JPMorgan Chase & Co. on Tuesday named Jennifer Piepszak its new chief operating officer, but the company’s four major department heads remain more likely successors to Chief Executive Jamie Dimon to head up the largest U.

Doug Petno, JPMorgan’s co-head of global banking, will succeed Piepszak as co-CEO of JPMorgan’s commercial and investment bank, alongside Troy Rohrbaugh. The move appears to make Piepszak the front-runner to succeed Jamie Dimon as CEO and potentially become the first woman to lead the nation’s largest bank.

The executive shuffle is the latest twist in the long-running question of who will succeed Jamie Dimon, the longest-serving major US bank CEO.