(Bloomberg) -- Allstate Corp., the largest publicly traded U.S. auto insurer, said pension obligations will reduce fourth-quarter earnings by $100 million to $125 million on costs tied to lump-sum payments for retiring staff.

“The value of lump sums paid to employees electing retirement in 2013 is elevated due to historically low interest rates,” the Northbrook, Illinois-based insurer said today in a statement distributed by PR Newswire. “Voluntary retirement activity during the fourth quarter was almost five times the typical level.”