JPMorgan Chase & Co. Chairman Jamie Dimon

JPMorgan Chase & Co. Chairman Jamie Dimon

Chris Ratcliffe/Bloomberg

Calls for JPMorgan Chase & Co. Chairman Jamie Dimon to relinquish the chairmanship have mounted since last May, when New York-based JPMorgan disclosed risk-control lapses in its chief investment office on credit-derivative bets that fueled a $6.2 billion trading loss and sparked regulatory probes.