Hackers Probing the Financial System Show Reason to Worry

Hackers are testing the financial system’s cyber defenses, and they can boast of some alarming success.

Let’s start with what we know. JPMorgan Chase & Co. says a breach of its computer systems exposed the personal information of 76 million households and 7 million small businesses. The intrusion lasted from June until sometime in August, so hackers had more than a month to nose around. They accessed names, addresses, phone numbers and e-mail addresses, although the bank says there’s no evidence they compromised account information, passwords or Social Security numbers, Bloomberg Markets magazine will report in its December issue.