"TD Ameritrade Holding Corp. said Friday one of its databases was hacked and contact information for more than 6.3 million customers was stolen.
A spokeswoman for the Omaha-based brokerage firm said more sensitive information in the same database, including Social Security numbers and account data, does not appear to have been taken.
The company would not share many details of its investigation, including when the hack took place, because it is still looking into the theft and is cooperating with investigators from the FBI.
Ameritrade's customers have received unwanted e-mail ads because of the data theft. Spokeswoman Katrina Becker said there is no evidence that any customer suffered financial losses or was a victim of identity theft."