Jamie Dimon, chief executive officer of JPMorgan Chase & Co., during the Pennsylvania Defense and Innovation Summit in Carlisle, Pennsylvania, US, on Wednesday, July 15, 2026. JPMorgan Chief Executive Officer Jamie Dimon has warned that leverage across financial markets remained elevated, adding that investors should be mindful that hidden borrowing could amplify market disruptions. "Margin debt is the highest it has ever been," he said in an interview with CNBC's Leslie Picker. "There's a lot of margin debt you don't see because it's not called margin debt. "The market leverage is pretty high."