Citibank customers will be given Visa's version of a stored-value card - called Visa Cash - which was tested at the Atlanta Olympics in 1996.

The Citibank customer said he was looking at mutual funds and getting out of C.D.'s.

She said that based on the numbers of transactions the company has blocked already, the issue appeared to affect a "small fraction" of Citibank customers.

In the group's June report, the most recent available, it said it had seen 492 different mass-mailings intended to fool Citibank customers.

"Ultimately we want a seamless and uniform service for Citibank customers around the world, which would include access to a single network."

The average Citibank customer has close to four different links to the bank, Ms. Markus said.

In some places, Citibank customers crisscrossed the city on futile scavenger hunts for an operating cash machine.

Citifinancial's borrowers default at a higher rate than do typical Citibank customers, but at a lower rate than holders of the bank's credit cards.

All the moves will affect only Citibank customers in New York, not in other states.

When a Chase employee asked where he currently did business, he said he was a Citibank customer.