Another Data Breach at Security Firm…ADT Loses 400 Billion in a Day

ADT Inc. (NYSE: ADT) shares fell 5.87% to $6.57 on the New York Stock Exchange on the 21st, sliding to roughly ₩9,900. The company’s market capitalization dropped to about $4.8 billion (around ₩7.2 trillion), erasing nearly $270 million (approximately ₩400 billion) in a single day.

The decline follows ADT’s acknowledgment in April that the hacking group “ShinyHunters” breached its systems and exposed the personal data of at least 5.5 million customers. The resulting trust concerns have kept the stock under sustained pressure. In March, the company approved a new $1.5 billion share repurchase authorization and issued guidance for 2026. In February, ADT acquired AI startup Origin for about $170 million (roughly ₩250 billion) to enhance the artificial intelligence capabilities of its home security products.

ADT is a 150-year-old brand and North America’s largest provider of electronic security, fire detection, and alarm monitoring services for residential and small-business customers. In 2020, Google invested approximately $450 million (around ₩700 billion) to become a strategic partner. Then, in 2023, ADT sold its commercial security division for $1.6 billion (about ₩2.4 trillion) to refocus on the home security market.