The City of London is too secretive about pensions investment and the government needs to act to make it open up, the Trades Union Congress (TUC) has claimed.
In its voluntary survey of how organisations voted in key annual general meetings (AGMs), only 26 gave information to the union, something the TUC claims is damaging trust in the pensions industry.
Brendan Barber, general secretary of the TUC, said he had always been sceptical about how forthcoming fund managers would be.
"The voluntary approach has reached its limit. The TUC urges ministers to listen to those who want to rebuild public trust in pensions and in corporate Britain, and give themselves the power to require investors to disclose voting records."
His comments come as the company law reform bill prepares to have its second reading in parliament after opposition parties managed to remove a "transparency clause" relating to fund management.
Mr Barber urged the government to reinsert this clause to ensure that investors will publish voting records.
Although companies supplying the TUC with voting information have generally risen since the union started collecting the data three years ago, it has fallen from the high of 28 companies in 2005.
As these companies deal with the pensions "of millions of working people", Mr Barber wants action now so that these same people know where their money is being invested.