At least three other pieces of personal information are needed for Ameriprise customers to gain access to their accounts, he said.

Brian Heath, president of the U.S. Advisor Group for Ameriprise Financial Services, Inc., apologized for the incident in a statement.

'We take our responsibility to safeguard personal information very seriously,' he said. 'Although the risk of misuse of the data contained in these files is very low, we apologize for any inconvenience or concern this situation may cause. We have made every effort to notify affected individuals and to make them aware of the situation and the steps we are taking.'