Citigroup says United Parcel Service has lost computer tapes containing personal information on about 3.9 million Citigroup customers. The tapes were being transported to a credit-reporting bureau when Big Brown lost track of them.

A UPS spokesman said the company has conducted an "exhautive search" and, although it hasn't found the missing package, claims there is "no indication that it was stolen."

In a statement, Citigroup said the tapes contained names, Social Security numbers, account numbers and other personal information of CitiFinancial customers in the U.S., as well as clients with closed accounts from its CitiFinancial retail services unit.

It said the tapes did not contain any information from its auto, mortgage or other business units and did not contain information on CitiFinancial customers in Canada or Puerto Rico.

"We deeply regret this incident, which occurred in spite of the enhanced security procedures we require of our couriers," said Kevin Kessinger, Executive Vice President of Citigroup's Global Consumer Group and President of Consumer Finance North America.

Kessinger said there is little risk to customers because the customers whose data is on the tapes have already received their loans from CitiGroup. He said that beginning next month, such data will be sent electronically in encrypted form.

Citigroup is far from the only organization so afflicted. In recent months, MCI, Bank of America, Wells Fargo, ChoicePoint, Polo Ralph Lauren Corp., the University of California and many other smaller companies and institutions have disclosed that customer data was lost, misplaced, stolen or sold to thieves.

Most of those bungling the data their customers entrusted to them have encouraged consumers to check their credit reports and ut fraud alerts on their files. Citigroup is offering its affected customers free credit monitoring for 90 days.