The FBI is investigating a hacking attack on JPMorgan Chase that caused a data breach, according to a U.S. official familiar with the probe.
A U.S. official told CNN the extent of the damage from the attack and where it came from have not yet been determined.
"Companies of our size unfortunately experience cyberattacks nearly every day. We have multiple layers of defense to counteract any threats and constantly monitor fraud levels," a JPMorgan spokesperson said.
The bank declined to comment further, but the FBI said it was working on a broad investigation into recent attacks.
"We are working with the United States Secret Service to determine the scope of recently reported cyber attacks against several American financial institutions," the agency said in a statement.
Hackers from Russia and eastern Europe are often top FBI suspects in cyberattacks. The timing has raised suspicions given the mounting tensions between Russia and the West over Ukraine and economic sanctions.