Final salary pension plans of FTSE 100 companies reached an aggregate surplus of £15 billion at the end of 2007, according to accountancy firm Deloitte.
This shows an improvement in performance of more than £55 billion as, at the beginning of the year, there was a pension deficit of more than £40 billion.
The surplus has arisen as a result of investment returns of around 3.5 per cent over the year, higher levels of contributions from employers that have helped to improve funding levels and the price of company bonds which are used to value company pension liabilities falling, reducing the assessed value of those liabilities.
Andrew Mewis, head of Deloitte's pensions division in the Midlands, said there were a number of key developments which shaped the pensions landscape during 2007, including the important role that pension scheme trustees have continued to play in corporate transactions.
He said: "Mega-deals such as the successful acquisition of Alliance Boots and the failed takeover of J Sainsbury have shown just how significant pension schemes are when doing deals.
"The effect of new pension funding regulation introduced in 2005 has also started to impact on schemes as companies are having to meet higher funding targets than ever before.
"As a result, companies are becoming concerned about pension scheme surpluses. They need to avoid 'over funding' their pension schemes since surplus cash could become stranded."
According to Mr Mewis, new players seeking to buyout pension schemes broke new ground in 2007, with several schemes agreeing to move their assets and liabilities to these firms - including Emap, Thorn and Threshers. And he said that more buyouts can be expected if surpluses continue to increase during 2008.
"This year companies will be looking to solve their pensions problems for good. Options that include transferring pension schemes to new specialist pension buy-out companies are beginning to look viable," he said.
Deloitte predicts that the FTSE 100 surplus will have risen to £30 billion by the end of the year.