What happened at Under Armour?
The athletic wear company announced Thursday that an unauthorized party gained access to the data tied to its fitness app, MyFitnessPal. The breach, which took place late February 2018, affected approximately 150 million user accounts.
The related information that was accessed includes:
Usernames
Email addresses
Hashed passwords
The company is urging MyFitnessPal app users to update passwords immediately.
https://www.nbcnews.com/tech/security/under-armour-says-data-hacked-150m-myfitnesspal-app-accounts-n861406
tl;dr - the attackers have your personal data because another app didn't use two-factor authentication.