"The funded status of the 100 largest corporate defined benefit pension plans dropped by $90 billion during January ... the eighth largest monthly drop in the 15-year history of the Milliman 100 PFI. The funded status deficit ballooned to $382 billion from $292 billion at the end of December 2014 due to the 42 basis point decline in the benchmark corporate bond interest rates used to value pension liabilities. Pension assets had a monthly above-expected return due to strong fixed income asset return and this helped to counter liability losses. As of January 31, the funded ratio decreased to 79.6%, down from 83.5% at the end of December 2014. The previous sub-80% PFI funded ratio was in December 2012."