Dive Brief:

• A security hack at the largest bank in the United States, JPMorgan Chase, hit some 76 million household accounts and seven million small business accounts, including retailers.

• The breach is far larger than one million accounts affected that was estimated earlier.

• The attack occurred this past June and was discovered in July, but further details were revealed in a securities filing Thursday.

Dive Insight:

This massive breach at the nation’s largest bank is especially unsettling. For one thing, household and business accounts include potentially far more sensitive information than what is compromised at retail breaches. And JPMorgan Chase seems to have done everything right, having made significant investments in cybersecurity systems and personnel.

It’s not clear how the bank or its customers will ultimately be affected, but the bank and law enforcement are still reportedly figuring out how it occurred and what the hackers will do with any information they did accrue. This is the latest nightmare for consumers and for retailers, who are increasingly wondering how to keep their data safe.