According to Phantom's writeup of what the description referred to as 'research,' both banks were cracked, but none of the databases or customer information were touched.
"Why? Because innocent people could get money lost if I did, so this is just [a] warning for you to withdraw your money from banks," Phantom~ wrote.
That's more in line with the fair-play principles the Occupy movement advocated and the more traditional hacker ethic of harrying the rich and powerful while ignoring or protecting the little guy.
Hacktivists aren't always so careful. The reign of annoyance Anonymous-affiliates LulzSec conducted this summer frequently hurt the little guy by exposing personally identifiable private data from the hacks of members. So did the serial hacks of various Sony networks.
The PoisAnon announcement of OpRobinHood warned that the attacks would extract money from banks using credit cards and other means, but didn't say how.
It did warn those belonging to what the Occupy movement refers to as "the 99%" of society to move their money out of large banks and into credit unions, where it would be safe from attacks by PoisonAnon or other groups.
However they accomplish extortion, fraud or extraction, PoisonAnon does not intend to damage the little guys they claim to represent.
"The only ones to be victimized in this Operation is the rich," according to tweets from OpRobinHood leader _f0rsaken. "Stop complaining & worrying 99%! Donations to Shelters start soon #OpRobinHood."
Attacks or claims to have penetrated banks in California and Long Island, however, are designed to make the point that defacing web sites, stealing passwords and camping out in public parks aren't the only ways populist hacktivist groups can cause trouble for big companies.