Panel A of Table 6 presents descriptive statistics on these within-firm pension estimate change frequencies. From Panel A of Table 6, the typical (median) firm changes its discount rate (expected asset return) in 88.9 (33.3) percent of firm-years. Again, the evidence clearly shows that changes are more frequent for discount rates than expected asset returns. This is consistent with the different factors likely driving changes in these pension assumptions. Discount rates are influenced by macro-economic factors that change frequently (e.g., market interest rates). Expected asset returns are based primarily on the portfolio allocations of the pension assets; these asset allocations rarely change significantly from year-to-year, and further, a small change in pension asset allocation might yield no measureable change in expected asset return.