Mutual funds have contributed to corporate America's excessive pay by voting in favour of companies' compensation plans, research by corporate governance experts will reveal today.

AllianceBernstein, Barclays Global Investors, Ameriprise and Bank of America's Columbia Management were the most consistent backers of management proposals to increase executive pay, according to the study. The Corporate Library and the American Federation of State, County and Municipal Employees, one of the largest trade unions in the US, analysed mutual funds' votes in 2008 annual shareholder proposals.