Defined benefit pension plans at 500 large, publicly traded U.S. companies ended 2007 with a median funded status of 94%, up from 89% a year earlier.

Mercer, an arm of Marsh and McLennan Companies Inc., New York, has published those figures in an analysis of the 377 S&P 500 companies that publish information about defined benefit pension plan liabilities in the Form 10-K annual reports.

The plans reported having $1.56 trillion in assets and $1.5 trillion in pension liabilities at the end of 2007.

Sponsors invested about 60% of the plan assets in stocks, Mercer reports.

The average asset return was 9.6%, down from 13% in 2006.