US companies will need to inject more than $100bn into their pension funds to cover market losses.

The 700 largest corporate plans were more than 100 per cent funded at the end of last year, but as of last week that had fallen to about 83 per cent, according to estimates.

Companiesâ?? pension fund losses also are expected to alter earnings this year, partly because of the introduction of the Pension Protection Act this year.

The American Benefits Council, which represents corporate pension plans, is lobbying for the federal government to suspend some of the PPA rules, which require mandatory contributions if funds fall below a certain level. The gap in pension funds is putting many companies in a cash squeeze at a time when it is difficult to raise money.