"CalPERS believes if the chairman was independent the board may be able to exercise stronger oversight of management," the organization said in a note setting out its voting intentions ahead of the meeting.
The group, which owns around $565 million of JPMorgan stock, said it would support executive compensation proposals, but warned it would "closely review" the effects of the trading losses when analyzing the 2013 say-on-pay vote.
The two leading proxy advisory firms -- ISS and Glass, Lewis -- are already backing the nonbinding proposal calling for a split of the jobs of chairman and CEO.
The California State Teachers Retirement System, the Florida State Board of Administration and the New York State Comptroller's office, which each oversee about $150 billion in assets, have said they will also vote for the split.
"Generally we support these kinds of proposals," said Ricardo Duran, information officer for CalSTRS. "We always look kindly on the separation of those two positions."
JPMorgan is likely to face a barrage of questions about what Dimon knew, when he knew it and how a bank that has boasted of its "fortress" balance sheet could make such a major mistake.
The shakeup from those trades started Monday, as the company's chief investment officer retired.