Shareholder support for executive pay plans may be weakening, but do shareholder votes really matter in the final determination of executive pay? More than 40 percent of institutional investors don't believe so.

According to a new study from the Stanford Graduate School of Business, more than four in 10 institutional investors believe that their say-on-pay vote ultimately has no influence on what executives are paid. Furthermore, only 38 percent of the 64 surveyed asset managers believe that corporate disclosure about executive compensation is clear and easy to understand.

"Shareholders want to know that the size, structure, and performance targets used in executive compensation contracts are appropriate," says Stanford professor David F. Larcker. "Our research shows that, across the board, they are dissatisfied with the quality and clarity of the information they receive about compensation in the corporate proxy. Even the largest, most sophisticated investors are unhappy."