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Here’s What You Need to Know About JPMorgan’s Data Breach

JPMorgan Chase & Co., the biggest U.S. bank, today described the size of its previously disclosed data breach, ranking it among the year’s largest-known cyber-attacks. Here’s what customers need to know:

Q. How big was the breach? A. JPMorgan estimated that data on 76 million households and 7 million small businesses were compromised, without identifying locations. For perspective, the U.S. had about 115 million households total as of 2012. The breach affected people who visited the firm’s websites, including, or used its mobile app, said a person briefed on the matter.