Two giant public pension funds joined forces to oppose corporate bylaw changes at the Bank of America Corp that would make Brian Moynihan both chief executive and chairman.

The California Public Employees' Retirement System and the California State Teachers' Retirement System sent a letter Monday to Jack Bovender, the lead director of the bank, saying that CEO and chair of the boards must be separate to avoid inherent conflicts. 

In the letter, Calpers and Calstrs said, "Since Mr. Moynihan's appointment as CEO in January 2010, the Company has continued to underperform, has failed important Fed stress tests, and has perpetuated a sub-par engagement with its shareholders. Given these missteps, we do not believe now is the time to reduce oversight of management by combining the roles of CEO and Chair."

A lot of investors are unhappy with the bank board members for deciding last October to change the bylaws of the bank and give the role of chairman to Mr. Moynihan, who is the current CEO since 2010. The board came to a decision to go to a transition without consulting institutional investors, who previously voted in 2009 that the position of CEO and chairman should be separate. The vote to separate the roles won during the heights of the financial crisis.

Also, according to the funds, the company didn't give any valid business rationale for deciding to combine the roles of chairman and CEO. Calstrs and Calpers owns less than 1 percent of the Bank of America's total shares outstanding.

Bank of America spokesman Lawrence Grayson said, "The board believes that having the same flexibility on board leadership that 97 percent of the S&P 500 now have, while still providing strong independent oversight, is in the best interest of stockholders."

A couple of days before the company's annual shareholder meeting in May, the bank announced that it will have a shareholder vote on the change on 2016. The vote will be on September 22's special shareholder meeting.