the company said that any "implication that sensitive personal information of tens of millions of customers has been compromised is unfounded."

"Importantly, at this time, we have no evidence to suggest this issue has affected UA.com or systems used to process payments or store customer passwords," the spokesperson said.

Shares were down 0.3% after hours. The investigation comes as cyberattacks grow more sophisticated, aided by artificial intelligence.

As of the close of trading on Thursday, Under Armour's stock had fallen around 19% over the past 12 months.

The company has tried to trim its merchandise selection and focus more deeply on core products in an effort to turn itself around. However, Fairfax Financial Holdings, over recent weeks, has continued to build up a large stake in the athleisure giant.

-Bill Peters

This content was created by MarketWatch, which is operated by Dow Jones & Co. MarketWatch is published independently from Dow Jones Newswires and The Wall Street Journal.

(END) Dow Jones Newswires

01-22-26 1948ET