Investors that control more than 16 million shares are calling for JP Morgan Chase to split the chairman and chief executive posts held since 2006 by James Dimon, citing concerns over a trading fiasco that saddled the company with more than $6bn in losses.

A major public employee union, the American Federation of State, County and Municipal Employees, and pension funds in Connecticut and New York are backing the new resolution asking the largest US bank to name an independent board chair. The proposal would come up for vote at JP Morgan's annual meeting this spring.