A typical large defined benefit pension plan may have ended February with only 60% of the assets needed to cover pension obligations.

The “funded ratio” of the benchmark plan that Towers Perrin Inc., Stamford, Conn., uses to assess the effects of moves in the investment markets has fallen to the lowest level since the firm began publishing the funded ratio data series in 1990, firm actuaries report.

The funded ratio dropped 3.9 percentage points in February, and it is down from about 90% in mid-2008, the actuaries estimate.

Towers Perrin actuaries gauge pension plan health by estimating the performance of a hypothetical benchmark pension plan that invests 60% of its holdings in stocks and 40% in bonds and other fixed-income instruments.

The benchmark portfolio would have suffered a 4.4% decline in February, Towers Perrin actuaries report.

Projected benefit obligations liability fell about 0.5% in February, Towers Perrin actuaries report.