Pension funds are facing calls to restructure their portfolios and improve oversight after suffering tens of billions of pounds in losses over the past few weeks.

The 200 largest privately-sponsored UK final salary pension schemes, which account for half of all UK pension funds, have lost £45bn since the close of August, according to data from Aon Consulting. And it is widely expected that some employers are likely to be forced to invest more in such "defined benefit" occupational schemes to restore funding levels and meet redemptions if equity markets fall further.