The Jamie Dimon Effect: Firms Veto Joint CEO-Chair Role

Jamie Dimon
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Jamie Dimon

Shareholders and boards are no longer happy for CEOs to also hold the position of chairman, according to research published ahead of the JPMorgan Chase investor vote on whether to split Jamie Dimon's roles.

(Read More: JPMorgan Chief's Fate Comes Down to Close Vote)

In its chief executive study, consulting firm Booz & Company found that only 12 percent of incoming CEOs were also appointed chairman of the board in 2012, a minimum seen only once before, in 2009.

(Read More: JPMorgan Chief's Fate Comes Down to Close Vote)

"This convergence on a low level of joint appointments is likely happening because more and more companies consider these appointments poor corporate governance. In some industries, notably financial services in recent years, regulators have also discouraged the practice," said Booz & Company's Ken Favaro, in the report, which he co-authored.

The report comes ahead of JPMorgan's annual general meeting in Florida, at which the results of the vote on Jamie Dimon's roles will be announced. Dimon has threatened to quit if his duties are divided, although a majority vote in favor of stripping him of the chairman's job would not be strictly binding.

(Read More: JPMorgan Shareholders Denied Access to Results)

Schroders fund manager Andy Brough noted that the CEO-chairman dual role is particularly problematic in the financial services sector.

"The complexity of the financial transactions, mean surely no one person can do CEO and chairman," Brough told CNBC. "Unless Jamie Dimon has got two or three brains, compared to the one most of us have got, with the complexity of the financial world, how on earth can you control the firm as CEO, and then offer direction?"

However, Brian Sullivan, CEO of executive search firm CTPartners, said that in the case of JPMorgan, Dimon was the best qualified person for both roles.

(Read More: Trading Jamie Dimon's Possible JPM Exit)

"Can one person run a bank the size of JPMorgan? If there is one person to do it, it is Jamie Dimon without question," Sullivan told CNBC. "The chairmanship takes up significantly less of his time. He is pretty much doing the chairmanship as he is doing the CEO, and enlightening his board as to directions they want to take."

By CNBC's Jenny Cosgrave;.Follow her on Twitter @jenny_cosgrave.