Pension liabilities for UK private sector final salary pension schemes reached £1.2trn in August.
Figures released by the Aon200 Index show a 20% jump in liabilities in the past 12 months.
Aon analysts say the main cause of the increase is the fall in yield on government securities, which in turn has been caused by a slowing global economy.
"The value placed on pension scheme liabilities has now hit an unprecedented £1.2trn," says Marcus Hurd (pictured), head of corporate solutions at Aon Consulting.
"Traditional scheme investment strategies are struggling to keep pace in rapidly moving markets. Only a year ago we balked at the landmark £1tn figure, but the woes just continue to mount.
"Pension scheme liabilities at this level pose a significant financial risk to UK businesses at a time when there are real fears that market conditions could deteriorate further.
"Rapidly moving markets emphasise the need for adaptable investment strategies and the need to reduce risk where possible when the opportunity arises."
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