Trustees have also cooled on investments in hedge funds and exchange traded funds, according to the European Equity Strategy research.
The switch has been driven by the need to find alternatives to fixed income funds, which have provided low returns.
Various strategies, such as hedge funds and private equity have become less popular because of high fees and poor liquidity respectively.
Interest in gold has declined, despite its price soaring in September, because of the lack of income it generates, it said.
The report, produced by Karen Olney, head of thematic strategy in European equities at UBS, highlighted the collapse in real government bond yields and said the proportion of pension fund assets invested in equities has fallen from 85 per cent to around 45 per cent over the last two decades.
Some major employers have turned to more unorthodox measures in an attempt to plug pension deficits and are putting assets, rather than cash, into the schemes.
Last year drinks group Diageo agreed a plan with its pension fund to use up to 2.5m barrels of maturing Scotch whisky to help tackle its deficit.
“As the whisky matures, the plan books income. This prevents too much cash getting siphoned off into the plan,” the UBS report said.
The report was produced after a pensions event with Jeremy Dell of actuarial and business consultants Lane, Clark and Peacock.