Table 5 summarizes the distribution of actual changes in discount rates and expected asset returns reported in the Compustat database for our sample firms over the period 2000-2009. Panel A of Table 5 includes descriptive statistics for all sample firm-year observations with data, including years in which the pension estimate did not change. Pension discount rates generally decreased over 2000-2009, with a mean (median) annual change of —14.7 (—25.0) basis points. Only 11.5 percent of sample firm-year observations involved no change in the discount rate estimate. Thus, over 2000-2009 sample firms changed their discount rates frequently and generally in a downward direction.
The distribution of expected asset return assumption changes over 2000-2009 is quite different. While the mean annual change was —11.1 basis points, both the median and 75th percentile change were zero. In fact, 64 percent of all sample firm-year observations with necessary data involved no change in expected pension asset return assumption over 2000-2009. Thus, relative to pension discount rate estimates, expected asset return assumptions are more sticky.