The business newspaper's sources, who it described as familiar with the investigation, said the Justice Department decided to look into the bank's dealings after the company agreed to pay $410 million to settle allegations raised by the Federal Energy Regulatory Commission that it manipulated markets in California and the Midwest. JPMorgan admitted no wrongdoing in the FERC case.
The Journal's sources said the probe is in its early stages with no telling how it would turn out.
"As we've said previously, we're working hard to remediate controls issues, strengthen business practices and address regulatory concerns," a JPMorgan spokesman told the Journal without discussing details of the investigation.
The latest investigation is just one of at least seven targeting JPMorgan, the newspaper said.