A new report calls the independent Massachusetts Bay Transportation Authority retirement fund an "expensive luxury" for the T, its workers and Massachusetts taxpayers.
The Pioneer Institute, a conservative-leaning think tank, estimated Thursday that the fund's value would have been about $900 million higher at the end of 2014 had it been managed by the state employee pension fund.
The report says the added pension costs are being borne by the financially-strapped MBTA, which is subsidized by the state.
The institute is urging lawmakers to do away with the independent fund and place its assets under the management of the state fund.
MBTA Retirement Fund executive director Michael Mulhern announced earlier this week he was stepping down after 10 years in the post, but defended the financial performance of the fund.